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Products => Test Equipment => Topic started by: BravoV on November 01, 2011, 06:57:59 am

Title: Tektronix 2465B oscilloscope teardown
Post by: BravoV on November 01, 2011, 06:57:59 am
(https://www.eevblog.com/forum/index.php?action=dlattach;topic=5397.0;attach=16685;image)


Acquired recently this scope at local tech surplus store,  and even its quite old now, still, it should be pretty good piece of equipment. Among peers & friends here, we called this Jim's scope cause Jim Williams (in memoriam) used it too at his personal bench table.

I have another similar thread, but its for asking some details -> https://www.eevblog.com/forum/index.php?topic=5258.0 (https://www.eevblog.com/forum/index.php?topic=5258.0) , and decided to post the teardown photos in this new thread instead of there.

Here we go, teardown and preliminary inspection, since I'm going to recap the whole scope and took shots for documentation and component inventory purposes.


The whole bundle, with the top pouch, front cover and a single Tektronix P6136 350Mhz probe. Every thing is nicely preserved by previous owner, I was told it was previously used in clean r&d lab at a big consumer electronic factory.


Click to enlarge the pictures.
(https://www.eevblog.com/forum/index.php?action=dlattach;topic=5397.0;attach=16687;image)


With front panel facing down, and main cover detached, the rear, top and left sides view. Top and left are covered by aluminium plates, these are HV and power sections.
(https://www.eevblog.com/forum/index.php?action=dlattach;topic=5397.0;attach=16689;image)


With top cover opened. Wait !! It looks so empty and spacious ? Is that it ? No folks, these are just the crt tube and the main power supply only. The middle module has two separate pcbs, which are linear and switching part placed side by side isolated by a thick metal plate. Both supply the power for the whole scope. I guess they opted to place these noisy parts crt & psu in the middle isolated room to reduce hf noise.
(https://www.eevblog.com/forum/index.php?action=dlattach;topic=5397.0;attach=16691;image)


The bottom and the right sides view, still standing vertically at it's face, look at the view, now we're talking.  :)
Bottom part is the main board for all analog stuffs there, while the left board is for the logic, cpu and control. What interesting about this view is, the big main board is using through hole components, while at the control board is using smd. Probably this was designed and made during the transitional period from through hole component to smd style.
(https://www.eevblog.com/forum/index.php?action=dlattach;topic=5397.0;attach=16693;image)


The main A1 board, handles all analog stuffs here. The middle black zigzag stick is connected from the main power switch at the rear to the front panel power button. All components are using through hole style.
(https://www.eevblog.com/forum/index.php?action=dlattach;topic=5397.0;attach=16695;image)


The A5 logic & control board, made it portrait view for better detail, almost all are using SMD components.
(https://www.eevblog.com/forum/index.php?action=dlattach;topic=5397.0;attach=16697;image)


The left side view without the metal cover, high voltage crt power supply and the horizontal & vertical control board at the middle.
(https://www.eevblog.com/forum/index.php?action=dlattach;topic=5397.0;attach=16699;image)


The power supply linear part and the main rectifier at the left side, while with switching part at the other side encased inside aluminium box. Few classic and popular to-220 linear regulator ICs are bolted at the bottom with thermal pad like LM 317, 7805.
(https://www.eevblog.com/forum/index.php?action=dlattach;topic=5397.0;attach=16701;image)


The rear cooling fan without it's holding metal bracket, very noisy and it will be replaced with new & better fan. Also it's cables termination will be replaced with small 2 pins ordinary fan connectors for easy detaching it for cleaning and maintenance in the future, instead of permanently soldering them directly at the terminal (see inset).
Another interesting finding is the fan's date code 9605, it has the latest date compared to other components throughout the scope, looks like its 1996 or later made. Anyone know what year Tektronix stopped releasing the 24xx model ?
(https://www.eevblog.com/forum/index.php?action=dlattach;topic=5397.0;attach=16703;image)


Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on November 01, 2011, 07:02:52 am
The Tek hybrid U800 IC part no 155-0241-02, that is really hard to find for the replacement but easily gets killed caused by overheating. This poor little ic is handling the whole horizontal part of the scope, and when powered on, it is very-very hot that almost burned my finger when touching the ic black body. The cooling path for heat dissipation is only through that metal tab at the IC, and goes through that tiny front bolt and rings as it's main heatsink, while the other bolt at the back is doing nothing for cooling, it just for holding this ic.  >:( 
Also its working at +87 volt and currently I'm still thinking on how to cool this IC better, maybe by attaching a small heatsink directly at that metal tab instead using heatsink at it's black body, but its not easy task because that bolt and the ic metal tab are not ground, they're -5 volt instead, damn !  :-\

(https://www.eevblog.com/forum/index.php?action=dlattach;topic=5397.0;attach=16705;image)


Another corner, rusty nut, guess its time to replace it before it starting to eat through the bolt.  :-[ Also the bnc connection for the 4th channel and the 3rd at the background.

(https://www.eevblog.com/forum/index.php?action=dlattach;topic=5397.0;attach=16707;image)


Same here, worry once the nut disintegrated by the rust, it will be become loosed by the heatsink tension, and finally cracked and burst or spread into small metal pieces across the board. Bad, really bad news if this happened.  >:(

(https://www.eevblog.com/forum/index.php?action=dlattach;topic=5397.0;attach=16709;image)


Interesting spot, looks like that tiny inductor coil is hand made.  ;D  Definitely HF area, just too scared and afraid to touch or bump anything around here.  :o

(https://www.eevblog.com/forum/index.php?action=dlattach;topic=5397.0;attach=16711;image)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: EEVblog on November 01, 2011, 08:52:44 am
Awesome teardown, thanks for sharing!

Dave.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on November 02, 2011, 02:34:14 am
My pleasure Dave, glad you like it.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Wartex on November 03, 2011, 03:33:49 am
Buy RAM chip heatsinks on eBay and use thermal epoxy to glue them right to the IC
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on November 04, 2011, 04:32:39 am
Buy RAM chip heatsinks on eBay and use thermal epoxy to glue them right to the IC

Thanks, yes, I have few of them made from pure copper, its just I'm not quite happy since they're too small and also by cooling that U800 ic's substrate black body is not very effective compared to putting the heatsink directly at the metal tab.

Pics of the ram chip sinks on the ic, they're not permanently applied yet.
(https://www.eevblog.com/forum/index.php?action=dlattach;topic=5397.0;attach=16757;image)


Other angle, as you can see, the front bolt and nut are useless, they're not touching any of the ic's body for cooling purpose, and whats the point of holding the IC when its already soldered at the pcb. I suspect originally these two bolts were designed to hold a custom shape heatsink for this scorching hot ic, looks like they never made it.   :-\
(https://www.eevblog.com/forum/index.php?action=dlattach;topic=5397.0;attach=16759;image)


The vent holes at the bottom of the scope, these are for air intake, and the U800 is positioned at the upper left rectangular shaped vent holes.
(https://www.eevblog.com/forum/index.php?action=dlattach;topic=5397.0;attach=16761;image)


Close up, the U800 is located right below here. From this vent holes position, its obvious that they're aware this location needs cooling, and should U800 have a proper heatsink, this is the right place for it.
(https://www.eevblog.com/forum/index.php?action=dlattach;topic=5397.0;attach=16763;image)


I've been thinking to make two pieces of heatsinks, illustrated by two rectangles, the blue one is for the body, will be secured by the left nut and a steel wire (yellow marking) across both nuts, no problem with the height clearance for the upper MC3346P ic since U800 is higher by about few milimeters, this blue heatsink should not have any problem here. While the other heatsink (red rectangle) will be applied directly at the ic's metal tab  and secured by the right nut, this one is definitely better in dissipating the heat than the blue one. Clearance is pretty tight here, and must be precisely made, may be its time to visit local cnc shop, two options, either make it shorter or with the fat "L" shaped to avoid the bottom left vertically positioned ic.  Those few resistors and diodes in front of the metal tab are about 2 millimeters lower than the metal tab, so the blue heatsink base won't touch them at all if its fastened properly at the right nut.
(https://www.eevblog.com/forum/index.php?action=dlattach;topic=5397.0;attach=16765;image)


Stay tune, I will be constantly update the progress here.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: rf-loop on November 04, 2011, 12:19:17 pm
Maybe you think that Tektronix EE's who design it are stupid?
They are not.

It works just perfect and thermal design is ok. There is NO any problem. Exept if someone take case off and use it without case. Also if FAN go bad it can go to thermal owerload.

I have study and inspect these oscilloscopes years (also I have no 3 pcs of these units in my lab for service and calibrate.

You can read Tektronix original full service and repair manual before you open oscilloscope if you design also power up it without case. It need use service enough airflow fan if need more time keep it running without case!

In the world you can find hundreds of defected Tektronix oscilloscopes just as burned hybrids and IC:s just becouse user do not care or "self learned service man" do not know how to handle these as professionals do who are specialised to make repair work with these nice scopes.

Before years they use different very expensive FAN in this scope but this version seems to be with this new fan what are in later manufactured units.

Before models have brushless hall controlled pulse driven motor what also have speed control as temperature change inside.

This airflow is calculated so that it is enough for cooling these circuits in full specified enviroment temperature range.
But it works only if scope have not much of dust inside and that air holes are open without dust.

U800 is very strong for high temperatures. It is also assembled to board just ok. Tektronix have long experience about use this circuit and if there is any big problem they have changed design after years of experience. This model is not one year design . 2465 models have been long time in production before your version and they have made many changes but U800 did not need make any changes for design. Not for circuit, not for mechanical and thermal design.
60 celsius is NOT hot. 90 celsius is not hot. 100 celsius is not hot. Also if uou know semi free air cooled chip. Thermal resistance between silicon and case is so that in free or small pressure air flow case temperature and silicon temperature have not big difference.

When case is closed and airflow work normally it keep it fully inside accepted temperature area.

If not believe you can put thermal sensor over chip and close case. Temp is more low than in free air temp.
same for these some maybe more sensitive hybrids.

Always if do example calibration  do it with service fan! Or do first adjustments what need open case and use service fan on the table. Then close case and let it warm half - one hour. Then continue these semiautomatic calibration steps.
Never touch any adjustments if have not needes test equipments. (and do not adjust these factory adjusted hand made looking coils without equipments and knowledge how to do.

In these units there are one problem Thiis NVRAM. They start be end of life.
Older version with separate soldered big lithium battery was more easy to handle.
If you loose this NVRAM data you loose all cal data and special data if scope have some options. (seems that you have not any options becous upside scope is nearly empty)

If you want change fan, kep special care its pressure/airflow data is perfect match. (it need know fan curve, noyt only free air volume. Best is change just same model. (littlebit can reduce noise if do floating assembly with thin and soft silicone isolating.
(this old model fan was more silent becouse there was no bearings noise connected directly to aluminium case.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: slburris on November 06, 2011, 03:33:51 am
I'd be less concerned about the U800 chip and more concerned about the 4 tantalum
surface mount capacitors on the A5 board.  They are known to leak with corrosive electrolyte
over time and can absolutely destroy the A5 board.

There's another thread on the forum about the A5 board, or you can look at this repair
guide someone put together:

http://www.condoraudio.com/wp-content/uploads/Projects/Tektronix-2465B-Oscilloscope-Restoration-Repair.pdf (http://www.condoraudio.com/wp-content/uploads/Projects/Tektronix-2465B-Oscilloscope-Restoration-Repair.pdf)

Scott
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: rf-loop on November 06, 2011, 01:27:46 pm
I'd be less concerned about the U800 chip and more concerned about the 4 tantalum
surface mount capacitors on the A5 board.
  They are known to leak with corrosive electrolyte
over time and can absolutely destroy the A5 board.


Also this issue is (maybe) related to manufacturing version (and  also where it have made).
If any suspect about possible leakage or fail. They need immediately take away, clean board and change new components.

And inside power unit are some famous weak electrolytics.

And also concern about this (mostly DALLAS) NVRAM. (this is designed lifetime!) Before they use EEROM and also RAM+Separate extremely good Lithium battery. (but reducing lifetime and costs...it is...what it is.)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: wkb on November 18, 2011, 06:26:46 pm
This week I had the case off my 2465CTS.  In some aspects it is quite similar to the B version in this thread, but for example the digital controller PCB (wow... an 68B08, nice, I grew up with 6800 and 6809 ;-) is through-hole and not SMD.

It was suffering from a rattling fan, which had an interesting cause: it had been stored (at work) on its side on some shelf.  And apparantly some fat-fisted colleague of mine had dumped it on its side hard enough to push the handle lever into the case.  This caused to whole case to dent and slightly deform. >:( The aluminium of the case is really quite soft.  End result was that the fan (mine has a "rodent wheel" style fan) just touched the plastic back of the scope. Which rattled.  Sigh..

Interesting (...) side effect was that the outer shell would not slide off the frame.  I had to "crowbar" the  side of the case somewhat to get it off.  Once it was off, I could hammer (yes.. I had to use a hammer to fix a scope..) the dent out, which made the case slide back easily onto the frame.
 
Oh.. And I had to fit a new 10Mc Xtal on the digital controller PCB.  That got stuck behind the dented case and broke off.  ::)

Ah well, it is back to its glorious self again.  I got it years ago (for free, can't complain there!)

Wilko
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: larry42 on November 19, 2011, 10:18:27 pm
Maybe you think that Tektronix EE's who design it are stupid?
They are not.

It works just perfect and thermal design is ok. There is NO any problem. Exept if someone take case off and use it without case. Also if FAN go bad it can go to thermal owerload.

Well I've seen quite a few Service Notes for HP equipment, with small upgrades and improvements. Perhaps all the perfect engineers worked at Tek  ;)

And yes MTTF goes down with temperature, so if the chip is seriously hot, I would *consider* adding a heatsink, or a small extra fan, though with the caveat of thinking how the whole airflow though the system is arranged.

Good points on the fan replacement though.


Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on November 20, 2011, 09:09:17 am
Maybe you think that Tektronix EE's who design it are stupid?
They are not.

It works just perfect and thermal design is ok. There is NO any problem. Exept if someone take case off and use it without case. Also if FAN go bad it can go to thermal owerload.

Who is calling those Tek EEs stupid ? Suggesting you to read again since I believe English isn't your native by looking at your respond here, and I guess you're somehow a tek fanatic aren't you ? :D

I was just questioning why those bolts are there at the 1st place ? They're not even grounded to aid the thermal dissipation, and also why mechanically secure the ic which already soldered at the board ? If you have better explanation, I will glad to hear that.


I have study and inspect these oscilloscopes years (also I have no 3 pcs of these units in my lab for service and calibrate.

You can read Tektronix original full service and repair manual before you open oscilloscope if you design also power up it without case. It need use service enough airflow fan if need more time keep it running without case!

In the world you can find hundreds of defected Tektronix oscilloscopes just as burned hybrids and IC:s just becouse user do not care or "self learned service man" do not know how to handle these as professionals do who are specialised to make repair work with these nice scopes.

I had the user and tech manual both printed in A3 paper "BEFORE" I got this scope, was that your personal experience back there in the past ? ;)


60 celsius is NOT hot. 90 celsius is not hot. 100 celsius is not hot.

Don't know how to comment on this one, just recommend you to read many more semiconductor's datasheet on their max temp junction, and the effect of silicon's life when exposed at high temp like close to 100C, definitely is not good for their life.


When case is closed and airflow work normally it keep it fully inside accepted temperature area.

No argument here, the cooling effect will be only effective if with closed case, thats why those air vents are made for.


If not believe you can put thermal sensor over chip and close case. Temp is more low than in free air temp.
same for these some maybe more sensitive hybrids.

Surface temp will never be lower than ambient temp if using air cooling at "a non evaporating surface", its the basic law of thermodynamic, not sure where did you learn yours.


And also concern about this (mostly DALLAS) NVRAM. (this is designed lifetime!) Before they use EEROM and also RAM+Separate extremely good Lithium battery. (but reducing lifetime and costs...it is...what it is.)

This nvram is already in the work list, it will be desoldered and I will put a socket there to aid future replacement.

Oh yeah, don't worry, once pulled, the calibration data will be backed up 1st. ;)


I'd be less concerned about the U800 chip and more concerned about the 4 tantalum
surface mount capacitors on the A5 board.  They are known to leak with corrosive electrolyte
over time and can absolutely destroy the A5 board.

There's another thread on the forum about the A5 board, or you can look at this repair
guide someone put together:

http://www.condoraudio.com/wp-content/uploads/Projects/Tektronix-2465B-Oscilloscope-Restoration-Repair.pdf (http://www.condoraudio.com/wp-content/uploads/Projects/Tektronix-2465B-Oscilloscope-Restoration-Repair.pdf)

Scott

Thanks Scott, yeah, already have that excellent document since the 1st day I got this scope. ;)

About this particular A5 model, its an early smd version which isn't plaque by the leaking caps like other late version, already got the confirmation at the TekScope yahoo group, but those caps will be checked too.


This week I had the case off my 2465CTS.  In some aspects it is quite similar to the B version in this thread, but for example the digital controller PCB (wow... an 68B08, nice, I grew up with 6800 and 6809 ;-) is through-hole and not SMD.

It was suffering from a rattling fan, which had an interesting cause: it had been stored (at work) on its side on some shelf.  And apparantly some fat-fisted colleague of mine had dumped it on its side hard enough to push the handle lever into the case.  This caused to whole case to dent and slightly deform. >:( The aluminium of the case is really quite soft.  End result was that the fan (mine has a "rodent wheel" style fan) just touched the plastic back of the scope. Which rattled.  Sigh..

Interesting (...) side effect was that the outer shell would not slide off the frame.  I had to "crowbar" the  side of the case somewhat to get it off.  Once it was off, I could hammer (yes.. I had to use a hammer to fix a scope..) the dent out, which made the case slide back easily onto the frame.
 
Oh.. And I had to fit a new 10Mc Xtal on the digital controller PCB.  That got stuck behind the dented case and broke off.  ::)

Ah well, it is back to its glorious self again.  I got it years ago (for free, can't complain there!)

Wilko

Bummer  :( , that poor thing, glad it works.



And yes MTTF goes down with temperature, so if the chip is seriously hot, I would *consider* adding a heatsink, or a small extra fan, though with the caveat of thinking how the whole airflow though the system is arranged.

Good points on the fan replacement though.

The whole airflow paths are quite clear from above pics, and the only exhaust is at the rear and the intakes are those vent holes scattered across the body which show those parts need fresh air.

Yep, replacing the fan is already in the list and will be using good fan like Sanyo Denki or similar.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: rf-loop on November 20, 2011, 10:35:47 am

If not believe you can put thermal sensor over chip and close case. Temp is more low than in free air temp.
same for these some maybe more sensitive hybrids.

Surface temp will never be lower than ambient temp if using air cooling at "a non evaporating surface", its the basic law of thermodynamic, not sure where did you learn yours.


There are so many misunderstoods in many places  becouse my poor english. I do not correct all, but this one I want try clarify what I mean (and it is extremely trivial case, only language is problem)

(of course there are three pathway for thermal power)

From silicon to out there is some thermal "resistance" between silicon and case outer surfaces including also pins.

If handle now only from case surface to air and leave these radiation and conducting away.

If case is open. There are only free air free convection what "flush" surface.
If case is closed and fan running. There is forced airflow directly to this componet surface. Amount of moving air is totally different and it moves more thermal power.  With case closed this component temperature is more low than with case open if there is not forced convection. This is reason why Tektronix rules that there need use service fan if use scope without case.
Of course becouse there is thermal resistance between case and silicon it also means that thermal current change means more thermal difference between surface and silicon if there is same thermal power generated.
If there is lower thermal current from case to enviroment then thermal difference between case surface and silicon is smaller (and hotter).
I have think these are so basic things that everyone can understand these without long explanation.

I have seen thermally damaged Tektronix hybrids. Sometimes reason is bad service man who forged scope runn without case and bottom down to table or even so that bottom of scope is upside but it is not very easy damaged. If fan stops there are no protection! And this is danger case. If case is closed as normally and fan fails. It may very easy overheat hybrids becouse there are anly low convection and radiation and conducting is not enough for cooling if it run long time. After hours there is very hot inside scope and some critical components may fail thermally.

Lack of thermal overheat protection is bad design.  How much it cost to watch fan or airflow (or temperature) nearly nothing if compare it to original price of this scope..

I have repaired these scopes and also years ago I have make many examinations about some design (and modifications) points inside these scopes for special use. Also this thermal question was one. And finally after many measurements and inspections I finally think, no need add heatsinks. (long time ago I was concerned just this same)
Yes it is true that component reliability littlebit go down if compare 60 celsius or nearly 100 celsisus.
But then need also remember what is product lifetime.  I have seen some this model what have >60000 hours and still working. 
Where are most common problems in these scopes (if keep out bad service damages).
(Fan (specially this older fan type), electrolytics, some resistors and diodes and capacitors specially in HV part and also input attenuators (mostly user mistakes but if unit have been in product testing and drived with computer there may also be worn attenuator unit). In older manufactured unit have different fan, it was very silent but also very fragile and hard work to change, and expensive!)
Units what I have in my lab have around 1500 - 4000hours.

If this scope need use in special enviroment then its thermal things need arrange different.
It need sometimes arrange separated closed inside air circulation and then  heat exchanger to outer cooling. (example in some explosive enviroment or if there is heavy dust or some other situation what is common example in military some other use)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on November 23, 2011, 03:29:26 am
rf-loop

Thanks for the reminder, definitely will have a big house fan blowing at that the A1 board when running without the case, also usually it was never turned on more than 15 minutes when without it for brief checking and measuring like I did last time at the J119 header.

About the environment, don't worry, it will be used 99.99% of it's time at my bench table.

Btw, since I don't have enough time to work on this yet, any clue where to look for for my read out cursors posistion problem ? I mentioned this at my other thread here -> https://www.eevblog.com/forum/index.php?topic=5258.0 (https://www.eevblog.com/forum/index.php?topic=5258.0) , currently I suspect the problem probably near the DAC ic and it's surrounding passive components at the A5 board.

About backing up the nvram, any suggestions or other tips ? My plan is to pull that dallas ic, do a backup externally and put it back but with ic socket installed. About the battery inside the nvram, I guess nothing we can do about it, its just a matter of waiting untill the internal battery ran out of power and have a replacement ready with the restored data.  :-\

If you have better solution, I'd love to hear that.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: rf-loop on November 23, 2011, 06:07:33 am
It looks that scope need service calibration.
If do adjustments it need follow _exactly_ Tektronix service manual. There are not words without meaning (even if it feels stupid..).

Also it need follow exatly this adjustment and calibration steps in the order what is  prescribed in manual, this order is important and manual tell what steps can do individually (there are not many these steps. First you start power unit voltages and reference adjustment and CRT itself adjustments (linearity etc things) and if then change these agen, oh well...do full service cal agen. So, follow manual, do not jump over any thing exept if manual tell specially that it can do, in other case it is prohibited..  (This manual need read so that what can do can clearly read on manual and if there do not read some thing is accepted then it is prohibited - just opposite than many other books - example law.)
Do NOT separate adjustments without knowing exactly if it interfere somewhere to some other thing (only some things can separately adjust without calibration procedure. Cursors need adjust inside cal procedure and in given order of steps.
What tell me that it need adj and cal. Cursosrs looks like fully out of order.  How is measurement accuracy?


How is this: "The power on message is "DIAGNSTIC. PUSH A/B TRIG TO EXIT", is this normal ?"

This is not normal!
This message tell that something is wrong (some rare cases it can do this once and reason may be "unknown" and in this situation it also can reset). 
Normally it do not appear without reason! If this appear, it can continue to normal scope  pushing a/b trig but now user  know that something is maybe wrong and it also need read as: "do not trust measurements before problem solved."

(exept if someone do manually "bad start" example keeping some button pressed during start up prosedure.)

But in older 2465  (B models with new SMD  HW I do not know)  it can also appear if oscilloscope shut down procedure fails (it may happend example if some capacitor is bad in this clever power unit and there is not enough power to run normal shut down procedure after switch off or loose mains electric...  This power up and power down "logic" can find in service manual. More serious case it may mean corrupted calibration or error in some circuit.

Becouse (in one your picture) cursors location is really bad it may tell that some calibration thing is not ok. (btw. now you have adjusted readings location without service calibration procedures - remember, they maybe now adjusted wrong and after (or better tell inside) service cal procedure you may need adjust also this agen).

Service cal must NOT START before sure that there is available all signals what need and just as they need be!
What ever step in procedure fails it can not continue AND id can not take back. There is no any "oops do not - take back" button after started cal prosedure (example vertical block) it need go from start to end and every step need just perfect cal signal from calibration generator and every step need adjust perfect becouse without this some other step may fail and it need do agen as long as it pass. (there is not "jump over" posibility -- oh yes there is is and result is what ever, maybe your cursors are from failed cal procedure if someone have not know what he is doing. Also in some things (some minor details) this manual is not very clear. 

Note also. Always before full calibration need inspect power unit voltages AND ripple. They need be well inside limits what service manual tell.  Selftest system give information what is wrong (what test number fails) but it do not know all. It do not know example if calibration data is wrong after some have done bad calibration.
This power up hours littlebit give feel that someone have reset system. If someone have done this, what other things he have done with oscilloscope in service mode.



Title: Re: Tektronix 2465B oscilloscope teardown
Post by: blueflash on November 23, 2011, 01:55:37 pm
Although the U800 post is some days ago here my solution, which is similar to Yours but I used a bigger Heatsink with a hole for the screw to avoid electrical contact. Bevor mounting the heat sink with normal super glue I isolated the screw with a plastic tube.

Also I have a question if You would be so kind to tell me if I'm right.
When I got my Tek2465A I wondered about the missing illumination. So I decided to open the front panel where I expected the bulbs - but I found nothing (see last picture). Shouldn't there be the illumination lights?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: rf-loop on November 23, 2011, 03:53:09 pm
There need be illumination lamp board together with light distribution clear (partially painted) plastic. Also these lamps are very special small soldered lamps. On the main board is lamp driving  circuit. (also it is designed just like perfectionists do)

You have not service manual? If I remember right there is also full explanation about this light system.

Someone have take this light module. Sometimes peoples have get scopes where are missing hybrids..  (do not connect not compatible lamps to connector on the main board, it is possible destroy this lamp driver circuit and then in worst case you need change one IC on the main board)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: blueflash on November 23, 2011, 04:09:29 pm
Yes I got a service manual, but the part with the illumination is not illustrated so good. So I thought it is better to ask some knowing guys about it  :)

Am I right when I suppose that the red marked connector is the supply connector for the illumination?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on November 24, 2011, 03:21:16 am
It looks that scope need service calibration.
If do adjustments it need follow _exactly_ Tektronix service manual. There are not words without meaning (even if it feels stupid..).
That is what I'm afraid of, cause I don't have enough supporting tools to do that, while sending it to certified calibrator is not an option since its way too expensive, the cost of certification might be more than a new 200Mhz china made digital scope.  :'(
While the price of this thing I bought is less than $300.


How is measurement accuracy?

So far I only tested with against the Tek 2901 time mark generator and these are the results :

(https://www.eevblog.com/forum/index.php?action=dlattach;topic=5574.0;attach=17237;image)
(https://www.eevblog.com/forum/index.php?action=dlattach;topic=5574.0;attach=17239;image)

(btw. now you have adjusted readings location without service calibration procedures - remember, they maybe now adjusted wrong and after (or better tell inside) service cal procedure you may need adjust also this agen).
Nope, checked with service manual, the adjustment I've made at R2918 to fix the readout vertical position is not part of the calibration procedure that will be stored as calibration data, check again your service manual.

For sure I will not touch or start any calibration until I have the adequate supporting tools to do that and aware that this must be followed step by step exactly as the manual instructed. Btw the service manual it self has flaw as pointed one of the member at tekscope group that there is an additional steps to be done to complete it.

Since you said you've done many calibrations on these scope before, what kind of tools you have there to help your job ?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on November 24, 2011, 03:28:36 am
Although the U800 post is some days ago here my solution, which is similar to Yours but I used a bigger Heatsink with a hole for the screw to avoid electrical contact. Bevor mounting the heat sink with normal super glue I isolated the screw with a plastic tube.

Thanks for sharing that, nice to see how other 2465x owner cooled their U800.

Also I have a question if You would be so kind to tell me if I'm right.
When I got my Tek2465A I wondered about the missing illumination. So I decided to open the front panel where I expected the bulbs - but I found nothing (see last picture). Shouldn't there be the illumination lights?

Yes I got a service manual, but the part with the illumination is not illustrated so good. So I thought it is better to ask some knowing guys about it  :)

Am I right when I suppose that the red marked connector is the supply connector for the illumination?

Although I haven't look into my front panel at the illumination part as yours, I believe yours are gone, sorry to hear that.  :-\

Looks like the previous owner pulled it out, anyway, there are few ebay seller are offering this part for few dollars.

Attached below of my cable connection at J181 connector and the picture from the service manual, apparently yours are missing the 11,12 and 15 parts.

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: rf-loop on November 24, 2011, 06:32:47 am


(btw. now you have adjusted readings location without service calibration procedures - remember, they maybe now adjusted wrong and after (or better tell inside) service cal procedure you may need adjust also this agen).
Nope, checked with service manual, the adjustment I've made at R2918 to fix the readout vertical position is not part of the calibration procedure that will be stored as calibration data, check again your service manual.


My thinking was: Now if you do full service calibration it may affect some things and maybe also these readings position slightly change and need maybe also agen adjust.  All adjustements are not directly related each others but it is better to follow service cal steps in order so work is more easy and do not need go back agen. But of course something can adjust.
But I see one your picture and readings was extremely bad position before your adjustments. How they have changed? This kind of change is not normal exept some component fail or someone have done bad adjustments.
How are vertical cursors and horizontal cursors if you measure some exactly known signal. Also how horizontal cursors accuracy if measure things together with B timebase.
Cursors horizontal accuracy is best in -4 to +4div from centerline. If visually signal trace is in good accuracy and if cursors display enough accurate it do not of course need any cal.  In normal use this check is enough.

If need real  calibration/ calibration with data (and traceable)  then all need measure accurate and write values to record and if need (limits breaks) then do full cal and agen do cal check data record. Normal user do not have this.

-------

I have tektronix calibration generators. Example CG5011 and CG5001.  Then also fast rising pulse generator tektronix 284. And of course oscilloscope(s) what can use inside cal procedure. (it need external and good analog oscilloscope or so good digital oscilloscope what I have never own. It can not do with Hantek, Owon, and of course nothing with Rigol) 
And other tools. Also enough reliable DVM for reference adjustments.  But this level and timing calibration signals is most important. Then specially timebase(s) calibration need this external oscilloscope. There is nice adjustment method inside this 2465 FW)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: blueflash on November 24, 2011, 10:40:14 am
Thanks for the reply, that confirms my speculation about the missing illu.

Btw, if someone has problems with the eproms on the digital board loosing their "mind" - I read them out and can share the files if needed. I guess they are different for the models 2465/2465A/2465B (my model is 2465A). 
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on November 25, 2011, 03:51:39 am
Thanks for the reply, that confirms my speculation about the missing illu.

Btw, if someone has problems with the eproms on the digital board loosing their "mind" - I read them out and can share the files if needed. I guess they are different for the models 2465/2465A/2465B (my model is 2465A).

No problemo, my pleasure and if you need other angles shot to compare with mine on other parts that you suspect that they're missing or tampered, just ask, I will try my best, got tons of close up shots here. ;)

Interesting offer, I take it although mine is 2465B, who knows someday I will need it even I'm pretty sure they're different.

Btw, is that 2465A has the same A5 board as mine that has the Dallas nvram ? or its using the older model with external lithium battery ?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: blueflash on November 25, 2011, 11:18:42 am
Seems to be the older model with lithium battery.

Find attached the binaries of the EPROMs in the hope that it will help somebody someday. I heard sometimes that EPROMS may loose their memory after 10 or more years - especialy if they work at higher temperature. So I deicided to save the EPROMs of my devices.

 
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: slburris on December 20, 2011, 06:06:57 pm
Note that there's a lot of Tektronix firmware archived here:

ftp://ftp.bluefeathertech.com/electronics/testgear/Tektronix/firmware

Scott
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on December 21, 2011, 07:33:49 am
Scott, thanks for that links and bookmarked, definitely a precious resources if my old scope hoarding nerves get excited again.  ;D
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: slburris on December 21, 2011, 04:54:21 pm
Oh, I forgot this other site for firmware (and manuals):

http://www.ko4bb.com/manuals/index.php?dir=04 (http://www.ko4bb.com/manuals/index.php?dir=04))_ROM_Images_and_Drivers

Lots of good people trying to keep old test equipment alive by
archiving firmware images against eventual bitrot.

Scott
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on December 24, 2011, 06:57:47 pm
Oh, I forgot this other site for firmware (and manuals):

http://www.ko4bb.com/manuals/index.php?dir=04 (http://www.ko4bb.com/manuals/index.php?dir=04))_ROM_Images_and_Drivers

Lots of good people trying to keep old test equipment alive by
archiving firmware images against eventual bitrot.

Scott

Yeah, I have that bookmarked already, good site it is,  thanks, personally I'm very grateful for these old resources maintained by these people all this time.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: m1gry on January 27, 2012, 12:31:42 am
I've just bought a 2465A from Ebay  ;D. I've had my eye on this model scope for a while as I'm interested in the high bandwidth. It came with 2 off P6139A 500MHz Tek scope probes. I've never used this particular scope before, so I was interested to test it out. Everything appears to work OK, diagnostics pass, and it shows 4000+hrs and 800+ on/off cycles. Serial is B0106XX. I have no idea how old it is.

There are a few quirks: the A/B timebase switch is a bit "woolly" (possibly because it has been used a lot!). If I select GND and change volts per div, the trace moves around, but is the same "offset" for 50/5/0.5, but different to  10/1/0.1, and different again to 20/2/0.2. Not a showstopper but could be an annoyance during use. At the two higher sweep settings 5 & 10ns the timing cursors are about 10% wrong, but appear OK at slower sweep speeds. I hope that this might be a calibration issue.

Also if the READOUT INTENSITY pot is moved any small distance away from centre, the trace gets very bright and unfocussed. Again not a showstopper, but it needs careful adjustment and I can't beleive that Tek designed it that way. The main INTENSITY also seems a bit agressive, but can be turned right down and the traces are sharp and clean.

Comments welcome (and I think this is my first posting to EEVBLOG  :)

--Gary
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on January 27, 2012, 06:29:21 am
Gary, 1st of all, welcome to the forum ! ;)

Congratulation on the scope, hope you got it with a good price, also its really nice it came with two high speed probes, cause this probes thingy is really important.

I've seen lots of people hunting old high speed analog scope without realizing the importance of having a good probes to work with, otherwise it will be come useless like using those China made crappy one with it.

Looking at your problems, I guess its time for another 24xx teardown thread of yours ? Especially on cleaning and fixing the mechanical switch, it should be interesting to observe.  :D
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: butmach on March 31, 2013, 06:54:32 pm
Hello everyone, this is my first post to EEVBLOG  :-BROKE

digging thru the forum, I have found a post from BravoV.
Did you manage to backup externally the DS1225 (or someone else did ?).

My calibration data in 2467B got lost during desoldering of this pesky chip. I tried to secure them ... but the worst-case scenario that I always feared fulfilled.

I do not have the whole reference equipment. I have calibrated CAL01 thru CAL08.

But the CAL09 procedure for parametric measurment is not passable for me ... I got only LIMIT messages !, can be that there is a malfunction somewhere in AB sweep or AB gates (PAL), but before unsoldering of DS1225 everything worked fine.

My question is: do you know what part could cause exceeding the LIMIT's in the CAL09 procedure.
Could you please send me your NVRAM dump as a file, I will programm a blank device in an external programmer and look if the "diagnostic push a/b trig ..." disapears.

I'd be happy to any answer :)
P.S. Also I need to do something with the cooling off U800, I think there is a factory fitting error, IMHO there should be no shims between the IC a PCB, U800 should adhere directly to the PCB.
After I get done with calibration, I will add additional heatsink.

Pawel
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: hepcat on March 31, 2013, 09:05:17 pm
<snip>
P.S. Also I need to do something with the cooling off U800, I think there is a factory fitting error, IMHO there should be no shims between the IC a PCB, U800 should adhere directly to the PCB.
After I get done with calibration, I will add additional heatsink.




There are three things that were done to the U800 chip on my refurbished 2467B:  1. The chip was de-soldered from the board and a machined pin socket installed.  2.  A small heat sink was attached to the metal tab.  3.  The hold-down nut on the opposite side from the tab/ heat sink was removed.  This is to remove bending stress on the chip.

Regards,


Jason
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: grenert on March 31, 2013, 09:37:17 pm
QService in Greece sells these NVRAM chips pre-loaded with standard calibration data:
http://www.qservice.tv/vpasp/shopexd.asp?id=1252&bc=no (http://www.qservice.tv/vpasp/shopexd.asp?id=1252&bc=no)

Perhaps they can sell/give you the data for your scope.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on April 02, 2013, 01:33:59 am
@Pawel (butmach),

Welcome to the forum on your 1st post.

Really sorry to hear you've lost the cal RAM  :'( , also my mistake on our earlier offline message, I misread your scope model, I thought its 2465B instead of 2467B, really sad to hear this happened at the best portable analog scope ever made.  |O

Not sure if both are compatible, although I doubt it, attached below zipped of two copies of NVRAM from two different calibrated Tek 2465Bs just in case you feel adventurous. Also too bad our resident Tek expert here Alan (w2aew) has 2467, not the "B" version.  :-\

Maybe as above grenert's advise to contact QService for the nvram image if you still unable to solve the problem.

Also I would like to hear from you how you're going to cool the pesky U800, please share few photos once you've done it.


@Jason (hepcat)

Thanks for the info, sounds very interesting.  :-+

Do you have any photo shoots on how mod was done at the U800 ? Really appreciate it if you could share it here, I'm very interested and pretty sure other U800 owners too.  ;)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: hepcat on April 02, 2013, 02:02:08 am
<snip>
@Jason (hepcat)

Thanks for the info, sounds very interesting.  :-+

Do you have any photo shoots on how mod was done at the U800 ? Really appreciate it if you could share it here, I'm very interested and pretty sure other U800 owners too.  ;)



The attached photo was sent to me by the person I bought my scope from.  If I remember correctly, it's from a 2465B.

Regards,


Jason
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on April 02, 2013, 11:10:34 am
Jason, interesting mod, as my thought and described at my earlier posts when I saw the nuts and bolts, its simply a design flaw, thanks a lot for sharing that photo.  :-+
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on April 05, 2013, 09:54:24 am
Sad news, a failed to attempt to find the better replacement for the pesky Dallas DS1225Y BBSRAM, cause the F-RAM Ramtron FM1608-120 is not compatible. It was an impulse purchase thru a friend visiting abroad without checking the detail 1st, and also I was mis-leaded by info gathered from the Tektronix's Yahoo mailing list.  |O

The reason is the DS1225Y needs the Chip Enable (CE) pin to be enabled only "once" for multiple read/write operations, while the F-RAM needs the CE to be toggled at every address change and latched at CE 's edge.

What a waste, another addition into the components bin labeled "It will be useful .. someday".  :palm:
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: butmach on April 05, 2013, 07:22:45 pm
In my 2467B all functionality is restored  :-DMM, as before the disaster, thanx very much, my old humble scope is reincarnated.
Next NVRAM loss will never happen again ... now I have a backup :)
I have also tested NVRAM dump from a 2445B, (provided by an attentive and helpful ham radio operator), it is also working perfect.
I have tested the calibration to 50MHz, the error of measurement is from 1 ... 3% on readouts (dT, d1/T, dV), im very lucky.
Now I'm waiting for a TG501 to test the scope in full range and if it will be necessary I will perform a calibration.

Pity it did not work with F-RAM Ramtron FM1608, almost bought them  :(
I ordered the M48z08 ZeroPower STMicroelectronics SRAM, but there is not any greater advantage over DS1225 - are more readily available.

If I make the additional cooling for the U800 I will of course attach a few photos.

Regards,
Pawel
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on April 06, 2013, 09:07:36 am
Pawel, congratulation on reviving back your 2467B  :-+, so you did use 2465B SRAM image or others ?

Also thanks for the photoshoots of that weird BBSRAM module using the EPSON chip, especially with that weird battery's position  :o, whats the part no of that thing ? Never saw such strange chip.

About the F-RAM, I've decided to use another version that doesn't need to toggle the CE pin for read/write, its FM28V020 F-RAM, and since its 256K bit, planned to use it with the 2 extra address pins on dip-switch, so it can be manually switched between 4 of those 64K banks. Hopefully it will work flawlessly, the chip is on it's way direct from Cypress Semi.

Btw, that IC pin sockets inspired me to do the same for my U800 chip, that method will provide plenty of space underneath the IC body for a custom copper block heatsink.  :-+

Cause the best heat dissipation path is through the metal body part straight under the chip's die. Shot of U800's bottom view, pardon the texts, made this pic while ago to someone else on precautions when handling this damn chip.  >:(
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: butmach on April 06, 2013, 08:52:14 pm
I'm using the 2445B image, because the measuring errors are satisfactory for me without calibration. Your images also operate normally, but the calibration data does not  match to my hardware - error of measurement is 15...20% in my scope.

I don't know the part no of this BBSRAM, originated from an old RICOH photocopying machine, was located on main control board PWB no. A1535112. The EPSON chip is a 256K-BIT SRAM with Extremely Low Standby Current. It's like a Dallas DS1225 without cover and with larger battery :). Address lines A13, A14 are grounded and disconected from scopes board. Did not work properly as they were connected.

I am curious how it goes with FM28V020. It's hard to get !

You are right with the heat dissipation path, but there will be a lot of work to disassemble the main board from scope.

My additional cooling is already fitted, some photos are attached below. Before attaching the heatsink I gave some silicone thermal grease between the chip and the heatsink. It works very well. The temperature without the housing is about 42...45 degrees Celsius. With housing it will be even lower due to the forced cooling by the fan ^-^

Regards,
Pawel
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on April 07, 2013, 01:42:50 pm
I'm using the 2445B image, because the measuring errors are satisfactory for me without calibration. Your images also operate normally, but the calibration data does not  match to my hardware - error of measurement is 15...20% in my scope.

Looks like all analog Tek 24xxB scope's SRAM image are compatible each other, never expected that, great finding.  :-+


I don't know the part no of this BBSRAM, originated from an old RICOH photocopying machine, was located on main control board PWB no. A1535112. The EPSON chip is a 256K-BIT SRAM with Extremely Low Standby Current. It's like a Dallas DS1225 without cover and with larger battery :). Address lines A13, A14 are grounded and disconected from scopes board. Did not work properly as they were connected.

Yeah, I was curious when seeing the pin 1 & 26 mod job, no wonder.

About this BBSRAM at Tek 24x5B scope, an interesting finding, if you check the scope schematic, the pin 1 and 26 are connected, while at the BBSRAM DS1225Y chip, those are NC pins.  :-//

Probably they were reserving that A13 & A14 lines for optional expansion when the scope was designed back then. Your problem with that grounded 2 extra unused address lines is confirming that, both pins are supposed to be pulled high or as in no connections as DS1225Y does, pulling both down definitely will confuse the CPU.


I am curious how it goes with FM28V020. It's hard to get !

Yeah, its hard to find, since this F-RAM is not as common as other like EEPROM, just a warning, never buy these kind of rare memory type from Chinese online store like at ebay or aliexpress, trust me, 99.99% are fake.

Ordered my FM28V020 directly at Cypress Semi's online store, even though not that cheap @$21.69 a pop :(, they're providing "free" shipping, so its worth compared to buying the pesky battery based DS1225-AD (DS1225Y replacement) through Maxim's distributors ranging about $17 to $20 price range but with crazy s/h charge.  >:(

Btw, I've been reading intensely the 256K FM28V020 F-RAM datasheet and comparing with DS1225Y lately, and so far it is quite promising. With the 4 times bigger capacity, I'm going to route the two extra unused address lines into a dip switch with 2 positions, so basically I could manually switch between the 4 x 64K memory space, enough for experimenting with different calibration values, or easy hacking/tweaking around the SRAM's content if needed  >:D.

For physical compatibility, since FM28V020 is SOIC 28, its obvious I need a custom breakout PCB for SOIC 28 to DIP 28 and with a dip switch placed at the PCB.

Btw, thanks for the U800 heat sinking photos.  :-+
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: grumpydoc on April 07, 2013, 01:52:43 pm
Quote
Looks like all analog Tek 24xxB scope's SRAM image are compatible each other, never expected that, great finding.

The 2445 and 2465 are pretty much the same 'scope so it's not that surprising.

A while ago there was an ebay seller in the 'states who was changing component values in 2445 front ends (to be the same as the 2465) to increase bandwidth and selling them (de-badged) as 2465's. As far as I can discern from the posts on the TekScopes mail list this doesn't quite turn a 2445 into a 2465 as there are differences in the PCBs and I think some of the inductors at least are fabricated from PCB traces.

Needless to say the mailing list's opinion of the seller was rather low!
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on July 25, 2013, 06:29:58 am
Got few PMs lately asking how I copied this scope's cal data from the battery backed up SRAM Dallas DS1225Y, all read from old chip & write to fresh chip was using the cheap MiniPro TL866 Universal Programmer as reviewed by Dave.

Btw, the DS1225 is officially supported by this programmer, check the list your self here, just ignore the Chinese characters at the beginning and scroll down to Dallas section -> http://www.autoelectric.cn/minipro/MiniProSupportList.txt (http://www.autoelectric.cn/minipro/MiniProSupportList.txt)

Edit : Quote from above link on supported Dallas chips :

[ DALLAS ]     19 PCS

DS1220 (RW)                DS1220 (TEST)            DS1225 (RW)            DS1225 (TEST)               
DS1230AB (RW)            DS1230AB (TEST)        DS1230W (RW)           DS1230W (TEST)             
DS1230Y (RW)              DS1230Y (TEST)          DS1245AB                   DS1245W                     
DS1245Y                      DS1249AB                    DS1249W                    DS1249Y                     
DS1250AB                    DS1250W                     DS1250Y       
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Stonent on July 25, 2013, 06:55:51 am
I'd be reasonably sure that 1996 fan was a replacement.  They wouldn't be using Dallas chips with a 1989 date code in a 1996 scope.  A lot of old Sun workstations use similar Dallas chips to hold the MAC address and configuration data and it is fairly common for those to have died with an FF:FF:FF:FF:FF:FF MAC address.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on July 25, 2013, 10:34:27 am
I'd be reasonably sure that 1996 fan was a replacement.  They wouldn't be using Dallas chips with a 1989 date code in a 1996 scope.  A lot of old Sun workstations use similar Dallas chips to hold the MAC address and configuration data and it is fairly common for those to have died with an FF:FF:FF:FF:FF:FF MAC address.

First I thought that too, but there are many other chips in there that have date code 1993, also I got a confirmation from an experienced Tek expert that this fan type is the original fan that came with similar 246x scope.

Btw, that 1989 Dallas chip is still kicking and working fine, intentionally put it back in there after I secured it's content just to see how long will it last.  >:D

Picture of that DS1225Y replacement with the cal data already copied into it DS1225AD, purchased from Digikey few months ago.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: PM33AUD on December 15, 2013, 05:06:05 am
Hello!

Figured I'd first try reviving this thread instead of starting a new one so info is consolidated.

I am hunting down a fan for my 2445B here... it is the same model as in this teardown.  It is a quite nice fan... aluminum frame and all.  Finding an 80x80x20mm fan is a bit of a tall order when looking for one that is of high specification.

Any leads?  It doesn't appear a 25mm thick fan will fit properly without modifying the airfoil (or whatever this is called).  Sanyo Denki makes some nice models with high life - I have a 9S0812F401 here but it is 25mm thick.

Thanks!
Phil
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on March 05, 2014, 01:49:04 am
80x80x20, on mouser:

http://www.mouser.com/Search/ProductDetail.aspx?R=AD0812HB-C70-LFvirtualkey66400000virtualkey664-D8020HB-12VLF (http://www.mouser.com/Search/ProductDetail.aspx?R=AD0812HB-C70-LFvirtualkey66400000virtualkey664-D8020HB-12VLF)

I bought that one and it should be here tomorrow or the next day.  I'll report back if it fits ok or not.

(clue: I was looking on ebay for a fan for the 2400(a/b) series and someone had this very fan pictured as an 'exact replacement'.  I searched on that model # and lo and behold, mouser had it!  if mouser carries it, its probably not a cheap POS fan).
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on March 06, 2014, 07:28:08 am
got my mouser order today.  I can confirm that that fan is an exact size replacement.  I have not turn it on or compared it to the old one, but size wise, its 100% exact.

fyi
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on March 06, 2014, 07:35:25 am
Even though chances of getting it wrong is quite low just for the simple DC fan replacement, suggesting to measure the working voltage & current of the old fan before installing the new one, and then re-measure again at the new one once installed, just an extra precaution on this little piece of good scope.

Great  :-+ , looking forward to see the process of your 2465B getting "the rejuvenation".   8)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on March 06, 2014, 07:42:40 am
good point about the voltage.  I just assumed 12v.  fortunately, I guessed right and both fans are marked as 12v.

fitting it to the scope was fine.

I did forget to make note of which way the old fan was facing.  I would assume it blows out but if anyone can confirm, that would be appreciated.  (it would not make sense to blow IN, but it never hurts to be sure).

the new fan is rated a slightly higher current draw but not by much.  the old fan has more blades, but I'm not going to worry about that.  I'm sure that its not going to be that critical.  certainly better than the dusty old one that was in there.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on March 06, 2014, 07:47:23 am
Confirmed, its blowing out.

At the 1st post of this thread, there is a picture of mine which is the original came from Tek factory untouched when it was shot, although its not very clear, you can see faintly the two arrows showing the rotation and air direction on the top of the fan.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on March 06, 2014, 08:04:54 am
thanks!

I should have noticed the label on your photo; that's enough to know which way the wind should blow ;)

all the parts from mouser and digikey came, but I'm still waiting on the chip programmer.  I'll probably replace some of the caps, replace the fan and put it back together to make sure I didn't 'go backwards' (do damage in my refurb effort).  I like doing incremental changes, anyway, so that if things don't work, you have some idea which thing you did between working and not-working.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on March 08, 2014, 01:56:15 am
bought a new friend for my 2465b:

(http://farm8.staticflickr.com/7348/13000931353_aba2a50e48_o.jpg)

(the scope cart, not the scope.  already had that scope from a purchase last year).

this cart was made for 2400 series and that's what will eventually go there.

went to my local shop, found this cart in decent shape (dirty as hell but not banged up) and just had to take it home with me ;)

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on March 08, 2014, 02:07:58 am
Nice score, now I'm so jealous.  :'(

How much did you pay for that ?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on March 08, 2014, 02:32:21 am
the cart was marked at $75, but I got it for 10% off when I talked nice to the salesman ;)

scope was $90 plus $25 shipping, about 2 years ago.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on March 09, 2014, 04:06:31 am
well, I replaced the 4 smd caps and the fan, then put it back together to do a quick check.

I don't think I like this fan ;(  its not at all quiet!  the original fan had more blades and maybe that helped keep it somewhat lower noise.  this one from mouser is not what anyone would call 'quiet'.  it works, I guess, and I think I'll have to live with it for now, but I don't suggest this model, really.  oh well.

next step for me, replacing the dallas module (not really looking forward to unsoldering it, to be honest.)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on March 09, 2014, 04:24:31 am
replacing the dallas module (not really looking forward to unsoldering it, to be honest.)
I'm afraid you just can not escape from that.  >:D

Please, post your original Dallas's content here once you backed it up.


Btw ...

(https://www.eevblog.com/forum/testgear/you're-going-to-be-so-jealous-of-my-workplace/?action=dlattach;attach=84396;image)

... c'mon, more photos please.  >:D
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on March 09, 2014, 08:11:36 am
here we go...

(http://farm3.staticflickr.com/2209/13028277734_88cf205fec_o.jpg)

dallas is removed with the help of hakko 808.  a few pins gave some trouble so I skipped them, did the rest and went back to the trouble ones with a soldering iron, some fresh solder and then re-attack with hakko 808.  no traces seemed to have gotton harmed.

the new dallas chip is there and a surplus gold pin socket, as well.  next step is to copy data over using that '$50 programmer' from china.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on March 09, 2014, 09:17:02 am
success!

(http://farm4.staticflickr.com/3317/13029010943_2fce723f9b_o.jpg)

the minipro copied the dallas chip just fine to the new digikey-supplied fresh chip.

I just bought another 10-20 years of cal data ;)  and the next guy does not have to unsolder that crazy chip.

firmware upload:

http://www.netstuff.org/tektronix_2465b/ds1225_firmware_linuxworks/ (http://www.netstuff.org/tektronix_2465b/ds1225_firmware_linuxworks/)

the .BIN file is the rom image and the .md5.txt file is the unix 'md5sum command checksum output (not needed for the chip programmer, but only used if you want to verify the file came thru ok on your download).

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on March 09, 2014, 06:21:58 pm
Bryan, good to hear it went smoothly, the cheap minipro just works for the 1st time without any problem here too.

I just bought another 10-20 years of cal data ;)  and the next guy does not have to unsolder that crazy chip.

With a refresh on the power supply caps + good luck, I pretty confident that the whole scope it self will last for another >10 years, especially yours was made in 1992, imo its still in very young age compared to others that were made in 80s and still working fine today.

Have you check it's power on hours and cycle counts ? Really curious to see yours.

Btw, thanks for RAM image file.  :-+
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: echen1024 on March 09, 2014, 06:30:53 pm
@Linux-works

That's really quite a clean scope. Not like some of the Israeli "boat anchors" or "totally harmonically distorted" equipment.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on March 09, 2014, 06:57:40 pm
I see that ebay site in israel that sells stuff in truly throw-away-and-don't-look-back condition ;)  what a funny thing to see how abused gear can be and they still want to sell it.  too weird!

this scope has some dings on the plastic front bezel (which I'm on the lookout for, to replace) but other than that its fairly clean and inside was no rust on any of the screws or nuts, like victor's had.  I bought this from a san diego seller and I suspect it spent its life in calif, so there would be little to no rust.

I'll check the power-on hours, but its not trustable since you can zero that out easily enough.

wish I could find a good clean front cover and also the top vinyl pouch; those didn't come with my scope and I'm on the lookout for a bargain on any of those.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: echen1024 on March 09, 2014, 07:15:01 pm
eBay auction: #231098193016

The description is just beautiful:

This unit powers up but not working,after powering the item up you see nothing on the display the display completely DAMAGED but when you press all the buttons you hear beep. it is mainly for part or repair,What you see in the pictures is exactly what you going to receive, if you have any questions please contact us.11819

"You see nothing on the display" Well really now? It's been damn smashed out!
 
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on March 09, 2014, 07:17:33 pm
"that meter kept lying to me, so I just punched his friggin face out!"

lol

maybe the main board was still good and worth that price.

but *I* wouldnt' trust it! 
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: jonpaul on March 09, 2014, 07:21:04 pm
Hello all, my first post, great teardown and good work on the NVRAM.
I have 2465B, 2467B, both need NVRAM, but I am NOT good with digital stuff, and getting on in years,  loosing the ability to do the very fine work you folks can do!

I would be interested to buy or swap for a few of these parts if someone can make them, prefer the one with the external lithium battery.

Happy to furnish the serial numbers and exact NVRAM part numbers in my units.

I have a lot of TEK and HP units, manuals and some parts for swap.

Kind Regards,


Jon
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on March 10, 2014, 02:02:33 am
Jon, welcome to the forum.

About fresh NVRAM chip + content sourcing, I guess linux-works can easily help you out since he is US too, its pretty straight forward and pretty quick to copy/write into a fresh DS1225 chip.

Its just I'm curious why you need that ? Cause every NVRAM image is unique since it has that particular scope's calibration values, and imo can not be used to other as it will cause your scope out of calibration.

If you've lost the NVRAM, you need to buy new Dallas DS1225AD and replace the old one, and send the scope to the calibration service to have a proper cal values in it.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: casinada on March 10, 2014, 03:11:19 am
Jon,
Probably if you say where you live, some Tek Fan /Blog Member might be in your neighborhood and willing to help you.
I was able to calibrate my 2465BDM starting from a downloaded NVRAM from the KO4BB web site, programming a new NVRAM and calibrate most of the settings with the equipment I have. I'm not a calibration site by any means but willing to help if you're in my neck of the woods (Tucson, AZ)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on March 10, 2014, 03:17:01 am
I don't have any new pics (nothing really exciting to photo) but I finally did replace the caps in the lvps.

I hate getting that board set out!  on my scope, its very hard to wiggle that board pair out of the metal; its wedged in there very tightly.  I don't like how tek designed this part; they could have used slides or rails to vertically align the boards and things could have slid in a LOT easier than they do.

if you remove the power IEC socket and pull off its wires/clips you can get more room for your fingers to pull off the 120/240v switch wires.  that was identified as one of the harder things to do when removing these boards.

I didn't replace every cap there; but I did replace the big silver ones and a few others.  I don't notice any change in the scope but at least I know I have fresh caps in the critical places.

I read on one lvps upgrade that if you find 2 100uf caps, you want to keep them exactly 100uf (for some reason).  I replaced those with exact values but using new caps, just for good measure.

it took a good 2 hours to do the power supply boards.  kept scratching my head on how to remove that board pair and not break anything.  putting it back in was just as hard.  something must have been bent since I had to flex the rear metal chassis (near the fan) to create clearance for the metal and plastic standoffs.

anyway, it seems done now.  I'd like to get it professionally calibrated but at least its rejuvinated.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on March 10, 2014, 03:18:14 am
jon is in my general area, so I'll contact him offline and see what we can do.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on March 10, 2014, 03:22:23 am
I was able to calibrate my 2465BDM starting from a downloaded NVRAM from the KO4BB web site, programming a new NVRAM and calibrate most of the settings with the equipment I have. I'm not a calibration site by any means but willing to help if you're in my neck of the woods (Tucson, AZ)

Any chance you could share how you do that in details ? What sort of equipments do you have there ?

As cheap cal service is basically none at where I live, I will be content even for a poor man cal process that yields only with a "good enough" result.  :'(


anyway, it seems done now.  I'd like to get it professionally calibrated but at least its rejuvinated.

Really curious on the upcoming result, is there any chance you can pre-arrange with the calibrator, that you can get the detail on how much that thing has drifted from the current cal ? This question also for Casinada for your DIY cal as well.

If yours doesn't drifted too much, with the recent components refresh, I guess it will be in cal for many years ahead as the references in side are cooked well enough and wont drift anymore.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: casinada on March 10, 2014, 05:08:28 am
I posted some pictures on the Yahoo TekScopes group last september:
https://groups.yahoo.com/neo/groups/TekScopes/photos/albums/1871970004
I used an arbitrary waveform generator that only goes so far in frequencies and I used a signal generator for the high frequencies. When you go trough the calibration procedures, if something is out of range it won't let you finish the calibration so you go back and forth until you get it right.
You need a good DMM to adjust some of the voltages.
I connected with a member of the Tektronix group that lives at a reasonable distance and had good equipment that we used to verify that my calibration was within specs. He has a leveled signal generator and frequency counters that are referenced to GPS. The Scope is not a precision instrument so is not that critical to have it calibrated by a Lab. If you can verify the amplitudes and frequencies are correct and it triggers properly
Then you should have a very usable instrument. You can spend as much time as you want trying to get it as perfect as you want. It can be lots of fun but then it can get tedious as some of the procedures are long. :)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: chksum3 on March 12, 2014, 02:31:18 pm
Congratulations to linux-works on your successful replacement of the 2465B's NV-SRAM.  I'm brand new to this Forum after having found a partially renovated 2465B on EBay. The offending caps had been replaced within the power supply and A5 board and a heat sink was fitted.  The DS1225Y was however not replaced... leaving that to me. I've followed the task of removing the chip, copying the calibration data from it, then writing the data to a new DS1225Y and re-seating it (via socket) to the A5 board.  Before opening the 2465B and removing the 1225Y, I went ahead and bought a new one (DS1225Y 200ns) from a local - SF Bay Area - supplier, Jameco Electronics, and a universal programmer (GQ-4X) off of EBay, which was supposed to read and write to the DS1225Y.  I thought it best to prove to myself that I could read and write to a new chip before getting involved in 2465B surgery.  Sad to say, I've been unable to read and write to the new chip (tried on 2 of them) with the GQ-4X programmer.  Reading that you were able to navigate these waters and successfully program and install a new chip has raised my spirits considerably.  Could you detail the exact programmer model number and the exact chip you used (the Y version, or AD, etc.).  I'd like to follow the path you've cut through the forest. Thank you!   -- Gary
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on March 12, 2014, 02:33:46 pm
if you can return the jameco part, you may want to do so.

I was advised by a 2465b repair guy that the jameco chips are old and not to be used or trusted.  what is the date code on your new chip?

I got mine at digikey (they seem to be out of stock right now) and my date code was 2012, so I know it was pretty fresh.

if you are in the bay area and need help programming the chip, let me know and we could meet to do the copy.  but you may want to buy the chip from mouser or digikey if your date code is not recent enough.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: chksum3 on March 12, 2014, 02:50:41 pm
Thank you for the information! I'll see about returning the chips to Jameco and will order a DS1225Y from digikey today.  I really appreciate your offer of reading the old and programming the new chip -- saves me having to find and buy a programmer that works.  Now, did you go with ordering a Y version or some other version of the DS1225? And, just for curiosity - what programmer model number did you use?  Once the new chip arrives from digikey I'll open the 2465b and desolder the old chip then get in touch with you for the read/write.  Thank you extremely! Re: date code on the jameco chips --> none present.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on March 12, 2014, 03:22:32 pm
I bought this programmer:

http://www.ebay.com/itm/321085130796 (http://www.ebay.com/itm/321085130796)

it arrived safely and quickly.

for the chip, this is the one I ordered but it seems to be out of stock right now:

DS1225AD-200IND+-ND

AD is a wider temperate range (I think) but nothing critical to the scope.  the 200 is the speed of the device and I used the same speed as the original chip.  not sure if going faster or slower would matter but I just matched the same chip speed.

mouser has one that is not AD but very close and that's probably also ok:

DS1225AB-200+

and those are in stock.

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on March 12, 2014, 03:28:58 pm
Chksum3, welcome to the forum.

About the Dallas chip DS1225, only buy from big distributor as they constantly refreshes the stock, also Ds1225Y is discontinued, and can be replaced by DS1225AD. This newer version has an unique feature that it's internal battery is disconnected internally until you used it for the 1st time.

Suggesting not to buy those Ds1225 chip from surplus shop as they are mostly very old, and who knows how is the battery freshness inside, and it does not have the new battery disconnected until 1st use feature as newer AD/AB version. Just watch the date code the one that linux-works has, its still very fresh.

Regarding the tl866, lots of info here -> https://www.eevblog.com/forum/blog/eevblog-411-minipro-tl866-universal-programmer-review/ (https://www.eevblog.com/forum/blog/eevblog-411-minipro-tl866-universal-programmer-review/)

Hope this helps.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: chksum3 on March 12, 2014, 03:51:43 pm
Thanks to linux-works and BravoV for all the info!  I just placed an order for the DS1225 from DigiKey. They did have the DS1225Y-200 in stock! (part#: DS1225Y-200+-ND; IC NVSRAM 64KBIT 200NS 28EDIP). Price: $23.13.  I was about to return the programmer (GQ-4X) that failed to write to the jamco chips; I'll hold off for a few days as the problem may not have been with the programmer. Again, many thanks for helping me out of the NVSRAM ditch.  -- Gary
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on March 12, 2014, 04:00:55 pm
jameco is usually ok.  they are not a surplus shop, they are like a mouser, but just smaller and not as common or as cheap to order from.  they go way back to the 70's when they were 'james electronics', so they are not new to the business.  but on this part, they may have old stock and for battery based things, that's not good.

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: chksum3 on March 14, 2014, 11:46:20 pm
I'm happy to report that I just received a new DS1225Y-200+ NVSRAM from digikey, plugged it into the GQ-4X USB Universal Programmer (under Windows Vista), and got a clean write and subsequent read of linux-works' 2465B calibration .bin file image. This verifies that two DS1225Y-200 chips purchased from Jameco were not functional, and that my GQ-RX programmer works just fine.  The next step is to take my nicely functioning 2465B, de-solder the aging DS1225Y, take that image, write it to the new chip, and install it - via socket - into the scope.  Thank you again to linux-works and BravoV for all your help! 

PS - In word of explanation: I decided to first buy the "Y" version rather than the "AD" version of the DS1225 given the initially frustrating attempts to write to the Jameco chips.  I understand the "AD" chip would have a freshness guarantee, so to speak, given its first turn on would be at first write, but ... I decided to limit variables and take small steps by installing an exact replacement type.  Now, once the .bin image is safely tucked away and the new "Y" is in, the process can be easily repeated with an "AD" version years down the line.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on March 15, 2014, 12:06:55 am
interesting how the jameco chip just would not work.  what was the date code on that one?

glad you got it sorted out.  sounds like you are on your way.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: chksum3 on March 15, 2014, 01:08:01 am
I'm not sure how to read the date code.  Here are the numbers associated with the two non-functioning Jameco chips:

NON-PIN SIDE --> Both chips: 1207C 386017
PIN SIDE         --> Both chips: DS1218  1102D1

Here are the numbers associated with the one functioning Digikey chip:

NON-PIN SIDE --> 1334D5 391308
PIN SIDE         --> DS1218  1314D1 113AT 

Are there dates coded here?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on March 15, 2014, 02:21:43 am
I'm pretty sure the 1207 is a date code (year 2012, not very old at all).

ds1218 though?  should be ds1225, no??

1334 is also a date code, and that would be 2013, very fresh chip.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: chksum3 on March 15, 2014, 03:32:06 am
I did a little Googling and found that a DS1218 is the CMOS circuit within the DS1225 that monitors power input to it (or not) and switches the battery on when appropriate to provide power to the SRAM module - converting it to a nonvolatile package.  That is, nonvolatile until the battery eventually dies.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on March 15, 2014, 03:34:16 am
ah!  now I know what you are referring to.  'pin side' meaning BELLY side of the chip (lol).  yes, I see that on mine, too.  the 8pin dip embedded (potted) inside the chip.

ignore that.  that chip is not the one you care about.  the whole module date (the top of the module, pins facing away from you) is the date code you care about.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on March 15, 2014, 04:18:26 am
Gary, good to hear you've solved the problem. The Digikey's one looks very fresh, date code 1334, thats 2013 week 34, manufactured about last Aug 2013. This chip even in use will last > 10 years. Mine pulled from the 2465B with date code manufactured in 1989 (25 years  :o) is still working fine when I tested few months ago. 

Meanwhile the two from Jameco are not that old either, made around Feb 2012 (date code : 1207), curious why they're broken ? Assuming these are never used chips.

How much these Jameco DS1225 cost you ? If its too cheap, afraid they're knock off/fake ones like those sold at Aliexpress, some are even selling them at $2 with free shipping.

Btw, since you're using linux-works's SRAM image now, which carries unique calibration settings, have you measure it with some references to see if the cal is out way too much ?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: chksum3 on March 15, 2014, 06:04:04 am
Thank you, but I've solved only the reading / writing to a new DS1225 to date.  I used linux-works' SRAM image as a test of the functionality of the new DS1225 and universal programmer -- I was able to get the image in and read it back out.  I haven't yet opened the 2465B, so I haven't yet gotten my hands on the SRAM image contained in my scope.  Once I gather a few more details, I'll dive in, hopefully be able to extract the chip without damaging traces, etc.  Only then will I read the data, program the new DS1225 and reinsert it via a socket.  In other words, there is a long way yet to go. 

Part of my preparation has been to review your terrific tear-down documentation from Nov. 2011.  My plan is to investigate any potential road-blocks in removing the A5 board, then determine whether my solder - desolder station will be sufficient to the task, and if so, what temperature settings and what kind of solder should be used in seating the new socket.  In other words, I plan to go slowly and try not to screw anything up! I've fixed a few things in the past (my ICOM R7000 receiver for example), but the complexity of the 2465B is another level altogether. <gulp>  Oh... you asked about the Jameco chip price -- they were ~$11.00.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: chksum3 on March 15, 2014, 04:57:40 pm
Well, I awoke and just couldn't hold back any longer.  The 2465B was opened and the DS1225Y chip was desoldered, read, re-read, inspected, and photographed. Its date-stamp is 9404D3, which I believe is April 1994 (?). The new DS1225Y was then written to and verified, then inserted into the scope.  Everything was reattached, screwed down, re-cased, and plugged in.  The switch was thrown and behold - the 2465B started up normally and functions perfectly.  Hurray! Again thank you for providing such clear instructions out here!  I'll work on uploading the calibration .bin file.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on March 15, 2014, 05:06:26 pm
Congratulation, well done.  :-+

Btw, if its not troubling you too much, please the photo of your A5 digital board, and also the zipped file of your SRAM image if you don't mind, and attach it here in this thread as another Tek 2465B references.

Hopefully it will be useful someday for other 2465B owners.

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: chksum3 on March 15, 2014, 05:28:13 pm
Thanks. OK, I've attached an image of the reinstalled A5 board and a zipped copy of the .bin file now safely written to the new DS1225Y-200.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on March 15, 2014, 05:34:59 pm
if you did not change out those 4 smd lytic caps, you will want to.  those are on the 'must change out' list.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on March 15, 2014, 05:36:12 pm
Thanks !  :-+

Wow, I noticed there are 3 dark spots that look like scorched badly, the damages caused by the leaked caps is really nasty.  ???

Btw, your firmware there at the EPROM labeled 160-5877-02, any chance you can read and post here too ? Really curious as mine (see the 1st post) is 160-5877-01.

My TL866 reader/writer just can not handle this rom type which is D27011.  :-//
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: chksum3 on March 15, 2014, 05:49:02 pm
I bought this scope on EBay from - rcatechalert_guy - as having been refurbished as follows: "The LV power supply filters (Capacitors) replaced with units with better specifications; The A5 control board SMD capacitors were replaced and potted.  Do you see evidence that this was not done?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on March 15, 2014, 05:51:26 pm
I agree, there are LOTS of black areas there!  what the heck is going on??  some exploded parts?

looks like someone also touched some of the red wima caps with a soldering iron? ;)

if you can get some close-ups of the dark areas of that board, that would be useful. 
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: chksum3 on March 15, 2014, 05:52:37 pm
The areas that look like scorch marks are actually a resin of some sort. I'm assuming that this was done to protect against any future capacitor leakage damage, but I can't see through the stuff.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on March 15, 2014, 05:53:08 pm
I bought this scope on EBay from - rcatechalert_guy - as having been refurbished as follows: "The LV power supply filters (Capacitors) replaced with units with better specifications; The A5 control board SMD capacitors were replaced and potted.  Do you see evidence that this was not done?

please do get us some closer photos.  if you want, I could help take some photos (if you are bay-area based).

I was very close to buying from that very person and I read his write-ups on ebay.  if that is 'potting', then I'm a monkey's uncle....

nothing should be 'potted'.  this is an SMD board and there are proper smd parts that should fit there.

I hope he did not butcher your board!

and if he did service on this board, why on earth did he not replace the dallas module?

this does not look good, I have to say ;(

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on March 15, 2014, 05:54:38 pm
The areas that look like scorch marks are actually a resin of some sort. I'm assuming that this was done to protect against any future capacitor leakage damage, but I can't see through the stuff.

that's not a typical repair procedure that I'm aware of.  you replace the bad caps, you clean the board and solder new ones there.  I used polymer caps so there can't ever be leaking again.  I can give you the part #'s from mouser if you want.

having work done on a board like that would make me quite uneasy about what else was done, and HOW well it was done.  yikes!

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: chksum3 on March 15, 2014, 06:04:30 pm
Here's a closeup of the resin covered areas.  Yes, I was disappointed to see the work up close and personal. On the other hand, the scope appears to be functioning well and, as they say, the deal is done.  With all the resin (?) now present, my first reaction is to leave it alone and not try removing it. If the scope at sometime fails, I'll of course be forced into action. 
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on March 15, 2014, 06:09:01 pm
I would also be concerned with any of that resin affecting the circuitry.  on high frequency layouts, capacitance and trace leakage can be an actual issue.  I don't know the a5 board well and maybe those things don't matter here (its not an analog input section or high z section) but it just looks real bad to me.

if I saw that in my scope, I'd return it and give the seller a super strong negative for being incompetant and claiming otherwise.  wow.  just wow.  maybe I'm over-reacting but I do not like the look of that one bit!

if it works, that's fine.  but it sure looks like a teenager hacked your scope and not a professional.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on March 15, 2014, 06:14:16 pm
Geezz Gary, I just downloaded your A5 board photo, and starred it for a while, must be really bad there. I slightly enhanced yours to show the dark spots, and compare with mine at the left side.

See the arrows I put there ? Also I'm very concern of the high precision 10 Mhz oscillator (blue box at the bottom), it seems like its so dark that I can't recognize it anymore.  :-//

Attached below the quite big sized picture I just made, suggesting to right click the thumb pic and view at other window for best resolution.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: chksum3 on March 15, 2014, 06:29:01 pm
Yep, the resin coating is ugly and inexplicable - I don't understand the need to have done this, unless there was leakage and damage then wire used in place of traces to reconnect the damage pathways, then resin to cover the whole thing.  Definitely a messy job at best. Why the 10Mhz oscillator is resin covered is another mystery.  Ugly, ugly, but appears to be functional.  I've decided to write the seller and ask what this is about.

Regarding the D27011 EPROM: my programmer also does not include that one on the list of supported chips.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on March 15, 2014, 06:37:44 pm
I would email that seller and have him explain himself.  his business seems to be fixing up old scopes and reselling them as refurbished units.

I don't want to make you feel bad, but I'm so glad I decided NOT to buy from this guy!  I had emailed him a few times and thought about buying one of his scopes, but I would have had some real issues with his repairs had I seen that in a scope I paid EXTRA for, for so-called expert repairs.

did you leave him feedback already?

I would try for a discount or even to return the unit.  its a disgrace.  sorry, but it is quite disgraceful given those pictures and the burn mark on the wima cap, too.

and to charge that much for the refurb scope and to NOT do the dallas module.  shameful.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on March 15, 2014, 06:40:30 pm
Another comparison photos yours vs mine, just in case you need it when "talking" with that seller. Hope it will ended well towards you, really, your A5 board looks scary to me.  ???


Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on March 15, 2014, 06:44:25 pm
hey victor, what camera are you using?  that's a REALLY sharp photo there!

I wonder what the burn marks are on the IDC (or is it IDT, I get those confused) connector.  just dirt or temperature issues?  victor's is quite clean and mine is also quite clean with no discoloration.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on March 15, 2014, 06:49:07 pm
now, I'm wondering if the seller used hot-air rework tools to try to remove the smd caps.  that might explain the burn marks (if they are actually that) on the plastic vertical pin idc/idt connector.

maybe he lifted traces when he did the repair, so maybe he had to run green wires and pot that.

you might also post this to the yahoo tekscopes group and get some opinions on this.

sharper shots would help, though.  if you can avoid using flash, put your cam on a tripod of some kind and set the self-timer to auto fire, you might be able to get some sharper, more telling shots.  I'd be happy to come by and take some decent SLR shots if you want.  this should really be documented so that people know what to expect from such a seller.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: GreyWoolfe on March 15, 2014, 08:47:22 pm
FWIW, it looks like he's trying to hide a bodged repair job |O.  If this is an smd board, there shouldn't be wires added.  If I couldn't get any satisfaction, as in returning it or getting a deep discount for the crappy repair job, I would see about getting a replacement board and keep that as an emergency spare if you have to fix the primary board.  Negative review and epic fail!
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on March 15, 2014, 08:53:56 pm
just a thought: since the seller 'repairs' scopes regularly on ebay, I'd ask to swap this 'fixed' board with a totally stock unfuc^H^Hixed board.

then just do the usual things needed for a5 boards yourself.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: chksum3 on March 15, 2014, 09:16:28 pm
Hmmm. I've thought about this all day, and I agree that the seller really should be expected to replace this board with a functioning and professionally refurbished substitute.  After struggling with this for awhile, and reading your identical suggestion - I did write to him again and ask that he fulfill this compromise. I asked for a professionally refurbished substitute board, as that is what I paid for in the first place (as I have no experience replacing surface mount components), and as I believe he should be given the chance to make good on the work.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: casinada on March 15, 2014, 09:28:14 pm
 ;)Not to defend anybody, that looks like a sloppy job. My A5 board was very corroded and it really crumbled to pieces as I was desoldering components. I was afraid I was going to lose traces but in the end everything worked out. I had to use some wire wrap wire to recreate traces. I removed the cotton traces after I took the picture :(
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: GreyWoolfe on March 16, 2014, 02:18:51 am
Your work is much better than the so called "professional" refurb job.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on March 16, 2014, 02:48:20 am
Hmmm. I've thought about this all day, and I agree that the seller really should be expected to replace this board with a functioning and professionally refurbished substitute.  After struggling with this for awhile, and reading your identical suggestion - I did write to him again and ask that he fulfill this compromise. I asked for a professionally refurbished substitute board, as that is what I paid for in the first place (as I have no experience replacing surface mount components), and as I believe he should be given the chance to make good on the work.

or, to make it easier on him (and you, too!) get an UNTOUCHED board from him, that way you don't trade one problem of his for another of his.  if its stock tek, then you can do the smd cap work and you already have done the unsoldering, so you are good at it, now ;)

you also have a copy of your eeprom data.  that data belongs more to 'the scope' than the a5 board (folks, correct me if I'm wrong about that) and so I'd restore that data to the new a5 board and you'd be whole again.

in fact, you already have the data in your NEW chip, so just keep the new chip. send the old chip back on the old a5 board (with the socket; leave that in, of course) and when you get the new untouched a5 board, do the socket thing again and you're back to where you should have been.

hope he goes for it.  by asking him for a non-modified board, it actually should be appealing to him.  he gets his 'work done to it' board, which he seems to think is worth something and you get to start fresh and do your own work on that a5.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on March 16, 2014, 02:50:07 am
oh, and if he does offer you an untouched a5 board, I'll help you out with the smd cap removal.  not a problem.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: chksum3 on March 16, 2014, 03:08:36 am
I emailed the seller and got his reply: an offer to receive the scope back for my money back.  I suspect folks out here will disagree with my decision, but I declined that offer and will keep the scope, aesthetic warts and all.   I am definitely bothered by the Ferrari with a Chevy bumper metaphor, but will fix all of that by finding another A5 board to work on myself. That will enable me to play with removal and replacement of SMDs in addition to replacing the NVSRAM again, which I found much easier than I thought would be the case.  All in all, it's all a learning experience, and it's all good.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on March 16, 2014, 03:15:39 am
you paid a lot for that scope and I would worry about 'what else could he have done wrong, to it'.  so far, you see the a5 'patches'.  you should probably look deeper to see if anything else was done.

yes, shipping is not going to be cheap, but a fresh start on another scope could be liberating ;)  and very likely, you'll be able to find one that is a good $150 or more cheaper and that could help offset the cost in shipping.  it would be fair if you two split the shipping cost; so he pays shipping out and you pay shipping back to him.

just a suggestion.  once there is doubt about a repair guy, I would want no part of anything he touched.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on March 16, 2014, 06:38:16 pm
Gary, what ever the decision, its yours. Hopefully it will last long and really interested to hear how it performs once its properly calibrated.

At least look at the bright sides, thanks to your sharing, which are don't buy Dallas DS1225 chip from Jameco  ::), and approach with extra cautions should anyone "desperately" needs to deal with that seller in the future.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: chksum3 on March 29, 2014, 03:15:18 am
Dear BravoV and Linux-works (I don't know your names)... thought I'd let you know that I changed my mind about the 2465b with the "potted" A5 board and returned it to the seller for a refund. I found that it also had non-linearity issues and was clearly not a properly calibrated instrument.  I've now purchased another 2465b that has not (I hope) been "refurbished," so I can go ahead and make that a project for myself.  Thank you again for your good advice and your patience.

-- Gary
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on March 29, 2014, 03:54:55 am
that's good to hear, gary.

at least it was a learning experience for all involved ;)

/bryan
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: chksum3 on April 03, 2014, 06:56:42 pm
The saga continues... I've now returned and received a refund for the previously purchased 2465b with the "potted" A5 components, and I've now received another scope (at a much lower cost) that functions well, but does show damage to the A5 board from the well described leaking SMT capacitors.  I've included 2 close-up photos of the leakage/damage, which seems localized.  What do you folks think: is this easily repairable, or not?  I've not (yet) played with SMD devices, but I'm eager to learn and experiment. 

Also, I note that the NVSRAM chip was manufactured 3/1992. If I go ahead with repairs, I'll order another DS1225 from Digikey along with the other needed components for a refurbishment of the A5 and the low-voltage power supply, as also appears to be recommended.   Thanks in advance for any advice.

-- Gary
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: casinada on April 03, 2014, 09:45:06 pm
It is good that the scope works but that corrosion looks nasty. Try to neutralize the corrosion as soon as possible. Worst case scenario you'll have to rebuild traces with wire. As soon as you try to remove some of the components, things will disintegrate, look at my pictures a few posts back. :(  Good luck with the scope :)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on April 03, 2014, 10:27:47 pm
if it was my board, I'd use hot air and remove as many of the smd parts near the corrosion as I could.  then clean with alcohol and ohm out the traces to see if the solder pads are connected (to the right traces).

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: chksum3 on April 03, 2014, 11:59:02 pm
Thank you both.  I'll be ordering parts tomorrow, and will be practicing SMT techniques over the coming few days before diving in.  I'll photo document my progress also. 

Another question: Could changing out old power supply capacitors change scope characteristics such that a scope calibrated within the past few years could then fail to function because of retained NVSRAM calibration factors that were recorded at last calibration, when the older components were in place?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on April 04, 2014, 02:36:41 am
Another question: Could changing out old power supply capacitors change scope characteristics such that a scope calibrated within the past few years could then fail to function because of retained NVSRAM calibration factors that were recorded at last calibration, when the older components were in place?

Don't think just by replacing the old "decaying" cap in the psu will affect the scope's cal, especially if the new replacement improves the psu output quality as the specification compared to previous state.

Remember, the psu output (as long within specification), is not the reference point for the measurements mechanism in the scope.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on April 04, 2014, 02:49:03 am
Had an offline discussion with Kibi when he was repairing his Tek 2445 (Here (https://www.eevblog.com/forum/testgear/tektronix-2445-repair/)) that he had to lift the huge A1 board, the mounts & connections which is identical to 2465/B, and he shared few photos that I think will be useful if anyone plan to detach the A1 board, and I think this photo tips is valueable and never seen elsewhere even at the Yahoo Tek maillist.

Thanks and credit to Kibi for allowing me to share this photos here.  :-+

Quoting his tips & photos on detaching the A1 board :

1. Must unsolder the wires that go to the X and Y plates.

(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=87803;image)


2. Now, I did not remove this PCB (HV) because it looked quite difficult to remove. The A1 PCB is easy to remove without taking this board out, but it's a bit more difficult to put the A1 back in because the pins don't line up nicely because of the A1 being at an angle when you put it back.

(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=87805;image)


3. Don't forget where these coax cables go and their orientation, (take some pictures).

(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=87807;image)


4. After removing the plastic front bezel, you must remove the strip of aluminium here to allow the front end BNC's to come out clear.

(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=87809;image)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MarkL on April 04, 2014, 11:48:43 am


Thanks and credit to Kibi for allowing me to share this photos here.  :-+

Quoting his tips & photos on detaching the A1 board :

1. Must unsolder the wires that go to the X and Y plates.
[...]

Just a minor note - You don't have to unsolder these wires.  They lead to single pin connectors on the CRT neck.  You can pull them off the CRT through the slot in the shield (carefully!).
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on April 04, 2014, 01:35:23 pm
Just a minor note - You don't have to unsolder these wires.  They lead to single pin connectors on the CRT neck.  You can pull them off the CRT through the slot in the shield (carefully!).

Thanks for the tiny detail update, didn't know that.

So are you saying that 4 wires some how get joined together into single wire, and it is connected to this white board pointed by the red arrow at photo below ?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MarkL on April 04, 2014, 03:55:40 pm
The individual wires are not joined together.  Those "pins" sticking out of the shield are actually connectors.  You can pull on them, gently, to detach them.

I've attached a picture of what it looks like without the shield.  (It's a different type of wire, but I'm just trying to illustrate what I mean).  This is a 2465 CRT (#154-0850-01) and you can see the three pins from your picture.  There are 4 pins on the other side where it attaches to the A1 board.

The CRT pins are thin and delicate.  Avoid bending them as much as possible since you don't want to stress where it goes into the the metal-to-glass seal.

I've also attached a picture of the whole gun assembly.  I think it's an impressive piece of glass work.  Those little dots taped to the outside are magnets to tweak the beam position.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MeloMel on April 04, 2014, 05:59:16 pm
Awesome thread and comments! I have the 2445B and I suppose it's much the same internals and should be helpful since I'm planning on opening my case and cleaning it out a bit. It's not been used in years, and is displaying an error code "Test 05 fail 44" - Main Board Positive level too positive. I've posted a thread for it already

Mel
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on April 04, 2014, 06:16:31 pm
The individual wires are not joined together.  Those "pins" sticking out of the shield are actually connectors.  You can pull on them, gently, to detach them.

I've attached a picture of what it looks like without the shield.  (It's a different type of wire, but I'm just trying to illustrate what I mean).  This is a 2465 CRT (#154-0850-01) and you can see the three pins from your picture.  There are 4 pins on the other side where it attaches to the A1 board.

The CRT pins are thin and delicate.  Avoid bending them as much as possible since you don't want to stress where it goes into the the metal-to-glass seal.

I've also attached a picture of the whole gun assembly.  I think it's an impressive piece of glass work.  Those little dots taped to the outside are magnets to tweak the beam position.

Thanks, but after seeing the tube and those metal pins and also the fragile glass that is holding them, why suddenly I had the chill and goose bumps.  ???

Anyway, this will come into mind if I'm going to lift the A1 board as plan B.

To be honest, I prefer to de-solder those Horz & Vert wires, only 4 and not too difficult and much less risk than cracking those glass while pulling the wires, imo.

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: casinada on April 04, 2014, 09:17:08 pm
Actually, if you need to take it apart is a good idea to disconnect and reconnect those pins as they tend to rust a little. So many problems can be fixed that way :)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MarkL on April 04, 2014, 10:05:02 pm
Actually, if you need to take it apart is a good idea to disconnect and reconnect those pins as they tend to rust a little. So many problems can be fixed that way :)
I'll second that.  When I got my 2465 the traces were intermittently jumping vertically.  I traced it to one of the deflection plate connectors.

It took a while to figure out.  The vertical plate pins on the A1 side pass *through* the CRT to the termination board on the other side.  I wasn't expecting that and I kept focusing on the vertical amp because I could see the output jumping.

I hate connectors.  It's always the connector.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on April 04, 2014, 10:11:39 pm
slightly OT: this is one reason (connectors suck) that I like wire-free builds as much as possible. 

on some pc's (mini-itx) you can have a full system with no cards (pci) and no wires at all.  the atx psu can be onboard, m-sata drives fit on m-sata connectors (the only connector you can't avoid other than RAM) and don't need power cables and everything else is soldered onboard.  for industrial use stuff, I try to remove as many wires and connectors as I can.

when I get old gear that has ic sockets, I also mistrust those, too.  cpu sockets seem ok but DIP sockets are often a failure point.  the old heathkit 'molex pins' sockets were the worst thing I've seen, for 'sockets'.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: chksum3 on April 05, 2014, 04:49:38 pm
re. 2565b A5 Board repair -->

I've now double checked the components on the A5 board here against the serial number of the scope (59877) and the service manual parts list to verify the board I have was not a swapped-out replaced board (different serial numbered boards used slightly different component values).  Everything checks out, i.e. this A5 is appropriate to the scope's serial number. 

I've also looked over the entire board under high magnification and have convinced myself that damage only extends from a leaking C2113 (10uF-35V electrolytic) to C2520 and C2222 (0.1uF-50V non-electrolytics). All other traces and components seem to have escaped damage. 

Before I can go ahead and order replacement components, I've got a very basic question for you all, as I am entirely new to SMDs and don't have a micrometer to do my own measurements.  From an earlier posting (here, or elsewhere - I don't remember) by H.Holden Oct. 2013, I plan to replace the four leak-prone cylindrical electrolytic units (C2011, C2331, C2113, C2965 - Panasonic FK SMD series devices) with tantalum SMDs instead.  I have no idea if there are preferable replacement types for C2520 and C2222 (the 0.1uF-50V) non-electrolytic capacitors.  Does anyone have the specifics re: sizes, manufacturers, etc. for these 6 components?  Thanks again...
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on April 06, 2014, 09:22:26 am
Gary, since you're going to clean it up 1st anyway, and you still don't know the extend of the damages at the traces and the cap's pads there.

Cause once all cleaned and damages are fully inventoried, there are chances they you may need to do some patch works to restore the cap's pads if they're heavily corroded, and "probably" it may need larger foot prints than the original ones, just a thought.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: chksum3 on April 06, 2014, 04:01:05 pm
Good point - I hadn't considered that! Thanks.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: chksum3 on April 10, 2014, 03:22:34 am
Progress report re: preparing to renovate my 2465B A5 board's SMT components: I just received a cheap, used Aoyue soldering tweezers station via eBay and tried it out on an old, discarded board populated with various SMDs.  It was surprisingly easy to desolder various components (all of which are significantly smaller than those populating the A5 board).  Resoldering, using a fine tip temperature controlled iron (also an inexpensive Aoyue unit), went just about as easily.  I've become a believer that SMD board repair is not a particularly difficult undertaking, provided the correct tools are at hand.  Many thanks to linux-works for his insight and suggestion to go with the tweezers.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on April 10, 2014, 03:27:42 am
I predict the tweezers are going to go up in price once people start to catch on to how useful those things can be.

I was watching a pace video that showed them removing large square smd chips with right-angle tweezer 'tips' and it was amazing to see how easy and fast it was!

one thing I am going to try, next time around, is this nozzle for hot air.  looks like just the thing for removing 2 lead devices:

(http://ecx.images-amazon.com/images/I/31dUmNR4mEL.jpg)

one nozzle is fixed and the other can move in or out, then you tighten the philips screw and do the hot air unsoldering.  I can't wait to try this attachment out ;)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: m1kta on April 10, 2014, 10:49:03 am
Seem to have lost the post to thread... ho hum apologies if this appears twice.

I have created photos and break down notes from my 2465CTS... slightly different model to what I have seen here and lot more packed inside.

http://m1kta-qrp.blogspot.co.uk/2014/04/oscilloscope-tektronix-2465cts.html (http://m1kta-qrp.blogspot.co.uk/2014/04/oscilloscope-tektronix-2465cts.html)

72

Dom
M1KTA
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: m1kta on April 10, 2014, 11:12:48 am
Images
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: KJDS on April 10, 2014, 02:00:23 pm
I picked up a 2465B today, which as it is in full working order isn't something I'm going to take apart, but have enjoyed seeing what's in there.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on April 10, 2014, 02:51:29 pm
I picked up a 2465B today, which as it is in full working order isn't something I'm going to take apart, but have enjoyed seeing what's in there.

If its still untouched from Tek factory, as least you need to do the A5 digital board to refresh the pesky Dallas bbsram that is holding the scope cal. , and definitely its already passed it's specified battery life.

Btw, just curious, you're well known here that have access or probably own many high end T&M gears and also selling them, which some beyond the reach of common hobbyists level, why still buy this "old clunker" ?  :o Sentimental value ? Anyway, welcome to the club.  >:D
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: KJDS on April 10, 2014, 03:49:47 pm
I picked up a 2465B today, which as it is in full working order isn't something I'm going to take apart, but have enjoyed seeing what's in there.

If its still untouched from Tek factory, as least you need to do the A5 digital board to refresh the pesky Dallas bbsram that is holding the scope cal. , and definitely its already passed it's specified battery life.

Btw, just curious, you're well known here that have access or probably own many high end T&M gears and also selling them, which some beyond the reach of common hobbyists level, why still buy this "old clunker" ?  :o Sentimental value ? Anyway, welcome to the club.  >:D

I bought it because it was the right price. I may need a fast scope soon, just bidding on some design work that may need a genuinely fast scope and the next fastest analogue scope I have is a 150MHz 2445. I do prefer analog scopes for looking at analog signals.

Thanks for the warning on the Dallas RAM.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: grumpydoc on April 10, 2014, 04:27:22 pm
The SMD caps on the A5 board in the 2465B are also notorious - probably should be replaced even if they look OK (see earlier in this thread).
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: m1kta on April 10, 2014, 04:30:47 pm
If its still untouched from Tek factory, as least you need to do the A5 digital board to refresh the pesky Dallas bbsram that is holding the scope cal. , and definitely its already passed it's specified battery life.
Does this effect ALL 2465 models?

Is this process documented/detailed anywhere?

Dom
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on April 10, 2014, 04:38:22 pm
not the base model or the A version, just the B version.

lots here on the 2465 series; you'll spend a bit of time searching thru it all, but its all explained here and on the yahoo tek-scopes group.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on April 10, 2014, 04:44:27 pm
The SMD caps on the A5 in the 2465B board are also notorious - probably should be replaced even if they look OK (see earlier in this thread).
+1, the well known problems for this Tektronix series which are the SRAM battery that is running out of juice, and the SMD electrolytic caps at the A5 board that leak like hell, this thread has a good example -> HERE (https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg406487/#msg406487), or HERE (The damaged vs the good one) (https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg406409/#msg406409) :o


Does this effect ALL 2465 models?

Is this process documented/detailed anywhere?

Dom
Dom, not sure about your 2465CTS, maybe you can share the photo of your A5 digital board about the caps and maybe its using the same Dallas DS1225Y too, not very sure my self.

On the Dallas, its a "Battery" Backed Static Ram (BBSRAM), and just read the datasheet yourself, it's specification on the battery life is maxed out only for 10 years. And if your 2465CTS also using it, its very likely already aged more than 10 years.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: casinada on April 10, 2014, 08:59:58 pm
On the B series probably above serial number 50000
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: guido on April 10, 2014, 10:39:02 pm
Does this effect ALL 2465 models?

A plain 2465 (no A or B) does not have SMD caps and no Dallas chip. Instead regular elco's and a very early kind of EEPROM (called EAROM).

I'm working on one. I've done a nearly full recap (elco's and X and Y caps), replaced two broken zeners and swapped the switches pannel. I'm now looking at a focus problem (found a broken pot, but there is more damage) and i need to get a new preamp module for one of the channels.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: m1kta on April 11, 2014, 10:31:40 am
The SMD caps on the A5 in the 2465B board are also notorious - probably should be replaced even if they look OK (see earlier in this thread).
+1, the well known problems for this Tektronix series which are the SRAM battery that is running out of juice, and the SMD electrolytic caps at the A5 board that leak like hell, this thread has a good example -> HERE (https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg406487/#msg406487), or HERE (The damaged vs the good one) (https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg406409/#msg406409) :o


Does this effect ALL 2465 models?

Is this process documented/detailed anywhere?

Dom
Dom, not sure about your 2465CTS, maybe you can share the photo of your A5 digital board about the caps and maybe its using the same Dallas DS1225Y too, not very sure my self.

On the Dallas, its a "Battery" Backed Static Ram (BBSRAM), and just read the datasheet yourself, it's specification on the battery life is maxed out only for 10 years. And if your 2465CTS also using it, its very likely already aged more than 10 years.

I'll drop a photo of the board here after lunch (about 3 hours from now).

The A5 logic and control board is the one the outside right of the scope looking from the front right?

Dom
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on April 11, 2014, 04:56:17 pm
I'll drop a photo of the board here after lunch (about 3 hours from now).

The A5 logic and control board is the one the outside right of the scope looking from the front right?

Dom
Yep, the long rectangle shaped board at the right side of the scope (front view), and if you see it closely, the board has almost all logic chips populated in it.

(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=89134;image)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: casinada on April 11, 2014, 09:20:38 pm
It has SMD components => s/n > 50000
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on April 12, 2014, 02:55:30 am
I bought it because it was the right price. I may need a fast scope soon, just bidding on some design work that may need a genuinely fast scope and the next fastest analogue scope I have is a 150MHz 2445. I do prefer analog scopes for looking at analog signals.

Hey KJDS, I just visited your ebay shop and I can see you're also selling a 500 Mhz DSO.   :o

Understand its an old DSO, its just I'm very curious why your prefer using a 400 Mhz old analog scope than the one you already have in hand ?

Please, if its not too troublesome for you, share on the real world examples or any reasons even its subjective that at your design work, this old clunker is better than that DSO, maybe create another new thread for that ?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: m1kta on April 12, 2014, 07:10:18 am
I'll drop a photo of the board here after lunch (about 3 hours from now).

The A5 logic and control board is the one the outside right of the scope looking from the front right?

Dom
Yep, the long rectangle shaped board at the right side of the scope (front view), and if you see it closely, the board has almost all logic chips populated in it.

Sorry didn't mange it at lunch... mine does not look like that. All through hole, no SMD

All the boards look like have zero corrosion on them and almost pristine condition (bit of dust).

So looks like might not have anything more too do. Those caps 0.068uF.... I have 0.1uF close enough or do I need to stick wit the value?

Dom
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: KJDS on April 12, 2014, 07:24:33 am
I bought it because it was the right price. I may need a fast scope soon, just bidding on some design work that may need a genuinely fast scope and the next fastest analogue scope I have is a 150MHz 2445. I do prefer analog scopes for looking at analog signals.

Hey KJDS, I just visited your ebay shop and I can see you're also selling a 500 Mhz DSO.   :o

Understand its an old DSO, its just I'm very curious why your prefer using a 400 Mhz old analog scope than the one you already have in hand ?

Please, if its not too troublesome for you, share on the real world examples or any reasons even its subjective that at your design work, this old clunker is better than that DSO, maybe create another new thread for that ?

I just prefer living in an analog world. There's no more logical reason to it than my choice of cars.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SL4P on April 12, 2014, 07:35:04 am
Gotta say - even though it's a long time ago - these photos remind me why the 2465 series are still my favourite old school scope.  No question. Before I used a 2465, it was easy to lug around a 465B - and it was lighter!
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: chksum3 on April 12, 2014, 11:58:11 pm
Progress report on repairing my 2465B with A5 board leak-damage from 2 of the 4 notorious electrolyic caps.  The 4 offending caps were removed with both a fine-tipped solder station and using a soldering tweezers.  Also, 3 of the small 0.1uf caps in the vicinity of the leaking electrolytics were also removed.  The electrolytics were replaced with tantalum types and the 0.1s with ceramics. 

I've attached two photos: 1) the pads and traces, one of which had decayed completely; a couple others were corroded but enough remained for resoldering.  After thorough cleaning, the damaged pad and trace were repaired with a small piece of adhesive backed copper foil I found at a local shop, and the new parts replaced.  The board was reinstalled and the second photo was taken. 

Oh, also the old Dallas NVSRAM was desoldered and read into a file, that file was then written to the new Dallas.  I decided to use a low-seat type gold plated machine pinned socket which offers a tight and secure fit without damaging the pins of the new Dallas. (I experimented first with the removed chip by installing it into the not yet soldered socket to see if pins bent, or if the pins stuck in the socket.  I was able to seat and to remove it without damaging anything, so I decided the wiper type socket wasn't needed.)  The socket was then soldered to the board and the newly written NVSRAM was socketed - again, without difficulty.

All in all - no surprises - all went well.  Very happily, the scope started, went through its routines normally and appears to be completely functional.  I am one happy guy, and very thankful to all of you for sharing your experiences and making it relatively easy for those of us down here on the learning curve.

Parts list for the repair:

DS1225Y-200+-ND 64Kbit 28EDIP chip (DigiKey part#: DS1225Y-200+-ND)
low-seated gold plated 28 machine-pin socket
C2011, C2965: 33uF 10v tantalum, size 2312, Vishay (DigiKey part#: 718-1075-1-ND)
C2113, C2331: 10uF 35v tantalum, size 2312, Vishay (DigiKey part#: 718-1052-1-ND)
C222, C2520, C2890: 0.1Uf 50v ceramic, size 1260, Kemet (DigiKey part#: 399-1250-1-ND)

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: GreyWoolfe on April 13, 2014, 12:13:19 pm
Congratulations on the repair job.  Enjoy the scope!
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: m1kta on April 13, 2014, 05:01:23 pm
I have created photos and break down notes from my 2465CTS... slightly different model to what I have seen here and lot more packed inside.
http://m1kta-qrp.blogspot.co.uk/2014/04/oscilloscope-tektronix-2465cts.html (http://m1kta-qrp.blogspot.co.uk/2014/04/oscilloscope-tektronix-2465cts.html)

Tnx all for help... fixed and working again.

http://m1kta-qrp.blogspot.co.uk/2014/04/tekronix-2465cts-scope-fixed.html (http://m1kta-qrp.blogspot.co.uk/2014/04/tekronix-2465cts-scope-fixed.html)

72
Dom
M1KTA
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on April 13, 2014, 05:13:26 pm
@Gary, congratulations !  :clap: Looks really neat after the re-cap  :-+, I can see the traces are not too corroded. Great, at least you don't need to worry about loosing the calibration and since yours also made in 90s, hopefully it will last many years to come.

Btw, if I'm not mistaken these made in 90s or with serial no. > 50000 don't use the crap high voltage cap anymore like Dom's, but just suggesting to check it out.

The left section is the high voltage mains area, there are two red boxed caps pointed by the blue arrows. This type should not be a problem.

(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=89407;image)


While bad example are like at older version which uses these well known transparent caps that will burst once aged.  :-\

(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=89405;image)

Dom, permission to "steal" your photo if you don't mind.  :P



@Dom, congratulation too, glad to see it works now, great job you've done there.  :-+

Btw, your A5 board doesn't use the bbsram and not infected by those leaky smd electrolytic caps.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: chksum3 on April 13, 2014, 05:47:07 pm
Many thanks!  After a little breather, I'll open the cabinet again and begin work on the LV and HV sections. Although all is well, I gather it is best to be proactive and swap out all those older electrolytics before disaster strikes.  I'll be sure to look for those highly problematic caps in the HV area first - just in case they were still being used.  Best to all.   
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: m1kta on April 14, 2014, 05:51:09 am
Btw, if I'm not mistaken these made in 90s or with serial no. > 50000 don't use the crap high voltage cap anymore like Dom's, but just suggesting to check it out.

The left section is the high voltage mains area, in there there are two red boxed caps pointed by the blue arrows. This type should not be a problem.

(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=89407;image)


While bad example are like at older version which uses these well known transparent caps that will burst once aged.  :-\

(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=89405;image)

Dom, permission to "steal" your photo if you don't mind.  :P

No problem.

I replaced with same cap type but if fails again I'll know where to look.

72

Dom
M1KTA
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: m1kta on April 14, 2014, 09:43:36 am
.... if I'm not mistaken these made in 90s or with serial no. > 50000 don't use the crap high voltage cap anymore like Dom's, but just suggesting to check it out.
BTW everyone do not assume just because the serial number (front panel to the right under the 2nd channel input) is >50000 these capacitors are not used.... my serial is B050949, visually check them, mine had a HV black cover over the area so you have to take that off first.

Anyone got the CTS manual anywhere? I can use it as a regular scope (2+2 channel) but not worked out the CTS bit yet.... or found a PC to scope interface I can clone.

Dom
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MarkL on April 14, 2014, 04:57:37 pm
Anyone got the CTS manual anywhere? I can use it as a regular scope (2+2 channel) but not worked out the CTS bit yet.... or found a PC to scope interface I can clone.

Dom
Look around the net for the regular 2465 option 09 (counter timer/word recognizer) and option 10 (GPIB) manuals.  The CTS was just a specially priced bundle of those options plus some additional probes.  After a quick look I'm not seeing a free PDF of them, but you can search some more.

I have a 2465 with these options, but not bought as a CTS.  Before you go through the trouble of getting GPIB connectivity, be aware that the GPIB functionality is very limited (read the option 10 manual).  You can set and query things as you would from the front panel, but you can't do automatic measurements (e.g., Volts pk-pk) since the 2465 can't do them natively.  The only exception to this is that you have full control over the counter/timer unit so you can do those measurements remotely.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: m1kta on April 14, 2014, 05:07:35 pm
Tnx 72 Dom M1KTA
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: fpliuzzi on April 14, 2014, 06:07:24 pm
Here's the link to the "24X5A/2467 Options Service Manual". It contains service info for the following options.

01 (DMM)
05 (TV)
06 and 09 (CTT & WR)
10 (GPIB)

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CCkQFjAA&url=http%3A%2F%2Fbitsavers.trailing-edge.com%2Fpdf%2Ftektronix%2Fscope%2F070-5857-00_24x5aOptions_Jun87.pdf&ei=nCFMU6DCI_bLsQSz64CwCQ&usg=AFQjCNE4Y_ZMzOg8JrgMinwOLnylrfTsIA&sig2=tzZ3mtsmt4uOkHgozdW3UQ&bvm=bv.64542518,d.cWc (http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CCkQFjAA&url=http%3A%2F%2Fbitsavers.trailing-edge.com%2Fpdf%2Ftektronix%2Fscope%2F070-5857-00_24x5aOptions_Jun87.pdf&ei=nCFMU6DCI_bLsQSz64CwCQ&usg=AFQjCNE4Y_ZMzOg8JrgMinwOLnylrfTsIA&sig2=tzZ3mtsmt4uOkHgozdW3UQ&bvm=bv.64542518,d.cWc)

I also wanted this pdf file because my newly acquired TEK 2445 contains option 05. I received some replacement electrolytics and Y2 safety capacitors from Digi-Key this morning so I should have the 2445 on my bench soon. I just need to find two small replacement knobs for the intensity and focus controls.

Regards
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MarkL on April 14, 2014, 07:36:07 pm
Here's the link to the "24X5A/2467 Options Service Manual". It contains service info for the following options.
[...]
These are for the "A" version.  From the old catalog info I have, the CTS version is based on the plain 2465 (no A or B).

The "A" manuals may or may not be suitable; I don't know the internal subtleties of all the different models.

I have a printed copy of the "2445/2465 Option 06 and Option 09 Counter/Timer/Trigger and Word Recognizer Service Manual", pub #070-4632-00, so I can say the service manual is not the same.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: fpliuzzi on April 14, 2014, 08:11:56 pm
Thanks for the clarification.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: guido on April 14, 2014, 11:16:24 pm
I just need to find two small replacement knobs for the intensity and focus controls.

If you find a source, please let me know. I need four times 366-2041-0x.

I'm currently fighting the edge focus circuit. Found a 10nF cap that measured 25 ohms. Low enough to kill the pot when turned to 42V. Put in a new pot and swapped the cap. Now the opamp is not behaving.... Work in progress  :D
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mwilson on April 15, 2014, 08:13:06 pm
Thanks for everyone's great info about replacing the leaking caps and battery-backed RAM in the Tek scopes. I just picked up a nice 2467B and it works great but does have a small amount of black sludge around the capacitors on the A5 board. I'm going to embark on the project to replace those caps and put a fresh BBSRAM on the board, but I'm curious what the best way to clean the sludge off the board is. Should I try to clean before desoldering the caps so I don't "cook" the stuff onto the board, should I just get the caps out of the way then clean, etc. Is Isopropyl alcohol the right cleaning agent to use?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: chksum3 on April 15, 2014, 10:12:07 pm
Please wait for others to comment on this, as my experience is very limited.  I had success with first removing the offending components, then repeatedly cleaning with 99% isopropyl alcohol and Q-tips.  I next removed every trace of old solder I could on the pads with gentle use of solder wick, and then again alcohol re-cleaned everything in sight until, under magnification, all gunk was gone and no residue was seen on the just used Q-tip.

Regarding the purchase of the NVSRAM: as recommended by other people out here, consider ordering from DigiKey. I first ordered (twice) from a local company (Jameco) and found that my programmer could not successfully write to either of the devices.  The word is, other people have had similar experiences.

If it's not too difficult, please consider uploading a close-up photo of the board damage for all to see.
 
Have fun, and congratulations on your new 2467B!
 
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: guido on April 15, 2014, 10:46:45 pm

A quick question for all the 2465 users here. One of the things i notice is that the brightness of the traces goes up if i switch on more channels. Doesn't matter which ones. So channel 1 on and then switch on 2; both become brighter. Switch on 3 and all three even more brighter. Ditto for the last one.

I'm wondering if this is a bug or a feature. It's normally the other way around with other scopes; switch more channels on and brightness goes down. Which is logical. So i'm wondering if this is over(?) compensation i'm seeing.

Thanks.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on April 16, 2014, 02:19:37 am
Thanks for everyone's great info about replacing the leaking caps and battery-backed RAM in the Tek scopes. I just picked up a nice 2467B and it works great but does have a small amount of black sludge around the capacitors on the A5 board. I'm going to embark on the project to replace those caps and put a fresh BBSRAM on the board, but I'm curious what the best way to clean the sludge off the board is. Should I try to clean before desoldering the caps so I don't "cook" the stuff onto the board, should I just get the caps out of the way then clean, etc. Is Isopropyl alcohol the right cleaning agent to use?

Congrats on the score, that beast you have there is probably the fastest portable analog scope ever made on earth.  :clap:

Yeah, de-solder 1st then clean, other wise worry the cap will still oozing out the nasty liquid while you clean it on board.  |O

Please, share some close up photos like before and after re-work, especially the affected area as it will be a good reference for others in the future.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mwilson on April 18, 2014, 12:47:56 am
.... if I'm not mistaken these made in 90s or with serial no. > 50000 don't use the crap high voltage cap anymore like Dom's, but just suggesting to check it out.
BTW everyone do not assume just because the serial number (front panel to the right under the 2nd channel input) is >50000 these capacitors are not used....

Confirmed. My scope is from late 1991, serial number B051767, and it has those transparent caps, not the red ones. Looks like getting that board out to replace the high voltage caps is more of an ordeal than getting the A5 board out for the other repairs. The transparent caps haven't burst yet but I should probably take care of those now before it does eventually happen. I'll grab pics for everyone as I go....
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on April 18, 2014, 04:11:21 am
I've read it somewhere that film cap with transparent case especially the old one, is plagued by that outer transparent plastic material it self, that it will dry out and crack once its aged enough.

The humidity from the air slowly sip into the structure through the micro cracks at thermal cycling, and water will slowly trapped/accumulated in the cap, and will create short circuit between the electrodes once its accumulated enough in there. Hence its common to see them burned/burst into flame and leaving charred mark everywhere.  |O

While the one like the opaque red case doesn't have this problem since it uses much better plastic material.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: iloveelectronics on May 01, 2014, 01:54:59 pm
I just joined the Tek 2465B club and got this unit from China last week. It seems to be functioning alright but BravoV told me to take a few inside pictures as mine looks like a Japanese made unit with a Sony/Tektronix badge on the back and a serial number that starts with "J3". I took it apart quickly and snapped a few pictures with my phone today, just before I had to leave the shop. I see some worrying images :(

Yes, I turned it on, before taking it apart:
(http://i.imgur.com/AvRuhKn.jpg)

There's a small blip near the second horizontal division with no signal (only on a couple of timebases):
(http://i.imgur.com/wU0J1QB.jpg)

Back side of the scope. You can see "Sony/Tektronix Corp. TOKYO, JAPAN":
(http://i.imgur.com/hZHGqN4.jpg)

Main board on the bottom. Apart from being a bit dusty, all seems to look good:
(http://i.imgur.com/H9iNZb6.jpg)

On the side:
(http://i.imgur.com/TWbuEJ3.jpg)

On the top, the CRT. Now this really doesn't look right :( That thing looks like a big piece of charcoal! Can anybody tell me what that thing is and what could have been going on here?
(http://i.imgur.com/tRUzyFc.jpg)

The power supply board. I haven't read this thread prior to taking this picture so I didn't know I needed to pay attention to the HV caps near the left side. From what I can see I've got those infamous transparent ones. Will have to take a closer look the next time.
(http://i.imgur.com/wxMYB1E.jpg)

Right side of the A5 board:
(http://i.imgur.com/ILaSGTA.jpg)

Left side of the A5 board. Again, I didn't read this thread so didn't know about the leaky caps area. I only reviewed the photo after I've taken it and I was shocked to see the corrosion and the completely missing electrolytic caps!!
(http://i.imgur.com/xPl6ZRx.jpg)

Here's an enlarged view:
(http://i.imgur.com/eUQS6DN.jpg)

I didn't expect to see what I saw as the unit was working while I tested it. What are those missing caps used for? And that charred part near the CRT?

Any help would be highly highly appreciated in restoring this unit. Thanks!


Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on May 01, 2014, 02:11:28 pm
missing caps!  wow ;(

amazing it even works.  I guess those caps are not mandatory but they are surely not OPTIONAL, either ;)

one thing that you lucked out on, and I'm jealous of: you have probe power sockets!!  I paid nearly $100 for a 1101 power supply just to give me probe power LEMO sockets.   with those, (5,15,-15v) you can power fet probes and stuff like that.  pretty cool and I have not seen one (photos) with probe power jacks before.  to me, that's worth $50 to $100 more just for that.

I used these parts, from mouser, for the caps:

647-PCF1C330MCL1GS
647-PCX1V100MCL1GS

organic polymer caps, not 'lytics, so they should last forever (in theory).

check me on those part numbers, but I think those are correct.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: grumpydoc on May 01, 2014, 02:29:34 pm
Quote
That thing looks like a big piece of charcoal! Can anybody tell me what that thing is and what could have been going on here?
It's the coupling for the final anode connector - so that you don't have to disconnect the cup if changing a CRT.

They often get covered in carbon soot which gets electro-statically attracted to the high tension, that's the sootiest I've seen though.

Probably worth cleaning all that soot off with some IPA (take care, the anode potential is 14kV so not one to do with the 'scope powered up and if you pull it apart bear in mind that a CRT anode connector can bite even with the power off).
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SeanB on May 01, 2014, 03:11:16 pm
A quick clean up of that anode connector, a generous application of polishing on the plastic and a spritz of anti corona spray and that will do for a long time. The caps will need cleaning of the board, looking for the dead bugs inside the case and soldering of new ones onto the board. As well you might want to read out the RTC chip and get a replacement one for when that one dies.

When I was working for the SAAF I got a 2223, and after about 6 months the digital board died. Unplugged the power connector and used it as a plain analogue scope for another 3 months till it's cal cycle time was due, and then plugged the board back in and sent it off. Came back with a new digital board.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: KD0CAC John on May 01, 2014, 03:39:41 pm
Will have to use this thread to look for the next broken piece of gear for my bench ;)
Being that disability is my regular source of income , I look for dead gear for my bench & ham radio shack .
And the next benefit to broken gear , is having to learn how to fix .
I've been in many trades and at least half of those , or more , were hobbies and then wanting to build / repair my own toys .
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: iloveelectronics on May 02, 2014, 02:31:06 am
A few more pictures...

The fan (after some cleaning up). Curiously, like BravoV's unit, the date code (if that's what it is) indicates a 2004 date while everything else inside has 89/90 dates.
(http://i.imgur.com/C0iTqGw.jpg)

The probe power sockets (option 22):
(http://i.imgur.com/oibheAu.jpg)

Another look on the power supply board, with the black plastic shield on the left removed:
(http://i.imgur.com/aph7Bdr.jpg)

Some solder joints look like they have some corrosion going on but they are actually fine. It's just some sort of reflection in the photo. Unfortunately this unit has the HV caps with the transparent housing. This one in the picture still looks OK:
(http://i.imgur.com/fhi2n0K.jpg)

Not the other one though. It's already cracked open:
(http://i.imgur.com/QfCENDc.jpg)
(http://i.imgur.com/FVWHuPg.jpg)

And here's a close-up view of the leaky/missing caps area after initial cleanup:
(http://i.imgur.com/oDpKuCd.jpg)

I've tested continuity and the one with only half a pad left seems to have lost connection to the trace. Shouldn't be difficult to fix given the proximity. The other pads are fine--ish.

I was trying to see if I could get the power supply board out but have had no luck. Can someone tell me how I should go about doing that? Does it come out together with the other board attached to it?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on May 02, 2014, 02:42:12 am
the power supply board pair comes out as a pair.  loosen the rear screws since its physically tight and very hard to remove the way tek designed it.  I struggled a lot to get my board pair out.  its not meant to be taken out, so you -have- to loosen a few chassis screws to -create- clearance to remove the boards.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: iloveelectronics on May 02, 2014, 03:23:09 am
the power supply board pair comes out as a pair.  loosen the rear screws since its physically tight and very hard to remove the way tek designed it.  I struggled a lot to get my board pair out.  its not meant to be taken out, so you -have- to loosen a few chassis screws to -create- clearance to remove the boards.

Thanks a lot! Loosening up the rear panel helped. I've now taken the PS board out. Yet more pictures...

Better look on the crack opened HV cap:
(http://i.imgur.com/4t8tQWp.jpg)

I didn't see where this dangling connector go while I pulled out the board  |O It's coming from the TV option board. Does it connect to J305 in the second photo (the other PS board in the pair)?
(http://i.imgur.com/5PhXRZe.jpg)
(http://i.imgur.com/OPSnbpB.jpg)

Does anyone have the part numbers for those 2 HV caps handy, before I dig into the service manual? Thanks a lot for all the help given in this thread so far!
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mwilson on May 02, 2014, 04:41:25 am
Does anyone have the part numbers for those 2 HV caps handy, before I dig into the service manual? Thanks a lot for all the help given in this thread so far!

Yep, I'm actually putting together a DigiKey order for repairing my 2467B right now. They carry those exact same caps, Kemet part number PME271M568MR30 (CAP FILM 0.068UF 275VAC RADIAL). I'm debating whether to replace with new ones of the same type that have proven to be dodgy or going for something different that should be compatible like Panasonic ECQ-U2A683ML.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on May 02, 2014, 09:47:23 am
Franky, thanks for sharing the photo shots, glad the corrosion caused by the leaked caps didn't do heavy damages there, and look like all traces still intact except for that half pad, btw great cleaning job you've done there.  :-+

Btw, this confirmed that these particular hv transparent film cap is cursed, in this thread alone already two proven cases, hope this will help others in the future as reference and replace them before bad thing happened.

I guess you have many home works to do for this beast, btw just remember, when powering the whole scope without the enclosure, make sure you have a big fan blowing the "whole" giant A1 board with the scope up side down position, so those unobtainium hybrid ICs get cooled properly.

Looking at your fan's date code, year 2004 ?  ??? Wow, if its the original fan came with the scope from the Japan factory, then your 2465B is definitely quite fresh imo.

Regarding your missing caps at A5 board, suggesting after you desoldered the old Dallas chip, install a good dip or sip socket for the new Dallas DS1225 chip, so it will be easy to backup & restore the calibration in the future.

Btw, spotted another missing cap at your A5 board at the right upper corner, besides the screw pointed by the red arrow. Also there are other A5 examples at this post -> Here (https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg406401/#msg406401) for comparison.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: iloveelectronics on May 06, 2014, 09:48:41 am
Got a little bit of time today so decided to desolder the two 250V film caps on the power supply board. The one that still looks normal measures about 83nF, which is still within tolerance I guess. But the broken one measures only 170pF! I'm really surprised this scope was working despite the missing caps on the A5 board and this broken film cap!

BTW, thanks BrovoV, for spotting the other missing cap on the A5 board! I've ordered them now from Mouser (using the part numbers given by linux-works), and hopefully will receive them in a few days. The Dallas NVRAM is on backorder though so it looks like I will have to wait a couple of months :( Will certainly backup the data when I work on the A5 board though.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on May 06, 2014, 05:49:50 pm
Even at the normal one if you look closely at the clear plastic case, it is already has so many fine cracks at it's surface.

Btw, about the Dallas chip, actually you can start desoldering it now while you're working at A5 board, buy & solder a good quality DIP or twin SIP sockets at the pcb, and the most important is to back it up 1st using your TL866, and put it back while waiting for the new chip to arrive.

Remember, the lithium battery that is holding the scope's calibration in your Dallas BBSRAM chip is > 20 years old now (date code 90xx), imo its wise not to trust your luck on it for too long.  >:D
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: guido on May 07, 2014, 11:31:03 pm
(http://members.home.nl/baltusg/2465_3.jpg)

One more up and running :D

Fixed two zener diodes (reference supply protection and attenuator supply).
Replaced a broken 10nF cap in the HV section (and swapped a similar one), which 'shortened' one of the trimmer pots to gnd (40V to ground = broken trimmer).
Replaced the whole pots/switches pannel (cheaper than getting separate time/div and volt/div switches, which were bent).
Replaced a broken attenuator (did swap channels for test and verified that the relays were ok).
Replaced all elco's and X / Y Rifas in the PS section.

Got it quite cheap, so all in all a good outcome.

PS, no Dallas chip in these early models but an EEPROM (called EAROM). I've noted all the values, so in the future i might be able to replace it with a modern solution if it would fail.

I've read the temperature stories about the U800 chip. But i was also told it is not related to temperature, but because of outsourcing the manufacturing from tek to a third party. The original tek chips don't break. If that is true, i'm safe as it is a very early 2465 (Guernsey). It is also full of factory installed bodges (as in reworks).


A quick question for all the 2465 users here. One of the things i notice is that the brightness of the traces goes up if i switch on more channels. ........

I'm wondering if this is a bug or a feature. .............

Well, RTFM. A feature. It is just that mine is adjusting too much. Specially going from one to two channels. Minor thing.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on May 08, 2014, 03:08:35 am
I've read the temperature stories about the U800 chip. But i was also told it is not related to temperature, but because of outsourcing the manufacturing from tek to a third party. The original tek chips don't break. If that is true, i'm safe as it is a very early 2465 (Guernsey). It is also full of factory installed bodges (as in reworks).

Well, my U800 chip was almost too hot to touch by fingers at the black ic body even there was a big fan blowing strong wind on it.

Yes, it was outsourced to Maxim IC after Tek decided not to produce it anymore, as far as I know, there are two versions of this U800 chip (TEK part no 155 0241 02) , photo of both attached below.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: w2aew on May 08, 2014, 02:57:34 pm
I've read the temperature stories about the U800 chip. But i was also told it is not related to temperature, but because of outsourcing the manufacturing from tek to a third party. The original tek chips don't break. If that is true, i'm safe as it is a very early 2465 (Guernsey). It is also full of factory installed bodges (as in reworks).

Well, my U800 chip was almost too hot to touch by fingers at the black ic body even there was a big fan blowing strong wind on it.

Yes, it was outsourced to Maxim IC after Tek decided not to produce it anymore, as far as I know, there are two versions of this U800 chip (TEK part no 155 0241 02) , photo of both attached below.

Well, not really outsource.  Tektronix had its own internal IC fab - called the Integrated Circuits Operation (ICO).  Tek sold ICO to Maxim in 1994.  It is still co-located on the Tektronix campus in Beaverton.  So, the name changed, but the fab remained the same. 

At the same time, Tektronix sold half-interest in their hybrids design and manufacturing group to Maxim, which formed the group known as MaxTek.  Several years ago, Tektronix bought out Maxim's interest in MaxTek, returning this group to be wholly owned by Tektronix.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: e-pirate on May 08, 2014, 04:44:54 pm
Hi folks!
A couple weeks ago I was lucky to get myself Tektronix 2467B. It's a end of 91 unit, produced in Japan by Tektronix-Sony (and seems to arrive somewhere from Japan because I found some papers with handwritten Japanese hieroglyphs inside pouch at the top of it). It's in a perfect visual condition and actually looks like a new device. TEST5 shows something under 2000 work-hours and about 900 power-on cycles, I'm not sure if I can trust this. But when I got into unit I was not able to find even a single tiny mark of dust on any of PCBs or parts, the only place that had just minor signs of dust is _original_ NIDEC fan, that is actually all most silent. Nothing soldered/repaired there. But dude, that sold it to me replaced A5 electrolytic caps and told me that the PCB is fine, and yes, it's virgin looking board without any signs of leakage. Besides, unit have active probe PSU option installed. I've had some time playing with this scope and seems that it work fine, all controls work as expected, all channels seem to be working fine to. So, meet another member in a 24xx club :)
But after reading this thread from the first page I came to conclusion that I still have some things to take care about.
Seems that I should start with A5 board (it is all SMD sure) and replace this pesky Dallas SRAM IC and then caps. Should I replace both electrolytic caps (I wish to replace them with solid state polymeric SMD caps) and this black one I don't know what type are they, seems that I've seen photos of them leaking to.
After I'm done with A5 board, I will go and check for HV and LV board and then recap A1 board.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on May 09, 2014, 01:14:13 am
Well, not really outsource.  Tektronix had its own internal IC fab - called the Integrated Circuits Operation (ICO).  Tek sold ICO to Maxim in 1994.  It is still co-located on the Tektronix campus in Beaverton.  So, the name changed, but the fab remained the same. 

At the same time, Tektronix sold half-interest in their hybrids design and manufacturing group to Maxim, which formed the group known as MaxTek.  Several years ago, Tektronix bought out Maxim's interest in MaxTek, returning this group to be wholly owned by Tektronix.
Straight from the horse's mouth, thanks Alan for clarifying this.  :-+

About the popular myth surrounding the Tek's hybrid ICs, is it true the chip design is gone caused by fire at MaxTek in the past ?

Alan, really wish if someday Tek will release the design of these hybrid IC's design, maybe begging contacting the PR dept about this possibilities ? Its like the good gesture in the past where Tek released all old scope's documentations to public legally.  :-+

There was an attempt to design the U800 ic replacement with discrete components like this -> Tektronix 2465/2467 series U800 IC replacement design (http://www.davmar.org/TE/Tek2465/lafay.html) created by Thomas Lafay, but if Tek released the hybrid IC schematic design, that will be like breathing a new life for these great 246x analog scope series.  :clap:

Please consider it.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on May 09, 2014, 01:16:38 am
Seems that I should start with A5 board (it is all SMD sure) and replace this pesky Dallas SRAM IC and then caps. Should I replace both electrolytic caps (I wish to replace them with solid state polymeric SMD caps) and this black one I don't know what type are they, seems that I've seen photos of them leaking to.
After I'm done with A5 board, I will go and check for HV and LV board and then recap A1 board.

The black rectangle box cap are tantalum, the ones that are affected are using common rounded smd electrolytic cap. Maybe a photo of your A5 will clarify that better.

Btw, congratulation on the score, really a great condition you got there.  :-+
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: e-pirate on May 09, 2014, 08:31:22 am
The black rectangle box cap are tantalum, the ones that are affected are using common rounded smd electrolytic cap. Maybe a photo of your A5 will clarify that better.
Well, unfortunately, I'm half a thousand kilometers away from my scope and I have no idea when I will return back. That what I'm doing now is preparing my road map for the feature, so I can do thins faster on the scope.
I always thought that tantalum caps are always enclosed in yellow plastic and black ones are just regular electrolytic of different type, but I wasn't right in that case. BTW, what does symbol "2" in a circle on the original black rectangle cap means? Kind of package size or value tolerance?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: e-pirate on May 09, 2014, 05:56:03 pm
Actually, after googling a little bit and searching through SM a found that this a just regular general purposes tantalum 15 uF 25V 20% caps. And symbol "2" in circle is just a Vishay Sprague logo, nothing exciting here :(
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: guido on May 09, 2014, 10:11:55 pm

Had a go at U800; better safe than sorry.

I've had a look in my spare parts and found a heatsink that screws right onto one of the screws from U800. Used the one connected to the metal of it obviously. It is not as big as the examples in this thread, but i guess it is better than nothing.

It is from a 7A13 plugin; a beefy TO18 heatsink which has a screw mounting hole on the top. Fits like a glove. There is a bit less space than normal, as there are bodges around U800 which are not present in a more modern 2465  :P

Sorry, no picture. The battery of the camera is dead.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on May 10, 2014, 01:10:00 pm
Actually, after googling a little bit and searching through SM a found that this a just regular general purposes tantalum 15 uF 25V 20% caps. And symbol "2" in circle is just a Vishay Sprague logo, nothing exciting here :(
Yep, but they don't leak overtime and I think they should be pretty reliable.

Btw, for newly acquired 246x scope, suggesting to check these system voltage rails first at the J119 header when opening it for the 1st time.

Remember, get a big fan blowing the whole A1 board while its turned on without the enclosure to cool down those unobtainium hybrid ICs.

Of course ideally these rails should be measured with another scope instead of just ordinary DMM to see if the ripples are up to the specification.

The J119 header location and the voltages specification & tolerances required by the scope to work properly, quoted from Tektronix 2465B service manual.

(https://www.eevblog.com/forum/testgear/2467-no-power/?action=dlattach;attach=58502;image)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: e-pirate on May 10, 2014, 08:20:42 pm
Yep, but they don't leak overtime and I think they should be pretty reliable.
Btw, for newly acquired 246x scope, suggesting to check these system voltage rails first at the J119 header when opening it for the 1st time.
Remember, get a big fan blowing the whole A1 board while its turned on without the enclosure to cool down those unobtainium hybrid ICs.
Of course ideally these rails should be measured with another scope instead of just ordinary DMM to see if the ripples are up to the specification.
The J119 header location and the voltages specification & tolerances required by the scope to work properly, quoted from Tektronix 2465B service manual.
Well, after reading this particular tantalum caps datasheet I came to conclusion that there is no need to change them. They have no lifetime parameter specified at all, so, probably, as they intact, I will live them. But I'm going to replace aluminum "wet" electrolytic caps on A5 with solid state polymeric "dry" caps. The have longer lifetime, lower ESR and have nothing lo leak out. And I have to replace this pesky Dallas SRAM chip, but that's no so easy to get a fresh one here in Moscow and I have to get a good programmer before.
Concerning rails you told me about: I have another scope (just a cheepy chines Hantek DSO) and a DMM, so, I will take a look on this. Anyway, I'm going to completely recap the unit to make it stay alive for another couple decades, I hope. But I will need help and advices, just cause I had never my hands on anything complected like this scope before.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: e-pirate on May 11, 2014, 04:10:48 pm
Everybody, who's going to replace DS1225 SRAM chip should take a look at Dr. Hugo Holden's document, concerning this procedure and possible chip replacement with FRAM and DRAM. Defiantly worth looking at http://www.worldphaco.com/uploads/TEKTRONIX_2465b_OSCILLOSCOPE_CALIBRATION___REPOWERING_THE_DS1225.pdf (http://www.worldphaco.com/uploads/TEKTRONIX_2465b_OSCILLOSCOPE_CALIBRATION___REPOWERING_THE_DS1225.pdf)!
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on May 11, 2014, 05:02:35 pm
Thanks for that document !  :-+

Yep, I bought few FRAM chips last year hoping I can throw away the DS-1225 (posted HERE (https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg213270/#msg213270)), and the problem I have is my MiniPro TL866 universal programmer can not copy the SRAM content into this FM1608-120, since it has non standard CE signaling, so currently I'm stuck with this Dallas chip.  :'(
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on May 11, 2014, 05:11:09 pm
Everybody, who's going to replace DS1225 SRAM chip should take a look at Dr. Hugo Holden's document, concerning this procedure and possible chip replacement with FRAM and DRAM. Defiantly worth looking at http://www.worldphaco.com/uploads/TEKTRONIX_2465b_OSCILLOSCOPE_CALIBRATION___REPOWERING_THE_DS1225.pdf (http://www.worldphaco.com/uploads/TEKTRONIX_2465b_OSCILLOSCOPE_CALIBRATION___REPOWERING_THE_DS1225.pdf)!

Great article. Thanks for sharing. Too bad the TL866 can not write to the FM-1608 though
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SeanB on May 11, 2014, 05:42:33 pm
Turn off ID check and tell it it is a DS1225 and it probably will write to it.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on May 11, 2014, 05:51:14 pm
Turn off ID check and tell it it is a DS1225 and it probably will write to it.

Nope, it won't work, the problem is this FRAM needs the /CE (Chip Enable) line to be strobed at "EVERY" write or address change, while DS1225 is just like ordinary SRAM which only needs the /CE line to be pulled down "ONCE".

The reason for strobing at the CE on every write is because of the nature how FRAM works, this action will latch the new address and preparing the "pre-charge" while CE is HIGH which is needed for FRAM ferroelectric cell operation, CMIIW.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: e-pirate on May 11, 2014, 06:26:35 pm
Well, probably the STK12C68 is a way to go? As mentioned in document above, you'll need a special PCB and a couple of spares to make it work, but I don't think it's a real problem. Having this chip instead of DS1225 you will have 106 cycles. According to it's way of operation, I'm pretty sure it's equivalent to power on count of the scope.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: e-pirate on May 13, 2014, 07:39:37 pm
Hi, folks.
During my conversation with mr. Hugo he told me that it's a good idea to have another fresh lithium battery in parallel with the old flattering one in old DS1225 desoldered from dcopes before they go to the reader. The trouble is that when the battery is almost flat, it will still hold data in SRAM and the whole thing will continue to work, but when DS1225 get into the reader, some of them MAY draw small current from its pins and that may lead to voltage drop and accidentally blank DS1225.
All information concerning paralleling the battery is in document.
As I'm currently facing the same problem, I will desolder DS1225 and will try to parallel the older battery with a fresh one before plugging it to a reader. I'm going to order the Wellon VP-390 programmer and try to read it.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: iloveelectronics on May 15, 2014, 07:25:10 am
Just to give a quick update. I reinstalled the missing caps on the A5 boards, replaced the film caps on the power supply board and finally also desoldered the DS1225 and backed up the data on it. I had to get myself a Hakko 808 to desolder the chip as my other cheaper Chinese desoldering gun wasn't working very well. Made a few burn marks on the board :( Turned out it was merely clogged but its tip never tins properly so it's time to replace it anyway.

A new DS1225AD-200IND+ just arrived today (much sooner than I expected) so as soon as I get a bit of time I will copy the data and insert it into the newly soldered socket on the A5.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on May 15, 2014, 07:53:37 am
Hey Franky, please take few photos if you had a chance, also the cal data zipped and attach it here as well, might be useful someday for someone, who knows.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: iloveelectronics on May 15, 2014, 09:36:51 am
Hey Franky, please take few photos if you had a chance, also the cal data zipped and attach it here as well, might be useful someday for someone, who knows.

I will take some pictures the next time I open up the case.

I just had a go with the new DS1225 but failed :( I'm using the MiniPRO TL866CS programmer. I thought being a brand new chip it would be all empty with all "00" or "FF" but when I read it there was already something in it, is that normal? I tried programming it a few times with the binary file I saved from the old chip but it simply didn't work...
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on May 15, 2014, 09:54:37 am
Thats weird, my experiences with DS1225 either the old one and new were without any problem at all using the minipro I purchased from you.  :-+

Heck, I even still use the old one, while the new DS1225 which already has the cal data copied into it is in the storage, just curious how long the old one will survive.  >:D

Where did you buy that DS1225 ? Read few posts back, there was a similar problem with new "old" stock of DS1225 bought from a surplus shop if I'm not mistaken, and problem solved by using the new DS1225 from authorized distributor.

Fyi, mine was purchased directly from Digikey with quite fresh date code, whats yours ?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: iloveelectronics on May 15, 2014, 10:16:06 am
Thats weird, my experiences with DS1225 either the old one and new were without any problem at all using the minipro I purchased from you.  :-+

Heck, I even still use the old one, while the new DS1225 which already has the cal data copied into it is in the storage, just curious how long the old one will survive.  >:D

Where did you buy that DS1225 ? Read few posts back, there was a similar problem with new "old" stock of DS1225 bought from a surplus shop if I'm not mistaken, and problem solved by using the new DS1225 from authorized distributor.

Fyi, mine was purchased directly from Digikey with quite fresh date code, whats yours ?

I bought mine from Mouser. Date code is 1415 so it should be about as fresh as it gets.

I read Dr. Holden's article about replacing the Dallas chip with other alternatives and saw that he had success with your RAMTRON FM1608 with the GQ-4X programmer so I also went and got myself one of those (haven't got the FM1608 yet though). I just tried using this programmer on the new DS1225 chip but still had no luck. This programmer allows me to set writing speed and it seems to be able to go a little bit further with slower speed but still no more than 3 lines of binaries max :( I wonder if I got a bad chip? Or did I miss any steps?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: iloveelectronics on May 15, 2014, 10:44:23 am
I just tested it some more and it looks like I can't write a "0" to the least significant bit of the high byte in each word. I can fill the chip with 10, 11, 12...1F, 30, 31, 32...3F, etc. but can't write 2x or 4x etc.  :palm:
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: e-pirate on May 15, 2014, 01:26:16 pm
Mr. Hugo suggests to use FM16W08 as it a newer version of FM1608 and capable of more read-write cycles. Bat it's not a direct replacement is it 4 banks of 8K x 8.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: e-pirate on May 15, 2014, 01:29:46 pm
I just tested it some more and it looks like I can't write a "0" to the least significant bit of the high byte in each word. I can fill the chip with 10, 11, 12...1F, 30, 31, 32...3F, etc. but can't write 2x or 4x etc.  :palm:
BTW, did you checked old DS1225  for a multiple read sequence? It's not mentioned in document, but mr. Hugo told me that results MAY be different with data "fading" away more and more after each read attempt.
How old is your original DS1225 is?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: iloveelectronics on May 15, 2014, 01:50:03 pm
BTW, did you checked old DS1225  for a multiple read sequence? It's not mentioned in document, but mr. Hugo told me that results MAY be different with data "fading" away more and more after each read attempt.
How old is your original DS1225 is?

No, I didn't try that. Perhaps I will try that when I open the case up again. My old DS1225Y has a 1990 date code, so it's 24 years of age already...
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: chksum3 on May 20, 2014, 11:33:56 pm
Regarding your problem writing to a newly purchased DS1225: I had the same experience with a DS1225Y-200 purchased from a local supplier (Jameco) despite its having a recent date stamp.  Per advice given here, I bought another chip from Digikey - that one could be read and written to flawlessly. 
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: e-pirate on May 21, 2014, 09:41:15 am
Regarding your problem writing to a newly purchased DS1225: I had the same experience with a DS1225Y-200 purchased from a local supplier (Jameco) despite its having a recent date stamp.  Per advice given here, I bought another chip from Digikey - that one could be read and written to flawlessly.
Could you provide us a photo of this two chips sitting one next to another?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: iloveelectronics on May 21, 2014, 10:04:18 am
I just replaced my DS1225Y with a Ramtron FM1608, and it works! Well, I've only tried some basic signals but everything is looking fine, just like it was with the 24-year-old DS1225Y :) I wrote the data onto the FM1608 using a GQ-4X programmer. The MiniPro TL866CS doesn't seem to be compatible with this chip.

Attached is the BIN file I saved from the DS1225Y chip in case anyone finds a use for it.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on May 21, 2014, 10:23:28 am
Sigh ... Don't feel like to buy GQ-4X programmer just to program this fram, I guess I'm stuck with my TL866 and 3 pcs of unused FM1608s.  :'(

Btw, thanks for the cal ram image.  :-+
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: iloveelectronics on May 21, 2014, 10:35:34 am
Sigh ... Don't feel like to buy GQ-4X programmer just to program this fram, I guess I'm stuck with my TL866 and 3 pcs of unused FM1608s.  :'(

Btw, thanks for the cal ram image.  :-+

If you don't mind mailing the chip back and forth I can help you write your data onto it.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on June 29, 2014, 10:08:22 pm
Well I think I toasted the calibration data on my Dallas.  Not sure what went wrong, but when reading it using my TL866 I just get values of 00 from Address 00000  to 0007F0 and 00 from address 001000 to 0017F0.  :( :(

When pulling off the Dallas one of the pins bent and crossed with another, so i am wondering if this somehow reset the stored values. Waiting for a 28 pin socket from Digikey before I see what error messages come up on the scope. Perhaps nothing is wrong and that is indeed my calibration data but I doubt it.

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: e-pirate on July 01, 2014, 10:09:48 am
Good news, folks!
Yesterday I succeed on reading an dying cause of it respectable age DS1225Y from my TEK 2467B. As Mr. Hugo Holden noticed in his article, that this NVRAMs may get corrupted while reading attempt in programmer because of some programmer may sunk current from ICs pins, this may finish off already discharged heroic lithium battery inside DS1225 (mine is actually produces in mid 91, so it at least 23 years old with only 10 years guarantee data storage). I decided not to relay on chance and do a surgery for my DS1225Y and shunt it's internal battery with external fresh one before putting it to programmer. I spend some unpleasant hours desoldering it from A5 board, primary because if tiny traces and sucker back-kick. After DS1225 was desoldered, I replaced it with gold plated socket with round contacts and started the main act. Using Dremel with very small grinding bits I dig into compound on the bottom side of the DS1225 to reach DS1218 pin 7 shat is connected to internal battery positive terminal. Then, I tin going to install a standard CR2032 battery socket, salvaged from an old mother board. As I'm going to replace DS1225 with Ramtron 16W08 or STK12C08 (I got both, see what will do better), I decided to temporary stick socket on the top of DS1225 with a dual side sticky tape and then solder positive terminal to pin 7 of DS1218 and negative to pin 14 of DS1225. After battery was installed and wires soldered, I put DS1225 back again to see if it still holds calibration data. My scope booted without any warnings and EXERCISE 5 showed correct power hours and cycles. So, I put DS1225 to my new Wellon VP-390 programmer and successfully read data from it. Then, I just removed the battery and put DS1225 back again. I have no idea how to safely place external battery on A5 board, but now, as I have a dump, I don't really care.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on July 07, 2014, 11:41:18 pm
You description of the failure reading the Dallas NVRAMs after desoldering them from the board match what I experienced doing the same procedure on my 2440 which had a pair of DS1230 memories.  My programmer would not work with the 20+ year old memories but did with the EEPROM based replacements that I used.

While testing to determine the problem, I believe I inadvertently overwrote the NVRAMs destroying the calibration data but the 2440 series external calibration is trivial compared to that of the 2465B series so I just did that after installing sockets and the new memories.  If I had been working on a 2465B, I would have been more careful and persevered.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on July 08, 2014, 01:25:47 am
You description of the failure reading the Dallas NVRAMs after desoldering them from the board match what I experienced doing the same procedure on my 2440 which had a pair of DS1230 memories.  My programmer would not work with the 20+ year old memories but did with the EEPROM based replacements that I used.

While testing to determine the problem, I believe I inadvertently overwrote the NVRAMs destroying the calibration data but the 2440 series external calibration is trivial compared to that of the 2465B series so I just did that after installing sockets and the new memories.  If I had been working on a 2465B, I would have been more careful and persevered.

What is strange is where one would expect a value in the address bank there is just 00's. It's almost as if the programmer couldn't read the value and substituted 00.

 
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on July 08, 2014, 02:16:19 am
What I saw was very similar if not identical.  It was like one or more of the address lines was causing the reads to be all 00 or all FF but reads from other addresses were good.

My hypothesis based on other information is that the control IC itself relies on the backup battery voltage being above a certain level or it fails to pass the chip select signal through.  Apparently at some point, the backup battery voltage gets low enough that while the SRAM contents are not immediately lost, the device cannot be accessed under any conditions even though external power is applied.

In this particular case, only some addresses were locked out for whatever reason because the backup batter voltage was just on the threshold before chip select would be completely disabled.

If I had been working on a 2465b or similar where the calibration is tedious, I would have been more careful and certainly tried accessing the backup battery directly so the calibration data could be read out.  I wonder if raising or lowering the temperature would have been enough to access the data.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on July 08, 2014, 04:56:25 am

If I had been working on a 2465b or similar where the calibration is tedious, I would have been more careful and certainly tried accessing the backup battery directly so the calibration data could be read out.  I wonder if raising or lowering the temperature would have been enough to access the data.

Well putting the chip back in the scope and it will not work, so I suppose what you suggest could be possible. Nothing would hurt to put it in the oven or freezer for a bit and retry. Since it's likely a loss cause i could always try and de-pot the area around the battery and add a replacement one in parallel and try and read it again. Never know, just might.

Some interesting reads on the Dallas 1225 and hacks.

http://www.google.ca/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CB4QFjAA&url=http%3A%2F%2Fwww.worldphaco.com%2Fuploads%2FTEKTRONIX_2465b_OSCILLOSCOPE_CALIBRATION___REPOWERING_THE_DS1225.pdf&ei=mHm7U92SG8G7oQT6-IHADA&usg=AFQjCNGFqXCfi2ArgRR6vCgu3btbZ-9B0Q&sig2=6BETUqeTL4Vv2wFvieI1rQ&bvm=bv.70138588,d.cGU (http://www.google.ca/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CB4QFjAA&url=http%3A%2F%2Fwww.worldphaco.com%2Fuploads%2FTEKTRONIX_2465b_OSCILLOSCOPE_CALIBRATION___REPOWERING_THE_DS1225.pdf&ei=mHm7U92SG8G7oQT6-IHADA&usg=AFQjCNGFqXCfi2ArgRR6vCgu3btbZ-9B0Q&sig2=6BETUqeTL4Vv2wFvieI1rQ&bvm=bv.70138588,d.cGU)

 
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Mr Simpleton on July 08, 2014, 07:57:53 am
So for those with a lost memory and a non-working 2465B, could the scope use "generic" cal data?
I.e. how poor would the scope behave if one used cal data from an other working 2465??
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on July 08, 2014, 08:22:57 pm
Tried the Dallas hack in the link I uploaded and added a external battery to the Dallas. The old one read 2.64v, unfortunately no luck in reading it on the programer, same issue. Just returns 00 in the addresses that should contain data. Oh well....
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on July 08, 2014, 08:25:10 pm
So for those with a lost memory and a non-working 2465B, could the scope use "generic" cal data?
I.e. how poor would the scope behave if one used cal data from an other working 2465??

I have a TG501 time mark generator and it is pretty much bang on with the Rigol so pretty comfortable it is within calibration. Will try it on the 2565B with a generic "cal data" and see how far out it is.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on July 08, 2014, 09:16:43 pm
So for those with a lost memory and a non-working 2465B, could the scope use "generic" cal data?
I.e. how poor would the scope behave if one used cal data from an other working 2465??

The horizontal, vertical, and other calibrations will be wrong but it should otherwise work.  I do not know if it would be any better than just clearing the calibration memory and operating the oscilloscope anyway.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: casinada on July 12, 2014, 05:46:59 am
I lost the cal data from the Dallas Chip. I downloaded the backups available from the ko4bb repository as a starting point, programmed the data on to a fresh DS1225 and then calibrated my 2465BDM using different generators, signal sources, power supplies, multimeters until I was satisfied with the results.

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on July 12, 2014, 06:25:23 am
Pretty much what I am faced with doing. Have myself a TG501 so that's half the battle. The rest I think I can do with my HP 50Mhz frequency generator, checking the outputs with a accurate DMM to test the amplitudes.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: richhas on August 02, 2014, 08:18:36 pm
Ok... Just received a 2464B and disrobed it for an initial inspection of A5 and the Main Board - having read this thread over several times.

I expected the worst wrt the A5 EC issues but think I'm pleasantly surprised - but I'm not an expert and thus my query here.

Both boards look super clean to me and I don't see any EC junk on A5. The thing that caught my eye have been the date codes. I thought that these units ceased production in '92-ish but I'm seeing date codes of '94, '95, and even a '97. Does anyone know how late these Beaverton units were produced? Or maybe these are replacement boards produced later than end-of-production. Could it be that Tek fixed the A5 EC issues late in the production?

In any case, it would great to get opinions from the experts here. Did I get lucky? Should I go ahead and replace the A5 caps? I'm going to heat sink U800 and socket/replace the damned Dallas ram - also update the LV/HV caps if needed.

This unit had 9330 hours spread over 1340 power cycles - approx on for 7 hours at a time. Makes some sense in a work environment - not too much cold start stress I hope.

The quality and experience from you guys has been super educational.

THANK YOU,

Rich
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on August 02, 2014, 09:40:49 pm
My notes say that the 2465B and 2467B were available from 1989 through 1996.

I suspect the U800 failures were more related to stress caused by the poor mounting than heat.

I believe the later oscilloscopes did not suffer from leaking surface mount aluminum electrolytic capacitors.  If that is the case, then I would not risk of damage to the oscilloscope while changing them unnecessarily.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: richhas on August 02, 2014, 11:04:56 pm
Thanks David... BTW the serial# is B065301.

I just went into the PS cage and many of the caps and other parts are marked '94 and some '95. The inspection sticker on the LV PS says mid '95.

Those transparent plastic covered caps on the PS pcb seem to not be cracked or such. Would your advise be the same - if is not broken, then...?

Best,

Rich
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Electro Fan on August 02, 2014, 11:25:24 pm
Kind of a big SWAG but...

If you took all the Tek 24XX and 22XX scopes manufactured between 1990-1995 that were subsequently humanely treated:
- used (turned on) a few hours per day (20 years x 4 hours per day x 250 business days per year = 20,000 hours)
- maintained in a decent environment (temperature, humidity, etc.)
- operated with proper respect

What percent of these humanely treated Tek scopes would make it to 2015 without needing any parts (other than a battery) replaced?

What percent would make it to 2020 without needing any parts replaced?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: richhas on August 02, 2014, 11:50:56 pm
No expert here but my guess is the cap plague with these EC lowered the average a great deal - amplified by the great tolerances tek tended to design in only served to hide problems until too much damage was done to pcbs... But just an old guy's guess.

Best,

Rich
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on August 03, 2014, 01:37:38 am
I think it was only the early surface mount aluminum electrolytic capacitors which had this problem in the 2465 series and it was not capacitor plague.  I suspect it had to do with washing after soldering where the capacitors or the capacitor seals were sensitive to halogenated solvents.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on August 03, 2014, 03:27:36 am
What percent of these humanely treated Tek scopes would make it to 2015 without needing any parts (other than a battery) replaced?

What percent would make it to 2020 without needing any parts replaced?

"In the year, twenty-five twenty-five
if tek is still alive
if agilent can survive
they may find..."


Title: Re: Tektronix 2465B oscilloscope teardown
Post by: richhas on August 03, 2014, 06:54:29 am
Very good!
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on August 03, 2014, 07:36:48 am
Rich, great score you got there !  :clap:

About the A5 board's electrolytic caps, have agree if I were you I will be facing the same hesitation too.

But, assuming you're very confident that you won't break the board while replacing them, I would say just replace them with best cap that is available now, just to have a good sleep knowingly they will not leak out any time soon, also those old SMD caps are made in early 90s, which already more than a decade old.

Still, its your call.

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on August 03, 2014, 01:26:55 pm
You could ask over on the TekScopes@yahoogroups.com email list or search the archive.  Someone there undoubtedly knows if the late 2465B series suffered from the surface mount capacitor problem.

I know of more than one instance now where someone changed all of the capacitors in one of these oscilloscopes and ended up breaking it.

Also, their is an error in the board layout diagram for the power supply which has two capacitors swapped so if you follow the service manual, it will short out the power supply.  It is a good idea to take notes and maybe photos as you go along.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on August 03, 2014, 01:36:45 pm
He is going to take out the whole big A5 board from the scope to desolder the big Dallas chip anyway, and solder the dip socket for new bbsram chip.

Imo, this task alone not a brief soldering job, and that will be the good opportunity to replace those caps at the board.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on August 09, 2014, 06:10:20 pm
I guess most of the Tek 24x5 owners are aware of the U800 chip vulnerability, just browsed Tek yahoo group pictures gallery and noticed this interesting pictures of A1 board captured using FLIR camera.

These pictures should speak for it self. Just remember to blow the whole A1 board with a strong fan when you're working without the enclosure, especially near the U800 chip.

(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=105009;image)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: iDevice on August 09, 2014, 06:53:03 pm
That raises a question I wanted to post and forgot to.
A few weeks ago, I scored a mint 2445B with only 270 hours.
The only problem I could find was a failure of the beam finder switch that remained in the activated state.
It was fixed by cleaning.
But while the scope was open I left it running to check if everything was ok, obviously with a fan directed on U800.
And after about 15m, U800 was still cold.
So I stopped the fan a few minutes and U800 was still at about 30°C.
After about half an hour, I could still hold my finger on it and it felt just warm, I didn't think to take a real temp measure though.

So I'm wondering if there are different versions of U800, (based on IC dates, scope was build in '94) or if the legendary U800 meltdown only happen with certain settings ?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on August 09, 2014, 07:04:31 pm
So I'm wondering if there are different versions of U800, (based on IC dates, scope was build in '94) or if the legendary U800 meltdown only happen with certain settings ?
As far as I'm aware, currently only 2 versions, one made by Tek, another one from Maxim , posted both photos -> post #185 (https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg440178/#msg440178) while ago.

Whats yours ?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: iDevice on August 09, 2014, 07:26:36 pm
I have the Tek labeled version.
Probably one of the last since they sold the factory to Maxim in '94, as it seems.

I'm waiting for a new DS1225, so I will open it again in a week or two.
This time I will take some shots with my TIC.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on August 09, 2014, 07:44:19 pm
This time I will take some shots with my TIC.

 :-+ , sounds great, looking forward to see further details at the temperature in A1 board, thanks !
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: guido on August 24, 2014, 11:20:59 pm

Had to calibrate the vertical after repairing the 2465. It got a new attenuator. As i don't have a PG506, i looked in the partsbin and found an AD CMOS switch. Put in on a pcb with a 555 and presto, a "chopper". Used a fluke calibrator to generate the DC voltages (20mV to 10V range) and managed to calibrate vertical and trigger. Not much of a circuit, but you need a decent calibrator to begin with  :D

(http://members.home.nl/baltusg/chopper_case.jpg)

The 20mV signal and source on a 2430A:

(http://members.home.nl/baltusg/chopper_scope.jpg)

And since it was open (you need to calibrate the markers with pots), i also took a picture of my wannabee U800 cooler:

(http://members.home.nl/baltusg/u800.jpg)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on August 25, 2014, 05:09:54 am
Before I got a PG506, I managed to generate the calibration voltages using a stepped attenuator but I know of others that had good results using analog switches.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on August 25, 2014, 08:20:02 am
Does the vertical calibration have to be a 1khz square wave of varying amplitude like the PG506 or can it be a DC voltage. I know there is many cheap very accurate voltage references like a Ref5050 from TI .05% accuracy and 2.55 ppm/Celsius temp coefficient http://www.ti.com/product/REF5050/description (http://www.ti.com/product/REF5050/description) that one could feed into a LTC1043 to divide/multiply to meet the required voltages. May need a couple different reference voltages to feed into the divider.  Suppose would need a buffer ie LTC1050
https://www.eevblog.com/forum/projects/should-the-ltc1043-voltage-divider-circuit-be-buffered/msg461531/#msg461531 (https://www.eevblog.com/forum/projects/should-the-ltc1043-voltage-divider-circuit-be-buffered/msg461531/#msg461531)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on August 25, 2014, 01:28:12 pm
I really should be a chopped square wave in order to reduce the effects of thermal drift and seven different voltages from 20 millivolts to 10 volts are needed.  Calibration of the automatic measurements absolutely requires a square wave.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on August 25, 2014, 09:41:58 pm
I do have a HP81161 pulse generator that I could use. Can output a 1khz square wave at 50% duty cycle and vary the amplitude to match the required calibration volatages for the 2465b. Only issue is I am not sure how accurate it is any longer. The performance checks for AC amplitude fall within the specs according to the measurements with my Uni-T multimeter. But can i really really on such a  cheap measuring instrument to confirm the HP outputs, especially on a a AC output.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on August 25, 2014, 10:41:15 pm
There are two different easy ways to handle the calibration in that case.

An RMS reading voltmeter may be used in which case the peak to peak value is twice the RMS value.  A good meter will get you into the accuracy range necessary to calibrate an oscilloscope which is not a precision instrument for voltage measurements anyway.

Alternatively an average responding AC voltmeter may be used with a correction factor.  For square waves, it will read 11% high.  This is usually a better option because average responding meters are usually both faster and more accurate than RMS responding meters.

When I do this I use both as a sanity check.  All of my good meters handle 1 kHz square waves with no problem.

One thing to beware of though when doing the above is that the duty cycle needs to be 50% or at least known so a correction factor can be applied.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on August 26, 2014, 01:14:51 am
The multimeter I have is a UTI-61E, below is a pic of the AC specs. I thought crest factor also had to be taken into consideration. Either way you are right, splitting hairs. Will compare the output of the HP to the  multimeter and on my Rigol1052e. The Tek is only rated for 2% vertical accuracy so I am probably well in the ballpark. Although it would be nice to have a calibrated 34401a. :D

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on August 26, 2014, 02:04:52 am
I thought crest factor also had to be taken into consideration.

The crest factor for a square wave is 1 so it is not a consideration.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: calin on August 26, 2014, 03:18:54 am
I also need to do a vertical cal on my 2465 and of course no PG506 .. I do have a nice working FG 504 very stable and nice, a 51/2 digit Fluke  multimeter and some scopes to compare ... but I am scratching a bit my head at how the vertical calibration signal should look like.


So it is clear, the calibration signal should be a 1kHz  square with 50% duty with the following values, 0.5V, 0.2V, 0.1V, 50mV, 20mV, 1V and 10V. Now here is what is not clear:


1) Are these voltages in 50 ohm or in high impedance ? I think is HiZ.
2) Yes voltages are peak-to-peak, are they 0 to 0.5V for or AC  +/- 2.5V ? I think they are 0 to +0.5 but better check first before I do something stoopid :)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on August 26, 2014, 04:47:29 am
And since it was open (you need to calibrate the markers with pots), i also took a picture of my wannabee U800 cooler:

(http://members.home.nl/baltusg/u800.jpg)

Guido, that heatsink looks like a stacked coins to me.  ;D
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on August 26, 2014, 05:13:21 am
So it is clear, the calibration signal should be a 1kHz  square with 50% duty with the following values, 0.5V, 0.2V, 0.1V, 50mV, 20mV, 1V and 10V.

I wish if there is an easy and relatively cheap to build such circuit, any experienced or experts want to contribute on the circuit schematic ?

Don't need to be high precision right ? <5% accuracy is enough maybe ?  :-//
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on August 26, 2014, 06:38:22 am

1) Are these voltages in 50 ohm or in high impedance ? I think is HiZ.
2) Yes voltages are peak-to-peak, are they 0 to 0.5V for or AC  +/- 2.5V ? I think they are 0 to +0.5 but better check first before I do something stoopid :)

Good question. I assumed they are 50 ohm impedance. Thea manual states the testing procedure switches to 50 ohm impedance in Cal 01, I just assume this carried over to Cal 02 (Vertical).

Upon entering CAL 01, the Input Coupling is
automatically set to 50 Q DC and the 50 Q OVERLOAD
protection is disabled. Before starting the procedure,
make sure any 50 Q OVERLOAD condition
has been cleared.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on August 26, 2014, 05:03:45 pm
I also need to do a vertical cal on my 2465 and of course no PG506 .. I do have a nice working FG 504 very stable and nice, a 51/2 digit Fluke  multimeter and some scopes to compare ... but I am scratching a bit my head at how the vertical calibration signal should look like.

...

1) Are these voltages in 50 ohm or in high impedance ? I think is HiZ.

What matters is the peak to peak voltage at the oscilloscope's vertical input with or without termination.

Quote
2) Yes voltages are peak-to-peak, are they 0 to 0.5V for or AC  +/- 2.5V ? I think they are 0 to +0.5 but better check first before I do something stoopid :)

Only the peak to peak value matters as long as the waveform can be positioned on the CRT.  The PG506 for instance generates square waves from 0 to +x volts in calibrated amplitude mode.

Calibration of the 2465 cursors and any automatic measurements might require 0 to +x versus AC though.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on August 26, 2014, 05:07:44 pm
Good question. I assumed they are 50 ohm impedance. Thea manual states the testing procedure switches to 50 ohm impedance in Cal 01, I just assume this carried over to Cal 02 (Vertical).

It cannot always be 50 ohms because a PG506 will not generate 10 volts into a 50 ohm load.

Another reason it cannot be 50 ohms is that then the calibration amplitude would depend on the accuracy of the 50 ohm termination value.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mwilson on August 26, 2014, 07:50:01 pm
Good question. I assumed they are 50 ohm impedance. Thea manual states the testing procedure switches to 50 ohm impedance in Cal 01, I just assume this carried over to Cal 02 (Vertical).

It cannot always be 50 ohms because a PG506 will not generate 10 volts into a 50 ohm load.

Another reason it cannot be 50 ohms is that then the calibration amplitude would depend on the accuracy of the 50 ohm termination value.

Yep... also, to remove any remaining doubt, the PG 506 calibration procedure calls for calibrating its standard amplitude DC voltage ranges with an exact 1 megaohm load (within 0.1%).
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: calin on August 26, 2014, 08:10:27 pm
Perfect thanks guys. Looks like I am not a total noob and I've been reading right :).  1kHz square, 50% duty, 0 to +X DC voltages into HiZ it is.  I will use the FG 504 and my trusty Fluke meter to measure RMS and try a vertical cal on my scope.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: guido on August 26, 2014, 11:22:48 pm
Guido, that heatsink looks like a stacked coins to me.  ;D

It is out of a 7A13 actually.

So it is clear, the calibration signal should be a 1kHz  square with 50% duty with the following values, 0.5V, 0.2V, 0.1V, 50mV, 20mV, 1V and 10V.

I wish if there is an easy and relatively cheap to build such circuit, any experienced or experts want to contribute on the circuit schematic ?

Don't need to be high precision right ? <5% accuracy is enough maybe ?  :-//

Take a 10V reference chip, make the voltages with some precision dividers and use such a cmos analog switch to chop it up. Driven by a 555 or function generator. Maybe use a low offset opamp after the dividers or switch as buffer. I used a 6.8nF cap on the output to stop overshoot. You might check this with a good scope for a good value for your switch/coax cable.

Check the PG506 manual for the precision requirements...

I wonder if a normal function generator will work at the low voltages. What i looked at, some had offset figure specifcations of +/- 10mV... You might need to use a high voltage square as output and divide using precision resistors. See if you can get the 20mV nicely on the screen of a good scope.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on August 26, 2014, 11:30:47 pm
Good question. I assumed they are 50 ohm impedance. Thea manual states the testing procedure switches to 50 ohm impedance in Cal 01, I just assume this carried over to Cal 02 (Vertical).

It cannot always be 50 ohms because a PG506 will not generate 10 volts into a 50 ohm load.

Another reason it cannot be 50 ohms is that then the calibration amplitude would depend on the accuracy of the 50 ohm termination value.

What would my best option be for attempting to calibrate with my HP8116a. It as far as I know can only output the stated output voltages at 50 Ohm.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: calin on August 27, 2014, 12:25:21 am
The HP can output into HiZ ... just the voltage seen by the scope will be double. But then if you measure RMS with a mutimeter that is the same as seen by the scope . Of course if you have a square wave with 50% RMS value for 5V pk to pk is 2.5 .  Same is my FG504 .. 50 ohm.  At 1Khz reflections on the line are not something to worry too much about i think. Yeah many FG-s cannot go that low .. you don't need precision resistors .. just precision dividing any resistor of the right value and a multiturn pot/trimmer will do as ong as you have a good rms meter and a comparision scope you are set.  We are not looking for ultra high precision and low tempco here .. if is stable for 5 mins until the cal step is done is good enough i guess
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on August 27, 2014, 01:53:27 am
The HP can output into HiZ ... just the voltage seen by the scope will be double. But then if you measure RMS with a mutimeter that is the same as seen by the scope . Of course if you have a square wave with 50% RMS value for 5V pk to pk is 2.5 .  Same is my FG504 .. 50 ohm.  At 1Khz reflections on the line are not something to worry too much about i think. Yeah many FG-s cannot go that low .. you don't need precision resistors .. just precision dividing any resistor of the right value and a multiturn pot/trimmer will do as ong as you have a good rms meter and a comparision scope you are set.  We are not looking for ultra high precision and low tempco here .. if is stable for 5 mins until the cal step is done is good enough i guess

Right, double checked the HPmanual and that is what it suggests, double the output. I just wish I had a calibrated DMM to double check the output from the HP. 2.5v output reads 4.99v or 5.12 depending on the number of divisions on the scope. Odd in itself and may be a problem with my Rigol.

If I did not have the HP I would look at some precision reference voltage chips and use a couple LTC 1043 chips, supposedly very good , very accurate voltage divider, multipliers.  Page 8 of the datasheet

http://www.linear.com/product/LTC1043 (http://www.linear.com/product/LTC1043)

One or two reference voltages and a couple LTC1043's and you could come up with all the required voltages needed Just wondering what circuit one could use to chop it into 1khz without any appreciable noise or loss.



 
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on August 27, 2014, 02:57:15 pm
It cannot always be 50 ohms because a PG506 will not generate 10 volts into a 50 ohm load.

Another reason it cannot be 50 ohms is that then the calibration amplitude would depend on the accuracy of the 50 ohm termination value.

What would my best option be for attempting to calibrate with my HP8116a. It as far as I know can only output the stated output voltages at 50 Ohm.

The way I did it with a function generator at low voltages was to use a stepped attenuator and 50 ohm termination while measuring the peak to peak voltage at the oscilloscope vertical input.  At high voltages the stepped attenuator and termination are not needed.

When dealing with voltages lower than can be accurately measured with an AC voltmeter, the stepped attenuator may be calibrated at a higher level and then the voltage can be measured at the input to the attenuator.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on August 27, 2014, 05:02:44 pm
Hmm, just got me thinking, could I not before the calibration procedure compare a precision DC voltage reference and the HP outputs on Channel 1 and 2 of the scope. Note the difference if any between the two and then subsequently adjust the HP outputs during the calibration standards. For example if the difference between the precision 1v dc and the HP 1v 1Khz AC is +10mv on the scope then when actually calibrating set the HP output for 90mv.

Or just don't worry about it and rely on the accuracy of my Uni61E to test the HP output. Thinking the scope comparison method may be more accurate in determining the output accuracy of the HP.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on August 27, 2014, 06:07:28 pm
Using two channels of the oscilloscope to make the comparison will not work because the offset and gain calibration of the two channels is independent.  One of the reasons to do the calibration is to match them as closely as possible.

There is an old technique which does exactly what you are proposing using one oscilloscope channel and it could be used to calibrate a signal generator.  It involves using a "differential comparator" which adds a precision offset voltage to the signal to be measured.  The offset voltage is adjusted to bring two different vertical levels into alignment and the difference represents the difference in voltage between those two signal levels.

The old Tektronix 7A13 does exactly this to 4 significant digits and with a resolution down to 1 millivolt although better resolution is available if an external voltmeter is used to measure the comparison voltage.

This is also known as a slide-back measurement.  I would have gone this route if I had lacked a modern AC voltmeter which could accurately measure low frequency square waves.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on August 27, 2014, 10:38:11 pm
Thanks David;

I did a Google search on Slide back measurements did not find much info. Any additional details you could share would be appreciated.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on August 28, 2014, 12:04:19 am
There is not much online about it.

Tektronix used and described the procedure in a couple of their service manuals where it was used for instrument calibration.

I suspect there is a detailed article about it in one of the TekScope publications but I have never seen an index of them to know where to look.  The 7A13 was first produced in 1969 so that would be the time period to search. 

There were earlier differential comparators as well and the operating manuals for them may describe how they can be used to make slide-back measurements.

The term also shows up in some old NIST publications.

Update: I did a search and found articles in November 1972 TekScope and January/Feburary 1973 TekScope but they are part 2 and 3 so there is an earlier one which I do not have.  They do not discuss the 7A13 differential comparator specifically but part 2 mentions slide-back measurement:

Let's see how we go about making a differential comparator measurement.  First, we establish a reference position on our display by grounding both inputs.  Then selecting the appropriate input (positive voltage source to the + INPUT, negative voltage source to the - INPUT), we switch the other input to the comparison voltage (Vc).  Next, the comparison voltage is adjusted until the trace "slides back" to the reference position.  What have we accomplished?  Using the "difference" principle we have introduced a "common-mode" condition in the form of the comparison voltage; that is, the comparison input voltage now equals the signal input.  We see that we now have the ability to measure any potential whether it be DC, complex in nature, or a combination of both - such as a complex wave superimposed on a DC potential.  Thus, we have an extremely versatile measuring tool.

The reason you would do this instead of reading the voltage directly off of the oscilloscope is increased precision and accuracy.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on August 28, 2014, 05:04:41 am
Let's see how we go about making a differential comparator measurement.  First, we establish a reference position on our display by grounding both inputs.  Then selecting the appropriate input (positive voltage source to the + INPUT, negative voltage source to the - INPUT), we switch the other input to the comparison voltage (Vc).  Next, the comparison voltage is adjusted until the trace "slides back" to the reference position.  What have we accomplished?  Using the "difference" principle we have introduced a "common-mode" condition in the form of the comparison voltage; that is, the comparison input voltage now equals the signal input.  We see that we now have the ability to measure any potential whether it be DC, complex in nature, or a combination of both - such as a complex wave superimposed on a DC potential.  Thus, we have an extremely versatile measuring tool.

Hi David:

Looks like to perform the differential comparator measurement as above  a differential probe is needed?.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on August 28, 2014, 01:43:53 pm
Looks like to perform the differential comparator measurement as above  a differential probe is needed?.

A differential comparator is a type of differential amplifier and may be used in place of a differential probe.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on August 29, 2014, 05:01:28 am
Well looked up on differential amplifiers and I am sure there is a way but way beyond me I am afraid, especially the complexity of one of the signals being AC. Ran my Rigol 1052E and a Tek 2465A side by side and compared the outputs of the HP, for the most part the Tek and the Rigol were very close in all the measurements. Under 1v outputs only a few mv difference between the two and 10's of mv above 2v. Where there was a large discrepancy was at the 10v range where the Rigol was almost .2v out compared to the tek. I think there may be a issue with the Rigol. The Rigol varies a fair bit in measurement depending on the vertical scale selected.

So in short I think the output accuracy of the HP is ok, at least for my hobbyist purposes to calibrate my 2465B.   
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on August 29, 2014, 02:44:54 pm
Well looked up on differential amplifiers and I am sure there is a way but way beyond me I am afraid, especially the complexity of one of the signals being AC.

Differential comparator slide-back measurements are one of those techniques which have been lost in time.  They are especially useful for measuring complex AC signals but as you observe, it would help to see how it is done in action and I know of no good examples showing this.

When first did oscilloscope calibration, I used an AC voltmeter to measure the peak to peak signal values instead of making a slide-back measurement which would have taken longer.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Phaedrus on September 04, 2014, 05:00:08 pm
I finally found the time to open up my 2465A I bought a couple months back. I was actually quite surprised; the date codes run up to middle of 1986. According to Wikipedia this model wasn't offered until 1987. So I think I might have gotten one of the first production batches.  :-+

All the electrolytics look good visually, but there's probably been some degradation anyway. I'm going to look into replacing them. Also probably stick a San Ace fan in there. How would you test to see if the U800 is having any issues?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on September 04, 2014, 05:58:23 pm
How would you test to see if the U800 is having any issues?

If U800 is having problems then it should be apparent on the display with horizontal drift or gain changes.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: e-pirate on September 10, 2014, 10:33:29 am
Hi, folks.
Some time ago I started my work on replacing NVSRAM (the DS1225) in my Tek2467B and ended with a success replacement with SIMTEK STK12C68. The STK12C68 is a fast SRAM with EEPROM and a schematics to store/restore data to/from EEPROM on power failure condition. It combines both infinity read/write cycles of SRAM and 100-year data retention in EEPROM without need of any external power (and that solves battery problem). As data stored to EEPROM only at power-off condition, this specs simply make STK12C68 lifetime grater then scope's.
The original idea belongs to Mr. Hugo Holden, who consulted me during my work. His fears goes to store operation, hi told me that hi was able to reproduce condition at witch scope failed to boot and data in  STK12C68 corrupted after very fast unit switch on-off cycles. However, with my STK12C68 I was not able to reproduce that behavior in unit. I did a series of unit power no-off-on-off as fast, as I was able to kick power button and then varying time delays. But that didn't convince no me, neither Mr. Holden. So, he suggested another test that I performed: I powered STK12C68 from a function generator, varying both duty cycle (10%-90% for square wave) and frequency from 0 to a couple hundred Hertz (that will never happen in real life) and even under that test contents of STK12C68 remained intact. So, this NVSRAM confirmed it usability. It work perfect in my scope: everything stored correctly, front panel and all settings stored/restored during reboot perfectly. Even after power button kick test.
The IC requires an external cap to store energy for power off EEPROM store cycle. I use the smallest recommended value: 68 uF tantalum, bypassed by 0.1 ceramic one. Besides, I use 0.1 ceramic to bypass the IC itself and 10K resister between pin 27 and VCC as recommended in datasheet. Previously I replaced DS1225 with a round pin socket. My current "adapter" is just a wire soldered STK12C68 to two raws of pins inserted to socket and some caps and resister soldered to all this mess and covered by a tape so it will not short to cover. But that work grate for testing.
P.S. The programmer I use for all my memory operations is Vellon VP-380. And I did a quick test reading an aged DS1225 (mine is '91 production code) without external parallel battery - and I can confirm that this universal programmer can read this old NVSRAM secure without corrupting contents.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on September 10, 2014, 03:44:22 pm
I had good results replacing the two DS1230 embedded lithium battery NVSRAMs in my 2440 with EEPROM based STK16C88s.  The STK16C88 has the advantage over the STK12C68 of not requiring an external capacitor so they were drop in replacements.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: e-pirate on September 11, 2014, 05:45:11 am
The STK12C88 is, probably, superior to STK12C68 in terms of external elements and cause it 4 times STK12C68 size, so using just a some jumpers we can get 4 storage banks. Yah, that grate! But unfortunately, I have no available this ICs on easy :(
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: iDevice on September 11, 2014, 09:04:12 pm
I have no available this ICs on easy :(
Really ?
http://www.ebay.com/sch/i.html?_mPrRngCbx=1&_nkw=stk16c88 (http://www.ebay.com/sch/i.html?_mPrRngCbx=1&_nkw=stk16c88)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on September 12, 2014, 02:59:32 am
It looks like Cypress is discontinuing their EEPROM based NVSRAMs.  They still list them but their distributors do not have them available anymore and Cypress does not sell them directly.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: miguelvp on September 12, 2014, 03:09:21 am
And if you don't trust eBay:

http://octopart.com/partsearch#!?q=STK16C88 (http://octopart.com/partsearch#!?q=STK16C88)
http://www.findchips.com/search/STK16C88 (http://www.findchips.com/search/STK16C88)

Maybe is because you typed STK12C88 instead and that would have found nothing.

Edit: in any event, not a lot of stock left and some that have stock don't list the price. My bad, if you click on the part they show the price at the distributors site
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: e-pirate on September 12, 2014, 04:28:21 am
There are STK16C88 available at my favorite semiconductor store, but they cost 1200 RUR a piece, where STK12C68 cost 220 RUR. Should I get more expensive part only to save a cheapy cap and a couple of resistors.. nop. And unfortunately, delivery prices to Russia are almost always unreasonable, at least from EU and US. But thats a different sad story :(
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on September 29, 2014, 05:06:54 pm
It looks like Cypress is discontinuing their EEPROM based NVSRAMs.  They still list them but their distributors do not have them available anymore and Cypress does not sell them directly.

I was wrong about this.  Cypress is discontinuing EEPROM based NVSRAMs in DIP packages or at least the commercial ones in favor of surface mount packages including SOIC.  They use different part numbers for the surface mount packages because they all require an external capacitor so they are not direct replacements for JEDEC SRAMs but with a surface mount package, a DIP sized module could be produced which includes the capacitor.  Most are 3.3 volt or lower but some are 5.0 volt.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Mr Simpleton on November 12, 2014, 10:47:56 pm
Having replaced the leaking caps, cleaned the A5 board it was the big time to remove the Dallas RAM. Everything worked like charm, and I put in a quality socket for easy replacement.
Now having a new Dallas chip, I started of playing with my old ALL-07A programmer, and to my surprise it could not read/verify this chip. Odd... everytime I do access this new chip I do get a new checksum.
Lucklily the old RAM still works and sits in my "scope".

Reading about misfortunes with MiniPro programmers, what would be the way to go?? Batronix seems to have a low-cost programmer just slightly 2x the price of the MiniPro...

I am tempted to put some glue logic around an Arduino and have a one-off construction for this project. Would be fun, but not sure I have the time. Clock is ticking in my old Dallas chip  :scared:
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Precipice on November 12, 2014, 10:57:50 pm
Now having a new Dallas chip, I started of playing with my old ALL-07A programmer, and to my surprise it could not read/verify this chip. Odd... everytime I do access this new chip I do get a new checksum.

There's not an RTC in there, is there? (Sorry, checking back in this thread, I couldn't see which Dallas chip you were wrangling).
Even if not, it might be worth saving a few dumps, and seeing if there's anything interesting going on.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on November 12, 2014, 11:38:48 pm
Now having a new Dallas chip, I started of playing with my old ALL-07A programmer, and to my surprise it could not read/verify this chip. Odd... everytime I do access this new chip I do get a new checksum.

Lucklily the old RAM still works and sits in my "scope".

I had the same problem reading the Dallas NVRAMs in my old programmer which should have worked and did with the replacement memories.  I never tracked down the cause.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Mr Simpleton on November 12, 2014, 11:55:43 pm
@David
What did you end up doing then?? Give up and calibrate or managed to transfer the data to a new chip? If so what type of programmer?

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on November 13, 2014, 02:18:10 am
@David
What did you end up doing then?? Give up and calibrate or managed to transfer the data to a new chip? If so what type of programmer?

It was with a 2440 oscilloscope which has a much less onerous external calibration procedure than the 2465B so I just recalibrated it.  If it had been a 2465B, then I would have bought another inexpensive programmer that was specified to work with the NVRAMs, built something, or contacted someone with the right kind of programmer.

What was weird is that my programmer worked with the replacement parts which used a different technology but not the Dallas NVRAM parts.


Title: Re: Tektronix 2465B oscilloscope teardown
Post by: nctnico on November 13, 2014, 02:44:24 am
Probably due to solder on the pins. That doesn't go well with ZIF sockets. If you solder the original NVRAM into a socket with turned pins then you'll see the programmer reads it just fine.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on November 13, 2014, 03:54:17 am
I cannot say that is impossible however the pins were cleaned of solder and flux and the same behavior occurred with both NVRAMs.  It looked like one of the lower address lines was not being latched properly and each complete read produced slightly different results.

The programmer was ISA based but running on a considerably newer system which had an ISA bus so I suspect there was a timing issue.  The newer NVRAMs were considerably faster, 45ns versus 120ns, and worked fine.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Mr Simpleton on November 13, 2014, 01:37:31 pm
The programmer I was using, listed the 1225 as supported, and still nothing. My take is there is a speed issue. Think the simplest thing would be for me to build a duplicator.
Use a address counter some glue logic and two 28 pin sockets. Make sure that the WR-pin is strapped to high to secure no write on source. Should be simple. Only thing is I will not have the data saved on file. Never mind...
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on November 13, 2014, 04:12:54 pm
The programmer I was using, listed the 1225 as supported, and still nothing. My take is there is a speed issue. Think the simplest thing would be for me to build a duplicator.
Use a address counter some glue logic and two 28 pin sockets. Make sure that the WR-pin is strapped to high to secure no write on source. Should be simple. Only thing is I will not have the data saved on file. Never mind...

Enough people have reported problems reading old Dallas NVRAMs that there may be something else going on.  One hypothesis I have read is that the heat of soldering interacts with the module in some way to cause problems.  Maybe this only occurs when the lithium cell voltage is low.

To me this suggests that cooling or heating the NVRAM before using it in the programmer might allow recovery of the data.

I also know that there is an issue where if the internal battery backup voltage is low enough, the internal logic which protects the memory from invalid writes fails.  The data is retained in this case but the memory becomes inaccessible even with external power applied.  I do not know how this would cause problems with a programmer trying to read the contents though when the memory still works in the original circuit.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Mr Simpleton on November 13, 2014, 08:10:07 pm
What puzzles me is that my programmer (supporting 1225) failed on a brand new chip... just wanted to verify programmer operation before plug in my precious old chip!

The only thing I can come up with, except for a faulty chip, is that there are timing issues, programmer acting too fast some signals.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Howardlong on November 13, 2014, 10:07:20 pm
I sold a 2465BCT on ebay about five years ago, as I also had a TDS2024B at the time and couldn't justify having both: I was doing paid-for work in software only at the time. I sold it for pretty much the same as what I'd paid for it eight or nine years earlier.

I've regretted getting rid of that 2465 ever since. So a couple of weeks ago I picked up a 2467B with the CT option, for about thes same price as I'd paid and sold my 2465 for. I so love these scopes, it's been like catching up with a long lost friend.

Unfortunately I've been so spoilt by DSOs in the intervening period, I had to refer to w2aew on tips for using the delayed/dual timebase, I'd almost completely forgotten how to configure this on a 2465/7. Ten minutes of w2aew video beat trying to make sense of the written manuals. It's my go-to scope now, in pole position right next to an Agilent 54831D on the bench.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: tymm on December 23, 2014, 03:38:00 am
Hi,

Wondering if anyone has attempted to hand-copy cal constants using the "Calibration RAM Examine" thingie in the exercisers (or has at least verified that they are stored as shown in the RAM)...

Here's the blurb (from page 6-17 of the service manual):

Code: [Select]
CALIBRATION RAM EXAMINE (Exerciser 02). This routine allows the operator to examine the contents of 256 decimal locations, 00 (Hex) through FF (Hex), in RAM. When entered, the Exerciser displays the contents of RAM location 00 (Hex) on the top line of the CRT display. One hundred and seventy calibration constants reside between addresses 01 (Hex) and AA (Hex). Calibration constants residing between 01 (Hex) and 6E (Hex) should have odd parity as explained below. The remaining locations may be of either parity. The readout display line has the following format:
AA DDDD P
The format is defined as follows:
"DDDD" is the 14-bit word stored at that location (13 bits of data and one parity bit).
"P" is a parity indicator for the data word: X indicates even parity; blank is odd parity.
Pushing the upper or lower TRIGGER MODE switch will increment or decrement the RAM address by 16 (10 Hex) respectively. Similarly, pushing the upper or lower TRIGGER SOURCE switch will increment or decrement the address by 1 respectively.

-- looks like it's time to replace the NVRAM on mine soon and hoping that a hand copy of the cal data might give a backup in case something happens during the procedure (I'm a little leery due to past experiences with data loss when moving Dallas NVRAMs from board to board; in that case I think one of the boards had residual voltage on the + rail & it was probably more user fail than IC fail... but still makes me hesitate).

best case would seem to be that those 340 bytes are just stored on the NVRAM starting at address 1 - and that if one takes a blank NVRAM and writes only those bytes, that nothing else will be required to make the scope happy (e.g. no other checksums or other data required for the scope to see that it's calibrated and work properly).
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: auato on December 23, 2014, 02:58:58 pm
Hi all.... instead I have this fault and unfortunatley I am not able to read the CRT anymore (the only evidence available is the internal self test @power-up which probably jams on test 05)

http://youtu.be/WNzYjhgLwis (http://youtu.be/WNzYjhgLwis)

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mikeselectricstuff on December 23, 2014, 03:25:17 pm
What puzzles me is that my programmer (supporting 1225) failed on a brand new chip... just wanted to verify programmer operation before plug in my precious old chip!

The only thing I can come up with, except for a faulty chip, is that there are timing issues, programmer acting too fast some signals.
I have a vague recollection that some NVRs have some sort of "factory seal" to maximise shelf life, and are activated by a special command to wake them up - could this be it?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: c4757p on December 23, 2014, 03:30:00 pm
The 1225 has this (they call it a "freshness seal" in the current datasheet (http://datasheets.maximintegrated.com/en/ds/DS1225AB-DS1225AD.pdf), which makes it sound rather like food...), but it's activated simply by the first application of power.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: peter-h on December 27, 2014, 10:04:09 pm
I have just read most of this thread, and I apologise if I have misunderstood something, but I have a 2465B (400MHz) on which all the illumination (except the CRT graticule variable illum) has just "gone funny".

Initially it all went blank when I turned on the scope today.

So e.g. I can't tell if ch1 is on

AC
GND
DC
GND
50 ohm DC

Then after about 1hr all the lights lit up, but ALL of them so I couldn't tell which of the options were selected :)

When I moved one of the buttons, it all sorted itself out and now seems to work.

I have had this scope for about 7 years and it has been perfect.

What is the likely cause? It looks like it might be temperature dependent.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: sparkybg on January 04, 2015, 12:31:16 pm
Hi,

Wondering if anyone has attempted to hand-copy cal constants using the "Calibration RAM Examine" thingie in the exercisers (or has at least verified that they are stored as shown in the RAM)...

-- looks like it's time to replace the NVRAM on mine soon and hoping that a hand copy of the cal data might give a backup in case something happens during the procedure (I'm a little leery due to past experiences with data loss when moving Dallas NVRAMs from board to board; in that case I think one of the boards had residual voltage on the + rail & it was probably more user fail than IC fail... but still makes me hesitate).

best case would seem to be that those 340 bytes are just stored on the NVRAM starting at address 1 - and that if one takes a blank NVRAM and writes only those bytes, that nothing else will be required to make the scope happy (e.g. no other checksums or other data required for the scope to see that it's calibrated and work properly).

I am planning a full recap of my 2445B next week. The parts are on their way from Farnell, and I also ordered FM18W08 to put on the A5 board. The dallas NVRAM still works on my unit, but I suspect it is a matter of time for it to fail. The date code of most of the chips inside is 1991, so I suspect my unit manufacturing date is not far from this. The serial is B062263. I bought it from one the "famous" Israeli ebay shops with readout problem. The problem was the well known cap leak on A5 which I repaired some time ago. Some 74HC chips were gone. Now I will do full restorarion and replace the DAC chip also, because I suspect it has a leakage path under it on the PCB.

Anyway, I've got EasyPro 90B programmer which has both Dallas 1225 and 1608/1808 chips in it's device list and I hope everything will be OK with programming. I will back-up the calibration data with the exercise you mentioned and the will try to find out where is it in the NVRAM.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on January 05, 2015, 11:12:39 pm
This one is for BravoV. I have the same vertical geometry problem you had [the words are too low to read]
You said that you adjusted the  vertical readout trimpot.
 I cant find this "vertical readout trimpot" in the schematics or troubleshooting. I cant even find those words in a 2445B or 2465B service manual.
Could you tell me what R number you adjusted? :)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on January 06, 2015, 11:06:54 am
This one is for BravoV. I have the same vertical geometry problem you had [the words are too low to read]
You said that you adjusted the  vertical readout trimpot.
 I cant find this "vertical readout trimpot" in the schematics or troubleshooting. I cant even find those words in a 2445B or 2465B service manual.
Could you tell me what R number you adjusted? :)

Malch, remember, I'm NOT the expert on this problem, and "maybe" my method is not the right way to fix this problem. So proceed with your own risk.

My suggestion, read the service manual, and understand what these 2 pots do. Also use a sharpie/marker to mark the current position at the pot, so if you suspect you screwed up  ??? while adjusting these pots, you can turn it back to the previous position.

The attached photo shots below should speak for it self where to find the pot, sorry, I forgot which one  :-//, but definitely one of these two, again, read and understand what are their purpose 1st before adjusting it.

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on January 06, 2015, 03:37:23 pm
I just received my 2445B, Its like new. The serial number is B064xxx , so I will have to change the caps in A5 and check the rest.
The Dallas has a 1990 date. It was last calibrated in Oct 2001.
I have the downloaded manual . I looked for many hours and could not find that fault mentioned.

So thank you very much for the info. I would not have found it as there are 8 possible trim pots.  :-+

P.S. Why does everybody hide their serial numbers?
 Got the failure prone .068uf caps.
Found the manual page for screen centering. page 5-22 CAL 07
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: linux-works on January 06, 2015, 03:40:46 pm
OT: but suppose someone sees your serial and makes a fake report to some police dept that your unit was stolen.

you just posted your unit with your serial number.  its now up to you to prove you did not steal it.

why even get into that mess?  why allow bad people to try to screw you over?

so, many of us avoid it by not posting the serial's.  no reason to give serials on gear away, anyway.  what gain (to anyone) would there be?  I've already listed at least one danger.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MarkL on January 06, 2015, 04:07:21 pm
Wondering if anyone has attempted to hand-copy cal constants using the "Calibration RAM Examine" thingie in the exercisers (or has at least verified that they are stored as shown in the RAM)...
I did this with my 2465, but I took a more lazy approach.  I took a video of the screen while flipping through all the memory locations.

The 2465 has an EAROM which hasn't gone bad (maybe yet), but now I have all the cal values if it does.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: tymm on January 06, 2015, 07:50:07 pm
Cool -- though do you know whether the constants can just be copied into a new IC and have it work?

I've copied down the data from mine - and think there's a good chance it would work just straightforward... though I can see lots of ways that it could be more complicated (cal data stored at an offset address in the NVRAM, secondary checksums, etc).

Looking forward to hearing from sparkybg; will probably just go ahead with mine and test whether things match if there's no confirmation by the time I'm ready to go.

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MarkL on January 06, 2015, 08:29:43 pm
Cool -- though do you know whether the constants can just be copied into a new IC and have it work?
No, I don't know.   I'm assuming it's accurately reporting the word at each location.  I'll have to test reprogramming in battle.

Living on the edge?  Maybe.  But I haven't heard any tales yet of the EAROMs going bad, and I don't use the scope enough to invest the time to fix what might not be a problem.

Another thing I've done on other equipment is to use an exercise routine to cycle through NVRAM and clip on a logic analyzer to capture the bytes.  Then you *know* whether or not you have all the cal data.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on January 06, 2015, 09:24:23 pm
Watch out you dont squash or bend the two little stiff wires going to the middle of the CRT
 while trying to get the psu cards out. :P
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: sparkybg on January 09, 2015, 12:04:42 am
Done:
- Full recap of power supply - the immediate result is sharper display, better triggering, and (although I am not completely sure) faster "boot-up" after the scope is powered up. I've used Panasonic FR, low ESR Nichicon and low ESR Rubicon caps.
- Full refurbishment of A5 board. I replaced the DS1225Y NVRAM with FM18W08 FRAM. No problems whatsoever. I was able to read the contents of my original NVRAM and put them in the FRAM without any problem. The scope boots and works normally.

To do:
- Full recap of main board.
- Replacement of the only electrolytic cap in the CRT supply.
- Full calibration, if I find a place with all the equipment needed, or at least vertical calibration. All other is OK, but vertical is with 2-3%  lower amplitude than cursors say.

The calibration constants from exercise 2 are located at addresses 1E00 - 1FFF in the NVRAM. I don't know if they can be used with another dump. Maybe I will try just out of curiosity. Maybe I will able to tell which constants are for vertical calibration when I calibrate the vertical.

I will post some pictures of the process when all the tasks are done.

Update: I have just tried a 2465B S/N B05xxxx dump on my 2445B S/N B06xxxx with my original calibration constants. It works flawlessly! So, it is a good idea to backup your constats from exercise 2 before you do anything with the NVRAM chip. It can save you a calibration if something goes wrong when you try to read your NVRAM after desoldering.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on January 09, 2015, 05:16:37 am
The calibration constants from exercise 2 are located at addresses 1E00 - 1FFF in the NVRAM. I don't know if they can be used with another dump. Maybe I will try just out of curiosity. Maybe I will able to tell which constants are for vertical calibration when I calibrate the vertical.

Great info !  :-+ Please, keep us updated on your quest for calibration constants if you decided to decode it.

I will post some pictures of the process when all the tasks are done.

 :clap:
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: tymm on January 09, 2015, 08:25:02 am
Update: I have just tried a 2465B S/N B05xxxx dump on my 2445B S/N B06xxxx with my original calibration constants. It works flawlessly! So, it is a good idea to backup your constats from exercise 2 before you do anything with the NVRAM chip. It can save you a calibration if something goes wrong when you try to read your NVRAM after desoldering.

Sweet -- thanks so much for testing it out and following up.  Really great to know that it works!
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: sparkybg on January 09, 2015, 11:14:34 am
Just two pictures of FRAM mod for now. Enjoy.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: sparkybg on January 09, 2015, 01:30:26 pm

Malch, remember, I'm NOT the expert on this problem, and "maybe" my method is not the right way to fix this problem. So proceed with your own risk.

My suggestion, read the service manual, and understand what these 2 pots do. Also use a sharpie/marker to mark the current position at the pot, so if you suspect you screwed up  ??? while adjusting these pots, you can turn it back to the previous position.


Use these pots without any marking or so. It is pointless - they are only to center the readout vertically. They have nothing to do with the calibration, or cursors. Try them - you will see for yourself that only the readout (top and bottom text fields on the crt) will move. One of the few things in this scope that does not interfere with something else. Maybe only horizontal or vertical readout jitter will have to be readjusted, but again - you can do this also without affecting anything else.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on January 09, 2015, 02:27:56 pm
Thanks sparkyb. I am going to get at pin 7 today to add a battery to my Dallas. I,m thinking of staying with the Dallas with a big battery.

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: sparkybg on January 09, 2015, 03:07:47 pm
The choice is yours of course.

But, from my point of view, the FRAM is much better solution. FM16W08 costs around 10EUR in Mouser Europe, than you need a SOIC28 to DIP28 PCB (maybe a dollar or so, from eBay for example), and you are done with this problem forever.

On the other side, no one has confirmed (nor can confirm) how long the external battery will last, considering it has a 20 years old battery connected in parallel with it. The desoldering of the old chip is the most hard work to do, and once it is done, you have completed 90% of the work anyway.

...well, I bought a ZD215 desoldering station recently, and desoldering of the old chip was a piece of cake with it. It was done in under 2 minutes with perfect result. The recapping of the PSU was also a pretty easy task using such instrument.

P.S.: Bear in mind that you absolutely HAVE to change the caps in the power supply, especially the polyester/polypropylene X/Y type ones. These are a ticking bomb waiting to explode. I had an older 2445 scope before and two of them exploded. Also, some of the electrolytic ones had 15 times bigger ESR compared to the the caps I replaced them with. You can leave the A1 board without recap, but the power supply and the A5 board are absolutely "must-do's" if you are planning to use your scope for some years.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Howardlong on January 09, 2015, 04:17:16 pm
My programmer wouldn't deal with the DS1225Y (a TL866A, it's listed, but it doesn't work), so I built my own.

It's been tested with both the DS1225Y and the RAMTRON FM18W08-SG (although only the bottom 8k bytes of the RAMTRON is used).

I built it with parts that I had in the lab, it's based on a PIC18F4550, and I breadboarded it. It's controlled from a TTL 3.3v level serial port. I used an FTDI TTL-232R-3V3, but a 5V one should work just as well. The device must be powered from 5V, it will detect a brown out and reset if the voltage falls below about 4.3V or so, this is to make sure that unexpected writes don't occur during power up/power down (control signals go Hi-Z and there are also pullups on /WE and /CE).

The NVRAM data is stored in the PIC's flash program area, so it remains in place after power down.

(http://i34.photobucket.com/albums/d123/photobucket391/P1000677_zpse17b1e65.jpg) (http://s34.photobucket.com/user/photobucket391/media/P1000677_zpse17b1e65.jpg.html)

Schematic attached (Eagle and PDF), and source code and .hex file for use MPLAB 8 IDE (compiler is XC8), although it should import into MPLAB X if that's what you prefer.

Here is how to use it:

Insert source NVRAM and power up...
Code: [Select]
1E: reset status

--- DS1225Y NVRAM copy programmer ---
Select:
  [R]ead NVRAM into PIC flash
  [V]erify NVRAM with PIC flash
  [W]rite PIC flash to NVRAM
  erase PIC [F]lash
  erase [N]VRAM
  [B]lank check PIC flash
  fill NVRAM with ran[D]om data
  fill PIC flash with rand[O]m data
  [P]rint NVRAM contents
  print PIC f[L]ash contents
  get [C]hecksums
> R

Erasing flash...
Reading 1F00
Read completed.
Verifying 1F00
Verify completed: success.

--- DS1225Y NVRAM copy programmer ---
Select:
  [R]ead NVRAM into PIC flash
  [V]erify NVRAM with PIC flash
  [W]rite PIC flash to NVRAM
  erase PIC [F]lash
  erase [N]VRAM
  [B]lank check PIC flash
  fill NVRAM with ran[D]om data
  fill PIC flash with rand[O]m data
  [P]rint NVRAM contents
  print PIC f[L]ash contents
  get [C]hecksums
> C
NVRAM checksum=0xF9AB
Flash checksum=0xF9AB

--- DS1225Y NVRAM copy programmer ---
Select:
  [R]ead NVRAM into PIC flash
  [V]erify NVRAM with PIC flash
  [W]rite PIC flash to NVRAM
  erase PIC [F]lash
  erase [N]VRAM
  [B]lank check PIC flash
  fill NVRAM with ran[D]om data
  fill PIC flash with rand[O]m data
  [P]rint NVRAM contents
  print PIC f[L]ash contents
  get [C]hecksums
>

Power down and insert new NVRAM chip, then power back up...
Code: [Select]
1E: reset status

--- DS1225Y NVRAM copy programmer ---
Select:
  [R]ead NVRAM into PIC flash
  [V]erify NVRAM with PIC flash
  [W]rite PIC flash to NVRAM
  erase PIC [F]lash
  erase [N]VRAM
  [B]lank check PIC flash
  fill NVRAM with ran[D]om data
  fill PIC flash with rand[O]m data
  [P]rint NVRAM contents
  print PIC f[L]ash contents
  get [C]hecksums
> W
Writing 1F00
Write completed.
Verifying 1F00
Verify completed: success.

--- DS1225Y NVRAM copy programmer ---
Select:
  [R]ead NVRAM into PIC flash
  [V]erify NVRAM with PIC flash
  [W]rite PIC flash to NVRAM
  erase PIC [F]lash
  erase [N]VRAM
  [B]lank check PIC flash
  fill NVRAM with ran[D]om data
  fill PIC flash with rand[O]m data
  [P]rint NVRAM contents
  print PIC f[L]ash contents
  get [C]hecksums
> C
NVRAM checksum=0xF9AB
Flash checksum=0xF9AB

--- DS1225Y NVRAM copy programmer ---
Select:
  [R]ead NVRAM into PIC flash
  [V]erify NVRAM with PIC flash
  [W]rite PIC flash to NVRAM
  erase PIC [F]lash
  erase [N]VRAM
  [B]lank check PIC flash
  fill NVRAM with ran[D]om data
  fill PIC flash with rand[O]m data
  [P]rint NVRAM contents
  print PIC f[L]ash contents
  get [C]hecksums
>

That's it.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on January 09, 2015, 04:32:16 pm
I already have all the fram pieces in my watch at ebay.
I also found an earom on ebay [new] and a earom burner.$$

Removing the Dallas and soldering the socket has been done.
I dug in the epoxy and checked the Dallas battery voltage=3.45v.
So now I will copy the Dallas to my hard drive before anything else.

My idea is to add a laptop battery [connector and all] and disconnect the original battery.
If that fails or is impractable I still have the bin to burn to a new chip-Dallas or Fram.

Mouser is sending all the caps for A5 and the LVPS cards.
Two points.
 If I had to do all over again I would only buy a 24x5b with a lower serial number than 50,000 to get rid of the SMDs.
 I am replacing 3 of them, but there are still 20 to 40 of them left in the scope.[replaced the 4 axial ones too]

It is a pleasure working on this scope mostly because of the people on this thread.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: sparkybg on January 09, 2015, 06:02:26 pm
Make sure you get "W" FRAM. FM18W08 or FM16W08. These lasts 100 times longer (10E14 cycles) then devices without "W" (10E12 cycles).

I have not seen "W" devices on eBay. And, I prefer to buy from well known reseller (Farnell, Digikey, Mouser) than eBay.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on January 09, 2015, 07:31:22 pm
This pic is for anybody interested in the battery connection  under the epoxy. A strap is spot welded to a watch battery with one end going straight to pin 14.
I drilled two holes, one on each side so I could get my side cutters in to make the fatal cut.
I used a 1.2mm carbide router bit in a Dremel to do the cut.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: grumpydoc on January 09, 2015, 08:44:04 pm
Make sure you get "W" FRAM. FM18W08 or FM16W08. These lasts 100 times longer (10E14 cycles) then devices without "W" (10E12 cycles).

I have not seen "W" devices on eBay. And, I prefer to buy from well known reseller (Farnell, Digikey, Mouser) than eBay.

Are you sure - the cypress datasheets list the "W" types as "Wide voltage" - i.e 2.7 to 4.5V max. The Non "W" 5.5V max devices are rated for 4.5 to 5.5V Vcc max.

Both are rated for 1014 operations.

Or, in other words if you sequentially accessed every location in the device at maximum speed (130ns cycle time) it would take 130ns x 1014 x 32768/8 = 16k years to wear the device out.

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on January 10, 2015, 02:30:57 am
@Howardlong

Thanks for sharing that !  :-+


.... 16k years to wear the device out.

Hmmm ... give it a really-really generous de-rating, say only 1% of 16K years = 160 years , ok, I'm content now.  :-DD
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: sparkybg on January 10, 2015, 02:56:57 am

Are you sure...
Yes, I am.

Both are rated for 1014 operations.
No, they aren't. Look again.

Here's FM1608 datasheet:
http://www.farnell.com/datasheets/82469.pdf (http://www.farnell.com/datasheets/82469.pdf)

And here is FM16W08 datasheet:
http://www.cypress.com/?docID=48242 (http://www.cypress.com/?docID=48242)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: grumpydoc on January 10, 2015, 10:23:05 am
No, they aren't. Look again.

Here's FM1608 datasheet:
http://www.farnell.com/datasheets/82469.pdf (http://www.farnell.com/datasheets/82469.pdf)

And here is FM16W08 datasheet:
http://www.cypress.com/?docID=48242 (http://www.cypress.com/?docID=48242)

Ah, I see your confusion

EDIT: I see mine as well - it's the newer FM1608B which is currently on the Cypress site - guess I missed that small part number change  :-\

You have compared the data sheet for a Ramtron part with the data sheet for a slightly different Cypress part and concluded that the difference in endurance is due to the slight change in part number - but failing to spot that there is at least one other difference between these parts.

The supply voltage on the FM1608 is 4.5 to 5.5V
The supply voltage on the FM16W08 is 2.7 to 5.5V

In fact if you look over all of the Cypress parts http://www.cypress.com/?id=4986&addcols=&parametric=html&filter_184=32Kb+x+8#parametric (http://www.cypress.com/?id=4986&addcols=&parametric=html&filter_184=32Kb+x+8#parametric) you will see that they are all specified as 1014 cycles, both the "W" and non "W" part numbers.

So in your example it was the manufacturer that made the difference between 1012 and 1014, however I suspect it is really process because the Ramtron data sheet is from 2007 and the Cypress one from 2014.

In fact there is a Ramtron FM16W08 which is wide supply voltage and 1014 cycles but the data sheet for that is quite recent as well (2012).

It's all moot anyway because Cypress acquired Ramtron last year.

So, yes, there are 32kx8 FRAMs with 1012 endurance and 32kx8 FRAMs with 1014 endurance, and buying the wide supply voltage FM16W08 should get you a part with the better endurance but the "W" in that part number does not denote the endurance, it denotes the extended supply voltage tolerance.

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: sparkybg on January 10, 2015, 06:14:42 pm
Now, go to eBay, seek for "FM1608", and all the parts you will get will be Ramtron ones.

Then, do the same with "FM16W08", and you will again get some Ramtron devices.

Then, on the Cypress page, look for "FM1608", and you will get nothing. 16W08 is there.

So, in practice, buying FM1608 from eBay, you cannot know what exactly you are buying - a device with 10E14 or a device with 10E12 cycles. Buying 16W08 you are sure it is 10E14.

P.S: I would like to see that datasheet for 1608 with 10E14 rating. I cannot find it anywhere. Can you please give a link or upload it here?

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on January 10, 2015, 06:21:27 pm
On page 3 BravoV posted this
 "Sad news, a failed to attempt to find the better replacement for the pesky Dallas DS1225Y BBSRAM, cause the F-RAM Ramtron FM1608-120 is not compatible. It was an impulse purchase thru a friend visiting abroad without checking the detail 1st, and also I was mis-leaded by info gathered from the Tektronix's Yahoo mailing list"
How come his chips didnt work but yours does?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: sparkybg on January 10, 2015, 06:29:31 pm
On page 3 BravoV posted this
 "Sad news, a failed to attempt to find the better replacement for the pesky Dallas DS1225Y BBSRAM, cause the F-RAM Ramtron FM1608-120 is not compatible. It was an impulse purchase thru a friend visiting abroad without checking the detail 1st, and also I was mis-leaded by info gathered from the Tektronix's Yahoo mailing list"
How come his chips didnt work but yours does?

The only difference between FM1608 and DS1225Y is that the FM1608 needs an impulse on CS every time the address changes in order to latch it and put the data at this address on the output. The DS1225Y does not need this - it can run with continuous CS low, and every time the address changes, the data at this address is available at the output. This is called "fast reading" or something like this. But, the 2465B processor is not using a fast reads and every time it reads or writes from/to the NVRAM it generates an impulse on CS. That's why it works.

P.S: Here is a link to the document: http://www.worldphaco.com/uploads/TEKTRONIX_2465b_OSCILLOSCOPE_CALIBRATION___REPOWERING_THE_DS1225.pdf (http://www.worldphaco.com/uploads/TEKTRONIX_2465b_OSCILLOSCOPE_CALIBRATION___REPOWERING_THE_DS1225.pdf)

From my point of view, reading this document, the FM16W08 is the best possible replacement - it just needs an SOIC28-DIP28 PCB and nothing more. The STK12C68 is another one. The read/write cycles then will be equal to powering up/downs of the scope. With 1000000 store cycles and 100 years data retention, in practice this will last forever. Although it needs a PCB with some additional parts on it.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on January 10, 2015, 06:37:31 pm
But it didnt work in BravoV's case. ?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: sparkybg on January 10, 2015, 06:42:40 pm
But it didnt work in BravoV's case. ?

I don't think Bravov ever tried it. This is stated on the datasheet as the only difference between classic SRAM ind this particular FRAM.

Anyway, let him tell us what was the case, but I can confirm it works - my scope is right next to me in this moment, and works flawlessly with FM18W08 on it.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on January 10, 2015, 06:56:44 pm
Thats one of the reasons I spent time putting a new battery in my Dallas. It works good by the way. It is supposed to last 26 years. :)

edit: maybe 130 years.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: grumpydoc on January 10, 2015, 08:25:08 pm
Now, go to eBay, seek for "FM1608", and all the parts you will get will be Ramtron ones.

Then, do the same with "FM16W08", and you will again get some Ramtron devices.

Then, on the Cypress page, look for "FM1608", and you will get nothing. 16W08 is there.

So, in practice, buying FM1608 from eBay, you cannot know what exactly you are buying - a device with 10E14 or a device with 10E12 cycles. Buying 16W08 you are sure it is 10E14.
I'll agree with you as far as "from eBay, you cannot know what exactly you are buying"  :)

Quote
P.S: I would like to see that datasheet for 1608 with 10E14 rating. I cannot find it anywhere. Can you please give a link or upload it here?
Now I look it's a FM1608B http://www.cypress.com/?docID=48234 (http://www.cypress.com/?docID=48234), Cypress don't currently list an FM1608, as you say.

You are correct that the FM1608 is 1012 and you are correct that buying the FM16W08 will be a higher endurance part, just that the "W" does not mean higher endurance per-se.

In fact the plain FM1608 is obsolete and the FM1608B is supposed to be the replacement - so that's the normal supply range but 10E14 endurance part - there are some notes about the differences here http://www.cypress.com/?docID=47983 (http://www.cypress.com/?docID=47983), note that the new part is not better across the board - it has higher standby current requirements and under some conditions has lower data retention.

The other reason that you are correct in practice is that I can't see anywhere with an FM1608B in stock, whereas the FM16W08 does appear to be available.

Sorry - it's splitting hairs and for that I apologize - but you know how it is (http://www.xkcd.com/386/)  >:D (actually that's a bit unfair as you weren't really wrong)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: sparkybg on January 12, 2015, 12:32:29 am
Sorry - it's splitting hairs and for that I apologize - but you know how it is (http://www.xkcd.com/386/)  >:D (actually that's a bit unfair as you weren't really wrong)
There's nothing to apologize for. :)

I just finished the vertical and trigger calibration. Finaly my 2445b is in one piece. :) I had to do a calibration generator out of old board I constructed several years ago - it had a 10 bit DAC on it, with opamps after it to give the needed 10V for calibration. I just had to add a resistor divider network. Everything is calibrated perfectly now. :) I will attach some pictures of the entire process in a day or two.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: sparkybg on January 12, 2015, 07:20:40 am
Another aspect of F-RAM programming - my programmer have 1608, 1808 and 18L08 (which is older low voltage part now obsolete). When I select either 1608 and 1808, the programmer refuses to program and read the first byte (at address 0000). I suspect this is because of 10ms "power to first access" time of the 18W08. But when I select 18L08 everything is OK. So, again the "W" part gives you the flexibility of trying more different devices in your programming software, if some of them don't work. In my case, only the 18L08 worked as it should. My programmer is EasyPro 90B, and the list of devices it supports is not updated so often.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: sparkybg on January 18, 2015, 12:00:37 pm
OK, here we go. I've decided to go one by one, and check if everything is OK after each step.

First , the PSU.

Nothing special, really. There was clear signs of electrolyte leak from some of the caps. And well known issue with the X/Y transparent caps. I've replaced them with EPCOS units.
Bear in mind that there are 3 bipolar electrolytic capacitors on one of the PCBs. They must be replaced with the same type. The only caps I did not replace are these bi-polar ones.

I've replaced most of the caps with Panasonic FR low ESR/long life units. On the last pictures there is a small comparison between the old ones and the new ones. As you can see, the capacitance is there even on the leaked ones, but the ESR is several times (between 5 and 20) higher than on the new ones.

Also you can replace all the 180uF and 250uF with 330uf 50 or 63V. I've replaces the 180uF with 270, and 250uF with 330.

The immediate result of this was clearer traces.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: sparkybg on January 18, 2015, 12:13:09 pm
Next, the A5 board.

When I bought this scope, it had some issues with the readout. Because of the leaked caps there was pretty intense corrosion on the board. Unfortunately while removing some of the caps, the pads were heavily damaged. I had to replace some of the logic chips around the upper left part of the PCB. Well, I replaced the chips and caps back then, made a good bath with isopropyl alcohol, and all was OK.

There are some missing parts on the photo, but I forgot to take a picture before I started the restoration.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: sparkybg on January 18, 2015, 12:25:10 pm
Unfortunately this was not enough. Recently the front controls began to work strangely, and the horizontal deflection of the CRT was a bit lower. When I made some measurements, the DAC reference was way out of 2.5V, and I was not able to correct it with the trimmer. There was not any reaction when I rurned the trimmer. Clearly there was a problem with it, so I decided to make a full replacement of all parts around the leakage with signs of corrosion on their legs.

The width of traces on this board is unnecessarily low, and the consequence of this is easy corrosion breaks just next to the pads the trace is connected to. So pay extra attention around the pads for broken traces. This is why I had to rotate one of the resistors. I replaced the DAC with a new one from Analog Devices.

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: sparkybg on January 18, 2015, 12:26:43 pm
And, here it is after the restoration. The replaced logic chips on the left are clearly visible.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: sparkybg on January 18, 2015, 12:42:33 pm
After I confirmed that everything works, I wanted to replace the DS1225Y NVRAM. It was a matter of time for it to fall out of specification and loose all the calibration data.
I bought a ZD-915 desoldering gun some time ago and desoldering ot the DS1225Y was pretty easy task using it. There was not any problem reading it with my EasyPro 90B programmer.

I bought a FM18W08 F-RAM and SOIC28 - DIP28 PCB. The process was easy. I leaved two terminals stated "NC" in DS1225Y's datasheet unconnected to A5 board, and connected them to the address lines next to them. This is visible on the pictures. I was able to write the data from DS1225 in the FM18W08 flawlessly, and everything worked.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: sparkybg on January 18, 2015, 12:54:52 pm
Next, full recap of A1 board, and heatsink mounting on the infamous U800.

1. You have have to desolder all the connections to back BNC connectors.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: sparkybg on January 18, 2015, 12:56:42 pm
2. you have to desolder all the connections to the CRT.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: sparkybg on January 18, 2015, 12:58:07 pm
3. Remove the front bezel, disconnect all the connectors to the front panel, and to the front controls (focus/brightness/etc.)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: sparkybg on January 18, 2015, 01:01:58 pm
4. Remove the A5 board and power supply. While doing this, pay extra attention not to touch and bend the CRT termination.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: sparkybg on January 18, 2015, 01:02:53 pm
5. Disconnect the connector to the HV power supply.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: sparkybg on January 18, 2015, 01:05:37 pm
6. Remove all the screws of the front BNC connectors, remove all the screws holding the A1 board to the frame. This will also detach the delay line case from the board. You will have to desolder the delay line from the board later.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: sparkybg on January 18, 2015, 01:16:51 pm
7. Remove the A1 board. You will have to pull the A1 board up to disconnect the connectors to the HV board, and next pull tha A1 board to the back of the scope to take it out. You will have to remove the small connector on the back which prevents you to pull the board up. You will have to push a delay line a bit to the front while doing this - the back BNC connectors prevents you to do it directly. Pay extra attention while removing the A1 board - there are several things you can bend or break while doing this. Pay extra attention to the focus/astig/brightness front panel connector while doing this. The back of the board needs to be pulled up and then back to remove theA1 board.

8. Once the A1 board is out, take a picture of the delay line connections, then desolder them. This is a bit tricky - you will need a pretty powerful soldering iron in order to desolder the outer mountings of the delay line. I desoldered them with the ZD-215 desoldering gun on 400C.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: sparkybg on January 18, 2015, 01:21:30 pm
9. The rest is more or less easy - just replace the caps. Again, with desoldering gun this is a piece of cake. I've replaced all the caps with Panasonic FR and Panasonic EB.

10. Put a good heatsink to U800 chip. I've used an FPGA heatsink for this. I bought it from Farnell.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: sparkybg on January 18, 2015, 01:22:41 pm
And, here it is, up and running again, with clear and bright traces and readout. It will last some more years for sure. :)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: sparkybg on January 18, 2015, 01:30:58 pm
11. I went through all the adjustment procedures I could, considering the equipment I have. The vertical calibration of my unit always was was out of specification, so I decided to correct this also. I had a mixed signal board I made some time ago with MCU, DAC and OPAMPs on it, able to give 10V peak to peak amplitude on it's output. I made a resistor network in order to have 10V, 5V, 2V, 1V, 500mV, 200mV, 100mV 50mV and 20mV out of it. I hooked my Agilent U1272A DMM to this in order to be able to correct the amplitude for best possible accuracy. I went through the vertical and trigger adjustment procedure, and finally my vertical cursors began to show exactly what they should show. Here's my setup.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on January 18, 2015, 09:24:47 pm
Finished my U800
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on January 25, 2015, 10:10:24 pm
Well all done. Moved the cal/nocal jumper to cal and fired it up.
The 10 v was out a little [9.98 v ] and I had to fiddle with the vertical jitter pot.
Ran test all and all passed.
What is the exerciser used for ? How do you know when it is finished? How do you stop it?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: sparkybg on January 26, 2015, 12:06:23 am
Well all done. Moved the cal/nocal jumper to cal and fired it up.
The 10 v was out a little [9.98 v ] and I had to fiddle with the vertical jitter pot.
Ran test all and all passed.
What is the exerciser used for ? How do you know when it is finished? How do you stop it?

Which exerciser? Calibration constants exerciser? If yes, on every step you have an address and the contents of this address. Just make a movie of the screen while you go from the lowest to the highest address. When you reach the highest address, it will turn back to the lowest. You can exit from exerciser at any time or any step you want.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mtdoc on January 26, 2015, 12:29:13 am
Finished my U800

Nice heatsink!  I hope it doesn't stick up far enough to touch the case though.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on January 26, 2015, 12:31:58 am
Measured twice cut once!
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on January 26, 2015, 12:36:43 am
sparkybg When you press t,v and slope you get a menu of calibration,test and exercise routines that are in a loop.
When I started the exerciser nothing happened. Why in the world would I make a movie of it?
Besides I dont have a movie camera.
I can exit the exerciser any time I want if I knew how to. :)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: sparkybg on January 26, 2015, 11:34:17 am
The cal/no cal jumper doesn't have to be in "cal" position for the exercise and test routines.

1. Turn the scope on.
2. Pres V, T simultaneously and then "SLOPE". You will see "DIAGNOSTIC. PUSH A/B TRIG TO EXIT" on top of screen and "ALL 00" on bottom.
3. Using "MODE" buttons, scroll to "EXER 02".
4. Push upper trigger "COUPLING" button. You will see "00 xxxx" on top of the screen where "00" is the address and "xxxx" are hexadecimal number.
5. Using upper trigger "SOURCE" button scroll from address 00 to FF address and write down the numbers. It is much easier to make a movie of the screen while you are scrolling. Every decent phone with camera can do this.
6. When you are done, press lower trigger "COUPLING" to exit exercise, and then "A/B TRIG" if you want to exit from diagnostic mode.

All this is written in the service manual, and maybe operator's manual as well.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SoundTech-LG on February 02, 2015, 08:28:52 pm
This is the best series of posts on EEVBLOG! Very informative, and interesting. My 2467B is on it's way from NYC off ebay. Cannot read SN well, but looks to be starting 05, so probably has the Dallas. Cannot quite read what is showing on the CRT either, so unknown if it has error messages. Seller did not seem to really know much. I figured out from the fuzzy rear photo that it has Option 05 TV Sync Sep, Option 06 CTT, Option 11 Probe Power. Can't wait to get it, open it, and see what's up... leaning toward the big battery option for the Dallas.

Martin
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SoundTech-LG on February 02, 2015, 08:48:04 pm
BTW...

does anyone have, or know about Option 01E? it's the Reference signal input. It was only $200 to begin with. Sounds like mostly installing a BNC jack, but don't know.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on February 02, 2015, 09:01:38 pm
It's not in my option service manual. just 01 and 01B. :)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SoundTech-LG on February 02, 2015, 10:30:57 pm
Hi,

Thanks for the reply. Yes, it was offered. maybe 1E...  anyway, shown on the original datasheet for $200.00
It's just an External Reference Clock input.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on February 02, 2015, 10:34:06 pm
Wikipedia notes 01E is for joining two scopes with one sync pulse.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Howardlong on February 03, 2015, 12:44:46 am
This is the best series of posts on EEVBLOG! Very informative, and interesting. My 2467B is on it's way from NYC off ebay. Cannot read SN well, but looks to be starting 05, so probably has the Dallas. Cannot quite read what is showing on the CRT either, so unknown if it has error messages. Seller did not seem to really know much. I figured out from the fuzzy rear photo that it has Option 05 TV Sync Sep, Option 06 CTT, Option 11 Probe Power. Can't wait to get it, open it, and see what's up... leaning toward the big battery option for the Dallas.

Martin

To wet your whistle, here's a comparison vid I took a few days ago between a 2465B and 2467B http://m.youtube.com/watch?v=ZGi1Uw8l-ac (http://m.youtube.com/watch?v=ZGi1Uw8l-ac)

CTT is nice to have, the 2467B I have has it but my 2465B doesn't. You can still measure frequency without the CTT but it isn't as accurate and it takes some time (and usually reconfigures your scope at the same time). With the CTT you can have a continuously updating frequency display shown, but not without it.

They are beautiful scopes. I use mine daily, the immediacy of operation compared to DSOs makes them such a joy to use. But no, I can't do an I2C decode with it. ;-)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Kartman on February 03, 2015, 02:29:52 am
As usual, I'm late to the party! I haven't read the extensive posts here, so please forgive me if I'm repeating stuff you already know. I have a 2465 that had some problems a few years ago. It reported a earom failure. Turned out it was the electro for the -42V rail in the power supply. I went through and did an ESR test on all the caps on that board and all but one cap was ok. I disassembled the code and found where the earom was accessed. Shouldn't be too hard to poke in some code to use a modern spi eeprom. Since I found the root cause, I had no need to do any mods.
One problem I had recently is the power switch. This looks like a standard ITT shadow part that was common years ago. Does anyone know where to source these at a reasonable cost? As in around $10-20 USD? I've just put wires across the switch for the moment and power off by pulling the plug.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SoundTech-LG on February 03, 2015, 04:22:59 am
Hi Howard,

Nice video. We have a variety of very nice scopes at work Agilent, and Tek DSO's, but I prefer working with the analog scopes. we have a 2465B in our Faraday cage, and I was checking it out. Best analog scope we have. Pretty bright, but yes, you proved the 2467B is much brighter. My eyes are not that good anymore, so I need it! Glad I chose it over the standard CRT.

Martin
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SoundTech-LG on February 03, 2015, 04:30:38 am
Wikipedia notes 01E is for joining two scopes with one sync pulse.

Hi, checked Wiki, but only found this...

Oscilloscope Options

The important oscilloscope options are:

01 - Digital Multimeter

03 - Word Recognizer Probe Pod (P6407)

05 - Video Waveform Measurement System

06 - Counter/Timer/Trigger (CTT)

09 - Counter/Timer/Trigger (CTT) with Word Recognizer (WR)

10 - GPIB Interface

11 - Probe Power

1E - External Clock

22 - Two additional Probes

1R - Prep for rack mounting kit

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on February 03, 2015, 04:32:19 am
1E - External Clock
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SoundTech-LG on February 03, 2015, 04:34:34 am
Right.

But no mention of "joining 2 scopes together"....
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SoundTech-LG on February 03, 2015, 04:44:55 am
I'm sure there are numerous uses for a Ref Clock input, and yes, one could be referencing 2 scopes to one clock signal.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on February 03, 2015, 04:51:43 am
My first Google brought up the first three here.

https://www.google.ca/search?q=1E+-+External+Clock&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a&gfe_rd=cr&ei=G1DQVKKLGpLu-QOBuoC4DQ#newwindow=1&rls=org.mozilla:en-US:official&q=TEXTRONIX+OPTION+1E+-+External+Clock (https://www.google.ca/search?q=1E+-+External+Clock&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a&gfe_rd=cr&ei=G1DQVKKLGpLu-QOBuoC4DQ#newwindow=1&rls=org.mozilla:en-US:official&q=TEXTRONIX+OPTION+1E+-+External+Clock)

But then I found this on a brochure.

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on February 03, 2015, 04:57:34 am
Kartman , I'm pretty sure you have tried this: S350  260-1849-00  DPDT 4A 250V   31918   NE15/F2U103EE   ITT SCHADOW INC

The  NE15/F2U103EE   comes up on all the military surplus sites. I suppose you tried them?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on February 03, 2015, 05:35:17 am
Attached scanned brochure of the original price list of the Tektronix 2400B Series as a reference, as it has all the options details.

PS : Not sure when it was printed, as there is no date there.  :-//

(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=133968;image)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on February 03, 2015, 06:15:03 am
Yup that's where I got it from.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SoundTech-LG on February 03, 2015, 04:34:10 pm
That datasheet was the initial source of my original question.  Not much detail of the 1E option.
My real question is how to wire in a BNC to accomplish it.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: tymm on February 05, 2015, 04:04:50 am
As usual, I'm late to the party! I haven't read the extensive posts here, so please forgive me if I'm repeating stuff you already know. I have a 2465 that had some problems a few years ago. It reported a earom failure. Turned out it was the electro for the -42V rail in the power supply. I went through and did an ESR test on all the caps on that board and all but one cap was ok. I disassembled the code and found where the earom was accessed. Shouldn't be too hard to poke in some code to use a modern spi eeprom. Since I found the root cause, I had no need to do any mods.
One problem I had recently is the power switch. This looks like a standard ITT shadow part that was common years ago. Does anyone know where to source these at a reasonable cost? As in around $10-20 USD? I've just put wires across the switch for the moment and power off by pulling the plug.

Not sure if this is what you're asking about, but I was able to get a replacement switch cover (the flip dot like thing that goes over the switch) from Sphere Research a few years ago.  Don't remember the cost, but I think it was in that range.  They may also have the switches themselves.

http://www.sphere.bc.ca (http://www.sphere.bc.ca)

They're great.

In some cases I've found that I needed to email them when looking for a specific part that I couldn't find on their site, but they've always been super helpful and pleasant to deal with.

** edit ** oops reread original post; you are talking specifically about the switch itself.  Still would suggest checking Sphere.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SoundTech-LG on February 16, 2015, 04:40:20 am
The time out on the CRT brightness on my 2467B seems to be 30secs according to the screen. Is this normal? Pretty silly having to turn a knob every 30 secs to keep the display on!!!
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: EV on February 16, 2015, 06:05:08 am
The time out on the CRT brightness on my 2467B seems to be 30secs according to the screen. Is this normal? Pretty silly having to turn a knob every 30 secs to keep the display on!!!

Is it same time if you adjust the trace darker?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SoundTech-LG on February 16, 2015, 04:01:23 pm
The time out is a normal feature I think on the 2467B, just not sure if 30 secs is the default, and if that can be changed. No, it makes no difference on the intensity setting, still 30 secs  countdown, no matter what. I'm sure it saves burns, but quite annoying!
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Howardlong on February 16, 2015, 06:26:57 pm
The time out is a normal feature I think on the 2467B, just not sure if 30 secs is the default, and if that can be changed. No, it makes no difference on the intensity setting, still 30 secs  countdown, no matter what. I'm sure it saves burns, but quite annoying!
There are two timeouts, one to dimming and the other to "shutdown" (as far as I cans see this is just a sleep mode, the scope comes back immediately when you hit a button).

The first timeout to dimming on my example seems a little random, but ranges from about 75s to well over three minutes, I don't know the algorithm it uses, or maybe it's just age!

The second timer, to shutdown, is about 3 minutes.

I usually just hit Beam Find as the benign way to get the display back again, and while it's a minor irritation you do get used to it. I have the timer turned on permanently, it's the EXER 09 setting.

Here's an OCR'd copy of the manual that has the relevant sections https://onedrive.live.com/redir?resid=2EDA80327053C74D!22445&authkey=!ABOYAYHimQYnnAs&ithint=file%2cpdf
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SoundTech-LG on February 16, 2015, 11:21:03 pm
Thank You Howard!     :-+

I have been looking for this , but could not find! It's exactly what I need!

Martin
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SoundTech-LG on February 16, 2015, 11:33:51 pm
Howard,

Do you know much about the differential aging feature? I was certain the CRT had light burn spots, (could see them in a flooded screen) but after reading the manual section on differential aging it sounds like I am just getting less beam amplification in those areas. Does that sound right?

Martin
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Howardlong on February 19, 2015, 11:57:16 pm
Sorry, I am no expert, if Alan w2aew comes by I am sure he will be able to answer far better than I can.

What does happen is that the readout text ever so slightly dances around the CRT, a pixel or two horizontally and vertically, at certain times, and it is by design. Unless I'd read about it in the manual, I probably wouldn't have noticed it to think anything much about it.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: w2aew on February 20, 2015, 11:04:57 pm
Sorry, I am no expert, if Alan w2aew comes by I am sure he will be able to answer far better than I can.

What does happen is that the readout text ever so slightly dances around the CRT, a pixel or two horizontally and vertically, at certain times, and it is by design. Unless I'd read about it in the manual, I probably wouldn't have noticed it to think anything much about it.

In my experience with the "non-B" 2467, and the 7104 mainframe that had the same microchannel plate CRT - the shutdown timer was most definitely proportional to the intensity that was dialed in.  It would range from less than 1 minute for high intensity settings, and more than 10 minutes when the intensity was dialed down to a somewhat dim value.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SoundTech-LG on February 21, 2015, 04:22:00 am
OK. so it was really, really messed up!!!

Display kept getting dimmer, and dimmer, and then got to the point that no matter what I did I could not get ANY display at all! I started worrying the CRT was failing, and died. But no! Did NOT adjust the CRT bias or touch anything in the CRT ckt. at all.

I checked all the PS DC voltages. Spot on. Then tried to adjust the DAC per the adjustment section in the svc man. It would not adjust to the 2.5 volt total range, and kept getting worse, and worse! Studied that bridge ckt. with the adjust pot, found R2013 10k COMPLETELY open. There was a small amount of electrolyte leakage from the caps, but this area looked perfect! No idea why that resistor would open!

So to my surprise this fixed not only all the brightness issues, but also many other problems that I was certain were going to require a complete CAL. NOT SO!!!  DAC adjusted just fine. Everything seems to be working now!!! Previously amplitude, and Freq measurements were pretty far off. I'm so pleased to get this baby runnin' like it should be. About $300 and a little troubleshooting. Yippeee!

Thank you all so much for your support, and guidance. Reassuring to get informative replies. Thanks!

Martin
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: tautech on February 21, 2015, 06:04:41 am
Good job Martin, your perseverance paid off.
Yep I often wonder why silly little things like a 10K resistor fails too.
Maybe its age or a crook one from new, probably why you ended up with it.

You learnt a lot and that will stand you in good stead to keep her running until you decide to get a new DSO.   ;)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SoundTech-LG on February 21, 2015, 06:45:11 am
Hi,

Thanks!

yeah, I use those DSO thingies at work sometimes, and I do have a Tek THS-720A here too, but I still prefer the analogs!!!
I guess you get so used to that warm green glow after so many years, that everything else seems cold by comparison :)

So fixing the 2467B was the good thing that happened today. The other thing that happened, was I found out I need an angiogram, maybe a stent, or even bypass surgery.
Maybe it's a really good thing... I might live to use the damn thing! :)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: tautech on February 21, 2015, 08:10:12 am
The other thing that happened, was I found out I need an angiogram, maybe a stent, or even bypass surgery.
Maybe it's a really good thing... I might live to use the damn thing! :)
Well at least the stress of the Tek has passed now.
But you need to know: old CRO's will do that to you.  :-DD

Good luck with the angiogram and stuff.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on February 21, 2015, 04:07:03 pm
Studied that bridge ckt. with the adjust pot, found R2013 10k COMPLETELY open. There was a small amount of electrolyte leakage from the caps, but this area looked perfect! No idea why that resistor would open!

Great to hear the happy ending.  :-+

Martin, any chance you haven't throw away that resistor, please, shoot a close up and post it here.

Who knows, probably this will help someone in the future.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SoundTech-LG on February 21, 2015, 04:20:15 pm
Yes, I saved it, and taking it to work to look under the microscope at it. I'll try to get some photos of that. The only thing I thought I noticed was a bit darker colorization of the red coating on top of the resistor. Maybe there was some electrolyte that seeped in, dried, and no evidence on the outside of the part. I'll try to get photos as is, and then scrape/pop the top off, see what's going on inside...

I have read at least one post on here, and elsewhere, that describe the symptoms of this problem exactly. I never saw any resolution of the problem posted/detailed.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SoundTech-LG on February 21, 2015, 04:37:34 pm

In the article by H. Holden, he found the adjust pot destroyed. R2013 is one resistor away from it...

http://www.worldphaco.com/uploads/TEKTRONIX_2465b_OSCILLOSCOPE_A5_BOARD_REPAIR.pdf (http://www.worldphaco.com/uploads/TEKTRONIX_2465b_OSCILLOSCOPE_A5_BOARD_REPAIR.pdf)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SoundTech-LG on February 23, 2015, 03:04:02 pm
R2013 is in the DAC adjust bridge. Problems in the DAC ckt. can cause a myriad of problems. I had what looked like calibration errors, and a CRT dimming problem that eventually worsened to the point of no display at all. There were also several error messages at boot before the CRT was no longer visible. When I tried to do the DAC adjust procedure, it would not adjust properly.

Here are some photos of what I found with R2013. When I cleaned the top with IPA, the coating easily flaked off in one area. Underneath the traces were corroded apart. The resistor appeared very normal on the outside mounted in the board. Hope this helps someone.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on February 24, 2015, 02:21:46 am
Martin, thanks for sharing those really nice macro shots of the dale smd resistor.  :clap:

I can't see clearly the resistor coating color as its quite dark, is it dark brown like below example shot of mine ?

The R2013 I have is the dark brown colored without any printed label on top of it.

(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=138431;image)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SoundTech-LG on February 24, 2015, 02:52:09 am
Yes, I just looked at the board again. Those 3 resistors in a row
(ending in R2013) are darker, and do not have values printed on them. so really, there was no outward indication this part had failed at all. The creeping electrolyte went in, and left no trace on the outside. All those resistors need to be measured if you suspect a problem (no DAC adjust/out of range) in that vicinity.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on February 24, 2015, 03:04:16 am
Thanks, and your experience is an important lesson, that the cap's leaked electrolyte can affect the SMD's coating, not only pcb traces.

Noted !  :-+

Once the cap's electrolyte leaked, and even the surrounding resistors or other components that still look perfectly good, we will have to assume that they already corroded or starting to corrode the metal inside.  :palm:
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mskobier on February 28, 2015, 12:12:11 am
sparkybg,
    I have a 2445B I recently acquired that I am in the process of repairing (channel 1 trace dead). Once I get that sorted out, I plan on doing the capacitor change out on the PS and A5 boards (no indication of leakage at this time). Since I will already have the A5 board out, I plan on also removing the Dallas chip, and replacing it with the Fram FM16W08 chip and adapter board. I have made a video of the current EXER 02 settings (thanks for the idea Markl) since it is probable that I will loose the settings (25 year old battery). Back in mid Jan  in this thread you discussed doing some NVRAM programming using the FRAM chips, and I have been reading that info with much interest. I also have a programmer that will work with both the Dallas chips and the FRAM chips. I have already downloaded a copy of the bin file for a 2465B and have been examining the file structure and information contained in the file using the program that came with my programmer. Your posts back then showed the calibration info from the 2465B would work in a 2445B with the appropriate data modified. I have programmed a couple of chips in my day (20 years ago), but I am having some difficulty in understanding how the EXER 02 data correlates to the HEX data in the downloaded file. Is it possible that you could give me a brief explanation on how the two data sets compare. Thanks in advance for any assistance.

Mitch

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: sparkybg on February 28, 2015, 03:23:40 pm
sparkybg,
    I have a 2445B I recently acquired that I am in the process of repairing (channel 1 trace dead). Once I get that sorted out, I plan on doing the capacitor change out on the PS and A5 boards (no indication of leakage at this time). Since I will already have the A5 board out, I plan on also removing the Dallas chip, and replacing it with the Fram FM16W08 chip and adapter board. I have made a video of the current EXER 02 settings (thanks for the idea Markl) since it is probable that I will loose the settings (25 year old battery). Back in mid Jan  in this thread you discussed doing some NVRAM programming using the FRAM chips, and I have been reading that info with much interest. I also have a programmer that will work with both the Dallas chips and the FRAM chips. I have already downloaded a copy of the bin file for a 2465B and have been examining the file structure and information contained in the file using the program that came with my programmer. Your posts back then showed the calibration info from the 2465B would work in a 2445B with the appropriate data modified. I have programmed a couple of chips in my day (20 years ago), but I am having some difficulty in understanding how the EXER 02 data correlates to the HEX data in the downloaded file. Is it possible that you could give me a brief explanation on how the two data sets compare. Thanks in advance for any assistance.

Mitch

Here I already explained it:
The calibration constants from exercise 2 are located at addresses 1E00 - 1FFF in the NVRAM.

This means that if you see "12BC - 00" this means the word at address 00 is "12BC" hex. This is stored on chip at address 1E00. So on address 1E00 on the chip you will have 12 hex, than on address 1E01 you will have BC hex. Than, if you got "3456 - 01" on the screen, this is stored as 34 hex on address 1E02 and 56 hex on address 1E03. And so on...

My chip was nearly as old as yours, and in the last 6-7 years it maybe had less than a hour per month  working time. Hope for the best - maybe you will be able to read it and program it to the new chip flawlessly, just as I did.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SoundTech-LG on March 01, 2015, 09:01:09 pm
Wikipedia notes 01E is for joining two scopes with one sync pulse.

Hi, checked Wiki, but only found this...

Oscilloscope Options

The important oscilloscope options are:

01 - Digital Multimeter

03 - Word Recognizer Probe Pod (P6407)

05 - Video Waveform Measurement System

06 - Counter/Timer/Trigger (CTT)

09 - Counter/Timer/Trigger (CTT) with Word Recognizer (WR)

10 - GPIB Interface

11 - Probe Power

1E - External Clock

22 - Two additional Probes

1R - Prep for rack mounting kit


While you could connect the Ref Signal to 2 scopes, as was suggested, it's not going to do much for you.
The External Reference Option 1E only works if you have Option 06 CTT, or Option 09 CTT with Word Recognizer installed in the scope.
All it does is give you one more digit, 8, instead of 7 on the CTT display, and the accuracy is determined by the stability, and precision of your Reference signal. I took a couple shots with the EXT Ref signal, (in this case a GPSDO) and a Rubidium 15mHz source for the input, and also from a Gigatronics 12720A for the (spec limit) 150mHz signal as well. You can see the 8 digit display, and increased accuracy. Quite an easy Option to install, just a BNC, and a plug for the J5990 header. :-+ Unless you have a Pre B05xxxxx Scope, then you need to install a resistor per TimB 08/12/2015

Title: Tektronix 2445B oscilloscope
Post by: ronnie_murphy on March 01, 2015, 09:32:04 pm
I have a tek 2445B scope that has the dreaded test 05 44 error which says a voltage is too positive.  Question 1, is this the right to ask this question and if so where or how do I find that voltage so I can understand why it is to high.  I checked all the voltages on the J119 IC socket and found all were within spec.  Also what on the main PCB would cause such an error.   :)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SoundTech-LG on March 01, 2015, 09:58:53 pm
According to the trouble chart 05 44 fail, you need to check U500 pin28. if you are triggering on an input signal, or doing line triggering, you should have 425 mV there. Check that first.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mskobier on March 02, 2015, 01:21:43 am
sparkybg, I sent you a private message.

Mitch
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: siggi on March 02, 2015, 01:26:53 am

I have a tek 2445B scope that has the dreaded test 05 44 error which says a voltage is too positive.  Question 1, is this the right to ask this question and if so where or how do I find that voltage so I can understand why it is to high.  I checked all the voltages on the J119 IC socket and found all were within spec.  Also what on the main PCB would cause such an error.   :)

This is often due to trouble on he A5 board, in the DAC machinery. The most common fault is leakage from SMD capacitors on that board.
You may want to join the TekScopes yahoo forum, there are good resources there in the archives.


Sent from my iPad using Tapatalk
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SoundTech-LG on March 02, 2015, 01:52:52 am
I'd agree with that assessment, having seen what happens with problems from unseen corrosion in the DAC adjustment bridge circuitry.
The DAC sets up quite a few voltages, and mine had several problems all exhibiting at once, then the CRT display died altogether.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: ronnie_murphy on March 02, 2015, 05:47:24 am
Thanks for your quick response.   :-+
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Kartman on March 06, 2015, 07:09:24 am
Thanks for the responses. Stupid me didn't realise tektronix have the part numbers in the service manuals!
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mskobier on March 08, 2015, 09:10:27 pm
Well, I went and did it now!  While waiting on components to arrive for the 2445B I found in the salvage yard a few weekends ago, I attended the Puyallup, WA hamfest/electronics swap yesterday. While I was there, I stumbled upon a guy that had two non working 2465's. One is a plain 2465, and the other is a 2456CTS. I was able to acquire them both for a very small sum of money. I purchased them mostly for parts, but I may end up repairing at least one of them. I plugged them in and ran a few tests. the first one has no trace, not even with the beam find button pressed. The second one does not have a trace either, but it does display a trace when I press the beam find. Various panel lights light up on both machines. The previous owner had removed the cases and lost the screws, but all the major parts are there. I figure I can find some 4-40 screws to put them back together again. Looks like a power supply recap on at least one of them, and we will see where the other leads me. Not that I need two more scopes, but I just could not pass them up.

The information I have found and things I have learned will be very useful for getting them back on line. So a big hearty thanks to everyone.

Mitch

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mskobier on March 12, 2015, 03:05:51 am
All,
  The repairs on my 2445B is progressing. The parts to repair the broken plastic nobs on the front arrived today. Got that all squared away, now just waiting on some electronic parts to make sure the A5 board doesn't take a dump on me while sorting out the channel 1 trace issue. Stillwaiting on the caps and a few other components to arrive.

I should have read more posts before ordering the replacement NVRAM chips. I had already ordered a couple of DS1225AD-200's and Ramtron FM1608 chips from a couple of sellers on -bay. Yes they were located in China before I read the post earlier in this thread about China sourced chips being counterfeit and not working, After I read the post, I ordered a DS1225AD-20o from Mouser. The china chips and the one from Mouser have arrived and been tested. I have access to two different programmers, a Sivava Willen and a TL866. None of the chips from china will program. The chip from Mouser works just fine with no problems at all. The DS1225 chips from china are dated 1317. So they should have been relatively fresh stock. Apparently not. The FM1608's would not program either. I have a couple of them coming from Mouser now too. In an effort not to kill my original programming, I have ordered the same programmer that sparkybg used. I had not planned on ordering the programmer, but a friend of mine has a 2465B that still has the original chip in it too. When I swap mine over, we are going to do his too. Hopefully the better programmer will work without any problems.

If anyone needs any front panel parts, knobs, shafts, indicators, etc, drop me a line. I'll see what I can do.

Later
Mitch
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: monz on March 13, 2015, 12:36:32 am
This pdf contains info on power supply rebuild and gives specific replacement part numbers for the input filter caps. Mine were cracked like this too. He used Vishay type KP339, digikey has them in stock part number BC2586-ND

http://www.condoraudio.com/wp-content/uploads/Projects/Tektronix-2465B-Oscilloscope-Restoration-Repair.pdf (http://www.condoraudio.com/wp-content/uploads/Projects/Tektronix-2465B-Oscilloscope-Restoration-Repair.pdf)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mskobier on March 13, 2015, 12:51:57 am
Monz,
    Thanks for the reply. I had already found that article. It definitely is a good tutorial on repairing the power supply.


All, Im going to move my posting over to the Repair section under a different thread so I am not hijacking this one.

Thanks
Mitch
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on March 13, 2015, 01:13:35 am
All, Im going to move my posting over to the Repair section under a different thread so I am not hijacking this one.

Mitch, I was going to ask you to share all the repair photos here, and I don't have any problem at all if you post them all here rather to have these 24xxB related infos scatter around.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mskobier on March 14, 2015, 04:25:30 pm
With BravoV's gracious request, I will post the pictures in this thread. Unlike BravoV's teardown, mine should be fairly simple. However, there were a few mechanical repairs I had to make before I attack the electronic ones. Here are some pictures showing the main panel damage after I cleaned it up. Then the teardown showing the sub assembly damage, and finally how it looks now.

The case had a number of dents too. I was able to mostly straighten them out, but the two 2465's I picked up last weekend provided me a very nice case.

I replaced the entire potentiometer sub assembly. It was easier to just replace it than to unsolder and remove the potentiometers from the ribbon strip it was attached to. Less risk of damaging the ribbon

The last picture shows the three extension shafts. The one on the right is broken and should be about 1in (25mm) longer. The parts board I picked up provided the replacement shaft and missing knobs.

I also attached some pictures of the A5 board. Looks like either I have a little bit of leakage, or the ceramic capacitor next to the caps has already been replace and I'm seeing flux residue. Either way, I'll remove the cap, clean around it and replace. This will also be the time when I remove the Dallas chip, and hopefully be able to copy the calibration data file. I've also been having some fun finding the replacement tantalum caps to replace the electrolytic. The caps on my A5 board show 10uf 35v and 33uf at 35v. The manual specs them out as 15uf 25v and 45uf 25v. I'll probably go with what the latest manual calls for, 15uf and 45uf. However, finding the 45uf in a C size form factor has been interesting. Kemet doesn't seem to make one. Will have to try a different manufacturer.

Enjoy
Mitch

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SeanB on March 14, 2015, 04:49:49 pm
47uF is as close as you can get to 45uF, and will work. Nice job on the repair, I wish I could find one locally that is not either close to new price or just a stop short of the crusher.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mskobier on March 14, 2015, 04:59:14 pm
SeanB,
      Actually, it is a 47, the 45 was a typo. I can find them in D size all day, but C size to fit the board is more difficult. I literally found this scope in the crush pile at the local metal salvage yard. Along with a HP 45601A that works great and two frequency counters, a Fluke 7220A and a BK Precision 1856C. Both of the frequency counters work too, they just need a good calibration.

Also, here is a picture of the potentiometer board ribbon connector. I chose not to unsolder the broken pot, and just replace the entire sub assembly.

Mitch
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mskobier on March 14, 2015, 10:45:56 pm
SUCCESS!!!!
Today, I was able to remove the Dallas chip from my A5 board and read the calibration data to a file! Then I promptly wrote it to the new Dallas chip and everything worked fine. What a relief! The original chip in my 2445B has a date code of 9026. That is a 25 year old battery That was still working. Anyway, as soon as the caps and IC socket arrive, I'll put it all back together and start the channel 1 diagnostics. I was hesitant to spend a lot of time of fixing that issue until I was sure I would not loos the calibration info in the Dallas since I lack the necessary equipment to perform a recalibration.

On a side note, I was able to read the chip with both the MiniPro TL866 and the EasyPro 90B. One strange thing about using the 90B. I was doing some experiments when I first got it and the new Dallas chip. I would program one of the bin files I have downloaded, and it would say everything was programmed correctly. When I would run a verification of the data on the chip, it would have two errors. Always in location 000000 and 000040. So I read my original chip in both programmers, and the data came out exactly the same. I could program the chip with the TL866, and it would program perfectly. I could read the chip in the 90B, and it would be correct. Strange to say the least. Anyway, I have a couple of copies of the data on two different computers and burned to a CD, as well as programmed on the new Dallas chip. I will be programming it to one of the FM1608 chips for safe keeping too. I know it is probably overkill for a scope that is 25 years old, but I don't want to take any chances. Of course, if I had lost the cal data, I would have been forced to pick up even more test gear. Hummm.......

Mitch

Here is the calibration file from my 2445B if anyone wants it.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on March 14, 2015, 11:06:28 pm
When I removed the Dallas chip I read and stored it.
Then I cut out the little battery and wired in a large battery. I read and stored that too.
I then compared the info between the first and second read with Beyond Compare.
In handling the chip so much to gain access to the battery some info was lost- about 10 lines.
After everything was done I burnt it to the first reading and it was successful.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: cutemonster on March 15, 2015, 09:10:03 am
I'm trying to replace Channel 1 BNC because it's loose and not usable.  Can you provide guide on how to replace it?
I have a 2465A.  Is the part easy to buy online?

thanks!
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mskobier on March 15, 2015, 01:16:05 pm
cutemonster,
      I'm fairly new to tek scope repair myself. Been learning a lot. I think the BNC is part of the attenuator module. I also think you have to remove the module to get to the BNC. I have a module on order, it should be here in a few days. When it gets here, Ill take a look to see what it takes. I do not know if you have to remove the A1 board to get the module out. Maybe BravoV can weigh in and give you better guidance.

Mitch
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on March 15, 2015, 03:02:15 pm
cutemonster try https://www.eevblog.com/forum/repair/tektronix-2445-repair/ (https://www.eevblog.com/forum/repair/tektronix-2445-repair/)

Two thirds of the way down this thread is a 2445A teardown showing the BNC connectors.
A 2445A should be close to a 2465A
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: cutemonster on March 15, 2015, 05:56:17 pm
thanks mskobier and malch.
I will try to open up and check.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mskobier on March 19, 2015, 01:41:45 am
Time for another update.

I have been working with the different versions of the replacement NVRAM chips as discussed in this thread. Here is what I have learned. When programming the DS1225AD chip with the EasyPro90B (same one sparkybg used) I had a similar issue with not writing the 000000 location and the 0000040 location. Don't have an explanation as to why, just that the error was consistent and repeatable. I ended up using The MiniPro TL866 to program it. No issues using that programmer and the DS1225AD

When programming the Ramtron FM1608, I had no problems with the 90B. The TL866 does not have that chip in it device list, and I was unable to program it.

When programming the FM16W08 (SOIC) on the adapter board, I got the same error as described by sparkybg in his post from Jan 12 2015. I kept getting the error at location 000000. All the other locations programmed fine. When I would run the verify routine, everything except 00000 took the programming correctly. I finally selected the 18L08 from the device list, I could get it to program, but when I ran the verify routine, it showed that I had errors in all locations starting at 00002000, all the way to 000017FF. Then it dawned on me that those memory addresses were outside the addresses that the FM16W08 chip has. I told the programmer to only program from 000000 to 00001FF, and ran the programming routine again. Everything worked fine then and the error at location 00000 was corrected. I tried a couple of different bin files. Everything was correct, and repeatable.

Many thanks to sparkybg for his many contributions to this thread.

Here is a picture of the ram chips I have programmed so far. Remember, when I get mine finished a friend has a 2465A that need to have the NVRAM replaced before it looses its calibration. We'll probably start on that in a couple of weeks. I also have the two 2465's. They take a different set of chips, but what I am learning will hopefully help me repair those.

I'm still waiting for the Tantalum smd capacitors to arrive so I can replace the electrolytics. Hopefully they will be here in a couple of days.

Here's the chip picture.

Mitch

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: flynwill on March 20, 2015, 04:05:01 pm
Thanks for the responses. Stupid me didn't realise tektronix have the part numbers in the service manuals!
Did you manage to find a suitable replacement for your power switch?  The switch in my 2465B is failing as well (arcing, sticking and sometimes giving of that fine odor of burning phenolic).  There are still manufactures making that form-factor of switch, but I haven't had a chance to tear the unit down, and do the necessary measurement to find a replacement.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mskobier on March 20, 2015, 05:42:20 pm
Got another question that maybe someone else has encountered. In the process of removing the leaky A5 board capacitors, I discovered that the component values on my board are significantly different than what the latest version of the service manual states they should be. On my board, I have in the C2011 position, a 33uf @10v. The manual shows a 15uf @25v. In the C2113 and C2331 position, I have 10uf @35v and the manual calls for 47uf @25v. So, has someone replaced the caps with improper values, or is there a later rev to the service manual that has different values? The manuals I have are from 1989. My scope was manufactured sometime in 1990. I recall seeing some where a picture of a board with the same values I have. So I guess the question is, which values should I use? I am strongly leaning towards using the same values that are currently installed.

I removed all of the suspect items from my board today, cleaned it up and found one pad/trace had failed. It is location R2016. I was able to install a replacement resistor using the one good pad to anchor then solder bridge to the existing trace. Other than that, everything looks great, and is ready for parts as soon as the capacitor question is resolved. I'll post before and after pictures later.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mtdoc on March 20, 2015, 05:59:38 pm
 I have seen mentions on the Yahoo Classic Tek scopes group (https://groups.yahoo.com/neo/groups/TekScopes/conversations/messages) of errors in the service manual re caps.  I don't recall exactly which ones but I'm sure if you pose the question to that group you'll get a quick response. It is a very active group.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mskobier on March 20, 2015, 06:43:31 pm
Thanks for the reply. I am a member over on the Yahoo Tek group. I should have posted my question over there too.

Mitch
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on March 20, 2015, 07:12:19 pm
I changed the caps with the free 2465B service manual like so many others.
 I haven't run that scope very much, so It's not much of a test.
There must be lots of recapped scopes out there.
Have you measured the voltage across C2011?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mskobier on March 20, 2015, 08:40:59 pm
malch,
    No, I have not measured the voltage. Currently the board is on the bench. I planned on using at least the same voltage rating as is already there. It was the capacitance rating I was concerned about.

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mskobier on March 22, 2015, 06:12:17 pm
Well, I've been a bit busy this morning. The caps I have been waiting for finally arrived yesterday afternoon. This morning I installed the replacement tantalums as well as a few .1uf ceramics. Everything went well. Here are a couple of pictures showing the replaced components. I did take before pictures of the bare pads, but they did not turn out well, so they don't get posted.

I also reinstalled the A5 board, and tested all four of the replacement chips. The first one was the replacement Dallas 1225AD , the second was a DIP FM1608 and the last two were FM16W08 on SOIC to DIP adapter boards. All four chips work just fine. The scope went through its startup routine and seemed to operate normally. So at this point, I am declaring the A5 board electrolytic replacement as well as the NVRAM replacement/upgrade to be a success.

I also pulled the power supply cover and saw that I have the problematic HV capacitors. Looks like I have a power supply cap replacement coming in the near future. I had hoped that mine was late enough that it had different caps. I visually inspected the HV caps, and they do not look bad at all. No indication from what I could see of near term failure. 

I also manually ran all of the self diagnostics. Its interesting in that the scope passed all test when I run the auto routine. I noticed that it cycles through each input channel. On all but channel 1, I get a bunch of little dots on the screen while the test of that particular channel is running. However, there are no dots on the screen when channel 1 routine runs. The display says it passed though.

Anyway, here are the pictures.

Mitch
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SoundTech-LG on March 23, 2015, 09:11:01 pm
Nice JOB!!!  :-+

Mine is not nearly as neat, and professional looking.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Howardlong on March 23, 2015, 09:59:59 pm
My 2467B is starting to show a few "signs", the CTT frequency counter for example is unreliable sometimes.

It serial number <50000, being lazy I am wondering if someone has an electrolytic cap BOM they'd care to share that they've used for one of these, or indeed a 2465B for serial <50000?

Many thanks!
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mskobier on March 24, 2015, 12:45:38 am
Howard,
     From what I have read, the power supplies in these 24XX series scopes are pretty much the same. With that said, here is a link to another guys webpage where he has a list with a major suppliers parts numbers that may be what you are looking for. Hopefully this helps

http://bradthx.blogspot.com/2014/01/tektronix-2445b-capacitor-replacement.html (http://bradthx.blogspot.com/2014/01/tektronix-2445b-capacitor-replacement.html)

Mitch
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on March 24, 2015, 12:51:34 am
Howardlong I sent you a PM.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mskobier on March 24, 2015, 12:52:27 am
SoundTech-LG
     Thanks for the compliment. Fortunately, I only had one trace/pad that was damaged so it made it easy to replace the suspect parts. If you look closely at the first picture, the third component above the tantalum capacitors I installed, you will see the resistor is installed just a little to the right of where it should be. That was the component that has the trace that came off during desoldering. Fortunately, there was enough of the thin trace to make a solder connection to. I put a drop of superglue at the base of the capacitor after I was done soldering to ensure it was mechanically anchored to the board. Not much trace there to hold it on the right side.

Mitch
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mskobier on March 24, 2015, 01:02:26 am
All,
    Last night while I was looking for a service manual for my Tektronix 221 battery powered scope (works great, bad battery) I stumbled upon a Tektronix Scope WIKI page that lists lots of information about Tek scopes. You can select by series, then individual model numbers within the series. Once you select a particular model, it takes you to a page where they usually have a link to manuals for the model selected. Its not 100%, but I was able to find the service manual for the 221. This is the only place where I have found the manual free online. I had not seen this page referenced in any of the posts I have read on this group. Anyway, take a look and see if its of use to you. Here's the link.

http://w140.com/tekwiki/wiki/Main_Page#2000_Series_Scopes (http://w140.com/tekwiki/wiki/Main_Page#2000_Series_Scopes)

Mitch

 
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on March 24, 2015, 01:24:15 am
Howardlong I sent you a PM.
I cant make the PM work. :(
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: miguelvp on March 24, 2015, 01:35:25 am
Howardlong I sent you a PM.
I cant make the PM work. :(

It works, but by default it doesn't save the messages you send, for that you have to go to the message settings:
https://www.eevblog.com/forum/pm/?sa=settings (https://www.eevblog.com/forum/pm/?sa=settings)
and check the "Save a copy of each personal message in my sent items by default." check box

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on March 24, 2015, 01:38:58 am
I did that but didnt log out.After logging back in I have sent messages now. Thanks for the tip.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mskobier on March 26, 2015, 03:19:21 am
All,
 I was given some guidance over on the Tek Scope Yahoo group on a test to run to see if the channel 1 trace is getting a position signal from the A5 board. Basically it was to check the signal at pin 17 on the channel 1 and 2 preamps. This pin receives position control from the A5 board and varies with the position control on the front. The voltages varies the same when I adjusted the vertical position controls for both channels. So with that said, it looks like the channel 1 preamp has an issue.

So, ignoring the fact I needed to go to bed, I removed the little shield over the solder connection on the channel 1 preamp, unsoldered the connection, then removed the nuts holding the preamp to the circuit board, installed the replacement preamp, and put it all back together. Plugged it in, and turned on the power. Low and behold, I now have a channel 1 trace! It moves with the position control and everything. I hooked it up to the internal cal post, which is supposed to measure .4volts, and the display said it was .43volts. Close enough for me tonight. Anyway, It appears that I now have all four channels working.

I still have to change out the power supply caps, but that can wait until a later date. Now I just need to learn all of the capabilities of this scope, and of course, I have the two 1465's to see if I can get back into service. The fun never ends.

Mitch
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Michaela Joy on March 27, 2015, 05:28:27 pm
Hi All,
This is my first post, so I thought I'd send best wishes to everyone here. :)

@BravoV: Awesome post! Thanks for the info here, and to everyone who contributed. I just purchased a used 2465B, and am looking forward to using it for my projects.
At some point, I will try the U800 modification.

Best,
:MJ
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on March 27, 2015, 06:26:42 pm
Michaela Joy  Boy are you going to have a lot of rewarding fun! This scope is one of the most pleasing . It has full schematics and other manuals. It is easy to work on. There are many fans to ask questions. and it is powerful- just ask w2aew.

Dont worry about what the Rigol fundamentalists say, they dont know quality when they see it.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Michaela Joy on March 27, 2015, 07:35:16 pm
Quote
Dont worry about what the Rigol fundamentalists say, they dont know quality when they see it.

@malch: The truth is, the 2465B was a better deal than the new digital scopes are. I don't need storage or FFT / math functions, I just need to look at signals.
As long as it functions ok, I'll be happy. I have some inexpensive probes that I'll be using until I buy the "correct" probes. The "good" probes are expensive, but worth the price. Then, I'll do the U800 mod, just to be safe. :)

:MJ
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: flynwill on March 27, 2015, 09:51:18 pm
I bought a pair of these http://www.caltestelectronics.com/ctitem/20-probe-oscilloscope-passive-voltage/CT3133RA (http://www.caltestelectronics.com/ctitem/20-probe-oscilloscope-passive-voltage/CT3133RA)

to go with my 2465 (300 MHz model) and have not been unhappy with them.  They may not be quite as accurate as the Tektronix ones, but they seem just as robust, and have all the extra bits you need.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: DC912 on March 28, 2015, 04:24:45 pm
Question Re: Dallas Chip Replacement

I recently picked up a 2465B locally, serial BO57xxx.  The scope will only be used for hobby purposes, and I know nothing about programming an IC (and would prefer not to make this scope my first experiment in programming an IC).  As a preventative measure, does it make sense to buy a pre-programmed IC (e.g., from the seller in Greece) and replace the existing chip with the pre-programmed chip or would it be better to have someone copy the info from my chip info to a new chip? What functionality/calibration information of potential significance to a hobbyist, if any, is lost by replacing the Dallas chip with a new chip pre-programmed with "basic" settings? Thanks.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Michaela Joy on March 28, 2015, 04:49:21 pm
@flynwill: Thanks for the tip. I found this on eBay. http://www.ebay.com/itm/CT2841A-Passive-Voltage-Oscilloscope-Probe-/251895651922?pt=LH_DefaultDomain_0&hash=item3aa6269e52 (http://www.ebay.com/itm/CT2841A-Passive-Voltage-Oscilloscope-Probe-/251895651922?pt=LH_DefaultDomain_0&hash=item3aa6269e52)

I'm sure that there others like it. If you wish to grab it, please do. :)
:MJ
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MarkL on March 28, 2015, 06:01:16 pm
Question Re: Dallas Chip Replacement

I recently picked up a 2465B locally, serial BO57xxx.  The scope will only be used for hobby purposes, and I know nothing about programming an IC (and would prefer not to make this scope my first experiment in programming an IC).  As a preventative measure, does it make sense to buy a pre-programmed IC (e.g., from the seller in Greece) and replace the existing chip with the pre-programmed chip or would it be better to have someone copy the info from my chip info to a new chip? What functionality/calibration information of potential significance to a hobbyist, if any, is lost by replacing the Dallas chip with a new chip pre-programmed with "basic" settings? Thanks.

Your chip contains calibration information specific to your scope.  You want to have a copy of that, so get someone to do it for you if that's an option.

I don't know how bad the calibration would be with a generically programmed chip, if that's what you're asking.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mskobier on March 28, 2015, 06:32:41 pm
DC912,
       You can copy down the calibration constants for your scope found by running the EXER 02 routine. Then download a copy of a bin file for your model scope. Using a bin editor, replace the portions of the downloaded file with your calibration data, then your ready when you replace the DS1225Y. That should  but you a bit of confidence you won't loose your calibration data. It's actually pretty easy to do. I'm sure you can find someone near you that can assist with programming.g the replacement chip.

Mitch
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: DC912 on March 28, 2015, 07:53:20 pm
Great. Thanks much.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SoundTech-LG on March 31, 2015, 08:30:12 pm
Question Re: Dallas Chip Replacement

I recently picked up a 2465B locally, serial BO57xxx.  The scope will only be used for hobby purposes, and I know nothing about programming an IC (and would prefer not to make this scope my first experiment in programming an IC).  As a preventative measure, does it make sense to buy a pre-programmed IC (e.g., from the seller in Greece) and replace the existing chip with the pre-programmed chip or would it be better to have someone copy the info from my chip info to a new chip? What functionality/calibration information of potential significance to a hobbyist, if any, is lost by replacing the Dallas chip with a new chip pre-programmed with "basic" settings? Thanks.

bought one a them Greek Dallas chips... don't bother. ALL I got was ??????????????????????????????????????????????????

at the bottom of the display.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: c4757p on March 31, 2015, 08:33:49 pm
That means it doesn't like the cal data. Bad checksum? Contact them, tell them you got a shit chip.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mskobier on April 01, 2015, 01:47:13 am
SoundTech-LG
    Did you ever get the Greek Dallas chip working in your scope? Did you do a full calibration, or did you just program the chip with another scopes calibration data?

I'm loving my 2445B now that I have it up and running. Looks like I may need to do a vertical section calibration, but the horizontal is dead on. I fed a 175Mhz signal into the scope, and it auto measured it perfectly. It also is accurate at lower frequencies too. Still need to get some good Tek probes to go with it. I recently purchased a couple of P6138 probes off of _bay. They should be here any day. Then the real testing can begin.

Mitch
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Michaela Joy on April 01, 2015, 02:50:58 pm
I just received my 2465B yesterday. I noticed that one of the front panel buttons was stuck. I managed to unstick it with a little bit of contact cleaner spray.
The scope seems to work well, although I think it needs to be opened and the front panel switches need to be cleaned. Cosmetically, it's in great shape. All 4 traces come up and I can see waveforms on the screen. I don't have 400 MHz probes to test it fully. I do have some inexpensive scope probes that will work fine for anything upwards of 10 MHZ.

I have a friend who has worked on His own Tektronix scopes before. He also does a lot of radio / RF work, so, I'll see what signal generators He has that will go up to 400 MHZ.
Then, we'll open it together, clean it, and see how far off the calibration is.

All in all, I'm super happy. I feel like I bought a "diamond in the rough".

:MJ
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on April 01, 2015, 02:55:26 pm
It would be a good idea to follow along with post #1 and see some possible problems.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SoundTech-LG on April 02, 2015, 07:51:53 pm
the Greek Dallas is screwy for sure because if I load on any of the .BIN files previously uploaded from this 2465 Teardown topic, it works fine with the scope (although would still need a CAL of course). Yeah, I should at least get a refund for the programming part of that Dallas.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mskobier on April 02, 2015, 08:42:46 pm
the Greek Dallas is screwy for sure because if I load on any of the .BIN files previously uploaded from this 2465 Teardown topic, it works fine with the scope (although would still need a CAL of course). Yeah, I should at least get a refund for the programming part of that Dallas.

So, as you stated, it sounds like the chip is good, just bad programming. That's too bad that the Greek programming is faulty. I was looking at contacting them for a standard cal for my 2445B while I was performing other repairs and afraid that my original Dallas chip would go flat and become unreadable. Fortunately for me, that didn't become necessary. At least you have a good chip to copy your calibration into. Do you still have the original chip, and is it still readable?

Mitch
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on April 02, 2015, 09:32:14 pm
mskobier  Have you tried this? ftp://ftp.bluefeathertech.com/electronics/testgear/Tektronix/firmware/24x5/2445B/
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mskobier on April 03, 2015, 12:46:47 am
malch,
    Yes, I am aware of that particular file. I downloaded it when I was not sure I was going to be able to save my calibration data from the DS1225 that was in my scope. Once I was able to recover my cal data, it became a moot point. The questions I was asking SoundTech-LG was to determine if he was able to salvage his cal data, and if not how he went about calibrating his scope.

I do not have access to the Tek cal fixtures. I have been studying all that I can find trying to determine what types (square wave, sine wave), amplitudes, and frequencies (1khz) I would need. To perform a vertical amp calibration on my scope. I have a Tektronix SG280 function generator that goes to 20mhz and up to 20v p-p that I can use to generate the square wave signal necessary to do some of the calibration, and a Boonton 102D that goes to 520mhz and up to 3v I can use for some of the other signals. I do not think my scope needs a full calibration, as the frequency measurements are dead on. The voltage measurements are where I am having some issues. When using the internal cal fixture, it is supposed to be exactly .4v p-p square wave. My scope measures .415v p-p. Not bad, but just a little out of spec. When I try to measure a sine wave signal, then things get a bit more interesting. Having a known RF signal of a know amplitude, the scope reads quite a bit higher than I think it should. About twice the expected value.  I still have a lot to learn about the operation of the scope. Might just be operator error. I'll figure it out eventually.

Mitch
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MarkL on April 03, 2015, 02:18:16 am
...
When I try to measure a sine wave signal, then things get a bit more interesting. Having a known RF signal of a know amplitude, the scope reads quite a bit higher than I think it should. About twice the expected value.  I still have a lot to learn about the operation of the scope. Might just be operator error. I'll figure it out eventually.

Mitch
RF and other high frequency sources are typically terminated in 50 ohms.  If it's not terminated (or loaded with a very high impedance like the scope 1M input), the amplitude will be double.

Are you using the 50ohm input coupling?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mskobier on April 03, 2015, 03:54:37 am
MarkL,
   Thanks for the reply. I tried it in both the 1meg and 50ohm inputs. At the moment, I do not remember what the differences were, it was way late and I should have been asleep. The next time I will put a 50ohm termination feed through as well as having the scope in 50 ohms to see if that makes things look better. Like I said, I still have a lot to learn about this particular scope. I do have another scope I have had for many years, but it is not nearly as much scope as the 2445B.

Mitch
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MarkL on April 03, 2015, 04:22:32 am
Hi Mitch,

You wouldn't need both the external 50 ohm and internal 50 ohm termination.  If everything is working and you did that, you would get an amplitude that's too low.

But your test is a good one since maybe your scope's internal 50 ohm termination isn't working.  You could also see how the other channel behaves.

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on April 03, 2015, 04:16:02 pm
I know my suggestions are sometimes off the wall, but they are search ideas.
Have you checked out w2aew's youtube  https://www.youtube.com/watch?v=SsoAe0kMYfc (https://www.youtube.com/watch?v=SsoAe0kMYfc)  for ideas?
 and post #244 to #264 ?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mskobier on April 03, 2015, 05:48:18 pm
MarkL,
      I got a chance to play with the scope some more this morning. I fed the output of a Boonton 103D signal generator (.125mhz to 175mhz) set at 10mhz to a T connector which went to two different oscilloscopes. The 2445B and my Kenwood CS-5170. I bought the CS-5170 new in about 1996 or so. So I have a high degree of confidence in its accuracy. I set the 2445B to 50 ohms coupling, and used a 50 ohm feed through termination on the CS-5170 and compared both displays. Both scopes read exactly the same (within a couple of decimal points) in both frequency and amplitude. These readings also agreed with the expected output of the signal generator. So it looks like at least for these simple tests that the scope is working as expected. One test down and many more to go.

malch,
    I had seen that youtube clip, but had not watched all of it. Good general information on how to cal a scope.

So, using the info from post#252, I need a 1khz 50% duty cycle square wave signal at 20mv, 50mv, 0.1v, 0.2v, 0.5v, 1v, 10v. My CFG280 function generator has the ability to do all of that with the exception of the precision p-p voltages. For that, I can use my Amprobe AM-530 to measure the output voltages in RMS and multiply by 2 to get the actual p-p voltage. I believe my AM-530 will go that low. The spec sheet states the lowest range is 0-400mv. Not sure I will be able to set the lowest voltage with the level of precision necessary. I may be able to use a stepped attenuator I have (Jarrod AV-50), set the output voltage to a range that the AM-530 can read reliably, and use the stepped attenuator to drop the final voltage to a level that is appropriate. Of course, at these low levels, every connection can have a significant effect on the final input voltage. The challenges never end!

Mitch
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SoundTech-LG on April 03, 2015, 07:00:46 pm
Unfortunately lost my CAL Data as I was placing the Dallas in the TL866. The external battery wire came unsoldered and touched another pin. Dallas is ok, just F'd the Data...  :palm:
I think I have all the gear together now to do the CAL. Just need to get up one morning and spend all day, and maybe the next twiddling it.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on April 03, 2015, 07:16:06 pm
Be happy you're not doing a TDSXXX
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MarkL on April 04, 2015, 01:40:29 pm
MarkL,
      I got a chance to play with the scope some more this morning. I fed the output of a Boonton 103D signal generator (.125mhz to 175mhz) set at 10mhz to a T connector which went to two different oscilloscopes. The 2445B and my Kenwood CS-5170. I bought the CS-5170 new in about 1996 or so. So I have a high degree of confidence in its accuracy. I set the 2445B to 50 ohms coupling, and used a 50 ohm feed through termination on the CS-5170 and compared both displays. Both scopes read exactly the same (within a couple of decimal points) in both frequency and amplitude. These readings also agreed with the expected output of the signal generator. So it looks like at least for these simple tests that the scope is working as expected. One test down and many more to go.
If I understand your setup, you would actually have *two* 50 ohm terminators.  One in the Tek scope and one external on the other scope.  So that would be 25 ohms because they're in parallel.

I can't find a manual for it, but the 103D is undoubtedly a 50 ohm source and its output amplitude would be calibrated assuming a 50 ohm load.  So, it's not adding up that you're seeing exactly what you expect with 25 ohms loading.  And the two scopes are also in direct parallel with eachother, so they would always display the same amplitude whether they were terminated correctly or not (not counting effects from reflections).

I guess the 103D could also have its AGC pick-off at the RF output and it might compensate for a 25 ohm load, but I think that would be unusual.  Or maybe you've already calculated for 25 ohms and that's what you mean by "expected"?

Anyway, if still in question, there's a quick check for a bad terminator.  Just turn on the 50 ohm termination on the Tek scope and use a DMM to check for 50 ohms at the scope's input BNC.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mskobier on April 04, 2015, 02:46:03 pm
MarkL,
     You are correct in regards to the miss match. What I was trying to state is that the amplitudes and wave forms were the same on both scopes. Yes the amplitude was off, but I was trying to see if the 2445B responded the same as my CS-5170, which was the case. I'll round up a 50 ohm splitter and replace the  BNC T with it. Or just run the one 50 ohm termination and see what the scope shows. I'll have to pull down one of my Boonton 92C RF Millivolt Meters and measure the output so I have a good reference. I know the output meter on the 103D is not calibrated and is out by some amount. It was originally a 75 ohm unit. After inspecting the schematic, I discovered that the only difference between it and the 50 ohm version, is that it had a 50 ohm to 75 ohm unun in line with the output. I even have a new 50 ohm meter face that I need to install then do a cal on it.

Mitch

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Howardlong on April 04, 2015, 09:30:20 pm
About a week ago I started on recapping the low voltage regulator and inverter boards in my 2467B after a few anomalies started showing up.

I would like to draw people's attention to an error on the board layout sheet fig 10-13 in the Service Manual 070-6863-01 that has C1115 and C1132 transposed on the inverter board (250uF/20V vs 10uF/160V). This took several hours to figure out, and a few burnt out parts too.

It was only while probing the underside of the caps during the fifth or sixth iteration of the fault finding flowchart (which also uses low voltage PSUs to diagnose but showed no fault) that I noticed that there was 30V on the supposed 5v unreg cap. This was after I deliberately disabled the over current protection that kept kicking in to have the lower voltage cap splutter itself unceremoniously when full AC was applied.

The symptoms are that on the low voltage tests no faults show, but on full AC the over current protection kicks in two or three times each second.

It made a two hour job into a three day event.

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Howardlong on April 04, 2015, 09:51:19 pm
Looking back on it, I am wondering how I'd have figured it out without disabling the overcurrent protection and blowing the cap. Must've gone over that board checking parts visually and electrically dozens of times now.

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MarkL on April 04, 2015, 10:56:58 pm
MarkL,
     You are correct in regards to the miss match. What I was trying to state is that the amplitudes and wave forms were the same on both scopes. Yes the amplitude was off, but I was trying to see if the 2445B responded the same as my CS-5170, which was the case. I'll round up a 50 ohm splitter and replace the  BNC T with it. Or just run the one 50 ohm termination and see what the scope shows. I'll have to pull down one of my Boonton 92C RF Millivolt Meters and measure the output so I have a good reference. I know the output meter on the 103D is not calibrated and is out by some amount. It was originally a 75 ohm unit. After inspecting the schematic, I discovered that the only difference between it and the 50 ohm version, is that it had a 50 ohm to 75 ohm unun in line with the output. I even have a new 50 ohm meter face that I need to install then do a cal on it.

Mitch
Hi Mitch,

Sounds like the 103D needs a little work.

My only concern was from a couple of posts back when you said you had double the amplitude when you didn't expect it.  The first thing that pops into my mind when I hear that is an unterminated connection.

I would just double check your internal 50 ohm termination on your 2445 channels with a DMM to make sure they're ok.  You might not even need internal termination for your calibration procedure, but you'll want to know at some point if they're working or not.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on April 04, 2015, 11:30:24 pm
Howardlong This is my board layout. Is it the same as yours?
C1116 is at 8B at the bottom of A3 board and C1132 is at 7.5C
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Howardlong on April 05, 2015, 12:15:29 am
Yes. That has the same error.

If you change the caps one at a time without referring to the layout diagram it isn't a problem of course. However if, like me, you removed all the caps first and then repopulated them using the layout diagram, you'll have the same problem :-(

C1114 and C1115 are the same value and voltage rating, but show as different sizes on the layout diagram if you use that as your guide.

If you look a picture such as this one from http://bradthx.blogspot.co.uk/2014/01/tektronix-2445b-capacitor-replacement.html (http://bradthx.blogspot.co.uk/2014/01/tektronix-2445b-capacitor-replacement.html) before replacing the caps, you'll also see that C1114 and C1115 look different sizes if you use the layout diagram to identify them.

(http://1.bp.blogspot.com/-b1PXd_qaBbk/UtNsdQkls4I/AAAAAAAAAqg/w-6nWUNheKY/s1600/Tektronix_2445B_power_supply.jpg)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on April 05, 2015, 12:34:19 am
In this repair the "before" pic has C1114 and C1115 different, but the "after" pic he replaced them with the same.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on April 05, 2015, 02:35:11 am
OK I couldnt stand it anymore. I took my 2445B apart and this is what I found.

C1113 and C1116 are 180uf/40v
C1114 and C1132 are 250uf/20v
C1120 and C1130 are  10uf/100v
C1115 is 10uf/160v

C1132 and C1115 are flipped in the service manual.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mskobier on April 05, 2015, 06:35:18 am

[/quote]
Hi Mitch,

Sounds like the 103D needs a little work.

My only concern was from a couple of posts back when you said you had double the amplitude when you didn't expect it.  The first thing that pops into my mind when I hear that is an unterminated connection.

I would just double check your internal 50 ohm termination on your 2445 channels with a DMM to make sure they're ok.  You might not even need internal termination for your calibration procedure, but you'll want to know at some point if they're working or not.
[/quote]

MarkL,
     You read correctly. I did some more checking, and realized I was sending a 50 ohm RF sine wave (10mhz) signal into the 1meg ohm scope input. That had things all messed up. I did some more testing this morning with the function generator set to 1khz square wave, and sampling the output with my Amprobe AM530 DMM, (which is supposed to be a true RMS meter). This signal was fed into the scope set to 50 ohm coupling. I expected to see about twice on the scope display as what I was seeing on the DMM, which is roughly what I saw. Actually the scope reading was a bit more than twice the DMM reading. Both of my scopes read very close to each other, so I think the scope reading are good, but the DMM reading may not be as accurate as I would like. Now the frequency readout on the scope appears to be very accurate. Tomorrow, I'll verify the accuracy by feeding the output of a rubidium frequency standard I have. That frequency has been verified by a frequency counter calibrated against a GPS disciplined clock a friend has. I expect the scope to be dead on from what I have seen so far. As for the amplitude readings, I'm sure its something I am doing wrong. Just need to get my head out of where the sun doesn't shine and figure it out.

Yes, the 103D does need a bit of attention. It, the 102C, the 102D, as well as most of the other pieces of equipment I have around here. That's what happens when you play with old equipment. It may not be as fancy as the new stuff, but it does work, just needs a bit more TLC. Gives me something to do in my copious amounts of free time. Spent most of today re-plumbing the toilet in the guest bathroom to make the domestic supervisor happy. I'm getting way too old to be crawling around under the house for long hours. 

Mitch
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Howardlong on April 05, 2015, 07:25:09 am
OK I couldnt stand it anymore. I took my 2445B apart and this is what I found.

C1113 and C1116 are 180uf/40v
C1114 and C1132 are 250uf/20v
C1120 and C1130 are  10uf/100v
C1115 is 10uf/160v

C1132 and C1115 are flipped in the service manual.

While I am delighted that I am not completely crazy, I really was questioning myself at times because surely this must be a known error? Perhaps it is, but I have not been able to unearth any references to it. I am sorry, but at the same time very appreciative, that you went to that trouble, you have to do a fair bit of disassembly to expose those caps.

When it finally came to putting mine back together after a few days being dismantled and a nasty dose of man flu later, it took me about four attempts to reassemble it and not have any spare screws/brackets/shields left over! After all, I had only anticipated a couple of hours for this repair.

I would imagine then that this affects 2445B, 2455B, 2465B and 2467B, all of which share that same inverter board, although I searched online and couldn't find board layout diagrams specific to all those models, I only have the service manual (including layouts etc) for the 2465B and 2467B.

Thank you once again for confirming my sanity, it is appreciated.

Edit: I guess we should be clear that they are only flipped in the board layout diagram, fig 10-13. The schematic and BOM are correct.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: tautech on April 05, 2015, 07:47:05 am
OK I couldnt stand it anymore. I took my 2445B apart and this is what I found.

C1113 and C1116 are 180uf/40v
C1114 and C1132 are 250uf/20v
C1120 and C1130 are  10uf/100v
C1115 is 10uf/160v

C1132 and C1115 are flipped in the service manual.
I would imagine then that this affects 2445B, 2455B, 2465B and 2467B, all of which share that same inverter board, although I searched online and couldn't find board layout diagrams specific to all those models, I only have the service manual (including layouts etc) for the 2465B and 2467B.

Edit: I guess we should be clear that they are only flipped in the board layout diagram, fig 10-13. The schematic and BOM are correct.
Everybody take note, make a note and stick it to your scope. Ohh shit it rhymes.  :palm:
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on April 05, 2015, 01:49:07 pm
Going through the schematic now. So the parts layout fig 10-13 should be remarked C1132 to C1115 and C1115 to C1132.


mskobier has a proper 2445B service manual. It would be handy if that manual proved to be incorrect.

I changed the fan solder point to a feed-through connector with plugs and sockets, so I can remove either the fan or LVPS without a soldering iron.
I cut out the fan punched-in area that interferes with the LVPS cards, so the cards come out in a minute.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MarkL on April 05, 2015, 04:06:44 pm
MarkL,
     You read correctly. I did some more checking, and realized I was sending a 50 ohm RF sine wave (10mhz) signal into the 1meg ohm scope input. That had things all messed up. I did some more testing this morning with the function generator set to 1khz square wave, and sampling the output with my Amprobe AM530 DMM, (which is supposed to be a true RMS meter). This signal was fed into the scope set to 50 ohm coupling. I expected to see about twice on the scope display as what I was seeing on the DMM, which is roughly what I saw. Actually the scope reading was a bit more than twice the DMM reading. Both of my scopes read very close to each other, so I think the scope reading are good, but the DMM reading may not be as accurate as I would like.
...
I think you're right.  The Amprobe AM530 spec sheet says its frequency range is only to 400Hz and it's unclear if that's a 400Hz sine wave 3dB point or the meter is good for measuring some number of harmonics past 400Hz if you're working with 400Hz AC line current.  Since you're using it to measure 1kHz, you can be suspicious of whatever reading it's giving you.  You could try 50Hz and see if they agree more closely.

The scope is going to have a better frequency response than the meter, so the fact the scope is higher doesn't surprise me. 

The 2445 has a basic amplitude accuracy of +/-2% for a 4 to 5 division signal display, and goes to +/-3% with the 50 ohm coupling on.


EDIT:  Oops "sine wave", not "since wave"....
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mskobier on April 05, 2015, 04:08:48 pm
All,
  My scope is currently fully assembled, so I could not look at the inverter board. However, I did consult my 2445B manual (also covers 2455B) and saw the same component size mismatch as shown in previous posts. I also have a copy of the service manuals for the 2445 and the 2465. Those have the diagrams with the physical size correct, but positioned slightly different. According to all three manuals I have, the parts list C1114 and C1115 as the same value. When looking at the 2445 board layout, the physical size of both C1114 and C1115 are the same, with C1132 being physically smaller. According to what I see in my manuals, C1132 is supposed to be 10uf@160v, C1115 is supposed to be 250uf@20v.

Mitch
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mskobier on April 05, 2015, 04:15:05 pm
MarkL,
      I knew it was something simple. For some reason  I was thinking the Am-530 went to 400khz, not 400hz. That would explain the discrepancies I have been seeing. I can try a lower frequency, or better yet, get a DMM that can handle higher frequencies. Any reason to get more test gear!!!

I need to go review the posts in the forum on DMM's.

Mitch
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MarkL on April 05, 2015, 05:39:49 pm
MarkL,
      I knew it was something simple. For some reason  I was thinking the Am-530 went to 400khz, not 400hz. That would explain the discrepancies I have been seeing. I can try a lower frequency, or better yet, get a DMM that can handle higher frequencies. Any reason to get more test gear!!!

I need to go review the posts in the forum on DMM's.

Mitch
Most DMMs don't go very far in RMS frequency.  Some of the best top out at a few hundred kHz.  And even then, the accuracy can be quite poor at the upper end.

Then you start getting into the realm of RF power meters, which can sink a pile of money if you like to buy test equipment.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Howardlong on April 05, 2015, 07:07:31 pm
All,
  My scope is currently fully assembled, so I could not look at the inverter board. However, I did consult my 2445B manual (also covers 2455B) and saw the same component size mismatch as shown in previous posts. I also have a copy of the service manuals for the 2445 and the 2465. Those have the diagrams with the physical size correct, but positioned slightly different. According to all three manuals I have, the parts list C1114 and C1115 as the same value. When looking at the 2445 board layout, the physical size of both C1114 and C1115 are the same, with C1132 being physically smaller. According to what I see in my manuals, C1132 is supposed to be 10uf@160v, C1115 is supposed to be 250uf@20v.

Mitch

It may be that only the "B" versions are affected judging from your layouts.

As stated before, the BOM and schematics are correct. Here are annotated uncorrected and corrected versions of fig 10-13 from service manual 070-6863-01

Uncorrected:
(http://i34.photobucket.com/albums/d123/photobucket391/2465002_zps556npulp.png) (http://s34.photobucket.com/user/photobucket391/media/2465002_zps556npulp.png.html)

Corrected:
(http://i34.photobucket.com/albums/d123/photobucket391/2465001_zpsr2x7bbbi.png) (http://s34.photobucket.com/user/photobucket391/media/2465001_zpsr2x7bbbi.png.html)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: malch on April 05, 2015, 07:17:55 pm
Yup that last pic is how my caps are laid out.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: zze110 on April 20, 2015, 10:38:25 pm
So... my 2445 power supply is dead. (Almost identical to 2465).

I went through and replaced all the electrolytic caps... no good.   I made it somewhat through the flowchart but sorta dead ended.

10 > Power Supply Troubleshooting > Audible clicking when power is applied?  YES > Current limit or startup problem > Refer to inverter procedure > Go to 11.

11 > Inverter troubleshooting Procedure > Disconnect Fan > Does supply start? NO > Fuses F1101 and F1102 open NO > Remove comb filter P232 > Connect +5V load to J303 > Does supply start NO >  Remove comb filters P233 and P234> Does supply start? "click click click RF whine from A3 inverter board"  > Check for excessive loading by regulator board shorted pass transistor or regulator IC.


I started measuring some of the resistors on the A2 regulator board.  None seem to meet spec or even close   R1334, R1331, R1332, R1358, R1357, R1354, R1355, R1352, R1353.  Most are between 20 and 70% off of marked value on the parts.  Any idea what is going on here?  How can every part on the board test bad. About 10% of the parts I measured are within 1% and perfect.

Thanks for your help!!
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Howardlong on April 21, 2015, 12:31:16 am
So just to confirm, with the three combs removed (not the three pin one), running on AC, and a dummy load on the 5V, all comb voltages look reasonable on the inverter board? I assume the whine isn't too loud either, it should be fairly quiet.

I'm not going to be much help on the regulator board, but man do I know that inverter board after finally finding that documentation error!
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mskobier on April 21, 2015, 12:44:41 am
zze110,

Did you measure all of the voltages on J119 as specified in Table 5-1 on page 5-3 of the manual prior to removing the power supply, and if so, what were the values?

Was the power supply dead, or is it not currently working as a results of the capacitor replacement?

Did you change out the problem prone poly caps?

Did you lift one end of each resistor before you took the resistance measurement? If not, then there is probably nothing wrong with the resistors, and you are seeing more than just the one resistor you were trying to measure. Did all of the resistors measure lower in value than expected? If so, that's probably the reason.


Sorry for all the questions, but it really helps to know what you have or have not done.

Mitch
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: zze110 on April 21, 2015, 01:01:00 am
Did you measure all of the voltages on J119 as specified in Table 5-1 on page 5-3 of the manual prior to removing the power supply, and if so, what were the values?
+10V was 0V, +84V was 1.21V... after that I gave up taking measurements.

Was the power supply dead, or is it not currently working as a results of the capacitor replacement?
Identical behavior before and after cap replacement.  It will power up once in 10 tries, the rest of the time I get the 'click click click' and nothing happens

Did you change out the problem prone poly caps?
I replaced them in the high voltage section of the regulator board.  Skipped them on the inverter board. I am getting an lcr meter so I can test the remaining caps.  I don't have another scope so my options are limited to lcr tester and dmm.  I checked the large transistors and they seemed good


Did you lift one end of each resistor before you took the resistance measurement? If not, then there is probably nothing wrong with the resistors, and you are seeing more than just the one resistor you were trying to measure. Did all of the resistors measure lower in value than expected? If so, that's probably the reason.
No, that was dumb I guess.

Sorry for all the questions, but it really helps to know what you have or have not done.
Mitch


Not sure if the voltage was OK or not on the inverter board.  I'm a bit afraid to touch this thing while plugged into the wall.  I pulled all 3 combs and it did the coil whine sound.  Pretty loud to me but I am sensitive to those frequencies.

Tomorrow I am going to replace my EMI filter on the input (leads are in really poor shape) and run the load test again.  Maybe I can get some better measurements this time.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mskobier on April 21, 2015, 01:20:31 am
zze110,
   You said you pulled the comb's, but you never said that you hooked up the test load. Did you make up a test load and did you hook it up? The inverter board needs that load for the inverter to start as stated in the manual under the test load diagram. If not try that and see what happens.

Mitch
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: zze110 on April 21, 2015, 01:28:58 am
yes, I did connect the test load as specified on the previous page.  I'm going to repeat the whole thing tomorrow.  btw this is a 1xxxxxxxx serial # scope, channel islands built (not sure if that matters in any way).

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mskobier on April 21, 2015, 02:17:34 am
zze110,
     It should not matter where it was made. I have a 2445B, a 2465 and a 2465CTS. The 2445B works great, and I am working out the bugs on the other two. the 2465 is a B01xxxxx and the 2465CTS is a B02xxxxx, so I am working with a similar vintage to yours. I have a hard copy of the 2445 and 2465 manuals, as well as electronic versions for the 2445B and 2465B series scopes. if you need a scan of anything in particular from the manual, just drop me a PM and I will do what I can.

Mitch
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: zze110 on April 23, 2015, 11:13:04 pm
Small update. I set the power supply on my bench (ESD mat 8Mohm to ground) and it started up with all the combs installed.  Observed behavior:

Pulsing fan on startup, very slow to start.  Eventually reached full speed.  Could smell something burning on the board so I looked around a bit...

On the A3 board, R1071 has a nice black burned section through the middle.  I cut the power and measured the resistance, still perfect.
Connect to that is C1072 (one of the caps I replaced).  Slightly warm after 15 seconds but not hot.  According to the PCB marks I have the cap installed the right way around... going to have to check the pcb tomorrow.

R1073 & R1069 test good.  On the part of the schematic right next to those there is a label "+12.6V"  I measured 11.5V but it was bouncing around a lot.

So, tomorrow I guess I will check out the C1072 capacitor.  It isn't shorted and seems to increase in resistance showing it is charging with a meter... and it is installed correctly according to the board.  So something tells me the board has the wrong + mark OR the capacitor is defective and they labeled the wrong lead as negative.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Howardlong on April 23, 2015, 11:51:13 pm
As I remember, I had a similar concern over that resistor in my scope. Turns out if the supply is not under enough load, it will get quite sweaty, and mine discoloured as a result. Spent a while chasing my tail on that as a result, when in fact all was working. This bit of the circuit is used as a temporary load at startup, and if there's not a load across the supplies this is what takes the hit. The 3.3uF C1072 is quite a high working voltage, 350VDC, I assume you have that?

It's quite a design that inverter board that's for sure!
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: zze110 on April 24, 2015, 12:23:59 am
Yes, I replaced C1072 with a panasonic 3.3uF 450VDC.  Having the circuit bake itself isn't what I'd call a good design but oh well...
I'll poke around a bit tomorrow with the 5V dc test load installed.  See if it still starts smoking.  I just need it to work long enough to do the real test  |O
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: zze110 on April 24, 2015, 11:06:05 pm
Got the supply working stable with the 5V dc load installed.  Started walking through the regulator troubleshooting guide.

TP201 measurement: 10.00V, perfect.
P232 Pin 1 @ 5V?: No, 5.87V, way out of spec.
Check +5Vd feedback by varying R1292: Feedback working?: No.  I measure -8.7VDC on P233 pin 1 regardless of potentiometer position. -> "Repair path through U1371C and U1040"

Not sure where to look next.  I guess i'll try to look at the circuits surrounding U1371C and U1040 for a bad part.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: schofield on May 26, 2015, 02:19:52 am
NOTE: This message has been deleted by the forum moderator Simon for being against the forum rules and/or at the discretion of the moderator as being in the best interests of the forum community and the nature of the thread.
If you believe this to be in error, please contact the moderator involved.
An optional additional explanation is:
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Ridgh on July 01, 2015, 12:48:37 am
Hello ALL!
I need - as far as I know - a major help and assistance:
I've bought 2 scopes: 2465A and 2465B. I've tested them prior purchasing for about half an hour and they worked perfect.
After a while, on the 2465B, I've observed that the trace and readout are dimming after approx. half hour up to disappearing completely. I found a friend that told me to change the capacitors on PSU and I did it.
The new capacitors are on specs, but maybe it was mentioned on this forum that 2 capacitors are interchanged on Layout. After this "incident", I got no trace or readout.
The 'scope does several tests (the 4 channels, and at ADD it remains stuck. After pressing A/B Trig, the panel lamps are working and responding, there are "clicks" when they should be (compared to the A version, but nothing appears on CRT. Just after several hours it is disconnected (5-24 hours), the beam appeared, without readout.
I understood that A5 PCB has a problem, and indeed I've found several leakages from electrolytic caps. There was a lot of "salt" on the solder, and as well a 10k resistor (0.1%) burnt. I exchange then with what I had on my lab and ordered new ones that are supposed to arrive within 2-3 days. All the voltages at J119 are good. The DAC shows me that I have inputs as they should be, the microprocessor pin 40 is high (it should be), and I have a good stable clock at pin 39. The DAC has normal measurements at pin 16 and 19.
The U800 is not too hot (approx. 50*C after 20 minutes).
These are the details so far. From time to time, (long time...) the 'scope has a beam, but it surf down the screen up to ~70%. It can be moved up or down, right and left. However, if I turn it off even for a second, I can see nothing again on screen.
The recall button works, I can recall the saved configurations. The beam finder doesn't work.
I'll be more than thankful if any of the members from this forum may help or get an idea for what I am supposed to look for further.
This is the summary, and I have no idea  what to do further...
Thanks in advance,
Ridgh 
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MarkL on July 15, 2015, 05:46:55 pm
I have a printed copy of the "2445/2465 Option 06 and Option 09 Counter/Timer/Trigger and Word Recognizer Service Manual", pub #070-4632-00, so I can say the service manual is not the same.
Dredging up this old thread...

I've had several requests for this manual since the 2445/2465 (plain version) CTT WR service manual doesn't seem to be out there anywhere.  I've scanned in my copy and you can pick it up here if you're interested (no index or OCR):

  http://employees.org/~markl/Tektronix_2445_2465_Opt_06_09_CTT_WR_Service.pdf (http://employees.org/~markl/Tektronix_2445_2465_Opt_06_09_CTT_WR_Service.pdf)

I've also uploaded it to http://www.ko4bb.com (http://www.ko4bb.com).  I will delete the above copy once KO4BB publishes it.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SoundTech-LG on July 19, 2015, 11:27:40 pm
Speaking of CTT...

I just now finally solved this on 2467B/2465B.

I got a CTT 87 error 78 message after having the TV/CTT option board out of my scope.
I swapped it with another board from another scope. Now both scopes had the same CTT error message.
I have been pulling hair trying to figure out what I blew up/ESD etc.

Nope... just hidden under the J101/J102 cables for the options board is another connector that connects to J104. :palm: In the case of TV options, it also connects to  J100, J103, J105, J109, but the error is generated off J104 not being connected.
You can't see this connection to the bottom edge of the option board, unless you peer down under the cables going through the main board hole!!!

Quite relieved to find this. Been playing around with this for months!
Something to be aware of if you remove the CTT or TV options board on 2465B's or 2467B's.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SoundTech-LG on July 27, 2015, 06:23:30 pm
Did the CRT replacement on one of the 2467B's. Pretty straightforward. Just be careful with the neck terminals. Quite fragile. Attaching the wires back on to the neck required a small flashlight. Hard to see in there at the mainboard. Threading the cables through the shield holes is critical for lead length, so take note as you remove them. I was able to find the CRT on ebay, which is a miracle in itself, but the fact that NO SCREEN BURNS was 100% true, was amazing. the original CRT had some, not real bad at all, very usable, and only noticeable under a full screen flooding. So now I have that one as a spare, just in case...
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: timb on August 11, 2015, 10:23:54 am
Hey guys, I got a 2465B (>B04xxx serial) back in January to fix up. I had taken it apart, cleaned it, checked caps, swapped the BBSRAM, etc.

Unfortunately, I had a bunch of other pressing projects come up so I didn't get the scope back together until last week. At least, it *seems* back together... I've got a mystery part that, for the life of me, I can't figure out where it goes. I've checked the exploded diagrams in the service manual with no luck.

Any ideas?

(http://images.tapatalk-cdn.com/15/08/11/67c5781ad2e8032b08a4bdafc37b6bb0.jpg)

(http://images.tapatalk-cdn.com/15/08/11/e7b5001cd6400c0c681adae378d0262e.jpg)


Sent from my Tablet
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: timb on August 11, 2015, 11:04:46 am
Annnnd nevermind. I found it in the 2465A Options Service manual, of all places... (http://img.timb.us/emoticon/ughh.gif)

(http://images.tapatalk-cdn.com/15/08/11/af5a71840cc872cc07755cf67aa89aa9.jpg)

(http://images.tapatalk-cdn.com/15/08/11/e9132a5d2421328472bfbc5bb5050926.jpg)

Oh, if anyone needs knobs, buttons or a replacement front panel board, let me know. The overlay on my unit was trashed and I scored a deal on an entire front panel assembly, so I've got parts!

(http://images.tapatalk-cdn.com/15/08/11/ef3544c4a1501b1dc5282adb3ed4ebcc.jpg)

(http://images.tapatalk-cdn.com/15/08/11/e7b61084692df23e22b76d8dd299d564.jpg)



Sent from my Tablet
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SoundTech-LG on August 11, 2015, 07:34:01 pm
knobs, shaft extenders, and pots. How much???
Title: Tektronix 2465B oscilloscope teardown
Post by: timb on August 12, 2015, 09:11:42 pm
knobs, shaft extenders, and pots. How much???

Send me a PM and we'll figure out something. Do you want the entire board, or just the pots? (The board 100% works and has been fully cleaned with DeoxIT.)


Sent from my Tablet
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SoundTech-LG on August 13, 2015, 04:31:08 pm
Sent the PM. not seeing responses... :-/O
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: timb on August 14, 2015, 12:16:29 am
Sorry, I've been tied up all day.  I'll get to it this evening! :)


Sent from my Smartphone
Title: Tektronix 2465B oscilloscope teardown
Post by: timb on August 14, 2015, 09:46:48 am
Sent the PM. not seeing responses... :-/O

Replied!

In other news, I got my 2465B back together tonight and it lives! Originally, I had put it back together on Saturday, but when I turned it on all I got was a flashing TRIG'D light. Turns out I had put the A20 (buffer board) ROM in backwards... Doh! Of course it was fried. Luckily, I had a dump of it! (Which was the entire reason it was taken out in the first place.)

Ordered some NOS M2732A's with a 1998 date code from a US seller that got here today. Programmed one, popped it in and everything seems to work! Hurray!

My unit is a 2465B-CT with a Pre-B049999 serial. I replaced the SRAM with FRAM, which works fine. Unfortunately I lost the cal data when trying to read the SRAM with my programmer while simultaneously keeping it powered. (These low serial units used a discrete battery and SRAM chip.)

Another issue I noticed is an error 06 02, which relates to the battery voltage. Obviously, since there's no battery installed there can't be any voltage to detect! The fix ended up being pretty easy:

Remove CR2770 and replace it with a 4.7K resistor, then add a jumper wire across the former battery + and - pads. The negative battery pad goes through a 10K resistor to ground; CR2770 connects the positive battery pad to the SRAM's VCC line.

Without the diode, +5VD flows through the new 4.7K resistor, which together with the existing 10K unit create a voltage divider. This feeds about 3.4V into the battery voltage detection op-amp.

Here's before and after schematics:

(http://images.tapatalk-cdn.com/15/08/14/1aacfc94a226b957226a51e1a1f2b645.jpg)
Before

(http://images.tapatalk-cdn.com/15/08/14/625d12c770f4ec8cc42a65dcd41ab761.jpg)
After

(http://images.tapatalk-cdn.com/15/08/14/0ce30c92a3a4121e2bf4123ddeb7dd0f.jpg)
The Mod

No more error 05 on startup! (I am getting CT TEST 81 FAIL 02 and 86 FAIL 02, but after having a look at the options service manual, these are related to calibration.)

Now, to figure out what I need to calibrate the unit...


Sent from my Tablet
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SoundTech-LG on August 14, 2015, 01:44:32 pm
Those Adafruit adapters are so nice to use...

The CTT Cal is pretty painless, as the manual mentions, set the sweep to 10nSec, V/div at 200mV, and then you need to supply a 1 Volt .5uSec pulse centered about 0 Volts (no offset), and triggered externally by the timing generator set for 1uSec markers. the onscreen prompts are fairly easy to follow. I am stating all this from memory,  :-/Oso excuse any errors, corrections to follow later, if any.
The CTT Options Service manual explains it...   oh here it is...
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: ehsmeng on August 14, 2015, 07:59:47 pm
Thanks a thousand times for this teardown. It just helped me fix a moving damaged 2465a.
Title: Tektronix 2465B oscilloscope teardown
Post by: timb on August 24, 2015, 09:58:53 pm
So, over the weekend I finally got my $80 eBay Calibration Special back together and working!

(http://images.tapatalk-cdn.com/15/08/24/4798250bcc691de6ff943d3978ce1b6d.jpg)

At some point this spring I picked up a TM 503 Power Module, PG 506 Cal Gen, TG 501 Time Mark Gen and SG 503 Leveled Sinewave Generator on eBay for $80. All the units had yearly cal stickers up to 2013. At first the units were behaving erratically, which turned out to be a power supply issue. $20 in capacitors and a new bridge rectifier in the power module solved that problem. After fully disassembling and cleaning all three units, I just needed to lube some switches, reseat all the ICs, replace some 74 Series logic and now everything works perfectly. Well, except the fast rise board in the PG 506; I broke one of the BNC connectors off the board when I over-torqued the nut. I'm trying to find a suitable pair of end launch BNC connectors to replace them with.

Anyway, it's amazing what you can find on eBay with a bit of patience and some luck. Hopefully I can get my scope calibrated this week, just waiting on some attenuators now.

(http://images.tapatalk-cdn.com/15/08/24/e41b631064e7ceac40e1972ad005ef68.jpg)

(http://images.tapatalk-cdn.com/15/08/24/6b3cb61730c8ad373b892c67edf67080.jpg)

Oh, I also modded the TM 503 a bit. It was a stock unit without the rear BNC/DB-50 option; but I found out the steel frame actually has the holes for the BNCs and cutout for the DB-50, they just put a cover plate on without the holes! So, I added BNC connectors, in case I need them, and also added an IEC power connector where the DB-50 would have gone. Since the built-in push-pull switch was wonky, I opted to replace it with a bog standard toggle switch in the hole that the hard-wired power cord formerly occupied. I'm really pleased with how it came out.

(http://images.tapatalk-cdn.com/15/08/24/41a6ca769685f5936c1d984b1225bb0e.jpg)


Sent from my Tablet
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: j ferguson on September 13, 2015, 10:38:11 pm
Has anyone here actually entered calibration data recorded from the scope Exer 02 display onto a generic NVRAM file ( to correct its calibration data for your scope) and successfully used the new chip?  Part of this question involves relating data addressing on the new file as shown on a typical hex editor. 

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: timb on October 07, 2015, 06:50:40 am
Anyone have the Digi-Key parts list handy for a power supply re-cap?


Sent from my Tablet
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mtdoc on October 08, 2015, 09:56:18 am
Anyone have the Digi-Key parts list handy for a power supply re-cap?


Sent from my Tablet

Here's the file posted to the Yahoo Tek scope forum. Mouser and Newark part no.s only though.

https://dl-web.dropbox.com/get/_2465LVPS_ReCap%2C%20A1%20recap-parts.xls?_subject_uid=315056499&w=AABBEwsyvXv8-MkXuvQXylKApXyus6nBmOsuJ0r-fgUkYw
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: timb on October 08, 2015, 09:57:05 am
Sweet, that'll work. Thanks!


Sent from my Tablet
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: med6753 on October 10, 2015, 01:06:46 pm
Since this has turned into a thread about Tek 24XX scopes in general I figured I'd join the fray with my recently acquired 2465 DMS. It was a business write off and  I managed to get it for free.

I've used many Tek scopes in the past but I wasn't familiar with this series. Upon power up I was greeted with a screeching fan and an error code of CT Test 81 Fail 02. I solved the fan issue with some lube on the motor shaft.  I started searching the net for manuals and found them for the mainframe as well as the options. And stumbled upon the Tek Yahoo group and joined up.

One of the first things I learned with these 24XX scopes before doing any troubleshooting is to verify all the supply voltages (This is true with any old equipment but seems to be really emphasized with this series). I was lucky in this respect. All the supply voltages are in spec and no caps have been changed. But I know the day will come where I'll have to pull the supply and inverter boards and re-cap them. That won't be an easy task with this fully optioned 2465 DMS.

CT Test 81 Fail 02 is a calibration fail with the Counter/Trigger option. According to the manual a Tek PG 502 Pulse Generator and a Tek TG 501 Time Mark Generator are required for calibration. I'm just a hobbyist and I don't have this equipment. But I do have a Heathkit IG-4244 Oscilloscope Calibrator that is capable of generating a very precise 1 MHZ square wave. With the help of the Yahoo group, a BNC tee, a 2X attenuator, and a DC supply to insure proper offset the Buffer board accepted the signal and performed a successful cal and cleared the error. See 1 MHZ photo.

After clearing the CT fail the scope passed all kernel and confidence tests, at least for a while. It is now getting a BU Test F1 Fail 10 on an intermittent basis which is a buffer board EAROM checksum fail. I need to investigate this further but the consensus is leaning towards a bad EAROM chip. For now I'm bypassing the error and the mainframe and counter appear to be working properly. See BU fail photo.

The DMM option is a total train wreck. The DCV spec'ed accuracy is 0.03%. Not even close. Example: with my 1.000 VDC standard it reads 0.9886 V on autorange. If I go up one range it reads 1.000 V. The kernel/confidence tests do not check the DMM cal directly other than basic functions. The service manual states to perform a cal if you suspect an issue. I did do some extensive resistance checking of the input networks just in case something was fried and found nothing. Proper calibration of the DMM option requires a Fluke 5101 with calibration constants ranging from .19 V to 450 V. As I stated before I'm just a hobbyist and there is no way I'm going to be able to get a Fluke 5101. I don't really consider this function important anyway since I have a Fluke 87 and a Fluke 8021B that take care of my needs. See DMM1 and 2 photos.

The A5 Control Board in a 2465 is pin thru hole, not SMD as in 2465A and B. It is not as prone to damage from leaking caps as many have discovered with the SMD board. Also, the 2465 uses EAROM's to store it's cal data and doesn't require a battery. See A5 photo.

The DMM board swings over or can be completely removed to gain access to the buffer board and supply/invertor boards. See DMM board photos.

Thanks for reading. Input/comments always welcome.   

                 
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: j ferguson on October 10, 2015, 08:00:53 pm
Has anyone here actually entered calibration data recorded from the scope Exer 02 display onto a generic NVRAM file ( to correct its calibration data for your scope) and successfully used the new chip?  Part of this question involves relating data addressing on the new file as shown on a typical hex editor.

Sparky was kind enough to share both a dump of the NVRAM on his 2445b and a video of the EXER (02) output taken from the screen prior to removal of the old Dallas NVRAM.  I stepped through the display a word at a time and copied down all 256 of the "words".  He was right, each word is comprised of two characters and the first one at 00h address in the EXER (02) sequence is written to 001Eh on the chip itself, second character to 001Fh and so forth. 

The data on his video and the data in the NVRAM dump starting at 001E agreed exactly.

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: timb on October 11, 2015, 01:12:17 am
If anyone in the VA/NC area needs a scope cal, I've got a calibrated PG506, SG503 and TG501 to do it with. You just need to bring your scope over.

You know, I wonder if it would be possible to take the main A1 board out of a 2465X, put it in another scope, do the cal and then move the board and NVRAM back to the original scope. That should work, right? As all the analog stuff is there. If so, that could make it a lot easier for people without the equipment to get their unit calibrated, as you wouldn't need to ship the whole scope back and forth, just the main board. Hmmm.


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Title: Re: Tektronix 2465B oscilloscope teardown
Post by: soren on October 11, 2015, 01:58:41 am
You know, I wonder if it would be possible to take the main A1 board out of a 2465X, put it in another scope, do the cal and then move the board and NVRAM back to the original scope. That should work, right? As all the analog stuff is there. If so, that could make it a lot easier for people without the equipment to get their unit calibrated, as you wouldn't need to ship the whole scope back and forth, just the main board. Hmmm.

Calibration depends on the 10V trimmer in the power supply and the DAC reference trimmer on the A5 board.

Removing the A1 board is also rather fiddly.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: timb on October 11, 2015, 02:03:07 am
Ah yeah, forgot about the DAC reference. It's a shame a scope's calibration involves so many factors; it would have been cool if they could have made a "Calibration Module" that you could pull/swap out, sort of like the HP 3455A DVMs.


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Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on October 11, 2015, 06:50:53 am
...<snip>...  I managed to get it for free.

I hate you. LOL ...j/k  >:D

Congrats on the score.  :clap:  :-+
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: med6753 on October 11, 2015, 01:28:21 pm
...<snip>...  I managed to get it for free.

I hate you. LOL ...j/k  >:D

Congrats on the score.  :clap:  :-+

Please don't hate me.   :-[   I was definitely in the right place at the right time.

But if I manage to find someone who has a Fluke 5101 AND they let me borrow it for a few hours THEN you can hate me.  :P
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SoundTech-LG on October 12, 2015, 01:29:25 am
If anyone in the VA/NC area needs a scope cal, I've got a calibrated PG506, SG503 and TG501 to do it with. You just need to bring your scope over.

You know, I wonder if it would be possible to take the main A1 board out of a 2465X, put it in another scope, do the cal and then move the board and NVRAM back to the original scope. That should work, right? As all the analog stuff is there. If so, that could make it a lot easier for people without the equipment to get their unit calibrated, as you wouldn't need to ship the whole scope back and forth, just the main board. Hmmm.


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The gains and electrode physical placement differences in each CRT will make that very questionable. At the very least H, and V gain, will quite likely need adjustment to compensate for each CRT. Most likely more.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: timb on October 12, 2015, 03:15:37 am
Anyone have the Digi-Key parts list handy for a power supply re-cap?


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Here's the file posted to the Yahoo Tek scope forum. Mouser and Newark part no.s only though.

https://dl-web.dropbox.com/get/_2465LVPS_ReCap%2C%20A1%20recap-parts.xls?_subject_uid=315056499&w=AABBEwsyvXv8-MkXuvQXylKApXyus6nBmOsuJ0r-fgUkYw

Link doesn’t work for me. Says I’m not logged in, despite being logged in.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mtdoc on October 12, 2015, 04:55:24 am
Anyone have the Digi-Key parts list handy for a power supply re-cap?


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Here's the file posted to the Yahoo Tek scope forum. Mouser and Newark part no.s only though.

https://dl-web.dropbox.com/get/_2465LVPS_ReCap%2C%20A1%20recap-parts.xls?_subject_uid=315056499&w=AABBEwsyvXv8-MkXuvQXylKApXyus6nBmOsuJ0r-fgUkYw (https://dl-web.dropbox.com/get/_2465LVPS_ReCap%2C%20A1%20recap-parts.xls?_subject_uid=315056499&w=AABBEwsyvXv8-MkXuvQXylKApXyus6nBmOsuJ0r-fgUkYw)

Link doesn’t work for me. Says I’m not logged in, despite being logged in.

That's weird. I'm new to DropBox. Let's try again. Try this:

https://www.dropbox.com/s/fvqo6oj8ktbm2pj/_2465lvps_recap%2C%20a1%20recap-parts.xls?dl=0 (https://www.dropbox.com/s/fvqo6oj8ktbm2pj/_2465lvps_recap%2C%20a1%20recap-parts.xls?dl=0)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on October 12, 2015, 05:02:31 am
Why not just zip it and attach here, it will be useful reference for others in the future, sorry , don't have dropbox account.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: mtdoc on October 12, 2015, 05:13:16 am
Why not just zip it and attach here, it will be useful reference for others in the future, sorry , don't have dropbox account.

Well doh!  I didn't realize you could attach zip files here. Here it is:
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: timb on October 14, 2015, 07:32:00 pm
Thanks, I made an order with Digi-Key. Though, I screwed up one part! Instead of three 1uF caps I ordered 10uF! I looked at the schematic, and it appears they're used in the Op Amp feedback path that goes to the inverter feedback. (C1274, C1291 and C1292)

I'm wondering if it's okay to use them? Normally it's okay to increase a cap's size when it's just for filtering, but when it's for an op amp's feedback I'm just not sure.


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Title: Re: Tektronix 2465B oscilloscope teardown
Post by: timb on October 16, 2015, 08:14:14 pm
Hurf durf, disregard last post. Upon looking at the caps in question, they are bi-polar electrolytics. Which, thinking about it, makes the schematic make much more sense!

I happened to have two new 1uF Nichicon BP caps in my parts drawer (thanks to Radio Shack going belly up). They're axial instead of radial, but I made it work. I went ahead and replaced the two that belong to the 10V ref circuit and just put back the original 1uF cap that belongs to the +5D circuit, as it tested OK. I figure the reference is the most critical so I might as well refresh those caps.


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Title: Re: Tektronix 2465B oscilloscope teardown
Post by: timb on October 16, 2015, 09:39:59 pm
Hmm, okay, new problem! I just noticed that according to the schematic C1132 is a 10uF 160V part and C1115 is 250uF 20V; however, on my board with the original Tektronix caps, it's the opposite (according to the layout diagram).

As I removed the original caps, I wrote down the values on a printout of the layout, so that's how I put them back. I'm going to assume the layout sheet has the numbers wrong and what's labeled C1132 is actually C1115. I feel this is a safe assumption, but I wanted to double check before I make an ass-umption of myself. ;)

(http://images.tapatalk-cdn.com/15/10/16/e9ae2f8df5edb34d41167f2a36206cc7.jpg)

(http://images.tapatalk-cdn.com/15/10/16/60230d2015682d5c3fcd1270f3422118.jpg)

(http://images.tapatalk-cdn.com/15/10/16/a24be33a3b9ae0e42e35cf9aa8bd5c3c.jpg)


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Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MarkL on October 16, 2015, 10:42:02 pm
Follow the traces to see which one is connected to CR1132.  That has to be the higher voltage cap.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: timb on October 16, 2015, 10:43:30 pm
Unless CR1132 is marked wrong too! XD


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Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MarkL on October 16, 2015, 10:51:10 pm
Well, trace as much as you need to satisfy your uncertainty.

The same side of CR1132 also goes to P223, pin 5.

Conversely, the other capacitor in question goes to P234, pin 4, and also L1115.  And the other side is ground.  That should be an easy giveaway.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Howardlong on October 16, 2015, 10:59:23 pm
Errr.... https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg644951/?topicseen#msg644951 (https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg644951/?topicseen#msg644951)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: timb on October 17, 2015, 07:35:12 am
Well, there you go! Thanks! This thread has been going awhile and I've read the whole thing, must have just glossed over that at the time.

So, I reassembled the scope, turned it on and...it worked...sort of. The readout and trace is super crisp, all supply rails are tight, but the fan doesn't work anymore! After a bit of poking around I noticed the fan wire that goes from the PS to the feed through cap had come unsoldered. (Which I didn't notice since I'd put heat shrink over the connection.)

I fixed it, however I don't think it was the problem. The fan still doesn't work. I guess I've got to take the power supply apart again. *Sighs*

I figure it has to be the LM317 as I'm not getting any voltage on the fan wire. Unless there's something wrong with the solder connection between the wire and the board or the wire itself. You know, looking at the schematic again, maybe the wire is the issue. There's a 300 ohm resistor between +15V and the fan wire, so even if the LM317 was bad, I should be seeing *some* voltage there.


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Title: Tektronix 2465B oscilloscope teardown
Post by: timb on October 18, 2015, 06:51:20 am
I feel like I'm banging my head against a wall with this thing. Turns out the fan was a broken wire. No big deal, fix, reassemble and now something is seriously broken.

Upon power up, all the front panel lights come on and stay lit. No readout or trace, no relay clicks, nothing. All rails are slightly low, so something is seriously pulling power, but not enough to trip the current. +5VD is the worst, there's 300mV ripple in the shape of a triangle wave on it.

I used my HP current tracer probe, but nothing appears to be pulling any serious power on the digital board.

I'm getting a 1.25MHz clock on the MPU pin, but the IRQ pin is toggling at like 100ms, instead of the few microseconds listed in the troubleshooting chart. Could be the aforementioned ripple though.

I guess first step is to build a load for the PS and test the rails. If that checks out I guess I start tracing signals.

*Sighs*



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Title: Re: Tektronix 2465B oscilloscope teardown
Post by: med6753 on October 18, 2015, 02:39:54 pm
I feel like I'm banging my head against a wall with this thing. Turns out the fan was a broken wire. No big deal, fix, reassemble and now something is seriously broken.

Upon power up, all the front panel lights come on and stay lit. No readout or trace, no relay clicks, nothing. All rails are slightly low, so something is seriously pulling power, but not enough to trip the current. +5VD is the worst, there's 300mV ripple in the shape of a triangle wave on it.

I used my HP current tracer probe, but nothing appears to be pulling any serious power on the digital board.

I'm getting a 1.25MHz clock on the MPU pin, but the IRQ pin is toggling at like 100ms, instead of the few microseconds listed in the troubleshooting chart. Could be the aforementioned ripple though.

I guess first step is to build a load for the PS and test the rails. If that checks out I guess I start tracing signals.

*Sighs*



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This is exactly why I am so lucky (Knock on wood) that the supply voltages on my 2465 DMS are (so far) in spec. You're not the first I've seen pull the supply and invertor boards and have the damn thing FUBAR upon reassembly. Those boards are apparently a PITA to get out on a typical 2465 without options. Mine has a DMM and C/T plus buffer board which makes it even more of a challenge. I feel for you. Hopefully you'll find the issue.   
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MarkL on October 18, 2015, 02:56:40 pm
The IRQ input should be 10us for every 3.3ms according to the flowchart.  A 1.25MHz processor couldn't possibly respond to an IRQ with a continuous period of only a few microseconds.

You could also take a look at the reset circuitry for the processor.  Iif you have instability on the +5V supply, it could be causing continuous resets.

But I would agree the 300mV ripple on the 5V supply is the main concern.
Title: Tektronix 2465B oscilloscope teardown
Post by: timb on October 18, 2015, 08:41:44 pm
The IRQ input should be 10us for every 3.3ms according to the flowchart.  A 1.25MHz processor couldn't possibly respond to an IRQ with a continuous period of only a few microseconds.

You could also take a look at the reset circuitry for the processor.  Iif you have instability on the +5V supply, it could be causing continuous resets.

But I would agree the 300mV ripple on the 5V supply is the main concern.

I couldn't remember the exact number, but yes 10uS is what it should be.

So, I read a thread on here where someone is having the same problem after a recap. His issue was a dead opto-isolator. I'm going to check mine tonight, but last night I tried varying the 10Vref pot; the voltage responded, as did all the rails *except* +5VD, which tells me it could be U1040. (Since the other rails are actively regulated.)

That 300mV sawtooth on 5VD could be the input to error amp U2 oscillating if U1040 isn't working, right?

Does anyone know what the substitute is for U1040? It's marked SOC123A in the schematic.

Edit: Parts list shows H11AX, which gives me 4N2X as well. I get the same when I search for SOC123A.  Seems like they're a family. Hmm, still in production too!


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Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MarkL on October 19, 2015, 01:28:22 am
I wouldn't blame U1040 just yet.  The frequency of the sawtooth might provide a clue.  Is it the switching frequency or something else?

Is the fan running now that you fixed the broken wire?

If things were working before you fixed the fan, go back a step.  Try disconnecting the fan or undo whatever you did, no matter how unrelated it may appear.

Can we get a screen shot of the ripple on +5VD?  Any ripple on the 10V ref?  How's the +15V unreg, which feeds the +10V ref circuit (and also the fan)?

Title: Tektronix 2465B oscilloscope teardown
Post by: timb on October 19, 2015, 07:45:58 am
Okay, I built a load and hooked it to the supply. I checked +-15V and both +5V rails, everything is in check. Less than 20mV ripple on the +5VD rail. I tested -5V and -8V, looks like they are sitting very low: -8V rail is sitting at -1.2V, -5V is sitting at -2.7V, but maybe I need to up the load resistors, because those rails were fine inside the scope last night, I think. I used 50 ohm on -8V, -5V and +5V; 100 ohm on +15V and -15V; 150 ohm on +42V; 2k on +87V; 2 ohm on +5VD.

To answer your question, I did try disconnecting the fan. One of the first things I tried!

Tonight I'll get a screen cap of the ripple on the 5VD rail.


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Title: Re: Tektronix 2465B oscilloscope teardown
Post by: timb on October 19, 2015, 09:41:57 pm
So, I'm about to start more testing, but I was reading the service manual earlier. Looks like the -5V rail relies on -8V, so one of them could be the problem. I'll check them inside the scope first.

The other thing I was thinking, what if the line up signal isn't getting through? That could hold the system in reset. Anyway, first thing's first, put the supply back in the scope and check the ripple again.


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Title: Tektronix 2465B oscilloscope teardown
Post by: timb on October 20, 2015, 07:00:30 am
Alright, so I changed all the 50 ohm resistors out with 100 ohm ones on my dummy load. Hooked it up and the supply was 100% in regulation. Put it back in the scope and it started right up. All rails are in spec and there's no visible ripple on +5VD (at least at 50mv/div).

This thing is gaslighting me!

Nearest I can figure is maybe one of cables that goes from A1 to the supply wasn't secure, though I swore I checked those.

I'll check deeper tonight, measure the ripple on all the rails. But yeah, there you go. Weird.

Edit: Oh, here's the load I made. Pretty simple and in the end worked great!

(http://images.tapatalk-cdn.com/15/10/20/7719c04181d0ccd53bc7ce6ce54c371d.jpg)

(http://images.tapatalk-cdn.com/15/10/20/5eb8e251c9403acd165da73bc46a8d20.jpg)


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Title: Re: Tektronix 2465B oscilloscope teardown
Post by: med6753 on November 07, 2015, 06:10:21 pm
The DMM option is a total train wreck. The DCV spec'ed accuracy is 0.03%. Not even close. Example: with my 1.000 VDC standard it reads 0.9886 V on autorange. If I go up one range it reads 1.000 V. The kernel/confidence tests do not check the DMM cal directly other than basic functions. The service manual states to perform a cal if you suspect an issue. I did do some extensive resistance checking of the input networks just in case something was fried and found nothing. Proper calibration of the DMM option requires a Fluke 5101 with calibration constants ranging from .19 V to 450 V. As I stated before I'm just a hobbyist and there is no way I'm going to be able to get a Fluke 5101. I don't really consider this function important anyway since I have a Fluke 87 and a Fluke 8021B that take care of my needs.
         

For about $45 USD in assorted parts I was able to get most of the DMM option calibrated....

DCV: the calibration constants required are 0.19V, 1.90V, 19.00V, 190.0V, and 500V. I used an LM723 to generate a precise 19.00V and then cobbled together a voltage divider to set 0.19V and 1.90V. For 190.0V I used this little device:

http://www.amazon.com/gp/product/B010UGJF1I?psc=1&redirect=true&ref_=oh_aui_detailpage_o01_s00 (http://www.amazon.com/gp/product/B010UGJF1I?psc=1&redirect=true&ref_=oh_aui_detailpage_o01_s00)

There were concerns that this inverter would be very unstable and hard to set precisely at 190.0V but surprisingly it was very stable. The processor in the DMM accepted all the constants fed to it and the DCV function is now calibrated and accurate up to at least 190V. I haven't figured out a way to get an accurate 500V so that range wasn't calibrated but for now I'm very pleased with the results.

Hi-Ohms and Lo-Ohms. I ordered .1% resistors from Mouser and these ranges calibrated quickly with no issues.

I did some spot checking of ACV and it looks reasonably accurate as is. I have the required constants to perform a full calibration but it does require a precise calibrator. ACV requires the same voltages as the DCV but some at frequencies other than 60 HZ. No easy way to achieve that. The DCA and DCA were also left as is. Again that requires very accurate standards. I have other DMM's to measure ACV and current if needed. 

This 2465 is now about 98% done and will serve as my “swiss army knife” with it's combination scope, frequency counter, and DMM. It still has an EAROM checksum error in the buffer board upon power up that I haven't quite figured out but it doesn't appear that it affects anything once bypassed. So for now I'm leaving it as is.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on December 22, 2015, 06:09:13 pm
I just got a 2465BCT for Xmas! However, it needs to be fixed up. I fired it up and started running it through its paces. It appeared to be working ok. I had two 100Mhz probes in x10 mode connected to the calibration output running at around 6Mhz. When I switched them to x1, the vertical trace went large (as expected) then I heard a "pop" and the scope went dead after a few seconds. I opened it up and found that C1016 on the A21 board had exploded and that R1015 was seriously burned. The main fuse had popped as well.

C1016 and R1015 form an RC bridge across hot / neutral just before the CR1011 bridge. Some sort of surge must have been coupled from the high voltage side when the CRT vertical voltage jumped which took out C1016. That probably short circuited and took out R1015 and, in turn, the fuse. The question is how that coupling could have happened? I don't currently have a clue.

The maximum voltage on the calibration output is 0.4V, so there is nothing that I should be able to do with the probes that would cause a scope failure! I am sure that there is an underlying cause, but I don't know what it might be. Perhaps someone will have a suggestion.

I could not find any other damage and the boards all look very good in general. The scope actually ran for a few seconds after I heard the "pop" so hopefully the new damage is limited to C1016 and R1015. This is a B010xxx scope so it is an early BCT. There are no SMT parts at all which is wonderful. No Dallas chip to deal with either.

So, my first approach will be to 1) replace the bad parts, 2) recap the board and possibly replace some of the resistors identified by dehav7 and 3) replace R6190 with C6190 to install option 1E. I am currently pulling together a parts list for Mouser. I would also like to replace the soldered in Lithium battery. Does anyone have a suggestion on how to do this without losing calibration data? Can I socket that? I don't currently have the equipment to perform a calibration so I don't want to risk losing the calibration data.

So far, I have only done a partial tear down to find the immediate problem and to visually inspect (most of) the scope. Since all of the tear downs I have seen have been for 2465, 2465A and later model 2465B scopes with SMD parts, I will post pictures when I do a full tear down. I will also post the parts that I am using. So far that is

   C6190 - C412C223K1R5TA Kemet 0.022uF MLCC, 100V, 10%
   C1016 - ECQ-U2A683ML Panasonic 0.068uF Film, 250VAC
   R1015 - 291-36K-RC  Xicon, 36K 5% carbon film

I don't have the relevant schematics for the option 1E modification, so all I have is the value for C6190 but not the voltage rating or suggested type. Other caps in the area are 25V, 50V or 100V so I am going ceramic with 100V.

The project may move a bit slowly given the need to order (and wait for) parts and the time of year. There will probably be several cycles of that as I discover more parts that need to be replaced. I also don't want to pull some of the more difficult boards more than once, so when I have one of them out I will do everything possible before putting it back in. That could cause additional order / wait cycles.

In the meantime, I look forward to any and all suggestions that more experienced people may have. This is my first major scope tear down and refurbishing (although I did repair a 60's vintage scope in the very early '80s - threw it out about 15 years ago, shouldn't have done that). Worse, I have had to interrupt a tear down and rebuild of a Revox B215 to do this one!

So - wish me luck and let me know anything that might help!
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on December 25, 2015, 11:34:18 am
I have created my parts list (attached). There may be a few errors because the service manual does not distinguish between radial vs axial, aluminum electrolytic vs. tantalum electrolytic (expect for one part) or polar vs. bi-polar. It also lists a single part as "ALUM" which I have interpreted as aluminum electrolytic, but perhaps it means bi-polar. I have taken my best guess by looking at the scope as much as possible and by reading other people's posts. I will update the list, as necessary, when I can compare individual items directly to the circuit boards. This is also a very early 2565B CT (serial number B010xxx). The actual board versions aren't in the service manual (some are -02 and the manual has -00 and -05 as the closest).

However, except for complete board differences (SMT vs. through-hole and the high voltage board) there do not appear to be any version differences that affect this list. I have ordered everything on the list except for the LTC-7PN battery (which is the exact part currently in the scope, so it is possible that has already been changed). I did include the fan board although that is probably not in the scope (just a single capacitor, so no big deal).

On additional consideration and taking into account other people's repairs, I am currently thinking that when I switched from x10 to x1 and the vertical size jumped that there was a minor current surge to handle the increased vertical deflection. The C1016 capacitor was probably very marginal and blew, shorting out. That would have stressed R1016, burning it due to excessive current (which would have then been directly across the main power supply at 132V) finally causing the main fuse to burn out. I have also discovered that C1018 - which is exactly the same type and value of part - is cracked. Since those two capacitors apparently tend to fail that may (with luck!) be the extent of the problem.

On the good news side, when I reported the situation to the vendor and said that I was planning on keeping the scope anyway, unasked the vendor refunded $50 of the purchase price. That has paid for most of the materials for a complete rebuild!
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: med6753 on December 25, 2015, 02:58:02 pm

So, my first approach will be to 1) replace the bad parts, 2) recap the board and possibly replace some of the resistors identified by dehav7 and 3) replace R6190 with C6190 to install option 1E. I am currently pulling together a parts list for Mouser. I would also like to replace the soldered in Lithium battery. Does anyone have a suggestion on how to do this without losing calibration data? Can I socket that? I don't currently have the equipment to perform a calibration so I don't want to risk losing the calibration data.


You have to bridge in the voltage while changing out the lithium battery or you will lose the calibration data. I forgot where I saw the procedure. If I find it I'll post the link. My older 2465 DMS has EAROM so no battery issues.

Looking forward to your teardown. So far I haven't had any power supply issues but I know that day will come where I'll have to recap to inverter and power supply boards. So far all the voltages are in spec.

One "gotcha" regarding the DMM option. The power up self checks do check some basic DMM functions but will NOT flag the  DMM calibration. The DMM option manual states to perform a calibration if you suspect it to be out of spec. That's exactly what I found out as I posted in this thread. If you find the same with yours I can give you some pointers on how to get a reasonable calibration cheaply  :-+     
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Gixy on December 25, 2015, 07:12:02 pm
To replace the battery, you can use a procedure described in the Yahoo Tek Group, well described in four pictures.
You can also use a bench PSU to back-up the battery while replacing it, but be careful not to have it grouded to earth because your soldering iron would then make a beautiful short when you solder the positive pin... In this case you can unplug your iron for the time of the soldering.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on December 26, 2015, 08:54:23 am

You have to bridge in the voltage while changing out the lithium battery or you will lose the calibration data. I forgot where I saw the procedure. If I find it I'll post the link. My older 2465 DMS has NVRAM so no battery issues.

Looking forward to your teardown. So far I haven't had any power supply issues but I know that day will come where I'll have to recap to inverter and power supply boards. So far all the voltages are in spec.

One "gotcha" regarding the DMM option. The power up self checks do check some basic DMM functions but will NOT flag the  DMM calibration. The DMM option manual states to perform a calibration if you suspect it to be out of spec. That's exactly what I found out as I posted in this thread. If you find the same with yours I can give you some pointers on how to get a reasonable calibration cheaply  :-+   

Thanks. This is a BCT which does not have the DMM, but does have the frequency counter. When choosing this unit, I had several priorities...

1. 2465B / 2457B - but preferably 2465B because the CRT is more easily replaced and is larger. I don't really need the CRT features of the 2467B. I wanted a 2465B because while it is far more than I need at the moment, but I can only afford to do this once so I want the most bang that I can get.

2. I wanted a unit without SMDs. Easier to maintain and appears to have a lot fewer service "updates" apparently due to Tektronix still trying to fine tune the SMD version. Also, no Dallas chip to deal with. Once the procedure is known, changing a battery is not a big deal.

3. I wanted a unit with the frequency counter because I need one. Option 09 gives 7 digits without an external time base and 8 digits with. Since my next purchase will be a GPSDO that is more than sufficient in terms of accuracy. Anything more than that - or even to match it - would be very expensive. So that narrows the field down to the BCT, BDM or BDV. Also, I have very limited space on my work bench and the integrated frequency counter helps there as well.

4. I already have a DMM of about the same accuracy as that provided by option 01. That accuracy is not much to write home about and increases the size of the scope. So while a BDM or BDV is ok, optimal is the BCT.

With this unit I hit all of my points exactly. It is an early model (s/n B010xxx), but there are no service updates listed for any s/n below B050000. There are some board variations, but those appear to more layout than anything else. So, while I paid more for it than I might have for a plain 2465B in the same shape, I think the cost difference was worthwhile. Certainly cheaper than buying a separate frequency counter. When it failed, the $50 rebate from the vendor paid for most of the parts which reduced the cost further (since I would have recapped it anyway - just not as soon).

I may need pointers on the tear down. I haven't taken out any board yet that requires desoldering. I have had the options out several times. There are two areas where it is a pain. First is the ribbon cable that tends to get pinched. It is hard to get that in right. The second is the two cables at the very end which go onto the same pins. It is not clear which cables go where. I figured that out because one of the pins goes to the resistor / capacitor that I will be changing for option 1E, but the manual is useless there.

The case and back were not the cleanest and had permanent marker, floor scum and sticker goo all over them. I have cleaned all of that of so the case looks nice now. I haven't had the front of the scope off yet, so it is still a bit grungy.

I may also need help identifying some parts. My part list was as accurate as I could make it, but I am sure that there will minor corrections (radial vs. axial / aluminum electrolytic vs. tantalum electrolytic / polar vs. bi-polar, etc.) which are not spelled out in the service manual. Also, I don't have the 24x5B / 2567B options service manual. I have been unable to find it online and am not willing to pay for what should be a free manual unless it is absolutely necessary. My understanding is that Tektronix made all of that information publically available.

Right now I am waiting on Mouser. The parts shipped on the 24th so they will probably sometime early next week.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on December 26, 2015, 09:04:59 am
To replace the battery, you can use a procedure described in the Yahoo Tek Group, well described in four pictures.
You can also use a bench PSU to back-up the battery while replacing it, but be careful not to have it grouded to earth because your soldering iron would then make a beautiful short when you solder the positive pin... In this case you can unplug your iron for the time of the soldering.

Thanks. That looks like an easy procedure - especially with the AAA battery case. It might be good to have a replacement for the capacitor on hand in case it gets damaged by removal. That will probably be the last thing I do. Having seen some other pictures of the battery, I suspect that it has been changed comparatively recently. Mine has the bright yellow label and is not the apparently older blackish version without a label. Also, the part number of mine exactly matches Mouser's part number.

I am trying to join the Yahoo Tekscopes group and the arc / arc2 groups as well. However, I refuse to get a Yahoo account - I keep fairly tight security policies and Yahoo doesn't need to know my phone number OR date of birth! The moderator may not accept an email subscription request so that avenue of knowledge may be blocked off (don't have a Google account either and only have a Microsoft account for downloading development tools). Otherwise, I have read everything else I have been able to find. This thread and the 1E thread (also on this board) have been very informative. I have read this thread once and will read it again while I am waiting.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: med6753 on December 26, 2015, 02:01:34 pm


3. I wanted a unit with the frequency counter because I need one. Option 09 gives 7 digits without an external time base and 8 digits with. Since my next purchase will be a GPSDO that is more than sufficient in terms of accuracy. Anything more than that - or even to match it - would be very expensive. So that narrows the field down to the BCT, BDM or BDV. Also, I have very limited space on my work bench and the integrated frequency counter helps there as well.

Yep, Option 09 is definitely a nice feature and I use it all the time. But keep in mind that the frequency counter is only good out to 150Mhz which is odd when you consider that the bandwidth of the scope is double that.


Quote
I may need pointers on the tear down. I haven't taken out any board yet that requires desoldering. I have had the options out several times. There are two areas where it is a pain. First is the ribbon cable that tends to get pinched. It is hard to get that in right. The second is the two cables at the very end which go onto the same pins. It is not clear which cables go where. I figured that out because one of the pins goes to the resistor / capacitor that I will be changing for option 1E, but the manual is useless there.

I have yet to do a tear down too. And I have the additional DMM board across the top of the chassis. Luckily it swings to one side and can be removed.

I've also had issues locating all the service and operating manuals. I have the vanilla 2465 ops and service manual. I have the DMM service manual but no ops manual. And no options ops or service manual but I did find the 2465A options service manual and 2465B options ops manual but they are only good for some reference because of the changes TEK made over the years. 
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on December 26, 2015, 04:34:34 pm

Yep, Option 09 is definitely a nice feature and I use it all the time. But keep in mind that the frequency counter is only good out to 150Mhz which is odd when you consider that the bandwidth of the scope is double that.

I have yet to do a tear down too. And I have the additional DMM board across the top of the chassis. Luckily it swings to one side and can be removed.

I've also had issues locating all the service and operating manuals. I have the vanilla 2465 ops and service manual. I have the DMM service manual but no ops manual. And no options ops or service manual but I did find the 2465A options service manual and 2465B options ops manual but they are only good for some reference because of the changes TEK made over the years.

For my near-term needs, 150Mhz is fine. Even a 60Mhz scope would have done. However, I only plan on buying an analog scope once and so I went with much more than I actually require at this time. That could change rapidly, so the 2465BCT is the best that I can do at this time.

I have the following PDF manuals...

   Tektronix 2465 Options 06 09 CTT WR Service
   Tektronix 2465A Options Service Manual
   Tektronix 2465B 070-6863-00 Service Manual
   Tektronix 2465B 070-6863-01 Service Manual
   Tektronix 2465B Operators Manual

I would like to find a PDF copy of the 24x5B / 22467B Options Service Manual. I think that the 2465A Options Service Manual will be pretty close. I don't think that there was much changed for the options. It has the GPIB, TV, CTT and DMM options in it.




Title: Re: Tektronix 2465B oscilloscope teardown
Post by: timb on December 27, 2015, 10:15:07 pm
It's good to 200MHz, not 150MHz.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: med6753 on December 28, 2015, 01:37:15 am
It's good to 200MHz, not 150MHz.

I think that depends on whether it's a 2465, 2465A, 2465B. I have the Tek 1986 Product Catalog which describes the 2465 and, unless I'm reading it wrong, the counter option is good for 150Mhz. I don't have a signal source greater than 100Mhz so I can't test it. But it would make sense that it would increase in response since the 2465A B/W is 350Mhz and the 2465B is 400Mhz.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on December 28, 2015, 05:36:05 am
It's good to 200MHz, not 150MHz.

I think that depends on whether it's a 2465, 2465A, 2465B. I have the Tek 1986 Product Catalog which describes the 2465 and, unless I'm reading it wrong, the counter option is good for 150Mhz. I don't have a signal source greater than 100Mhz so I can't test it. But it would make sense that it would increase in response since the 2465A B/W is 350Mhz and the 2465B is 400Mhz.

I have a 2465B CT, so mine is probably good to 200Mhz. I don't actually have anything that describes that for a 2465B.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on December 28, 2015, 09:05:40 pm
The parts for refurbishing my 2465B CT have arrived!

Here are the first batch of pictures. These are all of the outside. The next batch will be the inside after I open it up.

I couldn't manage to embed the pictures, so I have attached them. Also .jpeg files are not allowed! WTF! And apparently only tiny files are allowed! So, one per post. Sigh.

Front of scope.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on December 28, 2015, 09:06:44 pm
2465B CT Outside pictures continued...

Back of scope.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on December 28, 2015, 09:53:06 pm
2465B CT Outside pictures continued...

Left side of scope.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on December 28, 2015, 09:56:58 pm
2465B CT Outside pictures continued...

Right side of scope.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: med6753 on December 28, 2015, 10:00:56 pm
I couldn't manage to embed the pictures, so I have attached them. Also .jpeg files are not allowed! WTF! And apparently only tiny files are allowed! So, one per post. Sigh.


Your pictures are too big. Use a program such as "IrfanView". Resize images to 1920 x 1080. Save. Then you should be able to upload each pix in one post.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on December 28, 2015, 10:01:39 pm
2465B CT Outside pictures continued...

Top of scope.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: timb on December 28, 2015, 10:03:32 pm

I couldn't manage to embed the pictures, so I have attached them. Also .jpeg files are not allowed! WTF! And apparently only tiny files are allowed! So, one per post. Sigh.


Your pictures are too big. Use a program such as "IrfanView". Resize images to 1920 x 1080. Save. Then you should be able to upload each pix in one post.

Yeah. They need to be resized first. Or try something like www.imgur.com which should take care of resizing and give you (img) tags you can can copy and paste.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on December 28, 2015, 10:07:51 pm
2465B CT Outside pictures continued...

Bottom of scope.

P.S. I prefer to upload high resolution images. Extremely low resolution images such as 1920 x 1080 are annoying when you want to zoom in on the detail (which is something I do all the time and assume that other people do as well). I would rather not have compression used at all, but uploads are limited to 1M per file so a full resolution image of 25M or so doesn't work. I  should have done two per post, though.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: c4757p on December 28, 2015, 10:13:06 pm
P.S. I prefer to upload high resolution images. Extremely low resolution images such as 1920 x 1080 are annoying when you want to zoom in on the detail (which is something I do all the time and assume that other people do as well). I would rather not have compression used at all, but uploads are limited to 1M per file so a full resolution image of 25M or so doesn't work. I  should have done two per post, though.

Huh? Resolution is only useful when the actual image supports it. That picture is nowhere near sharp enough for a 5269x3573 resolution to be useful...did you even look at it? It's blurry! You're just wasting bandwidth and server space and annoying people on slow connections...

I size my photos based on the actual level of detail in the original. Works much better.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on December 28, 2015, 10:30:31 pm

I couldn't manage to embed the pictures, so I have attached them. Also .jpeg files are not allowed! WTF! And apparently only tiny files are allowed! So, one per post. Sigh.


Your pictures are too big. Use a program such as "IrfanView". Resize images to 1920 x 1080. Save. Then you should be able to upload each pix in one post.

Yeah. They need to be resized first. Or try something like www.imgur.com (http://www.imgur.com) which should take care of resizing and give you (img) tags you can can copy and paste.

Ok, if people really want small images, I'll see what I can do.

I tried www.imgur.com (http://www.imgur.com) and it didn't appear to work well for me. I am trying Ifranview - it resizes the images, but they are still 2.5M. Once I get it fixed I'll upload the images.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: grumpydoc on December 28, 2015, 11:09:02 pm
P.S. I prefer to upload high resolution images. Extremely low resolution images such as 1920 x 1080 are annoying when you want to zoom in on the detail (which is something I do all the time and assume that other people do as well). I would rather not have compression used at all, but uploads are limited to 1M per file so a full resolution image of 25M or so doesn't work. I  should have done two per post, though.

Huh? Resolution is only useful when the actual image supports it. That picture is nowhere near sharp enough for a 5269x3573 resolution to be useful...did you even look at it? It's blurry! You're just wasting bandwidth and server space and annoying people on slow connections...

I size my photos based on the actual level of detail in the original. Works much better.
It's blurry because the camera has focussed on the front of the knobs (the "var" is in focus on the three knobs) and there is little depth of field. The photo of the rear of the 'scope is actually quite sharp, not very exciting viewed at the actual pixel resolution though.

c4757p is absolutely correct - if you are going to post a huge image so that "people can zoom in" it is worth looking at it at the actual pixel resolution and making sure that there is detail to see.

Actually 1920x1080 is plenty big enough most of the time - I usually post something only a little larger such as 2400x1350 or 2400x1800 with a 1/4 size picture in the post linking to the larger pic if people want.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on December 28, 2015, 11:13:55 pm
2465B CT Outside pictures resized. I had to use GIMP to scale and compress, then I got imgur to work. I resized so that the maximum dimension was no larger than 1920 x 1080 at 96 dpi. Let me know if this is more appropriate.

Front       (http://i.imgur.com/vd0ObUY.jpg)
Back        (http://i.imgur.com/9XtlexQ.jpg)
Left Side   (http://i.imgur.com/9Bln0Fr.jpg)
Right Side  (http://i.imgur.com/tLynSpx.jpg)
Top         (http://i.imgur.com/LxYghO1.jpg)
Bottom      (http://i.imgur.com/S97ixzD.jpg)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on December 30, 2015, 06:05:46 pm
Here are the pictures for the inside of my 2465B CT, before removing any boards.

A1 Main Board               (http://i.imgur.com/ZxogM0F.jpg)
A5 Digital Control Board    (http://i.imgur.com/Tm0WPJ3.jpg)
A14 Dynamic Centering Board (http://i.imgur.com/LzfAM00.jpg)
A9 High Voltage Board       (http://i.imgur.com/8S5wmge.jpg)
Top Shield                  (http://i.imgur.com/10YSLTy.jpg)
Back                        (http://i.imgur.com/uFU5Rdc.jpg)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on December 30, 2015, 07:14:27 pm
Attached are the images for the options assembly tear down and refurbishing. Also, option 1E was installed. The "WR Out" photo shows the resistor (circled in red) that enables WR Out for the Word Recognizer Option. The "Option 1E" photo shows the resistor removed and a 0.22uF capacitor installed to enable Option 1E (disabling WR Out). Option 1E allows a reference frequency to be input to the scope increasing the frequency counter accuracy from 7 digits to 8 digits (+/- 1). Option 1E does NOT affect the scope's time base. The reference frequency is used to dynamically calibrate the CTT time base which is separate from the main scope time base. The WR Option will still function and trigger, but the trigger will no longer be available externally. There were only 5 electrolytic capacitors to be replaced, so this was a simple recapping.

Bottom Option Connection               (http://imgur.com/XmV2kKI.jpg)
WR Connector                           (http://imgur.com/2rZQHwg.jpg)
Options Assembly                       (http://imgur.com/8JO1YzQ.jpg)
A20 Buffer Board                       (http://imgur.com/4UiHBHt.jpg)
A23 GPIB Option 10 Board               (http://imgur.com/tfiszb4.jpg)
A27 Counter Timer Trigger Option Board (http://imgur.com/CIYBtxi.jpg)
Recapped CTT & GPIB Option Boards      (http://imgur.com/hGNB0Ym.jpg)
WR Out                                 (http://imgur.com/EgtokUo.jpg)
Option 1E                              (http://imgur.com/qukY0b7.jpg)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on January 01, 2016, 12:19:20 am
I am getting ready to remove the High Voltage board from my 2465B CT. I understand how to remove it, in general. However, there is one sticking point. The service manual says

   "Remove the high-voltage lead from the retainer cap"

Some of the terminology / parts are not clearly explained, but physical examination makes most of it clear. However, this is not clear. Assuming that this is the correct part

(http://imgur.com/JJl5Igs.jpg)

and, what is necessary, is removing the white plug from the black cap then I am not sure how that is done. The white plug turns freely inside of the black cap, but I have been unable to separate the two using reasonable force. Too much force and a back reaction could lead to damaging the small circuit board and CRT connections to the immediate left. Is there some trick to this, or is just especially difficult?

Thanks.


Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on January 01, 2016, 06:07:01 am
Tom Miller on the Yahoo Groups TekGroup confirmed that it just needed a bit more "pull".

That was all I needed and I have finished recapping the high voltage board (even if it was only one capacitor)! Hopefully, I got the CRT socket back on right. Apparently, any one of a dozen orientations would fit. Given wire length, probably no more than three in reality. I think that I did. Here is the after picture of the high voltage board. In spite of appearances, the metal standoff in the bottom right is not touching the replacement capacitor or even close for that matter. The original was a 100uF, 25V, 85c Sprague capacitor. The replacement is a 100uF, 50V, 85c Sprague capacitor. Slightly larger, but it fits.

(http://imgur.com/ATxA57U.jpg)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on January 01, 2016, 10:17:10 pm
Here is the photos of the A5 control board before and after recapping.

Before: (http://imgur.com/ksGlfoC.jpg)
After: (http://imgur.com/SMYdlv2.jpg)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: rafik on January 02, 2016, 02:09:37 am
Hello,

I am new in the forum am I find this blog very interesting.
I have searched about restoration of Tektronix 2465B PSU but I could find anything about it.
For this reason I write here, I hope not disturb. Well, at the present time, I am trying to repair the PSU of this wonderful scope but I could not more. I recap this stage and changed other parts but the PSU is now in a tick mode. Please someone could me help and explain why this happends and how could I go out of this mode? ....I do not know what to do... I hope you can help me with this...
Thank you in advance..
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: tautech on January 02, 2016, 04:00:40 am
Hello,

I am new in the forum am I find this blog very interesting.
I have searched about restoration of Tektronix 2465B PSU but I could find anything about it.
For this reason I write here, I hope not disturb. Well, at the present time, I am trying to repair the PSU of this wonderful scope but I could not more. I recap this stage and changed other parts but the PSU is now in a tick mode. Please someone could me help and explain why this happends and how could I go out of this mode? ....I do not know what to do... I hope you can help me with this...
Thank you in advance..
There's a good Tek pdf with a section on troubleshooting SMPS in this thread:
https://www.eevblog.com/forum/repair/repair-documents-and-links-sticky-me-please-mods/msg477909/#msg477909 (https://www.eevblog.com/forum/repair/repair-documents-and-links-sticky-me-please-mods/msg477909/#msg477909)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on January 02, 2016, 10:18:55 am
Hello,

I am new in the forum am I find this blog very interesting.
I have searched about restoration of Tektronix 2465B PSU but I could find anything about it.
For this reason I write here, I hope not disturb. Well, at the present time, I am trying to repair the PSU of this wonderful scope but I could not more. I recap this stage and changed other parts but the PSU is now in a tick mode. Please someone could me help and explain why this happends and how could I go out of this mode? ....I do not know what to do... I hope you can help me with this...
Thank you in advance..

Best thing you can do is download the service manuals. They are invaluable and the troubleshooting steps for the power supply are very good. Failing that join the Tektronix's group on yahoo. That's where the Tek experts/enthusiasts hang out.

https://groups.yahoo.com/neo/groups/TekScopes/info

I had a issue with a power supply on my 2465B and if it wasn't for the help on the group never would have figured out the problem. Aged and out of spec opto-isolator. Note if you recapped there is a error on the schematic and likely one of the caps was inserted backwards, can't remember which though.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on January 02, 2016, 09:49:13 pm
Hello,

I am new in the forum am I find this blog very interesting.
I have searched about restoration of Tektronix 2465B PSU but I could find anything about it.
For this reason I write here, I hope not disturb. Well, at the present time, I am trying to repair the PSU of this wonderful scope but I could not more. I recap this stage and changed other parts but the PSU is now in a tick mode. Please someone could me help and explain why this happends and how could I go out of this mode? ....I do not know what to do... I hope you can help me with this...
Thank you in advance..

Best thing you can do is download the service manuals. They are invaluable and the troubleshooting steps for the power supply are very good. Failing that join the Tektronix's group on yahoo. That's where the Tek experts/enthusiasts hang out.

https://groups.yahoo.com/neo/groups/TekScopes/info

I had a issue with a power supply on my 2465B and if it wasn't for the help on the group never would have figured out the problem. Aged and out of spec opto-isolator. Note if you recapped there is a error on the schematic and likely one of the caps was inserted backwards, can't remember which though.

The labels for C1115 and C1132 were reversed on the schematic.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on January 04, 2016, 03:22:15 am
Here is the tear down of the power supply section of my 2465B CT. I included the readout board because it was convenient to remove it to facilitate unsoldering the fan power cable.

A2A1 Regulator Board                           (http://imgur.com/Q4IExmF.jpg)
A3 Inverter Board                              (http://imgur.com/NDhX7cs.jpg)
A4 Readout Board                               (http://imgur.com/u9Y4gz5.jpg)
Inside Case with A3, A4 and A2A1 Removed       (http://imgur.com/5iqFqUF.jpg)
Shield Between A3 and A2A1                     (http://imgur.com/9CMemrA.jpg)
Back Panel Wiring                              (http://imgur.com/CnaaPG6.jpg)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on January 04, 2016, 03:36:55 am
Here is the damage, apparent bad components and recapping of the A3 Inverter board for my 2465B CT scope.

On the A2A1 Regulator board, C1016 RIFA capacitor has exploded. That has grunged up some of the nearby components, but does not appear to have done further damage. The C1018 RIFA capacitor has cracked open, but not exploded. Almost certainly non-functional. Resistors R1016 and R1018 have both been severely burned. They may or may not be functional. There are a couple of other resistors with dings and scratches which I will replace.

Additionally, on the A3 Inverter board there are three more RIFA capacitors and it can be seen that all three are cracked. They may still be working, but probably not for long. The A3 Inverter recap does not include those because I need to order replacements. It can also be seen looking at the bottom on the replaced capacitors that one looks like it was starting to leak, a second appears to have damage to the bottom (pre-leak?) and I am not at all sure if some of the rest are slightly bulging or not. They certainly aren't completely flat, but that may be a construction difference.

The only gotcha during replacement is the large axial capacitors. The leads are too short. I had to snip some lead from the original capacitors to extend the lead length. Also, even though these replacements have increased voltage ratings, increased capacitance or increased thermal rating and much better ESR, the replacements are generally smaller. In particular, the radial capacitor which was originally mounted on its side because it was too tall can now fit upright with no clearance issues.

A2A1 Regulator Board Damage                    (http://imgur.com/zuik04G.jpg)
A3 Inverter Board Bad RIFA 1                   (http://imgur.com/HF3CYoK.jpg)
A3 Inverter Board Bad RIFA 2                   (http://imgur.com/xwddyuR.jpg)
A3 Inverter Board Bad RIFA 3                   (http://imgur.com/OimaNkj.jpg)
A3 Inverter Board Replaced Capacitors          (http://imgur.com/LboLNmN.jpg)
A3 Recapped Inverter Board                     (http://imgur.com/pnUyrOJ.jpg)

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on January 04, 2016, 09:58:06 am
Here is the damage, apparent bad components and recapping of the A3 Inverter board for my 2465B CT scope.


Isn't the smell of those old leaky caps just lovely, mine had a horrible fishy oil smell.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: dan3460 on January 04, 2016, 04:46:16 pm
I repaired a 2465 a few months ago, and those square caps that exploded had exploded on mine too. They did have a weird smell, it could be the plastic they used or some of the components inside.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on January 06, 2016, 06:04:31 am
Here is the recap of the A2A1 Regulator board in my 2465B CT. This does not include replacing the bi-polar electrolytics or the damaged resistors. I am waiting on parts for those. As with the A4 Inverter board, when I get the missing parts, I will repost a final picture.

Regulator board (http://imgur.com/E1dyUP7.jpg)
Replaced capacitors (http://imgur.com/GlV9bub.jpg)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: tautech on January 06, 2016, 06:12:46 am


Replaced capacitors
 (http://imgur.com/GlV9bub.jpg)
You have hidden all the brand names.  :-// On purpose?
How many were faulty?
Care to list them for us?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SeanB on January 06, 2016, 07:30:54 am
RIFA, Nichicon, Sprague and Cornell Dublier is my guess.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: tautech on January 06, 2016, 07:44:42 am
RIFA, Nichicon, Sprague and Cornell Dublier is my guess.
Sure, but why guess?

We need this info for another thread Sean.
Can you correctly guess that one?  ;)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SeanB on January 06, 2016, 08:43:06 am
RIFa and Nichicon are easy, and the light blue Sprague are also a common sight. The grey are the guess, and from the age and colour.....
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on January 06, 2016, 09:57:17 pm
I will be happy to list the various brand names. I don't know which ones are faulty. This is a preventative recapping plus fixing known damage. I don't have an ESR meter, and my multimeter is flaky about testing capacitance - some times it works and sometimes not. No idea why.

Do you want the exact parts for this board only or for all boards that I have recapped? I haven't recapped the main board yet, but it is on my work table with the parts laid out.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on January 06, 2016, 10:21:27 pm


Replaced capacitors
 (http://imgur.com/GlV9bub.jpg)
You have hidden all the brand names.  :-// On purpose?
How many were faulty?
Care to list them for us?

There are 5 capacitors (gray), Tektronix part 290-0942-00, with the following on the label

   100uF
   0 - 25 VDC
   + (2) 672D +
   USA8814H - one, labeled with text top to bottom
   USA881 1H - four, labeled with text on side
   105 C

There are 2 capacitors (light blue), Tektronix part 290-0939-00, with the following on the label

   10uF
   0-100VDC
   (2) 672D
   USA8821H
   105C

There are 2 Nichicon capacitors (dark blue), Tektronix part 290-0943-02, with the following on the label

   VX(M)
   85c
   A8810
   nichicon
   47uF 25v

There are 2 RIFA capacitors (yellow and exploded), Tektronix part 282-1222-00, with the following on the label

   0.068uF X2 - top

   250V - SH - front
   565-1   LD2

   PME 271M - back
   40/085/56
   CW2

What do need them for? I have the complete parts list, with replacements that I have previously posted. There have been some updates as I have worked on each board. Do you need the updated list? I will be posting that later, but was going to wait until I have complete finished.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on January 07, 2016, 09:58:58 pm
I have knob problems with my 2465B CT scope. On the front panel, the two bottom halves of the VOLTS / DIV knobs have set screws that are stripped. Probably because somebody screwed them in far too tight. How do I get these off, and where can I get either a knob replacement or a set screw replacement (assuming I get them off without damaging the knobs)?

Additionally, two of the smaller knobs with a blank front (e.g. like the TRACE SEP knob) and two of the smaller knobs with a line on the front (e.g. like the POSITION knobs) have their internal "cap" broken. These are my fault because they were on so tight I had to pry them off with a screwdriver. Unlike the ones under the CRT, which came off with just finger pressure, all of the knobs on the main panel were stuck really badly. Where can I get a knob replacement for these?

These knobs are common to pretty much all of the 22xx and 24xx series, so I would think that they are out there somewhere.

Thanks.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: tautech on January 07, 2016, 10:11:21 pm
What do need them for? I have the complete parts list, with replacements that I have previously posted. There have been some updates as I have worked on each board. Do you need the updated list? I will be posting that later, but was going to wait until I have complete finished.
Only information for this thread:
https://www.eevblog.com/forum/projects/capacitor-quality/ (https://www.eevblog.com/forum/projects/capacitor-quality/)

I have knob problems with my 2465B CT scope. On the front panel, the two bottom halves of the VOLTS / DIV knobs have set screws that are stripped. Probably because somebody screwed them in far too tight. How do I get these off, and where can I get either a knob replacement or a set screw replacement (assuming I get them off without damaging the knobs)?

Additionally, two of the smaller knobs with a blank front (e.g. like the TRACE SEP knob) and two of the smaller knobs with a line on the front (e.g. like the POSITION knobs) have their internal "cap" broken. These are my fault because they were on so tight I had to pry them off with a screwdriver. Unlike the ones under the CRT, which came off with just finger pressure, all of the knobs on the main panel were stuck really badly. Where can I get a knob replacement for these?

These knobs are common to pretty much all of the 22xx and 24xx series, so I would think that they are out there somewhere.

Thanks.

http://www.sphere.bc.ca/ (http://www.sphere.bc.ca/)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on January 08, 2016, 11:35:39 am
I managed to drill the two offending knobs off using a Cobalt drill bit. Only minor damage to one shaft. Now, I just need to replace the bad knobs.

Otherwise, I have completed the recapping of the A1 Main board. Here are the photos...

Before Recapping (http://imgur.com/RACkcaZ.jpg)
After Recapping (http://imgur.com/3XtmjBF.jpg)
Replaced Capcitors (all Nichicon) (http://imgur.com/2jkLUrk.jpg)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: macboy on January 08, 2016, 03:18:48 pm
I have a 2465A, which has the digital board similar to the earlier 2465B serials, that is, with through hole components, and with the separate SRAM and battery, rather than a DS1225 module. My calibration data is intact but the battery is original, so I can assume that it will not be intact for too much longer.

The separate SRAM/battery is a mixed blessing: on one hand I can more easily desolder and replace just the 4 pin battery a 28 pin NVSRAM. On the other hand, I have no way to read out and save (or restore) the calibration data itself. After browsing the service manual, I got the idea to put the processor into the diagnostic NOP loop. It will cycle through all addresses on the address bus, with the intention of allowing the testing of address bus and decoding (chip selects). I thought that the data could be captured by using either a logic analyzer or by piggy-backing an NVRAM and supplying write pulses for each address so that it captures the data that the SRAM presents to the bus when it is addressed. One issue is that I don't have a logic analyzer. Does anyone have an opinion about either of these methods? Should I just replace the battery and cross my fingers that I'll never need to restore the data?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on January 08, 2016, 07:32:16 pm
You can replace the battery without losing calibration data. Essentially what you do is to solder in a temporary battery replacement, change the battery and then remove the replacement.

I don't remember where it is at, but there are a series of photos that show one fairly easy way to do that. If I remember correctly, the steps are

   1. Remove the capacitor just above the battery. That is C2470 on the 2465B.

   2. Take a AAA battery holder that holds three batteries and solder the wires in place of the C2470. Make sure to get the polarity right. This will keep your data alive. C2470 is not polarized, but you really don't want +3.75v going to ground!

   3. Remove and replace the battery.

   4. Unsolder the wires to the AAA batteries and solder C2470 back in.

There is another option, which I have not done yet, but am planning on with timb's assistance. That is to make some minor circuit modifications, replace the RAM with an FRAM and completely remove the battery.  Basically, you replace CR2770 with a 4.3k resistor, replace the battery with a link and replace the RAM with an FRAM. However, you need to copy the calibration data or do a full calibration (or, possibly both) so if you can't do that you are better off with the battery replacement.



I have a 2465A, which has the digital board similar to the earlier 2465B serials, that is, with through hole components, and with the separate SRAM and battery, rather than a DS1225 module. My calibration data is intact but the battery is original, so I can assume that it will not be intact for too much longer.

The separate SRAM/battery is a mixed blessing: on one hand I can more easily desolder and replace just the 4 pin battery a 28 pin NVSRAM. On the other hand, I have no way to read out and save (or restore) the calibration data itself. After browsing the service manual, I got the idea to put the processor into the diagnostic NOP loop. It will cycle through all addresses on the address bus, with the intention of allowing the testing of address bus and decoding (chip selects). I thought that the data could be captured by using either a logic analyzer or by piggy-backing an NVRAM and supplying write pulses for each address so that it captures the data that the SRAM presents to the bus when it is addressed. One issue is that I don't have a logic analyzer. Does anyone have an opinion about either of these methods? Should I just replace the battery and cross my fingers that I'll never need to restore the data?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MarkL on January 08, 2016, 09:08:41 pm
There is a diagnostic routine "Exerciser 02" which allows you to read out the 256 locations in the SRAM that contain the cal constants (service manual pg. 6-17).  You can take a video while you step through the locations so you have a record of them.

However, I'm not aware that anyone has ever gone from this display to re-creating the entries in the SRAM on an A or B series.  There was some discussion about it on the yahoo tekscopes list a month or two ago.

Your idea to let the processor loop through the locations sounds like it would work.  Instead of making your own capture memory, it might be easier to buy a cheap logic analyzer from ebay.  The memory cycle time of the processor is quite slow on the order of 800ns, so you wouldn't need anything extravagant.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on January 11, 2016, 06:13:20 am
I am nearing the end of recapping my 2465B CT. However, that still leaves modifications. One modification which many people have recommended is to put a heat sink on U800 because (at least on some machines) it gets pretty hot. That probably isn't necessary, but reducing heat can extend the lifespan of components. However, in looking at my U800, it appears as if it may already have a built-in heat sink. If that is the case then there probably isn't any need to add a second one. Some people have said that it gets so hot that it nearly burns them. Others have said that it only gets warm. Is it possible that there are two different versions, one with built-in heat sink and one without? Here are two pictures of my U800. The first is on the entire IC. The second is just of the bolt closest to the center of the A1 board. Notice that it has a thick slab of metal on the bottom that appears to be integrated with the IC. That sure looks like a heat sink to me.

Let me know what you think!

Entire U800 (http://imgur.com/VEpYWut.jpg)
U800 bolt only (http://imgur.com/qTzL41R.jpg)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Orange on January 11, 2016, 10:45:52 am
Tektronix had a change in their manufacturing process. At one point they closed their hybrid production plant, or it was sold to a subsidiary of Maxim.

When Maxim started to produce the U800 for Tek, the troubles were introduced. The bad chips are having the maxtek marking, and not the Tek marking on them.
There is a reliability report floating around on the internet with statistics on this chip, made by Maxim.

Basically what happens is the the die comes loose from the heat sink. if this happens, you will notice a gradual shift of the characters on the screen to the left on power on.
If this situation continues, eventually, the chip burns out....

In my scopes all U800 got an heat sink, despite the fact that they all were Tek branded. Be aware that the IC heat sink is a -5.2 volts

Added link to Maxim report https://www.maximintegrated.com/en/qa/reliability/general/RR-B2A.pdf (https://www.maximintegrated.com/en/qa/reliability/general/RR-B2A.pdf)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on January 11, 2016, 10:04:03 pm
Thanks.

Mine is a Tek part. My scope appears to have been manufactured in '88.


Tektronix had a change in their manufacturing process. At one point they closed their hybrid production plant, or it was sold to a subsidiary of Maxim.

When Maxim started to produce the U800 for Tek, the troubles were introduced. The bad chips are having the maxtek marking, and not the Tek marking on them.
There is a reliability report floating around on the internet with statistics on this chip, made by Maxim.

Basically what happens is the the die comes loose from the heat sink. if this happens, you will notice a gradual shift of the characters on the screen to the left on power on.
If this situation continues, eventually, the chip burns out....

In my scopes all U800 got an heat sink, despite the fact that they all were Tek branded. Be aware that the IC heat sink is a -5.2 volts

Added link to Maxim report https://www.maximintegrated.com/en/qa/reliability/general/RR-B2A.pdf (https://www.maximintegrated.com/en/qa/reliability/general/RR-B2A.pdf)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on January 14, 2016, 01:10:04 am
I thought I would share a quick bit of part supply information.

While I am waiting to order the rest of my parts for my 2465BCT, I was looking at other parts I may need to replace. In particular, I am could not tell by looking at them whether or not I need to replace the graticule illumination lamps. These are Tektronix part number 150-0057-01. I did not find an obvious source for these. I found a reference to Anchor Electronics, but they do not appear to have the part. After some research, I found that these are 5.0V 0.115A T-3/4 miniature lamps with wire leads with a very long life (40,000 hrs). They are type 7153AS15 and NSN 6240-00-183-0669.

Given all of that, I was able to find them at Mouser for just over $1 each. They are a 7153 lamp and Mouser has them, in stock, from two vendors (JKL and VCC). The Mouser part numbers are:  606-CM7153 and 560-7153. DigiKey also lists these same two vendors, but does not have them in stock. Newark lists another vendor (CML), but has a minimum order of 10 at $11.94 each. I have since found a few other locations, where sometimes they are in stock (usually not), but their pricing is always similar to Newark's. It looks like Mouser is the best source for these lamps.

EDIT: The Tektronix part has "AS15" added to it to indicate a closer tolerance on the brightness (+/-15% vs 25%). Mouser also has the 606-CM1753AS15 for about 50% more in cost. Mouser appears to have some typos in their listings. The CM7153AS15 listing erroneously says it is a T1-3/4 and the 560-7153 either has the listing wrong or the link to the datasheet wrong (I think it is the datasheet). My best guess is that any of them will do. If I order any, I will order the CM7153AS15 to stay closest to the original specification.

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on January 23, 2016, 11:17:26 pm
FireDragon:
Typically the recommendation is to avoid recapping the mainboard. Can't recall the specific reasons why, think it had to do with issues of the multilayer PCB. in any event good job, did you notice any improvements in performance in recapping the main board.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on January 28, 2016, 01:16:38 am
FireDragon:
Typically the recommendation is to avoid recapping the mainboard. Can't recall the specific reasons why, think it had to do with issues of the multilayer PCB. in any event good job, did you notice any improvements in performance in recapping the main board.

I have just received the last set of parts (mostly) and hope to finish this next week. After that, I will make sure it is working (if not, then who knows?) and I need to get it calibrated. Timb has graciously offered to help with that, and with the final battery modification (he can read the data, replace the chip and program the old data). I also still have a couple of modifications that are waiting on parts, but those can be done later. I will update when I have something new.

Right now, even though I have the parts, I can't do anything until I finish repairing my daughter's laptop that failed. Just the hard disk, but it has been a nightmare getting the OS reinstalled. Windows 10 doesn't like it even though it satisfies all of the published requirements and passed the compatibility test.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MSO on January 31, 2016, 07:14:35 pm
Here is the damage, apparent bad components and recapping of the A3 Inverter board for my 2465B CT scope.

Additionally, on the A3 Inverter board there are three more RIFA capacitors and it can be seen that all three are cracked. They may still be working, but probably not for long. The A3 Inverter recap does not include those because I need to order replacements. It can also be seen looking at the bottom on the replaced capacitors that one looks like it was starting to leak, a second appears to have damage to the bottom (pre-leak?) and I am not at all sure if some of the rest are slightly bulging or not. They certainly aren't completely flat, but that may be a construction difference.

A3 Recapped Inverter Board                     (http://imgur.com/pnUyrOJ.jpg)

I've been following this thread for days now, including all the links to other information.  This is a great thread full of good information and populated with great posts.  Thanks to all of you who have contributed here.

FireDragon, it appears as though you may have fallen prey to a documentation error. Specifically, on the A3 inverter board, the documentation has the info for C1132 & C1115 reversed.  It may just be the picture you've provided, but it's worth checking it out.

See this post from HowardLong https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/475/ (https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/475/) for complete information.

Again, I've been very impressed by the content and quality of this thread.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: tautech on January 31, 2016, 08:18:45 pm
Here is the damage, apparent bad components and recapping of the A3 Inverter board for my 2465B CT scope.

Additionally, on the A3 Inverter board there are three more RIFA capacitors and it can be seen that all three are cracked. They may still be working, but probably not for long. The A3 Inverter recap does not include those because I need to order replacements. It can also be seen looking at the bottom on the replaced capacitors that one looks like it was starting to leak, a second appears to have damage to the bottom (pre-leak?) and I am not at all sure if some of the rest are slightly bulging or not. They certainly aren't completely flat, but that may be a construction difference.

A3 Recapped Inverter Board                     (http://imgur.com/pnUyrOJ.jpg)

I've been following this thread for days now, including all the links to other information.  This is a great thread full of good information and populated with great posts.  Thanks to all of you who have contributed here.

FireDragon, it appears as though you may have fallen prey to a documentation error. Specifically, on the A3 inverter board, the documentation has the info for C1132 & C1115 reversed.  It may just be the picture you've provided, but it's worth checking it out.

See this post from HowardLong https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/475/ (https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/475/) for complete information.

Again, I've been very impressed by the content and quality of this thread.
Welcome to the forum.

Well said and a good reminder for the documentation error, it's been mentioned several times over the years.
We look forward to your further contributions.  ;)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on February 04, 2016, 05:03:02 am
FireDragon, it appears as though you may have fallen prey to a documentation error. Specifically, on the A3 inverter board, the documentation has the info for C1132 & C1115 reversed.  It may just be the picture you've provided, but it's worth checking it out.

Thank you. I am fully aware of the documentation error. I replaced the capacitors that were ACTUALLY on the board, in the same locations. I only used the parts list to create the initial order (which is why a follow-up order was needed). That list has been updated and when everything is complete, I will post the final version. Along the way, I verified that the documentation was in error. My process was NOT "remove 'em all and then replace using documentation" - instead it was "remove, verify and replace one-by-one". In some cases where there were multiple capacitors all of the same values, I removed all of them (as long as the correct orientation was obvious, marked or otherwise determinable) and then replaced them.

I have been delayed making the final fixes. My daughter's laptop repair / upgrade was only complete yesterday, and everyone here has had the flu. We did get Windows 10 installed and I stripped out most of the spying, but will still need to do some work / research there.

I have started just this evening on the final fixes. I have now completed A3 and will do A2A1 in a couple of hours. I will (as usual) post the final pictures when that is completed. Then, on to the magic smoke test!

I am waiting on two LEMO (knockoff) connectors from China to add two probe power sockets. The holes are already drilled (except for the plastic back panel), wire routing is determined, I have the plug connectors for the A2A1 probe power pins, so once I get the LEMO connectors I am all set there.

I also need 2-pin, shielded wire-to-wire plug & socket connectors (smallish, around 1/4" x 1/2") so that I can add Option 1E using a switch to select either the WR Output or 1E Input options as needed. I have the switch, the shielded cable and know what changes to make, but I have been totally unable to find an appropriate shielded wire-to-wire connector. I need the connector so that I can disconnect the wires for board removal.

Does anyone have a suggestion?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on February 04, 2016, 11:21:11 am
I have replaced the remaining parts on the A3 and A2A1 board.

A3 Board: (http://imgur.com/dnDgjtd.jpg)
A2A1 Board: (http://imgur.com/UO8L01g.jpg)
Replaced parts on A2A1: (http://imgur.com/ttKuheh.jpg)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on February 04, 2016, 11:38:11 am
Damn .. what happened to those toasted resistors ?  :o

Are their resistances still within the printed values especially for those are not toasted ?

Btw, thanks for the contribution to this thread.  :-+
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on February 04, 2016, 11:45:23 am
Well, my 2465BCT  failed the smoke test! It didn't actually smoke, but it remained dead as a doornail. When I checked, the fuse was blown. I replaced the fuse and found that if I plug it in, but don't turn it on the fuse doesn't blow. When it off, I read 468k between neutral and hot. Since there is a 470k resistor across, that appears to be reasonable. If I turn it on, but leave it unplugged, I cannot tell if the bridge is bad. I get around 20k-40k in either direction, but it jumps around.

Someone has suggested that one of the MOVs appear to be swollen and so may have failed. However, I am not sure that they are MOVs. These are RT1010 and RT1016 and are "thermal resistors". They do not have the same value and so may not look the same. I can't tell by looking if they are bad or not. If they are bad, I am not sure that the replacement part would be. If either RT1010 or Rt1016 failed open then the fuse wouldn't have blown. If they failed short that would not have directly caused the fuse to blow, so they may be a red herring. But, they may still need to be replaced.

Is my most likely culprit the bridge? Since it fails as soon as power is applied, the failure should be fairly early in the circuit.

Let me know what you think.

Area with Rt1010 / Rt1016: (http://imgur.com/YXG7gNr.jpg)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on February 04, 2016, 11:54:39 am
Damn .. what happened to those toasted resistors ?  :o

Are their resistances still within the printed values especially for those are not toasted ?

R1018 reads 30.2 and is specified at 30, 5%, 0.5W. R1016 reads 68.8 and is specified at 68, 5%, 0.5W. So they are within specification! These (and a few others) tend to fail over time because they apparently run too close to their rating. All of the resistors that I replaced were replaced with 1W versions. Actually the same size or smaller than the originals. Some people replace them with 3W or even 5W versions, but that is probably overkill. Only R1016 and R1018 were replaced because of damage, the others were replaced preemptively. Some of those had been chipped, but that shouldn't be a serious problem.


Btw, thanks for the contribution to this thread.  :-+

You're welcome.

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: electrongeek on February 04, 2016, 11:16:44 pm
RT1010 and RT1016 are negative temperature coefficient thermistors. They have a high resistance when cold to limit surge current when the unit is first turned on, then their resistance drops as they heat up to allow adequate current flow to the power supply. Perhaps one or both have failed shorted, or drop resistance too fast etc. If they allow too high an initial surge current, you certainly could blow the fuse.

Do they meet their cold specification?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on February 05, 2016, 05:48:40 am
RT1010 and RT1016 are negative temperature coefficient thermistors. They have a high resistance when cold to limit surge current when the unit is first turned on, then their resistance drops as they heat up to allow adequate current flow to the power supply. Perhaps one or both have failed shorted, or drop resistance too fast etc. If they allow too high an initial surge current, you certainly could blow the fuse.

Do they meet their cold specification?

Currently measuring things. One side of the bridge is shorted. I will replace that with a Visnay GBPC606-E4/51.  As far as RT1010 and RT1016, so far RT1016 appears to be around 7.8 at 20c - specification is 5 +/- 10%, so it may be a little high. RT1010 appears to be 10.5, specification is 7.5 +/- 10% so it may be a little high. However, without knowing the specification temperature, it is hard to judge. Being off by a single degree C would be enough to account for the differences. Even my estimate of 20C might be off a degree or two. Both respond to a can of (nearly empty) air with their resistance going up. Both surge suppressors E1001 / E1002 are good. I may replace those preemptively with Littlefuse's CG2230L.

I have not found a replacement for RT1010 / RT1016. Any suggestions?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on February 05, 2016, 08:58:12 am
I have discovered that both RT1010 and RT1016 were sourced from Ketema's Rodan division. That division was sold to Selas and renamed RTI Electronics. RT1016 has the manufacturer part number SG200-S. RTI still sells the SG200. The "S" was for "straight" leads. However, the current tolerance is 15% and not 10%. Otherwise, the part appears to be a dead match. That is Mouser part number 995-SG200 and is $1.33.

I have not found a direct match for RT1010. Its manufacturer part number is 75DJ7R5K-RO-220 which appears to be an older product. It is 7.5 ohm, 10% and 3.9%/C. The value of IMax is not given, but is 7A for RT1016 and so should be fairly close. These are used in opposite input legs of the power supply. However, the circuits are slightly different so the current flows will also be slightly different. The RT1016 has 3.3%/C and is curve "A". There is a curve "B" which is 3.9%, but it is only available for a 40 ohm part with much lower maximum current rating. The closest that I have found is SG64 (Mouser part 995-SG64, $3.62) which is 7 ohms, 15%, curve J (3.5%/C) and 10A for IMax. It may be acceptable. It may even be almost the same because RT1010 is larger than RT1016 which may be an indication of a higher IMax.

I have a query out to RTI to find the best modern match for RT1010 - they have several product lines and one of those may be better.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: electrongeek on February 05, 2016, 01:22:30 pm
I have no idea how NTC thermistors age or typically fail. Since at room temp they are close to their specified resistance, I'm kind of doubting that is your problem. I would keep looking for something else, but wouldn't hurt to replace them anyway I suppose.

I wonder if using a variac to bring voltage up more slowly while monitoring current with a clamp meter would be helpful? That might depend on how the switching power supply starts up, but might get you past the surge and you could at least tell if current draw was normal or not in the steady operating state.

Chip
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on February 05, 2016, 10:51:17 pm
I have no idea how NTC thermistors age or typically fail. Since at room temp they are close to their specified resistance, I'm kind of doubting that is your problem. I would keep looking for something else, but wouldn't hurt to replace them anyway I suppose.

I wonder if using a variac to bring voltage up more slowly while monitoring current with a clamp meter would be helpful? That might depend on how the switching power supply starts up, but might get you past the surge and you could at least tell if current draw was normal or not in the steady operating state.

Chip

The bridge has shorted and is almost certainly my problem. The NTC thermistors are used as surge limiters and do fail and do age. Mine are significantly out of specification. I am also preemptively replacing the surge suppressors.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on February 05, 2016, 10:53:04 pm
For those who might want (now or in the future) a replacement for the RT1010 thermal resistor, 75DJ7R5K-RO-220. This is 7.5 ohms, 10% 3.9%/Cpart. Contact

   Mehdi Samii
   mehdis@ametherm.com

at Ametherm. He is making a couple of free samples for me and stated that he is the contact for any future requests.

The RT1016 is SG200-S 5 ohm, 10% 7A and is still currently available. It is part SG200 (the -S means straight leads, kinked leads are now SG311). The Mouser part number is 995-SG200 for $1.33. It is also available at DigiKey.

These parts are used in many Tektronix products as surge limiters. They may not fail often, but do age. Mine haven't filed, but appear to be significantly out of specification.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MSO on February 06, 2016, 03:51:22 am
I've completed recapping the A3 and A2A1 boards on my 1995 era 2467B. I found only the C1101 on the A3 board actually leaking electrolytic and the RIFA capacitors (C1016 & C1018 on A2A1; C1020, C1052, C1051 on A3) with the gold tinged translucent cases showed mild crazing, but no actual breakage. All in all, everything was pretty clean.

Now I'm moving on to the A5 digital control board I intend to replace all the aluminum electrolytic capacitors (C2011, C2113, C2331, C2965) with new aluminum electrolytic caps.  Is it recommended to replace the tantalum caps as well?  I've ordered the replacements for the tantalums (C2010, C2350, C2420) as they were cheap enough, but I don't know if these are at all problematic.

The real challenge on the A5 board is replacing U2460, the DS1225Y-200 NVRAM with the built-in battery.  I've ordered a new chip and a socket and will perform a direct replacement.  My hope is that I'll be able to make a copy of the data in the old NVRAM and copy the data to the new NVRAM.  It seems that the chances of success doing this is pretty limited.

I've hand copied all of the calibration data (EXER 02) from the NVRAM so I have that information saved, but I don't know if it's necessary to save any/all other data from the NVRAM.  Perhaps the ROM information (EXER 04) should be saved as well?

If I'm unable to read the current NVRAM, I thought I'd read the new chip just to get a clean binary file that I would then edit to insert the calibration data or anything else I might need. The calibration data, as I read somewhere is this thread is located starting at address 1E00.  Now EXER 02 returns the calibration in the form of 16bit words instead of bytes. The 2467 uses the Motorola MC68B02P microprocessor so I assume it uses the Motorola convention for byte ordering.  The most significant byte is written at the lowest address followed by the least significant byte at the next address. Does anybody know if this is correct?

Any help here would certainly be appreciated.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on February 06, 2016, 06:18:57 am
The 2467 uses the Motorola MC68B02P microprocessor so I assume it uses the Motorola convention for byte ordering.  The most significant byte is written at the lowest address followed by the least significant byte at the next address. Does anybody know if this is correct?

The Motorola 68xx processors use the big endian byte ordering, so you are correct.

The tantalums are sealed, so they don't have the same failure modes as aluminum electrolytic capacitors. They do have their own failure modes, but generally they don't need to be replaced. Some people suggest measuring the ESR, but that is difficult to do without lifting one pin. Lifting a lot of pins unnecessarily just increases the risk of damage due to recapping. If you are going to lift one pin to measure, you might as well just replace it and be done with it. I would recommend leaving the tantalums alone unless you can trace a failure to one because the likelihood of failure is comparatively low.

The only things I have replaced (during a full recap) was all of the electrolytic capacitors, and some resistors on A1A2 which tend to fail due to overheating. I had two that were seriously burned (and two of my RIFA capacitors had exploded). I replaced the 0.5W resistors (and two 0.25) with 1W versions. Some people replace those with 3W or 5W versions, but 1W should be enough to prevent the problem and are the same size as the originals.

If your scope has failed, you might want to consider replacing more, but sometimes just the capacitors is enough. In my case, my scope had failed and the capacitors / resistors weren't enough. I found that the bridge was shorted, so I am replacing it, the surge suppressors and the two thermal resistors. Only the bridge is really necessary.

As far as the battery is concerned, I have a non-SMD version of the 2465BCT so I have an explicit battery. Even so, I plan on replacing the ROM with an FRAM. You can do something similar, but either way you need to save the calibration data. EXER 02 allows you to read the data, but doesn't do squat for putting it back. So you need to read out the data and then write the data to the replacement IC. That is a complicated process and I can't advise on that. There are people who have replaced their Dallas chips with an FRAM and a piggyback battery. You need to do some searching to make sure you fully understand what you are doing for that. If you can't read / write the data, then you need to do a full calibration. That takes specialty equipment.


Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on February 09, 2016, 05:38:34 am
My first posting!   Been following this thread for some months with interest, because it's one of the best.  I purchased a 2465B months ago with problems.   It worked great - except when it intermittently didn't.   Decided to keep and fix it because it was so clean inside and out with no physical damage.

Through this process I've learned that this scope is an electronic engineers dream.   That is; a manager puts together a team of engineers with free rein to design the best scope possible.   The result is; short of a signal trace memory, it includes just about every detail known to man at that time.   Consequently, it can be a dream for users - but a nightmare to fix when something goes wrong.   But at least it is designed to be repairable.

While searching for the cause of the signal trace going crazy, the first unrelated thing I replaced was the fan.   It was a bit noisy and I suspected it to be the original fan (Nidac, Mod. D08G-12th).   I replaced it with an NMB Technologies Corp. #3108NL-04W-B30-P00 which seemed to be a perfect match.

While confirming the fan polarities and air flow direction, I found the voltage at the fan feed through to be 6.7 volts.   This did not sound right as both the old and new fans were rated for 12 volts.   Further investigation revealed that they didn't simply just drive the fan with 12 volts when the scope was powered on - they put in a temperature sensing voltage controller, powered from the +15 volt power supply.   So when the shop and scope are cold, the fan will see a floor of 6.7 volts.   And as proven with hot air from a heat gun on the temperature sensor, the fan voltage increases - then decreases when blowing room temperature air.

Taking it a step further, with the scope back in its case on a clear bench with the front elevated a few inches by the carry handle, I turned it on.   Over time, I monitored the voltage through added leads extending out through the rear grille, and the exhaust temperature with a thermocouple in the exhaust port.   Over the course of an hour the exhaust T rose from 62 degrees F (shop T), to 83 deg. F where it stabilized.   That's a delta T of 21 deg. F.   The fan voltage increased from 6.7 to 9.7.   Therefore, I'm assuming that in a hotter environment the fan will see 12 or more volts.  A closer look at the new fan spec's found it's rated at 6-13.8 volts.   So from all this, I assumed the scopes cooling fan is working correctly.   Ok - - this is an elegant way to control the scopes temperature, but I question the value to cost trade off.

The other thing I found with the fan was that the sheet aluminum assembly that clamps the fan in place was a bit too tight.   It was deforming the fan spokes enough to cause a noise increase in the fan bearings.   looking at the original fan revealed that it's frame spokes were permanently deformed by the excess pressure on the center of the fan, rather than the outboard ears that were designed for mounting.   They were EE's not ME's :)   The old original fan now runs quieter on the bench with the mounting pressure removed.   To fix this, I tweaked one of the bends in the aluminum clamp, ever so slightly with long nose pliers, to remove most of the pressure on the fan.   it runs quieter now while still being firmly held in place.

More later
Old-E 
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MSO on February 09, 2016, 07:32:00 am
Thanks for the tantalum info FireFragon, I'm from the firmware side of things, so my EE skills cause me more problems then they solve.

My scope was working, so my goal was to replace all the electrolytic caps before they ruined the boards.  I did replace all the electrolytic caps with new electrolytic caps rather than attempting to spec tantalum replacements. From what I could gather, the tantalums require a bit more knowledge of their usage than I possess, so I stuck with the 'lytics.

I looked at replacing the DS1225Y-200 chip with the FM1608 family, but decided to just put in a new socketed DS1225Y-200 instead. The device currently in use is over 20 years old and I figured that I could easily program another one ten years from now and be on my merry way.

You did set a bit of a high standard when you replaced all the 'lytics on the main board, though, and it seems foolish of me not to do the same thing.  Did you replace the main board caps with tantalums or did you use new electrolytics?

OLD-E, thanks for the fan info.  Mine fan is a bit noisy too and I was going to order  a new one as well.  With only size, voltage and current specs to draw upon, I didn't feel comfortable specifying a replacement. I'll follow your lead and then blame you if it doesn't work out. (I'm kidding!).

I did order a new MiniPro TL866A programmer from amazon, but I didn't pay enough attention; seems mine is coming via slow boat from China and I won't see it until the end of March. So I've put the scope back together and it's still running fine.  I'll look into the replacement of the capacitors on the main board and double check all the info I can find about loading new data into the DS1225Y while waiting for my programmer to arrive. I have my fingers crossed and am hoping I'll be able to read an image from the old chip.  I expect that I'll have to parallel the battery in the old chip, but that doesn't appear to be as difficult as removing the chip from the board.

Thanks for all the contributions on this thread.



Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on February 09, 2016, 08:08:49 am
For those replacing the Dallas you may find some good information here.

http://worldphaco.com/uploads/TEKTRONIX_2465b_OSCILLOSCOPE_CALIBRATION___REPOWERING_THE_DS1225.pdf (http://worldphaco.com/uploads/TEKTRONIX_2465b_OSCILLOSCOPE_CALIBRATION___REPOWERING_THE_DS1225.pdf)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on February 10, 2016, 05:22:36 am
Thanks Bryan for the article.   I had found that one before starting on the scope and it has a lot of good info.

Back to cooling - Actually MSO, if that fan does turn out to be a problem, you would do me a favor by letting me know.   I bought it 3 months ago from Digi-Key (their #P15646-nd) for $13.61.   I think it has 15-20 hours on it so far and running good.

Another parallel effort was cooling U800, the IC that has been reported by others as running too hot.   As I recall from reading further back in this thread, Tektronix turned their production of this chip over to Maxim to produce.   As it turns out, my chip is an original Tektronix one which is said to run cooler.   Running uncovered on the bench, it runs fairly warm to touch, but not hot.   Looking closer, my finger indicated that the heat sink end of the chip was hotter than the opposite end.   So it would appear that their was a reason for putting the heat sink on that end.   Conclusion was that this Tek chip probably did not need additional cooling.   But, since it's all apart, a little more frosting on the cake can only help.   So the decision was to add a heat sink to the existing heat sink on the hot end of the chip.   Laying a heat sink across the top of the chip will certainly help, but the concern was the questionable thermal resistance through the plastic case.

This heat sink was aluminum machined to 5/8 " OD x 3/8" high with 8 radial fins on sides and top.   It screws onto the existing stud on the hot end of the chip.   I drilled the tap hole a few thousands smaller than normal to get slightly more thread contact for better thermal conduction.   Then I lubed the threads and the seating surface on top of the existing nut with a thermal conducting paste to further aid in conducting the heat out.   The heat sink bottoms out on the existing nut which was just high enough so that the bottom of the heat sink cleared the top of the IC.   The top of the heat sink is < the height of the surrounding parts.   This way, none of the existing hardware had to be disturbed, but it does rely on the thermal energy conducting up through the face of the nut and the threaded stud.   Could have made the heat sink larger in diameter, but didn't want to shade to much of the IC from the cooling air coming in through the bottom of the case.   It was an intuitive tradeoff.   The new heat sink feels to be the same elevated temp as the chip, so apparently it is conducting as planned.   But, the heat sink fins need air moving past them to do any good, as through the vent holes in the bottom of the case. 

I have pictures to insert, but can not figure out how to add them.   Tried Copy & Paste, and I found the Insert Image button, but nothing works.   "Help" only says that it can be done.   Can someone please advise?

More later with photos.
Old-E
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: tautech on February 10, 2016, 06:10:19 am
@Old-E
Using Atttachments and other options, select a forum compatible file and upload with your post. Pics do not have to be large to show good detail and normally ~100Kb is plenty.
When your post is made you'll have a thumbnail at the foot of the post and if you copy that URL you can edit your post with the URL inserted between the IMG quotes.

Use Quote on somebody's post with imagery to see the syntax used.  ;)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on February 10, 2016, 06:59:04 am
Thanks for the tantalum info FireFragon, I'm from the firmware side of things, so my EE skills cause me more problems then they solve.

. . .

You did set a bit of a high standard when you replaced all the 'lytics on the main board, though, and it seems foolish of me not to do the same thing.  Did you replace the main board caps with tantalums or did you use new electrolytics?

I only replaced the aluminum electrolytics. I did buy many of the tantalums, but decided to leave them alone. There really aren't that many tantalums, the problem is that the parts list does not distinguish between aluminum and tantalum and bipolar. The only way to find out is to have someone tell you or to actually look at the original parts. The latter can be difficult before removing the boards.

Some tips on removing the main board. The removal instructions give a complex process to remove the power switch assembly. Completely unnecessary. Just unscrew the screw at the front that holds in it, then you can just twist it out of the piece of connecting plastic and (holding it carefully!) remove the entire assembly in one piece. Putting it back is just as easy. Just be really, really careful with the CRT leads. They are very delicate. If you don't have a steady hand, lots of patience and plenty of small tools then I wouldn't recommend removing the main board - you really don't want to fark up the CRT!

Make sure to get lots of pictures on how things go back together - especially for the CRT leads which are in a dark hole. Also be careful replacing the capacitors under the delay line. I propped up the delay line with something to give me just enough room to work. It was still tight. There is also a wire that is held down by a retainer in the board. Mine broke! Pretty trivial, I will use a piece of Kapton tape to hold the wire down because I don't have a replacement, but hopefully forewarned is forearmed!

Here is my parts list for the main board. My scope is pre-B050000, but the parts lists does not list any changes that affect the electrolytics so my replacement list should be adequate. I purchased everything at Mouser. For a small shipment Digi-Key has slightly less shipping, but includes tax. In this case, Digi-Key either doesn't have the parts that I used or are as much as 50% higher in cost. To be fair, there are a lot of parts that Digi-Key has and Mouser does not (but not for this project).

   C0102  290-0973-00  100uF    20%     25VDC                 UPW1V101MPD  100uF  35V 20% 105c 0.24
   C0107  290-0943-02   47uF    20%     25V                   UHV1V470MDD   47uF  35V 20% 105c 0.212
   C0114  290-0943-02   47uF    20%     25V                   UHV1V470MDD   47uF  35V 20% 105c 0.212
   C0121  290-0943-02   47uF    20%     25V                   UHV1V470MDD   47uF  35V 20% 105c 0.212
   C0130  290-0776-01   22uF    20%     10V                   UPW1E220MDD   22uF  25V 20% 105c 0.16
   C0152  290-0943-02   47uF    20%     25V                   UHV1V470MDD   47uF  35V 20% 105c 0.212
   C0185  290-0943-02   47uF    20%     25V                   UHV1V470MDD   47uF  35V 20% 105c 0.212
   C0218  290-0943-02   47uF    20%     25V                   UHV1V470MDD   47uF  35V 20% 105c 0.212
   C0221  290-0943-02   47uF    20%     25V                   UHV1V470MDD   47uF  35V 20% 105c 0.212
   C0307  290-0943-02   47uF    20%     25V                   UHV1V470MDD   47uF  35V 20% 105c 0.212
   C0325  290-0943-02   47uF    20%     25V                   UHV1V470MDD   47uF  35V 20% 105c 0.212
   C0335  290-0943-02   47uF    20%     25V                   UHV1V470MDD   47uF  35V 20% 105c 0.212
   C0512  290-0246-00    3.3uF  10%     15V  Axial Tantalum
   C0536  290-0246-00    3.3uF  10%     15V  Axial Tantalum
   C0723  290-0943-02   47uF    20%     25V                   UHV1V470MDD   47uF  35V 20% 105c 0.212
   C0731  290-0944-01  220uF    20%     10V                   UPW1C221MPD  220uF  16V 20% 105c 0.25
   C0732  290-0944-01  220uF    20%     10V                   UPW1C221MPD  220uF  16V 20% 105c 0.25
   C0733  290-0943-02   47uF    20%     25V                   UHV1V470MDD   47uF  35V 20% 105c 0.212
   C0738  290-0943-02   47uF    20%     25V                   UHV1V470MDD   47uF  35V 20% 105c 0.212
   C0740  290-0943-02   47uF    20%     25V                   UHV1V470MDD   47uF  35V 20% 105c 0.212
   C0957  290-0804-00   10uF   +50-20%  25V                   UPW1V100MDD   10uF  35V 20% 105c 0.16
   C0977  290-0246-00    3.3uF  10%     15V  Axial Tantalum

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on February 10, 2016, 07:29:03 am
Thanks for the tantalum info FireFragon, I'm from the firmware side of things, so my EE skills cause me more problems then they solve.

My scope was working, so my goal was to replace all the electrolytic caps before they ruined the boards.  I did replace all the electrolytic caps with new electrolytic caps rather than attempting to spec tantalum replacements. From what I could gather, the tantalums require a bit more knowledge of their usage than I possess, so I stuck with the 'lytics.

I am also from the software side - including firmware. My EE skills definitely need improvement, but I am getting there.

I have seen a lot of statements that replacing a tantalum with an electrolytic requires around 10 times the capacitance. I think that is a hang over from the state of affairs ages ago. The reasoning seems to be that tantalums have a low ESR compared to electrolytics.

Things have changed! Tantalums are more reliable, but also most tantalums appear to have an ESR of 1-3 ohms. There are lower ESRs, but they are hard to find and apparently not common. So presumably not the subject of the older advice. Most of the electrolytics that I used for replacement have ESRs which are well below 1 ohm. So I don't see any need to replace electrolytics with tantalums. And if you REALLY need low ESR use ceramics which can be 0.01 ohms or even lower.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on February 10, 2016, 05:21:53 pm
With this set of replacements, the scope passes the smoke test and all diagnostics.  :)

Replaced bridge, surge suppressors, one more resistor and one of the thermal resistors. Only the bridge was necessary.

A major milestone, but the saga isn't over yet. I am still waiting on the replacement for the other thermal resistor. That is a custom part. Also I am waiting for the LEMO style connectors (knock off, from China) so that I can add two probe power sockets. And calibration along with replacing the RAM with FRAM. At this point none are critical, so I will take those in the order they become possible. I still have to LEARN how to use the scope! But it looks like all of the features are present and working, but without more testing I could still find problems.

Replaced parts. (http://imgur.com/p2kamJD.jpg)

Diagnostic test result. (http://imgur.com/mCxElwz.jpg)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Muxr on February 10, 2016, 05:28:45 pm
Nice!
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on February 10, 2016, 06:43:45 pm
Thanks tautech for the instructions on posting photos.   But I need more information!   I have the forum compatible photos ready to go.   Then - if I understand correctly -

1.  Place the curser where the photo is to be located on the text page and left click.   This pegs the location for the photo.
2.  Click on the "Insert Image" icon (located above on the far left side).   This displays the "IMG's" where the photo is to be located.
3.  Click on "Attachments and other options" (below).   This displays the "Attach:" path.
4.  Click on "Browse."   This displays the "Choose file to up load" page.
5.  Locate intended photo on the up load page, then click on the "Open" button (lower right).   This displays the photo file info in the "Attach:" path.

If this is correct so far, I got that.   But now what?   Clicking on "Preview" displays the message text, but no indication of a photo.   It appears that something is missing.   And if I click on "(Clear Attachments)," nothing happens.   I would like to get it right before posting on the blog, but there does not seem to be a way to do that!

Frustrated. 

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on February 10, 2016, 06:53:11 pm
Well, some how one of the photos attached to the last message, but I don't know how.   I'll experiment more to see if I can make it happen again.

Frustrated.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on February 10, 2016, 07:13:29 pm
I have been playing with my 2465BCT. So far everything that I know to try has worked. My only signal source is the calibrator signal, but it works on all four channels. The scope can do at least some measurements - but I need to learn more to really test that. I recreated everything I was doing when the scope failed and it all worked as expected.

I do appear to be missing a bolt. One of the two on the middle back that is about 3/4" long. I think that I probably used it somewhere internally because I have an extra short one. I got a replacement (Philips head, though) from my junk screw bowl and used that. If the original doesn't turn up, I will probably buy a replacement so that they all match.

There is one possible glitch - I am not sure the fan is working. After I had the scope on for some time (not sure, perhaps an hour or so), I noticed that the top was mildly warm to the touch. However, I was unable to feel any fan exhaust. Perhaps it wasn't hot enough to kick on or it was running very slowly.

But - perhaps the fan isn't working. I need to investigate that. It could be the fan, the soldered connections, the pass through capacitor or the fan control circuit. I'll look at that tomorrow, its about my bedtime now. I don't like the pass through capacitor. I shouldn't need to solder / unsolder the fan every time I want to do some maintenance. Also, it is much too close to the chassis. Just for safety, I put some Kapton tape on the chassis wall to prevent accidental contact with the fan's positive supply.

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MSO on February 10, 2016, 09:22:38 pm
FireDragon:

Thanks for the part list; it'll make the ordering process a lot easier.  I'll order those caps for the main board and the two caps on the A9 board.  Once they're in hand, I'll be pushed into actually replacing them.

Congrats on bringing your scope back to life; it's nice to see it performing again. I've made note of the surge protectors for future reference.  I didn't test mine when I had the scope apart.  BTW, I also came up with one extra screw; it's a short one with no washer attached. I'll keep you posted if I ever find where it came from.

OLD-E, that looks like a nice heat sink. Mine has one of those grounding fingers mounted on the heat sink end, but it is formed such that it won't touch the bottom of the case.  I don't know who did it, but it's there.

Here's (I hope) a picture of my scope with a 500MHz signal @ 13dBm fed into channel 1 with the x10 mag enabled. The old scope is pretty quick for its age.

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MSO on February 10, 2016, 09:32:46 pm
FireDragon,

 When I put my scope back together, I had mounted it backward so the support bracket was pushing on the fan axel preventing it from moving.  My 'lab' is kept cool, 60f or so, but the fan turns on immediately; at least it does after mounting it correctly.

I was suckered by the indents on the back side of the fan housing that matched up perfectly with the two little pegs incorporated in the fan mounting plate.  They fit together perfectly, they aligned the fan perfectly and there were no such indents on the front side of the fan. Hey, that's the way its got to go right? 
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on February 11, 2016, 02:49:23 am
FireDragon,

 When I put my scope back together, I had mounted it backward so the support bracket was pushing on the fan axel preventing it from moving.  My 'lab' is kept cool, 60f or so, but the fan turns on immediately; at least it does after mounting it correctly.

I was suckered by the indents on the back side of the fan housing that matched up perfectly with the two little pegs incorporated in the fan mounting plate.  They fit together perfectly, they aligned the fan perfectly and there were no such indents on the front side of the fan. Hey, that's the way its got to go right?

I may have done that. I will have to check after breakfast and a grocery store trip.

Is the fan supposed to blow into the case or out of it? Normally, a fan will blow into the case.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on February 11, 2016, 04:48:05 am
   C0102  290-0973-00  100uF    20%     25VDC                 UPW1V101MPD  100uF  35V 20% 105c 0.24
   C0107  290-0943-02   47uF    20%     25V                   UHV1V470MDD   47uF  35V 20% 105c 0.212
   C0114  290-0943-02   47uF    20%     25V                   UHV1V470MDD   47uF  35V 20% 105c 0.212
   C0121  290-0943-02   47uF    20%     25V                   UHV1V470MDD   47uF  35V 20% 105c 0.212
   C0130  290-0776-01   22uF    20%     10V                   UPW1E220MDD   22uF  25V 20% 105c 0.16
   C0152  290-0943-02   47uF    20%     25V                   UHV1V470MDD   47uF  35V 20% 105c 0.212
   C0185  290-0943-02   47uF    20%     25V                   UHV1V470MDD   47uF  35V 20% 105c 0.212
   C0218  290-0943-02   47uF    20%     25V                   UHV1V470MDD   47uF  35V 20% 105c 0.212
   C0221  290-0943-02   47uF    20%     25V                   UHV1V470MDD   47uF  35V 20% 105c 0.212
   C0307  290-0943-02   47uF    20%     25V                   UHV1V470MDD   47uF  35V 20% 105c 0.212
   C0325  290-0943-02   47uF    20%     25V                   UHV1V470MDD   47uF  35V 20% 105c 0.212
   C0335  290-0943-02   47uF    20%     25V                   UHV1V470MDD   47uF  35V 20% 105c 0.212
   C0512  290-0246-00    3.3uF  10%     15V  Axial Tantalum
   C0536  290-0246-00    3.3uF  10%     15V  Axial Tantalum
   C0723  290-0943-02   47uF    20%     25V                   UHV1V470MDD   47uF  35V 20% 105c 0.212
   C0731  290-0944-01  220uF    20%     10V                   UPW1C221MPD  220uF  16V 20% 105c 0.25
   C0732  290-0944-01  220uF    20%     10V                   UPW1C221MPD  220uF  16V 20% 105c 0.25
   C0733  290-0943-02   47uF    20%     25V                   UHV1V470MDD   47uF  35V 20% 105c 0.212
   C0738  290-0943-02   47uF    20%     25V                   UHV1V470MDD   47uF  35V 20% 105c 0.212
   C0740  290-0943-02   47uF    20%     25V                   UHV1V470MDD   47uF  35V 20% 105c 0.212
   C0957  290-0804-00   10uF   +50-20%  25V                   UPW1V100MDD   10uF  35V 20% 105c 0.16
   C0977  290-0246-00    3.3uF  10%     15V  Axial Tantalum

FireDragon  :clap: , thanks a lot for listing down the caps for the A1 board.

To recap this big A1 board is already in my to do list, its just I'm too scared, really appreciate the tips on removing it, noted in my to do list for my 2465B.

Just curious if there is any bad effects if I replace them with quality polymer cap like Oscon caps ? Apart from the price of course.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on February 11, 2016, 04:54:35 am

....<snip>.... Hey, that's the way its got to go right?
Is the fan supposed to blow into the case or out of it? Normally, a fan will blow into the case.

The fan is blowing out of the case at the rear as I dissembled it for the 1st time.

I'm not the expert, but after looking at the vent holes like these, I believe their purpose are to have fresh cooler air get suck in and to blow straight at the hot parts, like the U800 and others.

Reposting my tear down photos to show what I mean.

Scope's bottom view, the U800 is located at the left top one.
(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=16761;image)

Close up view on the vent holes, you can see the U800 is located straight below.
(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=16763;image)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MSO on February 11, 2016, 05:25:46 am

Is the fan supposed to blow into the case or out of it? Normally, a fan will blow into the case.

Straight from page 2-1 of the service manual:

    "INSTRUMENT COOLING" 
To prevent instrument damage from internally generated
heat, adequate air flow must be maintained. Before
turning on the power, verify that the spaces around the
air-intake holes on the bottom of the cabinet and the fan exhaust
holes in the rear panel are free of any obstruction
to airflow."

So the fan sucks in from the bottom and blows out the rear.  I wanted to make a joke here, but decided not to.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on February 11, 2016, 07:27:39 am
Ok - - we'll see if I can make the picture attachment work in order to conclude the cooling issues from a few days ago.

This is a picture of the U800 IC that runs warm - hot.



This shows the new aluminum heat sink added.

(http://)

The heat sink is designed to shed heat best when cooling air is being pulled in through the vent holes in the bottom of the case.   It's not as efficient when operating in the open like this in still air.   But, while the case was off the temperature was measured with a digital thermocouple (TC) meter anyway.   This was done by holding the TC in-between the fins of the heat sink with a tooth pick and a dab of thermal conducting paste.   Then it was moved to the stud at the opposite end of the IC.   The stabilized temps were -
120 deg. F on the heat sink.
114.4 deg. F on the threaded stud at the opposite end of the IC.
60.6 deg. F shop air temp.

A 55.4 deg. rise in temp seems like a lot, but this is with the case off.

Then at a later date the temp was measured again, in still air and with the old removed fan blowing, with the scope laying on its side as in the picture below.   The temps were -
122 deg. F on the heat sink in still air.   This is probably better for convection cooling than with the scope upside down.
84 deg. F on the heat sink in moving air.
65.1 deg. F shop air temp as seen on the digital meter.   In this photo the thermocouple can be seen suspended in mid air.

This illustrates how moving air helps in cooling the heat sink.

(http://)

Unfortunately, I didn't measure the temp before installing the heat sink, or while in the case.   So all I can say is that the heat sink should help and I'm not too concerned with the temp of this Tek chip ether way.   But, if it was running inside a tent on the Sahara Desert in the summer, I might be concerned.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on February 11, 2016, 07:34:26 am
Guess I still don't have the picture part working yet.   This is frustrating!   There must be detailed instructions some place on how to add pictures to a message.

Frustrated
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: miguelvp on February 11, 2016, 07:46:42 am
Service manual:

http://bama.edebris.com/manuals/tek/2465service/ (http://bama.edebris.com/manuals/tek/2465service/)

Other manuals here:
http://bama.edebris.com/manuals/tek/ (http://bama.edebris.com/manuals/tek/)

Look for:
2465b
2465b-mil
2465bfull
2465dmm
2465service (linked above)

As for posting pictures, click on the choose file and make sure it's one of the allowed fie types and the image is less than 1000KB as this screenshot depicts:
(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=200673;image)

Once posted click on the picture to make it bigger, right click on the image and select "Copy Image Address" (at least that's what it is in Chrome)

Then edit your message and add

Code: [Select]
[img]https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=200673;image[/img]
where the link between the begin img and end img is the link you just copied.

The example above is my image that I attached to my post and added later to my post.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: tautech on February 11, 2016, 08:34:23 am
Thanks tautech for the instructions on posting photos.   But I need more information!   I have the forum compatible photos ready to go.   Then - if I understand correctly -

1.  Place the curser where the photo is to be located on the text page and left click.   This pegs the location for the photo.
2.  Click on the "Insert Image" icon (located above on the far left side).   This displays the "IMG's" where the photo is to be located.
3.  Click on "Attachments and other options" (below).   This displays the "Attach:" path.
4.  Click on "Browse."   This displays the "Choose file to up load" page.
5.  Locate intended photo on the up load page, then click on the "Open" button (lower right).   This displays the photo file info in the "Attach:" path.

If this is correct so far, I got that.   But now what?   Clicking on "Preview" displays the message text, but no indication of a photo.   It appears that something is missing.   And if I click on "(Clear Attachments)," nothing happens.   I would like to get it right before posting on the blog, but there does not seem to be a way to do that!

Frustrated.
You've nearly got it.....

You can upload numerous files/pics in posts up to the limit allowed per post.
They'll be either a thumbnail or a file available for download by members.
So use "Attachments" and (more attachments) for more than one upload.

If you want to attach a large image do it like this:
Copy the thumbnail URL.
Edit your post and Paste the image/s URL within in the IMG brackets.

(https://www.eevblog.com/forum/index.php?action=dlattach;topic=5397.0;attach=200457;image)

Note this is a much larger file than is needed and to be fair to Dave's server you should reduce the size of images to les than 100Kb whenever possible.
Quote this post to see the syntax used.  ;)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on February 11, 2016, 08:53:28 am
Thanks miguelvp - Yes, I have the photos in the acceptable jpg format and reduced to < the pixel count limit.

Do I understand correctly that none of the icon buttons at the top are used to post a picture as I have been trying to do?

After clicking on "Attachments and other options" the "attach:" path is displayed.   But it's blank.   There is no "Choose file" or "No file chosen" as shown in your example.   The only other option I have is to click on "Browse" (or any place on the "Attach: path)."   This brings up my pictures displayed on the "Choose File to Upload" page.   From there I can select a photo, click on the "Open" button which displays the photo address back in the Attach path.   But then how to I get that attached to the message?

Maybe another problem I'm having is trying to locate photos between text lines.   Maybe photos can only be added at the end of the message.   Is this true?   I hate to clutter up the blog with test entries.   I've looked everyplace on this site for instructions.   The process seems much more complicated than necessary.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: miguelvp on February 11, 2016, 09:51:11 am
Attach one picture then and look what that does on the post.

As for the buttons, if you look on the 2nd row, the first column that is the icon that will allow you to get the format for inserting a picture, but you can type it too.
Code: [Select]
[img]url link to picture on the web or attachement[/img]

For now just use the attachment to post the picture. At least that way, members can click on the thumbnail and it will expand to full size.
Even if it doesn't look like my screen capture, use the browse to select the image to attach and say ok and then post.

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on February 11, 2016, 10:02:59 am
After investigation - the fan on my 2465BCT was NOT running!

However, the fan is ok and the control voltage is ok. It turns out that the feed through capacitor 281-0697-00 is shorted. I bypassed the capacitor and the fan works normally. So, I need to replace that. I don't have a really good definition of the part, but I think that 2425-018-X7W0-502PLF at Mouser is possibly a fit. It appears to match all of the available specifications. It has 8-32 threads which are close to the measured threads on the removed part. I can take it to Lowes to see if the existing part has 8-32 threads.

I did put the fan in so that it fit into the detents on the case. However, there is only one way to do so, so that the wires reach and the fan cover does not rest directly on the fan hub, preventing it from turning. In particular the logo of the fan faces outwards. So I had that correct and the only problem is the capacitor.

The above part is $7.84. I may replace the fan as well to reduce noise and / or improve air flow.

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on February 13, 2016, 07:47:20 pm
Back to refurbishing my 2465B scope with the cooling issues/solutions previously reported and laid to rest.

When first receiving it, it had an intermittent problem with the signal trace lines jittery.   While looking for the problem they continued getting worse to almost full time jumping around vertically.   But it always passed the initial self test and never displayed an error message.   Photo of display below is using a short time exposure.

But before any work could be done on the scope, it needed a fixture to stand it in for removing the case.   I'm told that tech's usually use the plastic face cover to stand it up in, but that was missing from scope.   And I understand that front controls are sometimes broken from owners trying to remove the case without any protection.   So first step was to make a stand-up fixture.   Photo below shows the one I made out of wood which works very well.

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on February 13, 2016, 07:53:11 pm
Still having picture problems.   Whenever I load one, it erases the previous one.   I've posted countless pictures on various media and blogs and never had this much trouble.

Anyway this is a photo of the jittery trace that was supposed to be with the last entry.

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on February 13, 2016, 08:34:33 pm
Once the case was off, a neighbor friend and I started looking for the cause of the jittery trace.

Fist step was a visual of everything inside looking for anything that did not look right, but nothing caught our attention.

Power supply voltages at J119 were all perfect.

When starting to probe through the digital logic on the A5 board we found the 3 leaking caps, C2011, C2331, C2113, which we had not previously read about.   But since, have found numerous entries here and other places about this time bomb.

We also found the 2 reference voltages (~ .142 mv) on pin 14 & 15 of the DAC, U2101, were moving around a few millivolts as measured with a digital voltmeter.   The resistor divider network feeding pins 14 & 15 are near the 3 leaking caps.

The photo below shows the original 3 aluminum electrolytic caps and the corrosive damage to the adjacent components.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on February 13, 2016, 08:44:19 pm
Unfortunately pretty typical issue. Make sure to replace the caps and I believe there is a fourth on the far right side of the board. I would also replace the SMD components near the corrosion and absolutely make sure you clean the board thoroughly around the corrosion. Hopefully there has been no damage to the traces.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on February 13, 2016, 08:55:13 pm
Regarding the jittery trace; looking more closely we found the 4th cap, C2965 on the A5 board also leaking.   The adjacent screw was also corroded.   It appears like much of the leaking material might be in a gas form, because of the way it collects on anything metallic in the area.   Photo shows the 4th aluminum cap with the adjacent damage.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on February 13, 2016, 09:28:27 pm
After finding the leaky caps - and numerous other entries looking just like this, the old caps were removed, board was cleaned with alcohol and new caps installed.   The old caps were measured after removal and found to have <1% of the original capacity.   The caps were replaced with 10 uf, 35 v & 33 uf, 10 v tantalums from Digikey for a few dollars each.   The corrosion had not eaten through any of the traces, so the mess was cleaned up and all the other parts were left, even though the solder had been clearly attacked too.

The result was no more trace jitter!   And the wandering reference voltages on pin 14 & 15 of U 2101 are now rock solid.   At this point the scope was working perfectly, so we started stepping through the functional tests when the readout digits started going crazy.   The individual pixels, making up each digit, were modulating in the z axis/intensity.   With time they got so bad they would temporarily disappear and they began to affect the trace line.

Photo below shows 3 of the 4 new tantalum caps (yellow) in place.   
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on February 13, 2016, 09:50:35 pm
At this point the scope was working perfectly, so we started stepping through the functional tests when the readout digits started going crazy.   The individual pixels, making up each digit, were modulating in the z axis/intensity.   With time they got so bad they would temporarily disappear and they began to affect the trace line.

Photo below shows 3 of the 4 new tantalum caps (yellow) in place.   

That could be a adjustment may be needed on the Grid Bias. Have a look at 2465B CRT adjustments -Grid Bias in the service manual.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on February 14, 2016, 10:07:54 pm
Thanks Bryan for the much appreciated suggestions.   Are you saying the grid bias pot may have become intermittent/noisy?   This scope is all a learning experience in process.

Continuing on (several weeks ago) in search for the cause of the jittery readouts, we started looking at various digital signals and voltage levels on the A5 bd.   In the mean time the condition was getting worse to where the readout digits started displaying rows of 1's and dashes across the screen and diagonally.

On the board, the first problem encountered was that some voltages were not showing up where they should be.   This led to ohming out signal lines which led to the realization that there are numerous errors on the schematic.   This is a surface mount bd with s/n > 50000 in a 2465B scope.   And the documentation in the Service Manual correctly reflects those numbers.   It appears that somewhere in the design phase, the last design iteration did not get updated on the schematic.   The thought of reverse engineering the bd by buzzing out every connection, to every other connection, seem impractically daunting.   The changes/errors found so far are in the vicinity of the gates across the lower part of the schematic, and add up to 13!   Some changes were also confirmed visually by following the traces on the bd.   In some cases where they disappeared under an IC, they could be found in close up photos taken by others of the bd after certain IC's had been removed.   

The next issues were found around resistor R 2590, listed as 1k on the "Readout" schematic.   A closer look found that the 1k resistor was really stamped as 332 ohms!   And the parts list showed it as 332 ohms.   But there was also a voltage drop across that resistor that did not compute.   Tracing signals to find what else was connected to that line, we found it fed inputs to 3 other gates which should all be high impedance and should not pull that line down to ~ 2 volts.   The digital lines running off the +5v supply should always be very near 0 or 5v, except when transitioning.   Something was abnormally loading it.   As much as I hated too, started lifting the input pins from the gates on that line.   The line remained loaded until the last one was lifted, pin 2 of U2890 A.   Soldering the pin back down again did not recreate the load, so maybe some thermally sensitive part inside fixed itself.

So U 2890 (74HCT00) was replaced.   Finally - clean and stable readouts!   But - there was sometimes a hiccup on power up when going through its self test.   It would stop midway and show something like TEST 03 PASSED.   Never indicated anything failed.   Pressing A/B TRIG returned the scope to normal operation where it worked perfectly.   Following a couple of days of occasionally fiddling with it, that problem went away and now it can not be recreated.   The scope was even set to continually loop through all the self tests - and it did that for hours without a hiccup.   Checked all the PS voltages at J 119 and they are all golden, but I did not follow them through the turn on cycle.   So something is still amiss and is highly likely to eventually return.

The Service Manual I'm using is -
Tektronix
2465B & 2467B
070-6863-01
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on February 15, 2016, 04:45:02 am
Still having picture problems.   Whenever I load one, it erases the previous one.   I've posted countless pictures on various media and blogs and never had this much trouble.

Old-E, pay attention at the attachment dialog box, to have more than one attachment, you have to click the "(more attachments)" at below example provided by miguelvp.

Watch closely below picture as its easy to miss  :P (its hiding between the two red highlighted box) , once clicked, it will pop up another "Choose File" dialog box for you to select another attachment for uploading, just keep doing that if you have more, and up to ten attachments are allowed in single post.

(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=200673;image)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on February 15, 2016, 08:41:12 am
Thanks Bryan for the much appreciated suggestions.   Are you saying the grid bias pot may have become intermittent/noisy?   This scope is all a learning experience in process.

No, what I meant is you may need to perform the Grid bias adjustment procedure. This adjustment will help the flickering of traces and readouts, although from what you describe your issue may be something much more.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MSO on February 15, 2016, 04:15:10 pm
OLD-E,

Probably a typo, but maybe wrong schematic. I was unable to locate resistor R2590 anywhere in the service manual.  I did find R2830 (322ohms) on the 10MHz line feeding one of the clock inputs on U2830.  U2890 drives one of the master resets on U2830, so I though that might be the one you were looking at.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on February 17, 2016, 04:42:38 am
MSO

That would really be nice to find it was as simple as the wrong schematic!   But looking again (on my paper work) - it is R2890 and it is next to U2890 B which is located on the schematic at position 6L which is confirmed by the parts list on the same page, as 6L.   The schematic I'm looking at is listed as Figure 10-10 in the Manual under LIST OF ILLUSTRATIONS on page iii.   But this schematic page is actually located between Fig. 10-10 & 10-11 and has no figure number on it.

As you probably know, when the manual pages are displayed, one can press F4 on the key board to bring up a column of thumbnail pictures down the left side of the monitor screen.   You'll have to reduce the size of the schematic page some to acquire the blank space down the left side.   These thumbnail page numbers are much easier to navigate through the Manual.   In that straight sequential order, this is page 433.

This page is listed for S/N > 50000,   The schematic for S/N < 50000 does not have a resistor on the output of U2890.   Also, R2885, located on the far lower right corner of the schematic is shown as 1k, but the parts list says it is 332 ohms.   And, likewise, R2885 does not seem to exist in the earlier S/N model.

Brian -

Replacing U2890 appears to have fixed the jittery readouts.   I've heard of the Grid Bias adjustments, but am not familiar with it, but will keep that in mind if the readouts act up again.

Regarding pictures;   Oh - THAT "More Attachments!"   Who would have ever thunk it?   Hmmm - well that one passed right through me.   Next time I'll have something new to try.   thanks!   
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on February 17, 2016, 06:20:54 am
Quote
Brian -

Replacing U2890 appears to have fixed the jittery readouts.   I've heard of the Grid Bias adjustments, but am not familiar with it, but will keep that in mind if the readouts act up again.


The Grid Bias Adjustment is one of the procedures outlined in the calibration procedure that you will no doubt be following shortly once your scope is all fixed and operating properly.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: tautech on February 17, 2016, 07:04:13 am
Regarding pictures;   Oh - THAT "More Attachments!"   Who would have ever thunk it?   Hmmm - well that one passed right through me.   Next time I'll have something new to try.   thanks!
LOL
Now you're got it.  :clap:
 :phew:
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on February 17, 2016, 07:30:17 am
I'm turning the scope on every day and so far it refuses to hiccup on the initial self test and everything is working perfectly including the calibration.   You might say I should not brag about that or it will speed the arrival of a problem.   But finding that illusive bug from a couple of weeks ago is exactly what I want.   It has to appear first in order to fix it.

In the mean time, need to move on to other issues.   And the next issue on the priority list is the Dallas DS1225Y with the embedded battery.   First order of business is to determine the date of manufacture, which is printed on it as date code 9134d3.   If I read that right in the Dallas spec sheet, it was manufactured in the year 91 (1991) & in the 34th week.   If that is correct, this battery is still running after nearly 25 years!   It's guaranteed for 10 years!   So that needs to be replace ASAP.

Reading Dr. H. Holden's great report "Tektronix 2465B oscilloscope - - - ," dated June 2015, I decided to follow his lead and replace the DS1225Y with the ferroelectric FM16W08 which does not need a battery.   But there is one issue with the timing of the /CE enable line.   According to Holden, the scope is wired to assert the /CE enable at each address location, which is what the FM16W08 requires.   While the DS1225 does not need that asserted for each address location, it will obviously work when it is.   Therefore as luck would have it, the FM16W08 should be a drop in replacement, except that it's only available in surface mount.   The existing DS1225Y is a DIP version soldered through the board.

The physicals of the surface mount issue can be easily fixed by ordering -
Adapter board # 28-650000-10 from Digi-key for $18.54
28 pin socket, to plug the adapter board into, # 828-AG11D-ESL-LF from Digi-Key for $2.34
FM16W08 from Mouser, to solder to the adapter board, for $10.29

The next challenge is to find a programmer to read the DS1225Y and then write to the FM16W08.   Again, I followed Holden's lead and bought a GQ-4X Universal IC programmer along with the other items above.   But I wanted to make sure this all works before removing the DS1225Y from the scope.   The GQ-4X supports the DS1225Y, but does not support the FM16W08.   So we set the programmer up for the DS1225Y with an FM16W08 in the socket.   With the help of a neighbor friend who is more up on programmers, we were able to read & write to the FM16W08 using another set of cal data found on line that was copied out of a another 2465B.   But it will only read the first address location which means it apparently does not assert the /CE for the additional addresses which, of course, is not required for the DS1225Y.

So- don't know how Holden got it to work.   We went on line and found an older version of software for the GQ-4X thinking Holden might have used that one which may have toggled for each address, but that software would not run on my newer version of the Programmer.   I had previously stepped the scope through the Hex codes in the internal test routines out of EXER 02 and hand copied them thinking that in the worst case I could manually enter the data into the GQ-4x to program the FM16W08 (it's a long list of codes, but not impossible).   But that won't work if the programmer won't write to the IC.   We also tried some trickery to no avail.

Next step was to contact the manufacturer of the GQ-4X.   They confirmed all what we had surmised and said that if we had their latest hardware version (GQ-4X4), it has more flexibility and the FM16W08 can be easily added.   The indications are that I have the latest version, not to mention that I just bought it.   So, I'm going to contact them again tomorrow to confirm my version and see what's needed to get them to add the FM16W08 to their programmer.

In the interim, incase this will take too long, I may just replace the existing DS1225Y with another new one that I can program.   Then switch it out (I'll be adding a socket) for the FM16W08 later.

So this is where the scope is now.   It's certainly a much bigger project than I ever imagined when I bought it.   But, it is an education.   And reading all the entries on the internet about the pitfalls and should dos, has been a great help.     
 
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MSO on February 17, 2016, 07:42:16 am
That would really be nice to find it was as simple as the wrong schematic!   But looking again (on my paper work) - it is R2890 and it is next to U2890 B which is located on the schematic at position 6L which is confirmed by the parts list on the same page, as 6L.   The schematic I'm looking at is listed as Figure 10-10 in the Manual under LIST OF ILLUSTRATIONS on page iii.   But this schematic page is actually located between Fig. 10-10 & 10-11 and has no figure number on it.

As you probably know, when the manual pages are displayed, one can press F4 on the key board to bring up a column of thumbnail pictures down the left side of the monitor screen.   You'll have to reduce the size of the schematic page some to acquire the blank space down the left side.   These thumbnail page numbers are much easier to navigate through the Manual.   In that straight sequential order, this is page 433.
 

Got it OLD_E, on my schematic it's listed as <7> Readout (hi-serial) on page 10-31; sequential page 433. I usually have the schematics and part layouts magnified up around 200% so rather than scrolling up or down to find where I'm at, I'll just go up to the File->Print... menu and then select current page in the left-center of the dialog. That will show the chapter/page numbers and then in under the lower left of the preview box it lists the sequential page number.

Anyway, R2890 is marked as 1K on my schematic as well with the parts list showing it to be 332 ohms also.  I was looking to see if perhaps my schematics may have been corrected.  No luck there.

I got my TL866A programmer today so I pulled the DS1225Y off the A5 board, put a socket on the board, plugged the NVRAM into the TL866 and got a good copy of the data.  After programming a new DS1225Y, I installed it into the new socket, installed that new fan you found, buttoned up the 2467B and everything is good to go.  With the socket in place and the 21 years the original DS1225Y lasted, I decided to pass on the FM1608 family of replacements. 15 years from now, I'll just pop the NVRAM out and replace it again. Of course, I'll be over ninety by then and will probably have replaced the 2467B with the new AgilTronics 6667A 50 THz quad channel self-calibrating storage scope and spectrum analyzer.

I decided that if any of the electrolytics on the main board leak, the drippings will fall harmlessly on to the bottom of the cabinet instead of on to the PCB, so I'll wait until I have a failure before recapping the main board. Discretion is the better part of valor or some such came to mind.

Good luck with your 'scope and thanks for the info on the fan.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on February 18, 2016, 03:04:22 am
MSO -
Thanks for double checking the schematic.   Unfortunately, there are many errors on that schematic of the A5 bd.

Good work with the DS1225Y!   Were there any particular challenges in removing that IC?      I'm looking forward to replacing mine, hopefully soon.  Looks like the board should be an easy removal.

When you removed the Dallas IC, did you use a solder sucker, or - - ?   Also, is there a problem if the pins on the IC are momentarily shorted during removal?   If that maters, keeping the solder sucker or iron from getting between them could be challenging.

Given that I'm apparently about the same age as you, going the extra mile to get more than 15 years of future life out of the IC replacement probably makes little sense.   But it's hard to shake the habit of believing that me and the stuff I work on will last forever.   And I'm thinking that the special scope on your wish list (and now mine) may be waiting for me at my next destination.   So there's no point in spending your cash on it in 15 years, when you can't can't take it with you anyway.   At least that's what they say.

My next task after the Dallas IC is the PS Bd caps which are still working fine for now.   Then I'll take a good look at the main bd including reports from others.   leaving it may be a good choice.   Thanks.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MSO on February 18, 2016, 05:14:08 am
OLD_E,

I've had many runarounds with manuals from the web; pages missing, out of order, illegible and some, without taking the time to prove it, with pages mixed from different versions of the manual in question. Particularly with those oversized pages such as schematics and part locators.  So I generally double check my work.

The DS1225Y came out with no trouble; I did cheat though, I used my Hakko 808 desoldering gun.  About eight years ago, I built an Elecraft K2 with all available options, four Elecraft transceivers and just about every kit they offered. I was new to kit building then, so the Hakko 808 saved my bacon when I lost focus on the task at hand. It was a real life saver then and it handled that DS1255Y with aplomb.

I don't think you need to worry about shorting pins while removing the hybrid.  The positive terminal on the hybrid's battery is only connected to pin 7 of the embedded DS1218 and pin 7 is connected to nothing else. Short of slicing into the hybrid and shorting pin seven to ground, the power supply should remain intact.

I thought about the 'best' solution to the SRAM backup problem, but with more than 20 years of use already on the original DS1225Y (25 years on yours) I looked on the datasheet for the FM1608 and saw that it had a data retention life of 10 years at 85 C and just thought I'd have to replace it as well somewhere down the road, so better the horse I know than buying a pig in a poke.  Besides, while I doubt very much that Tektronix is going to offer an upgrade to the ROM chip that changes the behavior of the CE line, I can't know for sure that that the scope always drops the CE line for every write.  When the choice is between something I know will always work and something else that appears to work to most of time, my OCD kicks in to high gear.

As you delve into the power supply boards, beware that caps C1274, C1291 & C1292 on the A2A1 board are bipolar. I almost missed that, but when looking for the polarization orientation on the caps, I found that there weren't any.   I replaced those with the Nichicon 1uf 50V cap UVP1H010MDD1TD with good results.

Here is the list of caps I found and those that I replaced them with:

Board A2A1:
C1016   0.068uf 250v      -  0.1uf 630v 110c   KEMET F862BK104K310ALR0L
C1018   0.068uf 250v       -  0.1uf 630v 110c   KEMET F862BK104K310ALR0L
C1220   10uf   100V 105c         -  10uf  160V 105c      Nichicon UPW2C100MPD
C1240   10uf   100V 105c           -  10uf  160V 105c      Nichicon UPW2C100MPD
C1260   100uf   50V 105c   -  100uf 50V  105c      Panasonic EEU-EB1H101S
C1274   1uf   50V  85c           -  1uf   50V   85c      Nichicon  UVP1H010MDD1TD
C1280   100uf   50V 105c   -  100uf 50V  105c      Panasonic EEU-EB1H101S
C1291   1uf   50V  85c           -  1uf   50V   85c      Nichicon  UVP1H010MDD1TD
C1292   1uf   50V  85c           -  1uf   50V   85c      Nichicon  UVP1H010MDD1TD
C1300   100uf   50V 105c   -  100uf 50V  105c      Panasonic EEU-EB1H101S
C1330   100uf   50V 105c   -  100uf 50V  105c      Panasonic EEU-EB1H101S
C1350   100uf   50V 105c   -  100uf 50V  105c      Panasonic EEU-EB1H101S
C1400   47uf   25V  85c           -  47uf  35V  105c      Nichicon UPW1V470MED1TD
C1402   47uf   25V  85c           -  47uf  35V  105c      Nichicon UPW1V470MED1TD

A3:                        
C1020   2200pf  250V      - 2200pf 1.25KVDC   KEMET PHE850EA4220MA01R17
C1021   290uf  200V   85c   -
C1022   290uf  200V   85c   -
C1025   100uf  50V   105c   - 100uf 50V  105c      Panasonic EEU-EB1H101S
C1051   2200pf 250V      - 2200pf 1.25KVDC   KEMET PHE850EA4220MA01R17
C1052   10000pf 250V      - 10000pf 1.25KVDC   KEMET PHE850EB5100MB04R17
C1066   4.7uf   35V      - 4.7uf   50V           Nichicon UPS1H4R7MDD1TD
C1072   3.3uf   350V   85c          - 3.3uf   350V         Nichicon UVZ2V3R3MPD1TD
C1101   100uf  50V   105c   - 100uf 50V  105c      Panasonic EEU-EB1H101S
C1102   100uf 50V   105c   - 100uf 50V  105c      Panasonic EEU-EB1H101S
C1110   250uf 20V   105c   - 330uf 50v  105c      Panasonic EEU-EB1H331
C1111   250uf 20V   105c   - 330uf 50v  105c      Panasonic EEU-EB1H331
C1112   4.7f   35V    85c           - 4.7uf   50V           Nichicon UPS1H4R7MDD1TD
C1113   180uf   40V   105c   - 330uf  50V  Panasonic EEU-EB1H331
C1114   250uf   20V   105c   - 330uf 50v  105c      Panasonic EEU-EB1H331
C1115   10uf   160V   85c           - 10uf 16V  105c       Nichicon UPW2C100MPD
C1116   180uf   40V   105c   - 330uf  50V  Panasonic EEU-EB1H331
C1120   10uf   100V  105c   - 10uf  160V 105c      Nichicon UPW2C100MPD
C1130   10uf   100V  105c   - 10uf  160V 105c      Nichicon UPW2C100MPD
C1132   250uf   20V   105c   - 330uf 50v  105c      Panasonic EEU-EB1H331

Good luck with your adventures.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on February 19, 2016, 07:41:17 am
Good news DSO!   I'm apparently a day behind you and it all works!!!

As written before, I was wanting to replace the DS1225Y on the A5 bd before it's nearly 25 year old embedded battery expired, loosing the cal data.   To do that I had bought a GQ-4X4 programmer on line for $99 from MCUmall.   It's software included the DS1225Y, but not the FM16W08 that I wanted to replace the DS with.   Tried making it work by calling the FM a DS, but there was one difference in the way it enabled the address line and so it would not read data off the FM.

Two days ago , the 16th, I contacted support at the GQ manufacture and they modified their existing program to include the FM IC, and e-mailed it to me last night!!!   I was unable to get to it before noon today, but the deal was, I was supposed to do the testing since they didn't have that FM IC in hand.

With the help of a programmer, neighbor, friend, we tested as much as we could with cal data copied off the internet from someone else's scope - and it worked!!!   So we removed A5 bd, then desoldered the DS IC from the bd using a recently purchased Aoyue, INT 474++ desoldering system.   This was my first real use with a vacuum solder remover.   It worked great on all but about a half dozen of the 28 pins, which took more coxing with some solder wick.   But eventually the DS was free with no damage to anything.   In the GQ programmer, it was able to read the data on the DS IC, and successfully write it back into the FM IC.

Back at the scope, a 28 pin socket was soldered in place where the original DS IC had been.   Then the surface mount FM16W08, which was soldered to a 28 pin dip adapter board, was plugged into the socket.   Results were; today, the 18th, the scope turned on with its function and calibration as if nothing had been done to it - it all worked perfectly.   More later.
     
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on February 20, 2016, 04:53:04 am
More on the Dallas IC up-grade.
I powered up the 2465B again today and all appears well, so the FM16W08 appears to be holding its memory.   But, just in case, I ordered a spare DS1225AD today to copy the scopes cal data to and then put it in storage, just in case.   I have a spare FM16W08 and adapter board that I'll do the same with.   AT this point, it's cheap & easy backup.   Then if we get hit with an EMP or a super solar storm, maybe one will survive, assuming the rest of the scope makes it.

DSO - I think there may be some confusion about the data retention of the FM16W08.   See data below.   The 10 years at 85 Deg. C is hot.   At 65 Deg. C (that's 149 F) the data retention is 151 years - according to the Cypress data sheet.   So, if I keep it below 75 F, it might even out live us.

(http://)

There was a concern of shorting the pins on the Dallas DS1225Y when removing it.   But after looking at the expanded diagram of that IC posted by Holden, I concluded that if they were momentarily shorted, it would be through high impedance paths.   So the battery should survive that.   And I used the smallest tip on the vacuum desolder tool, so I don't think they ever shorted.

After removing the DS1225Y, I was about to plug it into a conductive piece of black foam, but then had second thoughts about it discharging the battery through possible high impedance paths via. the foam.   But, then while looking up DSO's concern about the IC's life, I found where the data sheet seems to think it's not a problem - if I understand it correctly.  So, you're probably right - not a problem.

Also, for the sake of science, I want to excavate through the top of the old IC to the battery, to measure the remaining voltage.   If done right, the IC will not be functionally harmed.

DSO - When using my vacuum desolder tool, most of the pins desoldered ok.   But half dozen or so pins were a challenge.   It just would not pull all the solder out.   Even turned the board upside down to get help from gravity.   Cleaned the tip orifice, but it was clear and the vacuum was working at the tip.   Since this is my first real application with it, I wanted to ask what temp you had yours set to?   This one was set to 300 C.   Another possibility was, the tip might be too small to transfer enough heat through the multi-layer board.

Below are photos of the board before and after replacing the Dallas memory IC.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on February 20, 2016, 05:01:46 am
Well, the pictures were lost again.   This is the most unfriendly picture loader.   No way to see in advance what is ready to be posted.   Will try to get 3 of them back here.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MSO on February 22, 2016, 07:18:24 am
OLD-E,

On the DS1225Y, the battery is located near the bottom of the chip, not the top (at least that's what I gleaned from Holden's write up).  Holden goes on to recommend evacuating pin 7 on the embedded DS1218 memory controller if you need direct access to the battery's positive node.

When sucking solder with a Hakko or any other desoldering gun, it's common to have some pin/hole combinations not fully evacuate. The normal course of action is to resolder those pins and then try again. The fresh solder aids the heat transfer from the gun through the pin/hole and usually results in complete evacuation of the solder.

It's recommended that when using a desoldering gun to get the pin into the orifice of the gun and apply side pressure on the pin to aid heat transfer. I also try to get the gun to the solder filet itself, but not far enough to actually touch the solder pad. When I see the solder melt, then I apply the vacuum and that usually clears the solder. Some of the pins have been bent over to hold the chip in place during the manufacturing process, so those pins require a two step process; just touch the solder filet with the gun and suck up as much solder as will easily come. Then straighten the pin, apply new solder if needed and then follow the normal sequence.

Finally, you will encounter situations where the soldered pad has little thermal relief; the pad is part of a large trace or ground plane that dissipates the heat from the desoldering gun, making it difficult to get an easy flow of solder.  In these situations, you may need to raise the temperature of your desoldering gun to get enough heat to get the solder to flow easily.

Having said all that, I set Hakko 808 to 350 C when desoldering. That high of a temperature requires a lot of care not to lift a pad.  While it's good to touch the pin and the top of the solder filet, you really don't want to touch the pad itself and you don't want to apply the heat for too long.  If the joint doesn't fully desolder, move on the next joint and come back to the failed one later.  Apply new solder to the failed joints and then try those again.

There may be a joint or two (I didn't encounter any when re-capping the 2467B) that simply won't submit to the desoldering gun. With those, you'll either have to heat with an iron while simultaneously lifting the component or, in the worst case, cut the pin off on the component side of the board and then use solder wick to clear the hole.

Almost forgot; I used a desoldering tip with a 1.0mm hole for all of the components on the 2467B.  The two large 290uf caps C1021 & C1022 on the A3 board had the largest diameter leads and pushed my 1.0 mm tip to its limits, but with a little solder wick to remove the excess solder on the top of board, I was able to use the gun to clear those whales properly.

As an aside, I checked all the caps that I pulled out of my 2467B and found only the RIFA caps (those rectangular caps with translucent plastic cases) were out of spec.  All the aluminum electrolytics, even those that had started leaking, were still measuring OK, so it looks as though I caught them all in time.

It's good to hear that you were able to save your calibration data; I know I sighed a huge sigh of relief when I was able to read mine with my programmer.  I was paranoid enough, though, to read the bin file and double check that all the calibrations I had recorded via EXER 02 before starting work on the scope matched those in the bin file. I now have backups of the DS1225Y on another DS1225Y, on my hard drive, on a backup hard drive, on a USB memory stick stored with my manual and on a CD rom.  How's that for OCD?

 
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on February 23, 2016, 03:44:08 am
I now have backups of the DS1225Y on another DS1225Y, on my hard drive, on a backup hard drive, on a USB memory stick stored with my manual and on a CD rom.  How's that for OCD?

Not bad for the OCD :-DD, but you forgot putting it into cloud storage, and another usb stick stuck with duct tape inside the scope.  >:D
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MSO on February 23, 2016, 04:18:44 am
I'll get there Bravo, I'm just getting warmed up.

BTW, thanks for all your contributions to this thread. I don't think I would have been successful without the myriad pictures, tips, observations and comments that you and many others have made here.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on February 23, 2016, 05:08:45 am
MSO, my pleasure and thanks to other contributors too that made up this thread.  :-+

PS : Actually I created this thread just to share this beast teardown photos at 1st, never thought it grows into this giant.  :o
Title: 2465BCT Repair and Modifications
Post by: FireDragon on February 23, 2016, 08:26:42 am
I got the latest set of parts in and made the latest round of repairs and modifications.

I replaced the feed through fan capacitor (which was shorted) and the fan with a higher capacity fan with about the same noise level. I also added an 0.1uF ceramic bypass capacitor to help suppress noise on the fan input voltage to prevent it from feeding back into the scope. That should reduce the overall temperature inside the scope because the default will be higher airflow.

Additionally, I was unhappy with the noise level on the various power supply voltages. All of them were well within specification, but the noise was still much higher than I liked. So, on board A2A1 I replaced the 100uF filtering capacitors - C1260, C1280, C1300, C1330, C1350 - with 150uF capacitors. Additionally, I added a 150uF capacitor across VR1293. The reason for this, is that all of the output voltages have some sort of filtering across them - except for the 10V reference voltage. Its noise specifications are very loose, and any noise on it will be copied by all of the other output voltages because they will attempt to match the reference voltage, noise and all.

I also added a 50 ohm resistor between ground and the Option 1E input signal to provide proper termination.

Finally, I replaced the 10.000Mhz crystal with a 10.0000Mhz crystal. To support that I changed C2550 and C2551, respectively to 33pF and 39pF (this was actually no change for C2550, but I replaced it anyway). This gives me 10.00014Mhz whereas before it had been somewhere around 9.99280Mhz. I am measuring the frequency with the scope itself and I have reason to believe that it is reading high - but by how much I don't know yet since the scope isn't calibrated yet and I don't have a calibrated frequency reference. Changing the crystal won't improve the scope's performance or accuracy, but it should bring the resulting calibration constants closer to "zero" and so less likely to hit an extreme point. I couldn't easily get the frequency close to 10Mhz. When I had C2551 at 33uF I had 10.00047Mhz, and 39uF gives me 10.00014. The next step up would be 43uF which would probably be too much - especially if the scope is reading the frequency high.

The result of the power supply changes is a drastic reduction in noise on the all of the output voltages.  I probably should have replaced C1220 and C1240 but I didn't have any higher voltage, high capacity capacitors on hand. Still, most of the output voltages now have total noise at around 1-2mv with no observable line noise. One of the  +5v supplies (J119-2) has about 20mv noise which may be line related, but up to 30mv line related noise is allowed and up to 150mv total noise. So, a definite win!

I'm getting pretty good at taking this scope apart and putting it back together with all of the practice I'm getting!

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on February 25, 2016, 06:21:23 am
LOL - - Following the stress, and then the joy, of getting the cal data out of the old DS1225Y, I understand the desire to have back up memories for the backups, etc.  So it might be said; the more intense the emotional experience, the more memory backups.

My new DS1225AD arrived today, so I can program it along with a spare FM16W08.   Then I'll have 3 back ups (counting the hard drive) in addition to the new FM IC installed in the scope.

In addition to all that, I still have the old DS1225Y removed from the scope.   I excavated through the epoxy of its underside this evening to get to pin 7 on the DS1218 as MSO suggested.   It probably was easier than going through the top to reach the top of the battery case.   The end result was that I reached the pin without damaging the function of the IC (I think).   I was surprised to measure the battery at 3.304 volts!   So it appears that it still has considerable life left.   Dr H. Holden claims in his article that it remains functional down to ~1.8 volts.

But in the process, I ran into an unexpected snag.   When I reached the first sign of metal, while following Holden's sketch on page 6 of his article, I tried to read the voltage, but kept getting zero.   So I kept excavating and testing with no progress.   Finally, returning to square 1 and working back through everything, I found that his illustration was wrong!   Important to know for anyone else trying the same.

His illustration shows a bottom view of the DS1225Y.   But the 2 rows of pins are transposed - move the upper row straight down and the lower row up and all is well.   Looking at the illustration, I had the meter lead clipped to the "Gnd" on the lower right pin, and it should have been on the upper right.   He has another illustration on page 21 which is a top view of the DS1225Y and those pins are not transposed.

Over the last many days, I've powered up the scope to confirm that all is well.   But recently the previously mentioned bug occasionally reappears.   It always happens on power on when it goes through its health check.   Some times it stops with all 1's and dashes where the readouts should be.   It has also read "TEST 03 PASSED."   One time it stopped reading "ALL 00   FAIL 03."   Another time it read "TEST 03   FAIL 02," which the lookup says is "Readout Ram failure."   It did this this before I replaced the DS1225Y.   But in all cases, pressing "A/B TRIG" returns the scope to normal operation where everything is perfect.   I even retuned to test mode and started it looping through all the startup tests and left it run for an hour with no hiccups.   I have some remote ideas to look at, and I want to recap the power supply.   Thanks to MSO I have his capacitor list for guidance.

FireDragon - Thanks for sharing.   A lot of good info on this site.   Starting at the beginning with BravoB's 1st entry it took a long time to read it all.   But like a best seller, it was hard to put down.

Thanks DSO for all the tricks in using a vacuum tool.   Yes, I was using the small, 1mm tip too.   I'll get more experience on the PS board. 

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on February 25, 2016, 06:58:22 am
I well up in tears when I read users who successfully replaced their DS12257. I tried replacing mine  a year or so ago, did everything right in prep, unsoldering properl. Went to read it on the programmer and all the data was 00 or FF, can't remember, something went wrong during the removal process and it erased the memory. Tried all the tricks I could dig up in trying to recover, but I guess the battery in mine was at the point that the removal or memory read brought the voltage down ever so slightly past the threshold and everything was lost. Didn't know at the time that the memory was available on screen, could have taken some pictures and added the data back manually to the new chip with the programmer. Oh well.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: casinada on February 25, 2016, 07:10:31 am
If you lost your data ( I did) you can use somebody else's backup as a starting point, that way your scope might be out of calibration but it will be easier than to start from scratch. In some cases it will come back without showing errors. Calibrating can be lots of fun. I had to do it with my 2465BDM  :)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on February 25, 2016, 07:11:54 am
Yes, that's what I did, had to try a number of backups that are available, I think I came close, but it still will need a full calibration.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on February 25, 2016, 04:04:30 pm
Bryan - Yes, I remember reading a ways back about losing your memory.   Bad news!   But maybe - I'm new to all this - but some thoughts are, you might try reinstalling it back into your scope to see if it may still work.   If you happen to have installed a socket, it would be an easier install.

Another (better) thought is; according to Holden, the battery could go below the threshold level of the embedded DS1218 battery controller.   But the memory is not actually gone.   In that case, an external battery could be piggy backed on to the DS1225Y to bring the voltage back up.   Then it could be read on the programmer.   As written below, I just excavated down to pin 7 of the battery controller for the positive battery connection.   Then the return line goes to pin 14 on the DS1225Y.   That can be done in a hour or so.

Another possibility could be that a lack of static control might have caused a non-fixable problem.   From what I could see, shorting the pins should not be a big deal.   Maybe if shorted for a long time (years) , it might speed up the discharge of the battery.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on February 25, 2016, 08:10:08 pm
More thoughts.   To avoid soldering to the the dead DS1225 before inserting it into the programmer, one could connect the external battery return wire to pin 14 by just looping it around the top of the pin, or inserting the return wire into the pin receptacle of the zero insertion force socket of the programmer.   Likewise, once pin 7 (+battery point) is exposed, one could just hold a sharp pointed probe on the pin during the programmer read time.   Again, no soldering to the DS2018 pin.   And it is my guess, that even if your battery connections are noisy, the existing battery will take on a certain amount of charge which will produce a constant voltage above the threshold to the DS1225Y during the read time.   This is all for a temporary read, so make shifting might be a safer and quicker way to go.

Picture below is of my DS1225 after excavation.   And I removed more potting than necessary for a temporary connection.   The exposed metal pin is visible next to the body of the DS2018.   Excavation was accomplished with a pointed X-acto Knife and a needle pointed probe tip.   The biggest challenge was in to minimize bending the DS1225Y pins during excavation.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on February 26, 2016, 04:44:51 am
Thanks, yes I had tried that when I originally attempted to replace the Dallas. No luck at the time, may try again, perhaps I may get lucky. But doubt it. The voltage of the battery was less than a volt.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on February 26, 2016, 04:00:11 pm
Oh - bad news!  My condolences.

A battery voltage down to 1 volt is probably not enough to keep it alive.   I'm curious (for the sake of science) did you happen to measure the battery voltage again after the external battery had been disconnected?   Based on my battery experience, I'm betting that the nearly expired battery will take on a charge that will last much longer than needed to read the memory, maybe even for days.   If that is true than one would not need a makeshift probe on the underside of the DS when reading.

Thanks for sharing.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on February 27, 2016, 09:39:31 am
Oh - bad news!  My condolences.

A battery voltage down to 1 volt is probably not enough to keep it alive.   I'm curious (for the sake of science) did you happen to measure the battery voltage again after the external battery had been disconnected?   Based on my battery experience, I'm betting that the nearly expired battery will take on a charge that will last much longer than needed to read the memory, maybe even for days.   If that is true than one would not need a makeshift probe on the underside of the DS when reading.

Thanks for sharing.

The voltage of the battery is after it had been in storage for over a year. Always thought there was a hope of recovery, but nope. Tried again on the programmer and all I get is 0x00 and 0xFf in what seems to be 3-4 banks of memory. I am not sure what went wrong, could have been anything. Still kicking myself for not taking pictures of the CRT that shows the memory allocations. Would have been a lot of work to rebuild, but at least I would have had something.

I have a TG501 and a SG503 so think I have the basics for a decent recalibration by myself. Just need to put together some accurate voltage references. Although going by memory the voltage levels have to be a square wave. Can probably use a function generator and calibrate the voltage level. Just needs to be within 3% anyways. I find I don't use the scope much, handy if I want to look at some higher frequencies than what my Rigol DS1052E can do. Afraid the days of the analog scope are becoming closer to a end, just so much more you can do with a digital scope. Although nothing sweeter than the glow of a CRT, one of the reasons I still keep it<g>
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on March 01, 2016, 06:33:28 am
Seems that everything has its share of kinks (trivia reporting).

Got together with my programmer friend yesterday to get the stored cal data transferred from my old XP computer, into the 2 spare IC's.   I had soldered the spare FM16W08 onto the adapter board and the spare DS1225AD had arrived, so repeating the data transfers should have been an easy task.   We started out by reading what was on the FM IC, and that appeared to work.   So we tried to perform some simple tests, like entering all ff's for example, and it would not complete the write,   Tried transferring real data into it with similar "failed" status.   So thinking that maybe the FM IC had a problem, we plugged in the new Dallas IC and had similar problems.   After spending a few frustrating hours on trying to get something to work, we decided to at least get a screen print of the data file from the programmer so that I could have a hard copy for my note book.   But then could not get the printer to work without freezing up.

Decision was finally made to quit for the evening with a plan to start at square one on Monday.   So, today I put in a call to my Computer Angel service, that I have available on call, to go through the older XP computer to get it cleaned up and debugged if needed.   Once I feel comfortable with that, then the plan is to reload software into the programmer, etc.   Eventually we'll get it - I hope.   But at least we have a new working FM IC in the scope - whew!

Today the computer allowed me to get a hard copy of the cal data printed out so something is strange there.   With cal data printed out, I was then able to easily compare that with the hand copied data from the scope CRT.   It takes awhile, but it can be done.   This turned up about a dozen errors.   From that, I compared the errors directly with the digits on the CRT.   Bottom line was, in all cases the printed out data from the programmer agreed with the data read off the scope CRT.   This is what should be, but just wanted to confirm that.   In most cases, the errors were where the spine of a B or the left edge of a 3 was perfectly centered under a vertical reticle line.   So using an eye loop and fuzzing out the focus a little, I was able to see the spine of the B showing on both sides of the reticle line.   So I think my hand copied data off the scope screen, and the printed data from the programmer is now all correct.   So while some things are coming together, it's not without its challenges and set backs.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MSO on March 03, 2016, 05:56:33 am
OLD-E,

I just spent the better part of hour writing a response to your last post and then a made a typo of some sort and lost the entire post. The replay window simply disappeared. That’s probably much better for you as I now, by rewriting the response, I can eliminate some of redundancies and extraneous comments.

I would expect some differences to exist between the NVRAM currently installed in the ‘scope and the DS1227 that you replaced.  Running time, the On/Off count and the set up in effect the last time you used the scope come to mind.  I’m not sure if there would be any changes made to the calibration area of the NVRAM; for instance balancing the channel 1/channel 2 inputs might end up there.

When you have doubt about your programmer reading the device properly, you’ll find a tool such as Beyond Compare to be invaluable.  Simply read the NVRAM device in the programmer, save it to a binary file then read it again and save to a second binary file. Using Beyond Compare, compare the two files just read. If there are differences, then you know the programmer isn’t reading properly.

Be aware though, that many programmers keep the data they last read in an internal buffer and won’t modify that saved data if they can’t read the device a second time. So it’s best to force the programmer to dump the data in its internal buffer before reading the device a second time. If the programmer’s software allows you to directly edit its buffer, insert a series of known values near the start of the buffer; I’ll usually use a few series of AA, 55, AA, 55 values to ensure that the programmer actually read the device a second time.  Depending upon your programmer/software, you may have to close the software and restart it again or try loading a different, unrelated binary file between first and second reads.

You can use this approach when comparing reads between two different NVRAM devices as well. If one of the devices has more memory than the other, then just ensure that the two devices match up to the size of the smallest device.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: ChunkyPastaSauce on March 03, 2016, 06:09:01 am
Question...

I bought one for basically nothing because from a university. Basically nothing because it doesn't work....other than that,very good condition  ::)

The calibration is probably still there as the date code isn't that far out.

It likely died due to a very failed fan. I measured the voltage rails..... they are all over the place. Some of them are low and if I remember correctly....some of them higher than they should be.

So my question...... is it worth trying to fix the PSU when some of the rails are higher by like 150%? Or is it likely the higher voltage damaged other parts of the scope and not worth the effort?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MSO on March 03, 2016, 07:36:16 am
ChunkyPastaSauce,

I'm not knowledgeable enough to answer your primary question (is it worth it), but having re-capped both power supply boards and the A5 control board for roughly $50, I'd say it's worth a shot. My suspicion is that the overheating may have damaged a couple of the main board chips, but for $50 and little time and effort (for me it's an enjoyable hobby) you can determine if its worth pursuing further.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on March 04, 2016, 02:01:46 am
The 2465B is pretty rugged and well designed, I would invest in the time and cost to get the power supply fixed and go from there. More than likely the caps are toast and there may be some other issues on the power supply board. If you scour the service manual you will see that much of the other circuitry on the power supply board and other boards have pretty good protection if something goes wrong on the power supply side of things.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: ChunkyPastaSauce on March 04, 2016, 03:10:55 am
Ok, thanks to both  :) It looks to be a nice scope, certainly better than the working one I have now (which isn't bad either tek2235).
Typically pass on doing anything on PSU high sides.... basically they frighten me. Also the fact there is a CRT. Right now, I'm nervous about getting the board out.....

Ive checked the main caps on the PSU for residual charge at the black plastic shield check points, they are empty. Anything else on the PSU board I should be aware of that may have the potential to make me have regrets messing with it? Or generally pretty safe if the charge check points, at the black plastic shield, are around 0V? 

I've check all the caps for obvious problems that can be checked, without having to pull the PSU boards out.

Thanks again.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on March 04, 2016, 03:31:56 am
Chunky,

I happen to love the fine qualities of my Tektronix 2465B scope (assuming that's what you have).   For me, it's worth the dollars & effort to have a reasonably great and high performance scope, not to mention the education and hobby element.   From what I've seen on E-bay, these scopes in good clean condition and working perfectly are going for $1,000 - $1,400.   I saw a copy of an old brochure (circa 1990) advertising a new scope like mine for $9,200.

But if your thoughts are to get it working in order to turn a quick profit, well, that might work if you value your time at 10 cents an hour (exaggerating, well maybe).   If your interests are profit (nothing wrong with that), then you might be better off parting it out on E-Bay or selling it as is.

My concern would be that the failed fan, followed by failed power supplies, leading to over voltage conditions, could have wiped out many IC's, etc.   This could be a costly / time consuming over hall relative to the numbers we're talking about.    You say the memory IC has a recent date stamp.   But if it's older than 10 years, which is the guaranteed life, then you should be looking at replacing it.   The cost of a replacement IC, or later version with no life limits, plus a programmer will total about $150.   The other parts, as MSO indicated, are fairly cheap, providing all the mechanical stuff is ok.   Then there is quite a bit of labor.

But, if you are interested in, and reasonably ok at working with electronics, and would find a project like this rewarding, then this could work well for you.   Forums, like this one, are a treasure trove of information and help.   Others here may have different thoughts. 
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: ChunkyPastaSauce on March 04, 2016, 06:06:00 am
Hi Old-E

Yep it's the 2465B 8) If I can get it working, not selling it, unless it's not for me for some reason. I bought it for fun at $35 knowing it would be some level of a project and knowing I might not be able to get it working at my skill level, somewhere beginner-intermediate hobby range (I'm a ME not EE). If I can, great, if I can't then no big deal and Ill probably put it up for anyone willing to pay shipping if they want to have ago at a fairly desirable analog scope or need parts.

I went ahead and pulled the inverter and regulator boards out.. Nothing too horrendous looking (the board is very clean by the way, no dust except a cm or 2 at the fan entrance). The rectangular cap packages, a number of those are somewhat bloated...almost all have hairline cracks. The other caps looked ok visually, except possibly some of the silver guys near to bottom but hard to tell (Edit - found some baddies after removing  :-+). I checked the diodes and all of them seem reasonable.. I thought I found some bad ones but after lifting they were fine... got excited for a few.

So Ill pull the caps; although I plan on replacing all anyway, ordering ESR meter for fun.


On the date code, I was reading about that. I thought it was 20 year life but now looking at the spec sheet..... uhoh lol. We will see...  Wouldn't the cal data be kinda useless after repairing the power supply board, it would need a recal anyway?

Thanks again
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: ChunkyPastaSauce on March 04, 2016, 09:51:35 pm
Baddies.

(http://i.imgur.com/gNu41uG.jpg?1)

All of these probably, hairline cracks on case likely ballooned caps
(http://i.imgur.com/TuZayZo.jpg?1)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on March 05, 2016, 02:36:54 am
Another tell tale sign is the caps will give off a horrible fishy smell once unsoldered.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on March 05, 2016, 05:01:42 am
Mr. Sauce,

You wrote:  "Wouldn't the cal data be kinda useless after repairing the power supply board, it would need a recal anyway?"
I don't know of any reason the calibration would change when rebuilding the power supplies.   I counted 9 regulated voltages not counting the CRT HV.   But all of those are supposed to be at specified DC levels.   These voltages and their tolerances, including allowable ripple, are noted on page 5-3 of the "Tektronix Service Manual" and are available for measurement at J119 on the main board (bottom of scope).  Service Manual is available on line.   You may already have all this info.

I have not started on my PS boards yet.   But beware - there is an error in Service Manual regarding value & location of a couple of the caps.   Replacing them with the same ratings as is there now works ok, but removing them all and then using the Service Manual as a guide to install the new ones will be a problem.   Previously, and on page 26 MSO explained in more detail, and made a number of entries on replacing these caps.   Also, I made a recent entry on replacing the fan including the part # that may be of use for you.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: tautech on March 05, 2016, 07:03:46 am
Baddies.
All of these probably, hairline cracks on case likely ballooned caps
(http://i.imgur.com/TuZayZo.jpg?1)
Quite common in X and Y rated caps, they can survive for years in this condition in a dry climate.
When they finally let go...poof, it's more of an inconvenience than anything else plus the mess they can make.  :palm:
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: ChunkyPastaSauce on March 05, 2016, 07:04:44 am
Mr. Sauce,

You wrote:  "Wouldn't the cal data be kinda useless after repairing the power supply board, it would need a recal anyway?"
I don't know of any reason the calibration would change when rebuilding the power supplies.   I counted 9 regulated voltages not counting the CRT HV.   But all of those are supposed to be at specified DC levels.   These voltages and their tolerances, including allowable ripple, are noted on page 5-3 of the "Tektronix Service Manual" and are available for measurement at J119 on the main board (bottom of scope).  Service Manual is available on line.   You may already have all this info.

I have not started on my PS boards yet.   But beware - there is an error in Service Manual regarding value & location of a couple of the caps.   Replacing them with the same ratings as is there now works ok, but removing them all and then using the Service Manual as a guide to install the new ones will be a problem.   Previously, and on page 26 MSO explained in more detail, and made a number of entries on replacing these caps.   Also, I made a recent entry on replacing the fan including the part # that may be of use for you.

Thanks!  :-+ I have the service manual, but miss understood the difference between a recalibration and performance check & adjustment. Manual saya to do a performance check /adj if any repairs are made to power supply, but doesn't mention the need for a autorecalibration. Autocalibration, has to have correct equipment, performance check & adjust is a lot more flexible.....So hopefully mine still holds the calibration constants...

Thanks for letting me know about the caps, Ill check the pages you mentioned. Ive only removed the 6 silver caps so far.... so hopefully I can sort those out. I didn't take pictures or log because i was going to go via the manual ::)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: ChunkyPastaSauce on March 05, 2016, 07:07:57 am
Another tell tale sign is the caps will give off a horrible fishy smell once unsoldered.

Didn't know that...looked it up...Dimethylamine
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: ChunkyPastaSauce on March 05, 2016, 07:19:12 am
Baddies.
All of these probably, hairline cracks on case likely ballooned caps
(http://i.imgur.com/TuZayZo.jpg?1)
Quite common in X and Y rated caps, they can survive for years in this condition in a dry climate.
When they finally let go...poof, it's more of an inconvenience than anything else plus the mess they can make.  :palm:

Hmmmm... I was feeling motivated but now a laziness opportunity...  replace now or be lazy....  :-//

Most of the others have cracking but are flat on the sides at closer look, this one has a bulge on the side (hard to see in pic), so I think this one maybe ready to go if it's not already gone.

I was wondering about the design of these, the casing is to keep humidity out?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: tautech on March 05, 2016, 08:38:26 am
Baddies.
All of these probably, hairline cracks on case likely ballooned caps
(http://i.imgur.com/TuZayZo.jpg?1)
Quite common in X and Y rated caps, they can survive for years in this condition in a dry climate.
When they finally let go...poof, it's more of an inconvenience than anything else plus the mess they can make.  :palm:

Hmmmm... I was feeling motivated but now a laziness opportunity...  replace now or be lazy....  :-//

Most of the others have cracking but are flat on the sides at closer look, this one has a bulge on the side (hard to see in pic), so I think this one maybe ready to go if it's not already gone.

I was wondering about the design of these, the casing is to keep humidity out?
Of course and humidity/and or time spent unplugged will allow ingress, then pop.
As these X and Y caps are across mains AND when they go pop, it's not just the mess but the physical damage the might do to the PCB not to mention the chance of carbonising the top layer and resultant chance of further flash overs in the future.
C'mon do the job properly or not at all, they're easy to get, cheap and peace of mind that they've been replaced will help you sleep well.  :)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on March 05, 2016, 09:37:00 am
There is a few spreadsheets floating around if you need the drop in replacements for the replacement caps. Here is one that I have and slightly modified to correct for some issues that I encountered with wrong pin spacing on some of the caps.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: ChunkyPastaSauce on March 05, 2016, 07:29:32 pm
C'mon do the job properly or not at all, they're easy to get, cheap and peace of mind that they've been replaced will help you sleep well.  :)


Thanks. Ill be doing it right. Laziness opportunity was more of a joke... as well as a small dream.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: ChunkyPastaSauce on March 05, 2016, 07:34:03 pm
There is a few spreadsheets floating around if you need the drop in replacements for the replacement caps. Here is one that I have and slightly modified to correct for some issues that I encountered with wrong pin spacing on some of the caps.

Thanks a ton for this! Takes a lot of the work out.

I noticed are replaced with different values, is this an availability/convenience thing or an 'upgrade' thing? [edit] Excel states upgrade
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on March 05, 2016, 08:49:42 pm
Thanks to all those who published their parts lists for cap replacements.   I made hard copies of them (data not lost to an EMP) for the upcoming replacement project.

Mr. Sauce -

If I understood your question correctly regarding capacitor replacements; They can be replaced with higher voltage ratings.   Actually higher is better for longer life.   As technology advances, sometimes the same size capacitor is available in a higher voltage rating.   Also, if the original voltage is not available, the next size up is better, providing it will physically fit the board.   Sometimes higher voltage means larger physical size.

Capacity values (uf) should be closer to the original size.   In the case of filter cap's which I think most on the PS boards are, their capacity values can be increased to the next available size.   The larger capacity values will filter the DC line they serve to a higher degree, which is good.   But increasing the capacity too much, or too many higher values on the same PS line, could have an additive effect that could be a problem.

A capacitor tends to look like a short circuit to ground for the first small fraction of a second after power is applied.   Depending on the circuit design, if the capacitor is too large, it can stress the components feeding it, or even blow a fuse in an extreme case.   Like many things, sometime more is better, but beyond a certain point becomes detrimental.

For example; (without looking at the circuit) the first capacitor listed is .068 uf.   Increasing it to .1 uf, as shown, should be ok.   Increasing the voltage from 250 to 630 is great, providing the physical size will fit.

There are other places where capacity values are critical, like in timing applications.   In those cases, the value (uf) should be the same, even if you have to combine cap's to obtain the same value.   In the case of critical values, it should be called out on the documentation, or maybe have a much tighter tolerance.

You may already know much of this.   If not, hope this helps.   
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: tautech on March 05, 2016, 09:01:33 pm
There are other places where capacity values are critical, like in timing applications.   In those cases, the value (uf) should be the same, even if you have to combine cap's to obtain the same value.
You may already know much of this.   If not, hope this helps.   
One could add that timing caps are not normally under the same stresses as PSU, local bulk capacitance or decoupling caps and therefore the need for replacement is uncommon.
Sure, when there's trouble obtaining the range of adjustment needed in timing circuits (that can be adjusted) the timing caps then should be suspect, but not always.

Widespread replacement of caps should be avoided IMHO, excluding PSU's and local bulk capacitance of course.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on March 05, 2016, 09:18:05 pm
Just a note, if you want to power the power supply boards outside the circuit. (recommended if you make a mistake) you HAVE to use the appropriate load resistors and they have to be rated correctly. Without the correct load resistors you will likely also notice Q1062 and R1071 getting hot. On mine R1071 actually burned up. This had me sidetracked thinking something was wrong in this area, but it wasn't and had me chasing ghosts. Probably just a bad design and the circuit started oscillating. Could also hear a faint whistling. Anyways point being is the service manual I believes states to start at the 87v and work downward (actually it's the 10v reference) so there is probably a short somewhere on one of the voltage lines and the current limiting is kicking in.

On the 87v I used a 2k resistor. In the theory of operation in the service manual. 87v rail should not exceed 100ma. -8v rail should not exceed 480ma.. +42v rail should not exceed 400ma, so I used a 150 ohm. Basically size your resistors accordingly so not to overload and have the current limiting kicking in, which will start part of the power supply to shut down making it difficult to diagnose.

I did not find it necessary to load the +10v reference.

As well as it has pointed out there is a error on the schematic for one of the capacitors and it's orientation so take a picture of your board caps before removing for references. On certain board revisions , and I am going by memory there is one more or one less bi-polar cap. I think it was one more.

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on March 05, 2016, 11:30:01 pm
It's all good advice for me too.

Tautech - I agree completely with your thoughts on caps.

MSO - Regarding the programmer, yes, most of those things are or have been done.   The two different IC's have the same memory capacity, pin outs and voltage ratings, etc.   One exception is the toggling of the address line, which is supposed to be compatible with the 2465B.   I had also read where that conversion had been done successfully, so proceeded ahead.   And we did successfully copy the data from the old DS1225Y and transfer it to the new FM16W08 without any snags.   And the scope does work as well as it did before changing IC's.   We also successfully compared Write & Read copies off the programmer as you suggested.   Problem I'm having now is getting the next (spare) FM16W08 to be programmed.   As a test, tried programming another DS1226AD (they are supposed to be the same as a Y version), and it was having problems too.   Have a message into the GQ Support office that I may get a response to on Monday.   Thanks for your thoughts that are always appreciated.

On a different issue - FYI
I'm set up with all the anti-static hardware for working on the scope.   The mat was in good condition, but used long ago.   So I cleaned it up and put it back in service.   But the question was - how can I test it?   Common ohm meters don't work, and I would hate to be adding ESD failures to the scope's existing issues.

Solution - I found a short thread on this Forum where others had the same concerns.   Then it occurred to me.   There's a really simple way to test it.   My write up is at the end of this thread.  https://www.eevblog.com/forum/beginners/measuring-surface-resistance-of-esd-mat/ (https://www.eevblog.com/forum/beginners/measuring-surface-resistance-of-esd-mat/)
 
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: med6753 on March 06, 2016, 04:28:29 pm
Mr. Sauce,

You wrote:  "Wouldn't the cal data be kinda useless after repairing the power supply board, it would need a recal anyway?"
I don't know of any reason the calibration would change when rebuilding the power supplies.   I counted 9 regulated voltages not counting the CRT HV.   But all of those are supposed to be at specified DC levels.   These voltages and their tolerances, including allowable ripple, are noted on page 5-3 of the "Tektronix Service Manual" and are available for measurement at J119 on the main board (bottom of scope).  Service Manual is available on line.   You may already have all this info.

I don't completely agree with this statement. Power supply issues can potentially affect calibration, especially if you have a 2465 series with options. When I acquired a 2465 DMS with the DMM and CTT (Counter, Trigger, Timer) options it had a power up fail stating that the Counter was out of calibration. I also discovered later on that the DMM was in need of calibration but the power up routines don't check that. (And that's as per the DMM options manual). If the cal data is stored in ROM how did these options get out of calibration? I can't say and I don't know the history of this 2465 DMS. I was able to get both options calibrated and operating properly but lately I noticed an issue that led me to believe that subtle power supply issues can possibly affect calibration and definitely will affect operation.

Lately I noticed that DMM and Counter were both drifting slightly. For example: against my 10.000 VDC standard the DMM would slowly drift to 9.997 VDC. Against the 1.000 VDC and 100.0 mv standard it was rock steady. The Counter over time against a 1.000 MHz signal would drift down about 50 Hz. Granted, that's not a lot but I still wondered why this was occurring. I suspected there was a power issue that I was missing and it turns out I was correct.

The DMM board takes a 5.5 VAC @ 25KHz from the Inverter board and steps it up to +/- 12VDC. Those voltages were in spec. But it also gets a +5.00 VDC digital voltage from the mainframe. That measured +4.78 VDC which is out of spec. But if I measure the +5.00 VDC at J119 on the main board it was exactly +5.00 VDC. Clearly something is not right and I found the cause. All the options (DMM, CTT, etc) get their +5.00 VDC directly from the Inverter board, not the Regulator board. So I guess it's time to pull the Inverter and Regulator board and at least re-cap them. I bought all the caps a few months ago for that day when I'd have to pull it apart so for the past 2 days I did it.

I don't care what anybody says. Pulling one of these puppies apart to get to the power supply boards, especially if you have full options, is a royal pain in the nutz.  :-- Not enjoyable to me at all. But I got it done. It appears that all the caps were original 1985 build vintage. But I didn't find any leaking or swelling. I didn't test them. I just did a mass replace. The result? That +5.00 VDC supply to the options boards now measures +4.90 VDC. Success!

I still have to go back and verify the calibration of the DMM and CTT but I'm pretty sure the drifting issue is fixed. Time will tell.

I have some pictures that I will share. I really wasn't concentrating on doing a “show and tell” teardown. I just wanted to get the damn thing done.   


Here is the section of the Inverter Board that supplies the +5.00 VDC to the Option boards at J303. From Section 9 of the 2465 Service Manual. I assume 2465A and 2465B are similar.


The DMM Board before removal


The top plate after removing the DMM Board. The CTT Board and Buffer Board are attached to the underside of the plate and pull up with it when removed.


The A5 Board on the older vintage 2465 (no suffix). No Dallas chip or battery to deal with. Uses EAROM for cal data.


The Regulator Board before re-cap. As near as I could tell all caps where original 1985 vintage.

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on March 08, 2016, 12:21:00 pm
I finally got all of the parts I needed to install the probe power connectors on my 2465BCT. This is Option 11, but is not available from the factory for a BCT because there aren't enough allocated connector locations. Previously, I installed Option 1E, but is just removing a resistor and adding a capacitor on the CTT board (I also added a 50 ohm resistor for proper termination which Tektronix (intentionally) omitted). I found two locations that would work, and drilled the holes for the connectors while I had the board out of the chassis. The cable routing for the top connector wasn't a problem. For the bottom connector, I slightly enlarged an existing hole in the chassis (the hole was due to how the metal was folded).

The bottom connector would have been too close to the main board. So, I took a 1/2 OD, 3/8 ID steel bushing, and cut off appropriate lengths from each end (so that one end of the resulting standoff washer was rounded and the other flat). That also moved the top of the connectors to near the surface of the plastic.

I also had to make two small nibbles on the edge of the plastic shield. One at the top for the edge of the washer & nut for the top connector and one at the bottom for routing the bottom cable. If I had placed the top hole just a fraction of an inch (0.05, perhaps) to the left I could have avoided the nibble at the top.

Unfortunately, I did not have my drill press and the need to measure the placement of the holes in the plastic extremely accurately resulted in some raggedness of the holes in the plastic - and one drill mishap that nicked the nearby plastic. Still, not too bad.

One parts gotcha is that the maximum wire size for the LEMO type connector (actually, I used a knock-off from China - a good bit cheaper) is 26 ga stranded  or 24 ga solid. The only two wire sizes for the header were 22 ga and 24 ga. That meant that I had to use 24 ga, solid. Of all the wire I have sitting around, that was not one of the sizes. I had to make an extra DigiKey order to get 2$ of wire.

Here are the pictures for the modification.

Probe Power Parts                      (http://imgur.com/jdqkpvC.jpg)
Top Probe Power Connector              (http://imgur.com/JEvVgbS.jpg)
Bottom Probe Power Connector           (http://imgur.com/VdaxT7K.jpg)
Top Probe Power Connector in Case      (http://imgur.com/WXaJqWY.jpg)
Bottom Probe Power Connector in Case   (http://imgur.com/e99mC5k.jpg)
Top Probe Power Shield Nibble          (http://imgur.com/tFrmYQI.jpg)
Bottom Probe Power Shield Nibble       (http://imgur.com/EbjJrfK.jpg)
Probe Power Headers 1                  (http://imgur.com/5q5dGux.jpg)
Probe Power Headers 2                  (http://imgur.com/iObL35d.jpg)
Probe Power Routing 1                  (http://imgur.com/8V88Yok.jpg)
Probe Power Routing 2                  (http://imgur.com/lvS5cS3.jpg)
Bottom Probe Power Routing 1           (http://imgur.com/8SEb8Rf.jpg)
Bottom Probe Power Routing 2           (http://imgur.com/EnTkSRu.jpg)


Title: Re: Tektronix 2465B oscilloscope teardown
Post by: z01z on March 13, 2016, 03:32:12 pm
I've a 2465A, on this all replaced caps were still in specs but all the 180uF/40V and 250uF/20V caps started bulging plus the Kemets developed some cracks.
The backup battery was also replaced, the original still had some juice in it after 29 years!  :-+

Just for the fun I've also made a few thermal images, enjoy!
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: FireDragon on March 14, 2016, 07:46:37 am
Just for the fun I've also made a few thermal images, enjoy!

The thermal images are nice!

Note that the temperatures are low enough that heat sinking the U800 isn't needed. They aren't any worse that a hot summer's day down south (in the US) and better than the desert areas.

Of course, when I'm down there, I need a heat sink!

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: z01z on March 14, 2016, 12:33:23 pm
About the heatsink on U800, it did have one, sorry.
So I took it off, took some pictures, put it back on and took some more.

Without the heatsink the U800 definitely runs warmer.
Now, it can be argued how good the heat transfer to the heatsink is. From the close-up image it appears that the body underneath has about the same temperature as the heatsink.
Another thing is that these images show a state when the board is in the open and a fan blowing on it. When the case is on, it will surely change the whole situation and not for the better I think.
 
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on March 14, 2016, 07:36:31 pm
Should be remembered that the thermal images are without the case.   As pointed out here many times, the holes in the bottom of the case directly under U800 force moving air past U800.   That should make a considerable reduction in temperature, especially with a finned heat sink installed.   A "case on" temperature measurement would be an interesting test.

Thanks for the images.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: z01z on March 15, 2016, 06:23:26 pm
OK, last test from me. The pictures were taken after the scope running ~30min both with and without heatsink on U800 with the case on. Then the scope was powered off, the case was quickly removed then the pictures taken.
The difference now is smaller than the scope was running open, U800 still appears to be the warmest spot.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on March 16, 2016, 04:35:56 am
Nice work z01z!   If I understand correctly, the temperature with the heat sink in place, and in the case, is about the same as when it is out of the case and an external fan blowing on it.   That seems to make logical sense.   And the heat sink appears to be doing some good too.

I previously missed the part about an external fan blowing on U800 with no case.

Thanks
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on March 16, 2016, 04:49:01 am
z01z, thanks for sharing those IR shots, really appreciate it.  :-+

Hope this will bring more awareness of blowing the whole big A1 with a big fan when working without the case.

If its not too troublesome, appreciate if you can post photos of your U800 mounted with heatsink, curious how does it look like.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: z01z on March 16, 2016, 08:14:54 am
If I understand correctly, the temperature with the heat sink in place, and in the case, is about the same as when it is out of the case and an external fan blowing on it.
Exactly. Except that it took some time until the case was removed and the picture taken, so it must have been a bit warmer inside the case than on the pictures.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: z01z on March 16, 2016, 08:27:23 am
If its not too troublesome, appreciate if you can post photos of your U800 mounted with heatsink, curious how does it look like.
Sure, no problem, I can take pictures when I get home.

I've used this heatsink (http://uk.farnell.com/fischer-elektronik/ick-pga-17-x-17-x-12/led-heatsink-with-pins-square/dp/1850035), cut it to match the width and filed away some of the fins so that the nut can be fit. I've also put a small insert between the metal tab and the heatsink.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on March 24, 2016, 04:08:36 am
Ok - As written above, was successful in removing the original DS1225Y from my 2465B scope and retrieving the cal data using a GQ-4X4 programmer.   Then the data was successfully written onto an FM16W08 which has been working great in the scope for the last several weeks.

The last problem was getting the same data to write to a spare FM16W08.   It's symptoms were that the D1 data line would only write a "1."   Contacted GQ Support for suggestions (they supplied the custom software for me that includes the FM device).   They made some general suggestions that we had mostly tried, and said they would order an FM IC and troubleshoot the software problem at their location.   So I ordered 2 more FM IC's as a shot in the dark from my end.

My replacement IC's came in yesterday.   Soldered an FM IC to the new adapter board, inserted it into the GQ Programmer - and it work perfectly!

We re-tested the failed FM IC and the problem with the D1 data line was the same.   Taking a closer look at the physical pins with an eye loop, magnifiers and bright lights from various directions revealed that pin 12 (D1 data line) had less solder than all the other pins, but otherwise looked ok.   As another shot in the dark, I re-soldered pin 12, inserted it into the programmer - and it worked perfectly!   Whewww!

Then we turned to the new DS1225AD I had previously purchased for a parallel effort with the FM16W08.   Problem was, it too had failed to write/load correctly.   As before, it loads all the data correctly except for the first byte which displays "FF" (hexadecimal code).   Again we tried everything thinkable with no luck.   The DS IC does not need an adapter board so there are no solder issues there.

Sent this most recent information off this evening to GQ Support including the issue with the DS IC.   So, the present status of my coveted scope cal data is - - -  One new FM IC installed in the scope.   Two spare FM IC's on adapter boards correctly programmed and stored.   The cal data is stored on my XP computer.   The cal data is stored in 4 places in my Windows 8.1 computer.   A copy is on a memory stick.   And I have a hard copy of it stored in the scope binder.   And, not to mention the DS1225AD that may get working.   And, the original DS1225Y that was removed from the scope is still alive and showing good battery voltage.   Oh yeah - someone else here suggested that one needs another memory stick duck taped to the inside of the scope housing.   This way, when the EMP strikes, at least one memory of the data should survive - but of course the scope won't :palm:

Nothing paranoid here about saving cal data.   Its just that it takes so much effort to retrieve and save, that no one wants to risk loosing it.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: ChunkyPastaSauce on March 24, 2016, 05:07:42 am
I need to order those caps....

Send an e-mail to yourself if you have something like gmail, or upload to cloud.

Or upload here so if people what to look at the cal data they can and you have a backup copy.

Id put one of the FM ICs inside the case. Then if you need it, it's there.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on March 24, 2016, 05:18:30 am
Old-E, really appreciate the sharing of your experiences here, thanks.  :-+


.....<snip>...

   And I have a hard copy of it stored in the scope binder.   ...


Do you mean hard copy as printed in hex at paper ?  :o

If it is, make sure you're using acid free paper that will last few hundreds of years.  >:D  ...j/k


Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on March 24, 2016, 07:56:41 pm
Good point!   Share it here and use the forum like a cloud.

Anyway, I can attach the Xcel file here of the Hex code that was manually read from my scope CRT display.   Preceding it is a page showing how to get to the scope data in order to manually copy it (not to be confused with electronically reading it from the DS1225Y once removed from the scope).

For simple minds like myself, start in the upper left corner on page 1 where it says "Press delta V & delta T + SLOPE" using the control buttons on the face of the scope.   This gets you into the Diagnostic mode which is displayed on the CRT as noted in the display column of the Excel form.   "ALL 00" is displayed at the bottom of the CRT.   Moving right the 3rd column shows that the "VERT" button is illuminated.

You may continue moving right or return to the first column and press "MODE up" button to cycle from ALL 00 to "TEST 01, which illuminates the "CH-1" button.   To test any of these routines, move to the 4th column "Action" and press "COUPLING up" button.   If that test finds no problems, it will display "TEST 01 PASS."
The chart on the 2nd half of the page is an extension of the first half, extending to the right as shown by the connecting line.

To find the cal data, toggle down to "EXER 02" and find the upper left corner of page 2.   Then follow the sequence - press "TRIG COUPLING" to display the first data point (for my scope it is "0013").   Then to continue cycling through the rest of the cal data, continue pressing "TRIG SOURCE."   The first 2 digits to the left of the cal data starting with "00" is the address location for the stored data.   This shows up in the data copied from the DS1225Y shown on the GQ Programmer display.

Following the order of the sequence laid out in the Excel spreadsheet it should be pretty straight forward and probably easier then following my verbal description here.

Note:  In theory, one could manually enter this data into a programmer and then write it to a replacement IC.   It would be time consuming and it would need to be double or triple checked to eliminate any errors, but it could be done.   I copied my data manually first because the DS1225Y was way past it's battery life expectancy, and just incase it died before it could be read electronically, at least I would have a printed copy of the cal data.  (An error in this paragraph has been corrected)

I'll write more about this later.

(The attached Excel spreadsheets have been updated with a couple of corrections, additions and an improved layout - easier to follow.  4-23-2016)
 Problem:  Page 1 of the new Excel spreadsheet wants to come up in portrait rather than landscape format.   To fix; after opening click on "Enable Editing" at the top of the page and the formatting will fix itself.   Sorry about that.   Unable to find the cause.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: ChunkyPastaSauce on March 24, 2016, 08:10:49 pm
Cool, pretty nice too
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on March 25, 2016, 08:10:12 pm
Regarding my last entry, might also mention that one could download the attached Excel file to your computer and erase just the cal data (hex code).   Then you would have a blank form to enter your own scope data on as you read it off the CRT display.

Another thought is that if you should lose your scope cal data, my understanding is that you could program your new RAM IC using this data.   Your scope then would not be precisely calibrated, but it would be close enough to get it back in operation.   Also, your recorded operating hour and power cycles would not be relevant to your scope.

Attached below is a screen print of the GQ-4X4 Programmer with my scope's cal data displayed in the buffer as if ready to be written to a FM16W08.   The FM16W08 device, indicated in the upper right, has been called up from the GQ library.   The reason I'm able to pull that IC up from the library is because I'm using the new "Hotfix" software from GQ Electronics, Support group.

FYI - Looking at the screen print shown, find the far left address column in pink.   Then find address location "00001E00."   That is where the cal data for my scope starts.   That can be seen by comparing the first series of bytes "00 13 06 BF 26 EB," etc,. - to the first data points in my Excel data sheet, page 2 (attached in my previous entry) "0013, 06BF, 26EB.   Those bytes should compare correctly all the way to the bottom of the screen print where once again we can compare the last bytes "00 27 00 00" - to the bottom of page 3 of my Excel spreadsheet where 0027, 0000 was copied from my scope's CRT display.

Obviously, above address location 00001E00 of the screen print, is a lot more recorded Hex data.   So, what is that?   It apparently it is not cal data, because it is not displayed on my scope.   I believe it is non-critical stuff, like hours of operation, scope set up sequences (where one can record the scope settings by pushing a button, and then retrieving it in the future for the same setup, and who knows what else.

Correction - In my previous entry, I wrote -  (Previous entry now corrected)
Note:  In theory, one could manually enter this data into a programmer and then write it to a replacement IC.   It would be time consuming and it would need to be double or triple checked to eliminate any errors, but it could be done.   One problem with this is that, the GQ Programmer that I used here is not sophisticated enough to manually load data - per my limited knowledge.
Facts are - A friend pointed out that the GQ Programmer can manually load data!   But if one was loading only what was copied off the scope CRT, it would be missing all the data we see in memory preceding the cal data.   And this brings me back to the question of, is the preceding data critical to operations?

Another thought that might work (per my limited knowledge), would be to load a full set of data from another scope electronically into your RAM IC.   Then go back and manually modify just the cal data part to what you had copied off the CRT display on your scope before the Dallas IC died.

I'll write more later. 
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: tautech on March 25, 2016, 08:19:43 pm

Correction - In my previous entry, I wrote -.........

I'll write more later.
Do consider Edit or Modify to a previous post so your great info reads correctly in that one post.

I't not a crime to make Edits and best if you also make a post to say that you've done so in case readers had saved your very good info.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on March 25, 2016, 09:29:26 pm
Tautech - Good suggestion.   Correction above dually noted.   Thanks.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on March 26, 2016, 07:46:56 pm
More about the GQ-4X4 Programmer.

As mentioned before, the GQ programmer does not include the Ferromagnetic IC FM16W08 in its library, that some of us have used to replace the battery powered RAM DS1225Y.   The advantage of switching to the FM16W08 is that it will not lose it's recorded data when the power is switched off - no need for battery backup.   To the external world, everything looks the same (voltages, pin outs, etc.) except for one detail.   And that is the way the data lines are toggled.   But the good news is that the scope happens to be logically configured to work with either IC.

So, following someone else's report, I bought this GQ Programmer and tried to write to an FM16W08 by using the DS1225Y listed in the Programmer's library.   And it didn't work.   Even tried down loading some older software thinking that maybe the report writer might have used it with success.   But no luck.   I contacted GQ Support for help.   They confirmed that the GQ programmer would not load an FM16W08 in place of a DS1225Y.

And further more, only their recent latest model, GQ-4X4, could even be configured to do that (GQ-4X model could not).   The way to determine if you have the 4X4 version is you will hear 2 audible beeps when you apply power to it using the USB cable to your computer.   Mine beeped twice.   Wheeew!

John in Support was very helpful and, a number of communications later, he sent a custom Hotfix program for my Programmer.   After loading it, there was the FM16W08 IC in the library.   Skipping more details, the Programmer worked great in transferring the data from the DS1225Y to the FM16W08.   John said they would be including that IC in their next updated software version.   I get the impression they release newer versions every year or so.

Getting to the bottom line here, I received confirmation from John at GQ Support a couple of days ago, that it would be ok to share the modified software with anyone that wanted it.   I had told him about my entries in this forum about the GQ Programmer, and had received a request for a copy from one of the forum people.   The latest standard software version is 7.07,   This modified version is 7.08 (3.81 meg).

Assuming this attachment process works, and you have it down loaded on your computer, I would suggest that you disconnect your computer from the internet for the duration that your Programmer is displayed/open.   Reason is; as soon as you open it, the programmer automatically goes on line looking for the latest version of software.   Version 7.08 is later than 7.07, so this should not be a problem, but I didn't want to chance getting the 7.08 version overwritten with something else.

Got a problem - This attachment will not work here.   Tried several times.   Error message says it may be too big of a file.   So plan B might be to see if it can be made available on line for readers to download from the GQ site.   In the meantime, I can send it by e-mail to any individuals that contact me at  don9@tds.net

Sorry about that!
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on April 02, 2016, 01:34:40 am
Finally - total success!!!

Received the latest version of custom software from GQ Electronics.   The degree of special help I've received from them has been amazingly positive!   My communications are almost always answered in a few hours, and almost anytime of day or night!   It's pretty incredible!

This software version 7.08B was to also add the DS1225AD to the library.   I was unable to write correctly to the AD version when using the Y version in the library.   Both chips are supposed to be the same, in that respect, so it appears there was a bug in the Y version of the software.   But, regardless, the AD version is there now and works with an AD chip.   The DS1225Y has been noted as obsolete, and superseded by the AD.   So, now I have more than an adequate number of IC's loaded with my scope's cal data.

For anyone wanting to obtain a copy of the latest version of custom software that now writes correctly to the DS1225AD and the FM16W08, I'll be happy to e-mail you a copy, because the file is too big for this Forum.   Eventually it will be included in GQ's next published upgrade.

Don
don9@tds.net

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MSO on April 02, 2016, 06:20:20 am
Nice work, Don.

For those who might attempt restoring their calibration data from the data read using EXER 02, the bytes are not swapped in binary image; that is if a location reads on the scope's display as 2071, it's 2071 (not 7120 as Intel does it) in the binary image as well.

I've attached both a binary copy and an ascii (human readable) copy of my NVSRAM image for those who might find it useful.  My 2467B is serial number is one of the newer ones beginning with B053xxx. I don't know if it makes any difference, but just so you know.

You can load the binary (.BIN.HEX) file directly into your programmer; the ascii (.TXT) file would have to be converted to binary before it would prove useful. Beware though, most programmers will load the text file and write it out to chip, making the chip as useful as pebble, so don't do that.  I use the text version just to browse the data and see what's in it.

 
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on April 05, 2016, 04:57:00 am
Bit of trivia - - 

:palm:    "Finally - total success!!!"   Opening my last message with this sounded a little too absolute at the time.   And sure enough, as soon as I notified the world, including this forum, that the last remaining obstacle in the GQ software tested good, I received this message back from GQ Support -

Hi? Don?

Thank you for your update.

It is the best to test the new software with FM16W08 .  Because there are partially over lapped.

The new version will be released once other chips been added.

Best Regards.
John

In other words, their last software mod that fixed the DS1225AD problem had elements common to the FM16W08.   So, confirming that the DS1225AD worked, did not mean that the FM16W08 still did.   This produced the Ohhh! Nooo! moment.

So, over the weekend, I pulled one of my previously programmed FM16W08's out of storage to run through a test routine.   FYI - That consisted of loading all FF's in the programmer buffer.   Then writing that over the top of the scope cal data, and reading it back to confirm that indeed all FF's were displayed.   All FF's sets all the inputs high.   Then it was repeated with all 00's to set all the inputs low.   Then repeated again with all 55's, and then all AA's, to load the IC with alternating highs and lows.   When that was successful, the scope's cal data was loaded back in the IC, and confirmed before putting it back in storage.   Wheeew!

It worked!   So now I don't have a lot of explaining to do.   Notified GQ Support and received the following reply.

Thank you very much for your testing.

Now we can claim those two chips are supported.

Cheers.

John


So, whenever GQ's next software version is released to the market place, these 2 IC's will be in it.   In the meantime, I can share it with the forum.
Title: Re: Tektronix 2465B cal
Post by: Mosaic on April 08, 2016, 04:16:20 pm
Hi all:
I justed posted this item on EBAY 131775163056
It is for the SG504 Leveled Sine wave gen - a better substitute head.

Ancel
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: RF_Pursuit on April 09, 2016, 07:23:40 pm
After thanking med6753 for welcoming me and his valuable suggestions, I continue my post which I started here
https://www.eevblog.com/forum/repair/tektronix-2465b-tear-down-and-rejuvenation/ (https://www.eevblog.com/forum/repair/tektronix-2465b-tear-down-and-rejuvenation/)

Today, I cleaned the A5 board from oil leaked from the capacitors and made a list of Tantalum capacitors to order and substitute.

I added a 1mm thick copper plate as cooling fins to extra cool the U800, not optimum, but a T-shirt less for the Summer!

And here comes the adventurous part (I'll post the images later). I dismantled the A5 board and I immediately started milling the DS12225 as I read in this article  http://www.worldphaco.com/uploads/TEKTRONIX_2465b_OSCILLOSCOPE_CALIBRATION___REPOWERING_THE_DS1225.pdf, (http://www.worldphaco.com/uploads/TEKTRONIX_2465b_OSCILLOSCOPE_CALIBRATION___REPOWERING_THE_DS1225.pdf,) because I once got an error message (test 05 fail 44).


Unfortunately, I reached almost 4.5mm deep until I saw three metal traces. I measured one of which (the mid one) to find it is 3.25 volts!

but I struggled to solder a wire on it and then sealed the hole and fixed the wired with resin.
I have the CR2032 but solder doesn't stick on it. I have to wait to buy a lithium battery micro size.

Fortunately, the SD1225 hasn't lost data.

Now there are two other problems, a broken SEC/DEV potentiometer which I fixed with  instant adhesive, and the bend traces of channel 1 and 2.  I assume this one has to do with aging capacitors in the power and vertical horizontal circuits???? I'm going to work on these boards after some consideration and collecting information.







Title: Re: Tektronix 2465B oscilloscope teardown
Post by: RF_Pursuit on April 10, 2016, 09:05:14 am
Can someone please tell me how to get to the information on 'Switch on off times' and 'Number of Operation Hours'? Thanks!

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: rf-loop on April 10, 2016, 05:02:55 pm
Can someone please tell me how to get to the information on 'Switch on off times' and 'Number of Operation Hours'? Thanks!

RTFM!  (example: 070-6873-00_2465bSvc_Sep89.pdf )


All is explained in service manual. Also even how to change these values what ever you want. (But, seriously, because you need ask this question: Warning, DO NOT enable CAL and play with CAL routines if you do not know exactly what are you doing there! )

Without enabling CAL, just only need use front panel. You need go to EXER 06 routine. It tell this info.

Page 6-10 in service manual. There is "Diagnostic routines" explained. Also how to enter to these routines.

Or, more easy: Operator manual.
http://exodus.poly.edu/~kurt/manuals/manuals/Tektronix/TEK%202445B,%202455B,%202465B%20Operator.pdf (http://exodus.poly.edu/~kurt/manuals/manuals/Tektronix/TEK%202445B,%202455B,%202465B%20Operator.pdf)

There Appendix A "Extended functions with diagnostic exercisers"

Manuals are for reading!
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on April 10, 2016, 07:05:59 pm
RF_P -
The total scope hours and the number of power on/off cycles can be found in the scopes memory.   To access that place in memory you can follow the procedure in the Service Manual as rf-l indicated, on page 6-10 or the actual page count is 232.

Simple way to get there is -
Hold down the delta V & delta T buttons on the front panel, , then simultaneously press "+ SLOPE."   This enters you into the diagnostic mode and you will see "ALL 00" displayed at the bottom of the CRT screen.

Then press "MODE" up, button to cycle from "ALL 00" to "TEST 01."   Continue pressing "MODE" up button to cycle down to "EXER 05."   Here, you will see that the "ADD" button is illuminated.   (Pressing the "MODE" down button reverses the order)

Then press the "COUPLING" up button.   This should display your scope's hours and power cycles across the top of the screen.

To exit - press the "COUPLING" down button.   This returns you to the DIAGNOSTIC page.

Then press "A/B TRIG" to exit the DIAGNOSTIC page, returning your scope to normal operation.

There are many more options that can be accessed in the diagnostic mode.   This is just the straight line path to your requested information.

Let us know your scope numbers.   By the look of the dirt accumulated on the fan, it would appear that it has been operated outside of a clean room environment.   This can and should all be cleaned up.   And the 4 electrolytic capacitors on the A5 board should be replaced ASAP.   It appears that the board around those caps in your photo is still in good shape.   So, count your blessings.   Too often the stuff leaking out of those caps eats up traces and other components in the near vicinity.

My scope indicates over 20,000 hours & 1,100 power cycles.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: RF_Pursuit on April 13, 2016, 10:15:41 am
Can someone please tell me how to get to the information on 'Switch on off times' and 'Number of Operation Hours'? Thanks!


Also even how to change these values what ever you want. (But, seriously, because you need ask this question: Warning, DO NOT enable CAL and play with CAL routines if you do not know exactly what are you doing there! )

Without enabling CAL, just only need use front panel. You need go to EXER 06 routine. It tell this info.

Manuals are for reading!

Thanks a lot I appreciate your drawing my attention not to fiddle with CAL, you're right I could've fallen in that swamp!

I was mainly busy downloading different manuals and skimming through them. And of course looking for A3 schematics but I managed this by magnifying the A4s.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: RF_Pursuit on April 13, 2016, 10:33:24 am
RF_P -
The total scope hours and the number of power on/off cycles can be found in the scopes memory.   To access that place in memory you can follow the procedure in the Service Manual as rf-l indicated, on page 6-10 or the actual page count is 232.

Simple way to get there is -
Hold down the delta V & delta T buttons on the front panel, , then simultaneously press "+ SLOPE."   This enters you into the diagnostic mode and you will see "ALL 00" displayed at the bottom of the CRT screen.

Then press "MODE" up, button to cycle from "ALL 00" to "TEST 01."   Continue pressing "MODE" up button to cycle down to "EXER 05."   Here, you will see that the "ADD" button is illuminated.   (Pressing the "MODE" down button reverses the order)

Then press the "COUPLING" up button.   This should display your scope's hours and power cycles across the top of the screen.

To exit - press the "COUPLING" down button.   This returns you to the DIAGNOSTIC page.

Then press "A/B TRIG" to exit the DIAGNOSTIC page, returning your scope to normal operation.

There are many more options that can be accessed in the diagnostic mode.   This is just the straight line path to your requested information.

Let us know your scope numbers.   By the look of the dirt accumulated on the fan, it would appear that it has been operated outside of a clean room environment.   This can and should all be cleaned up.   And the 4 electrolytic capacitors on the A5 board should be replaced ASAP.   It appears that the board around those caps in your photo is still in good shape.   So, count your blessings.   Too often the stuff leaking out of those caps eats up traces and other components in the near vicinity.

My scope indicates over 20,000 hours & 1,100 power cycles.

I'm grateful to you as you saved me a lot of time and eye sharpness for the coming years! I appreciate pädagogical and informative instructions which help one to arive at target.

As for the A8 board, I cleaned it thoroughly and I am going the change all capacitors as I ordered them. I'm going to replace most/ all of the capacitors on the power baord too; these I have to order them from different sources as I couldn't easily find them at one store!
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: SoundTech-LG on April 13, 2016, 02:31:46 pm
Great to know about the GQ support folks. I've been searching for a better alternative for my TL866 programmer, which did successfully read/write several of my 246xxx series scopes Dallas ICs, but having issues with some Atmel AT89C51ED2 / AT89C51RD2 MCUs in another project. I don't see those in the GQ-4X4 list of supported devices, (I only see AT89C51).
and have an email to MCUmall to see what they say. Still sounds like a great programmer for the bux.

Thanks for all the info!!


Title: Re: Tektronix 2465B oscilloscope teardown
Post by: med6753 on April 14, 2016, 08:53:31 pm
Update since my last entry on March 7th......

There has been progress and also a major setback.

After replacing all the caps on the supply boards I did a 6 hour “burn-in” to insure all was OK. I verified the 10 VDC reference and it was 10.1 VDC which is in spec. (It was prior to the re-cap too) All the supply voltages to J119 on the main board are in spec (Again, they were prior to the re-cap) The minor drifting issue with the Counter and DMM options is fixed. I performed a re-calibration of the Counter and it's now dead nuts as shown:

Sidelight: The 2465 does not have the EXER 05 and I can't check the power on hours or on/off cycles. And I haven't found any reference in the service manual to access it.

Major setback: I accidentally damaged the front end in the DMM option while attempting a calibration. It now has a solid DC offset error and won't zero. I had originally performed a DC calibration with the required “constants” of 0.19 VDC, 1.9 VDC, 19.0 VDC, and 190.0 VDC. The last “constant” required was 500 VDC. I built up a source to supply this constant. Unfortunately the source had an intermittent connection and it threw a spike into the DMM. I discovered that this DMM option does not have the best input protection and something got FUBAR'ed.       

I verified that all the precision resistors in the input/attenuation network are OK so now I'm going after the active components. Troubleshooting in this area is very difficult because of the high impedances and even a 10MEG DMM loads down the circuit. So I chose the most likely suspects and doing a mass replace. I've sourced all the parts except one op-amp which appears to be unobtanium. Luckily it's further down the chain of components so hopefully it's OK. I'll update after I get and replace the parts.

And finally. I still have this pesky BU Test F1 Fail 10 on power up. It's a Buffer board EAROM checksum error. As near as I can tell it might only affect the GPIB and the Word Recognizer options. I don't use those options so this error is low priority at this time. While going through the cal routines I noticed the ability to calibrate the Buffer board but no mention of it in the 2465 Options Service Manual. But it IS in the 2465A Options Service Manual. So I performed the calibration and on the first power up cycle the error went away. But then it came back. So this needs more work but after I get the DMM fixed. 
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MarkL on April 14, 2016, 10:02:42 pm
...
And finally. I still have this pesky BU Test F1 Fail 10 on power up. It's a Buffer board EAROM checksum error. As near as I can tell it might only affect the GPIB and the Word Recognizer options. I don't use those options so this error is low priority at this time. While going through the cal routines I noticed the ability to calibrate the Buffer board but no mention of it in the 2465 Options Service Manual. But it IS in the 2465A Options Service Manual. So I performed the calibration and on the first power up cycle the error went away. But then it came back. So this needs more work but after I get the DMM fixed. 
Here's the 2445/2465 (plain, not A or B) of the CT and WR service manual if you want it:

https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg710773/?topicseen#msg710773 (https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg710773/?topicseen#msg710773)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: med6753 on April 14, 2016, 10:15:18 pm
...
And finally. I still have this pesky BU Test F1 Fail 10 on power up. It's a Buffer board EAROM checksum error. As near as I can tell it might only affect the GPIB and the Word Recognizer options. I don't use those options so this error is low priority at this time. While going through the cal routines I noticed the ability to calibrate the Buffer board but no mention of it in the 2465 Options Service Manual. But it IS in the 2465A Options Service Manual. So I performed the calibration and on the first power up cycle the error went away. But then it came back. So this needs more work but after I get the DMM fixed. 
Here's the 2445/2465 (plain, not A or B) of the CT and WR service manual if you want it:

https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg710773/?topicseen#msg710773 (https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg710773/?topicseen#msg710773)

Thanks. I have all the manuals for the 2465, both the mainframe and the options manual. What is strange is that the calibration routines that appear on CRT give the ability to do a Buffer Board calibration but the 2465 options service manual makes no mention of it. I just happen to have the 2465A options service manual and it does mention it. Either it's an error or most likely I'm missing an update.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MarkL on April 15, 2016, 02:57:39 am
...
Thanks. I have all the manuals for the 2465, both the mainframe and the options manual. What is strange is that the calibration routines that appear on CRT give the ability to do a Buffer Board calibration but the 2465 options service manual makes no mention of it. I just happen to have the 2465A options service manual and it does mention it. Either it's an error or most likely I'm missing an update.
The 2445/2465 Option 10 GPIB Service Manual (pub #070-4640-00) mentions that "BU CAL F1" has to be performed before the GPIB cal "GP CAL 11".

But there's no description of exactly what "BU CAL F1" does.  What does it do on the 2465A?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: med6753 on April 15, 2016, 11:44:04 am

The 2445/2465 Option 10 GPIB Service Manual (pub #070-4640-00) mentions that "BU CAL F1" has to be performed before the GPIB cal "GP CAL 11".

OK, I figured out what's going on. The 2465 options service manual I have only covers options 6 and 9. I have a separate 2465 service manual for the DMM (option 1). Do you know of a source for the Option 10 manual?

But there's no description of exactly what "BU CAL F1" does.  What does it do on the 2465A?

The 2465A options service manuals covers all the options. Here's what it says with regards to calibrating the Buffer Board.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MarkL on April 15, 2016, 03:26:28 pm
OK, I figured out what's going on. The 2465 options service manual I have only covers options 6 and 9. I have a separate 2465 service manual for the DMM (option 1). Do you know of a source for the Option 10 manual?
The 2465 service manual is equally uninformative; (irr)relevant page attached.

I only have the GPIB Option 10 service manual in electronic form and I don't recall where I found it.  It was at least 11 or 12 years ago.  I will send you a PM to get it to you.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on April 16, 2016, 05:30:56 am
SoundTech-LG -

Yes, I found GQ Support to be unbelievably helpful.   Of course I'm only a sample of one, which does not say much about a continued trend, but it is a good start.   If you wish, feel free to use my name and experience with them as a reference.

Regarding the AT89C51 listed in the GQ-4X4 library, the question that comes to mind is; are the electrical characteristics close enough to your IC's to work correctly.   GQ Support should be able to answer that.   If they are not compatible, it has been my observation that they probably/might be interested in adding it.   They sound like they are always on the lookout for additional IC's to add.

Just for the record, I'm a novice in the world of programming.   Learning as I go.   A neighbor friend has been helping me over the hard spots with the DS and FM IC's and explaining things as we go.   While I now feel pretty comfortable in reading or writing existing programs to IC's, I think there's so much more out there that I don't even know exists yet.

Let me know how things go with GQ. 
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: RF_Pursuit on April 16, 2016, 06:24:58 pm
Hi everybody!

On the road to change as many capacitors as possible in the power supply  PCB, I replaced most of the capacitors except C1016 and C1018 those are plastic (0.068uF X2 250VAC) can I replace each with a RIFA PME 271 M (220n X2 275VAC)?

I also have a some (0.1uF 275VAC) but not X2 can I use these to replace the 0.068uF X2? Which would be suitabel the 220n X2 or the 100n?

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: med6753 on April 16, 2016, 06:37:57 pm
Hi everybody!

On the road to change as many capacitors as possible in the power supply  PCB, I replaced most of the capacitors except C1016 and C1018 those are plastic (0.068uF X2 250VAC) can I replace each with a RIFA PME 271 M (220n X2 275VAC)?

I also have a some (0.1uF 275VAC) but not X2 can I use these to replace the 0.068uF X2? Which would be suitabel the 220n X2 or the 100n?

See attached list.....which I give credit to the Yahoo Tek group. I used the recommended 0.1 uF 275VAC X2 for C1016 and C1018 and they are working fine.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: RF_Pursuit on April 16, 2016, 07:42:58 pm
Hi everybody!

On the road to change as many capacitors as possible in the power supply  PCB, I replaced most of the capacitors except C1016 and C1018 those are plastic (0.068uF X2 250VAC) can I replace each with a RIFA PME 271 M (220n X2 275VAC)?

I also have a some (0.1uF 275VAC) but not X2 can I use these to replace the 0.068uF X2? Which would be suitabel the 220n X2 or the 100n?


See attached list.....which I give credit to the Yahoo Tek group. I used the recommended 0.1 uF 275VAC X2 for C1016 and C1018 and they are working fine.

Thank you, I followed the that list in ordering the capacitors. Unfortunately, I couldn't get all of them as recommended.


And reading the tiny writing on the 0.1 capacitors I found the X2 within. So, that's done with.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: tautech on April 16, 2016, 07:47:42 pm
Hi everybody!

On the road to change as many capacitors as possible in the power supply  PCB, I replaced most of the capacitors except C1016 and C1018 those are plastic (0.068uF X2 250VAC) can I replace each with a RIFA PME 271 M (220n X2 275VAC)?

I also have a some (0.1uF 275VAC) but not X2 can I use these to replace the 0.068uF X2? Which would be suitabel the 220n X2 or the 100n?
The absolute value is not as critical as the X2 and voltage ratings that must be maintained.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Micma on April 19, 2016, 07:09:29 am
Hello everyone, I am new to this forum and wanted to thank you all for sharing valuable information!
A friend of mine gave me a 2465B does not work (he wanted to throw it!) and recently I bought another one in like-new condition!
Unfortunately I have to replace the NVRAM. Following the instructions that I found in this forum I have already ordered everything needed and  it should reach me in a few days.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on April 24, 2016, 03:12:47 am
NOTE -

The Excel spreadsheets attached to Reply #703 back on 3-25-16, have been replaced.   The updated version has a couple of corrections, additions and an improved layout - easier to follow.  (4-23-2016)
 Problem:  Page 1 of the new Excel spreadsheets wants to come up in portrait rather than landscape format.   To fix:  After opening click on "Enable Editing" at the top of the page and the formatting will fix itself.   Sorry about that.   Unable to find the cause.   It opens fine on my computer, but opens strange in the forum.

These are the spreadsheets showing the sequence to access the internal tests and Calibration data stored in the scope's RAM.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on May 07, 2016, 02:56:07 pm
CHASING THE ILLUSIVE MILLIVOLT & NANOSECOND – PART I

My 2465B appeared to be working perfectly (even though the PS caps have yet to be replaced) until it was pressed toward its limits.   Then some anomalies turned up that I felt needed to be understood.
Started by looking at sine waves from my fastest generator which tops out at 264 MHz (Tek. SG 503).   Peak to Peak (P-P) voltage was measured by using the manually adjusted cursors, accessed by pressing delta V.   This indicated 177 mv P-P.

Then pressing the lower red “HELP” button, followed by the “CHAN 2” button, commands the scope to measure the voltage from internal sources.   This indicated 134.7 mv P-P (reads on screen “CH1: PK-PK 134.7 mv”).  This is 24% lower than the cursor set measurement above.

Ok, so which number is correct?   I trust my digital multimeter, but not at that frequency.   So using a 60 Hz generator, the test was repeated.   This time, the internal scope function measured 2.5% higher than the manually adjusted screen cursors, and 1.7% higher than the digital multimeter.

Returning to the high frequency generator, I compared the voltage readings at different frequencies.   The result was; the internal sourced voltage measurements compared more favorably to the cursor reading as the frequency was reduced from 264 MHz.

On a hunch, I used a Tek. PG 502 pulse generator to generate a flat topped pulse train.   The short version of the findings were that the internally sourced voltage measurement needs some dwell time at peak voltage to capture the P-P voltage number.   That dwell time was experimentally found to be about 12 ns.   Problem with a sine wave is that it has very little dwell time at its peak voltage.   Following data illustrates the accuracy vs. flat top dwell time, with 1.00 volts high pulses displayed on screen.
3 ns = .934 v P-P
5 ns = .964 v P-P
9 ns = .996 v P-P
10 ns = 1.001 v P-P
12 ns = 1.011 v P-P
100 ns = 1.010 v P-P
(http://)

Next question is; what happens to the flat top time requirement when the repetition rate of the pulse train is varied?   For this test the top pulse width was set to 10 ns.   Then the rep rate was adjusted between 10 us and 10 ms.   But no significant difference was found.   So pulse repetition rate does not appear to affect the internal P-P voltage measurement.

Ok, so where does that inaccuracy begin with a sine wave?   Skipping to the bottom line, the following data was collected by using the SG 503, inputting 100 mv P-P at various frequencies, and then commanding the scope to measure the P-P voltage.
5 MHz = 99.9 mv
10 MHz = 99.6 mv
15 MHz = 99.1 mv
20 MHz = 98.7 mv
25 MHz = 97.2 mv
50 MHz = 89.7 mv
75 MHz = 85.8 mv
100 MHz = 83.1 mv

Conclusion: The scope can accurately measure P-P voltage of a flat topped pulse, providing the flat top is longer than 12 ns.   And, same for a sine wave that is <20 MHz, depending on the accuracy one is looking for.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: med6753 on May 07, 2016, 10:22:50 pm
Update from my last entry on April 15th.....


The DMM Option Board is fixed. The culprit was dual FET Q5070. I also had on hand Op-amp U5060 but it's OK. Luckily Op-amp U4970 is also OK because so far that part has been unobtanium. I calibrated the DC voltages with my home built calibrator with the exception of the 500VDC range. I don't want to risk blowing out that FET again. I don't foresee needing to accurately measuring voltages that high anyway. I also recalibrated the ohms. AC volts calibration is pending until I can figure out an accurate calibration constant source of 0.19V, 1.9V, 19.0V, 190.0V, and 500V.

Here's the schematic of the front end of the DMM Option.

And here's a sample measurement to my 10VDC standard.


The last repair pending is the Buffer Board checksum error.   
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on May 08, 2016, 04:13:05 am
CHASING THE ILLUSIVE MILLIVOLT & NANOSECOND – PART II

While testing the scope’s limits, the next area of interest or anomalies is the frequency measurements.   This was accomplished by using a Tek. SG 503 sine wave generator at its highest frequency setting of 264 MHz.

Comparing the scope to itself, in the 1st photo, I carefully measured the cycle time at 3.82 ns using the manually adjusted screen cursors by pressing delta T.   This calculates out to a frequency of 262 MHz.   Then pressing the delta T & delta V simultaneously reads out the frequency, which also indicated 262 MHz.

In all of my tests, the numbers measured from the manually adjusted cursors were always exactly in agreement.   That includes the period & frequency, and the screen grid or graticule.

Then pressing the red lower “HELP” button, followed by the “CHAN 1” button, commands the scope to automatically measure the frequency from its internal sources (no connection to the cursors).   This indicated 266 MHz, which is 1.53% higher than the cursor measured number.   The frequency meter on the SG 503 generator indicated 264 MHz (only reads 3 places), which is in the middle of the numbers.
   
To determine if the input frequency has any effect on the accuracy,  the above measurements were repeated at various frequencies.   These included one point at 462.5625 MHz.   This came from my FRS Walkie Talkie.   I held its antenna near the scope probe while transmitting.   Can’t say anything about the amplitude, but this frequency is accurate for channel 1.   At this frequency, the 400 MHz scope and 300 MHz probe have rolled off quite a bit in amplitude at 462 MHz.   But, the scope manual says it will trigger up to 500 MHz, and so it can display 462 MHz as seen below.

Adjusting the cursors closer together will indicate a frequency up to 20 GHz (20,000 MHz), but of course the scope won’t actually display anything that high.   Need to find a higher frequency source to see how high it will go.

Letting the scope automatically measure the 462 MHz frequency via. the red HELP button, indicated 474.7 MHz, which is 2.3% high.

Additional lower frequencies were set up with the screen cursors, and then compared to the scope’s internal frequency measurement via. the red HELP button.   They were 100 MHz, 10MHz, 1 MHz, 50 KHz and 60 Hz.   These lower frequency readouts all agreed within the limits of being able to set the cursors which is a fraction of 1%.
 
Conclusion; All the lower automatic frequency measurements appear to agree well with the screen set cursors.   However, they read a few percent high at the higher frequencies.   And given that the cursor settings were right on for 60 Hz and 462.5625 (the 2 frequencies I knew for sure), and they mostly agreed with the lessor known accuracy of the frequency meter built into the SG 503 generator, I believe the cursors are accurate across the scope’s frequency spectrum.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on May 16, 2016, 05:04:27 am
CHASING THE ILLUSIVE MILLIVOLT & NANOSECOND – PART III

In search of more performance limits, I looked at RT (Rise time).   RT can be theoretically determined from the frequency.   The 2465B has a specified frequency response of 400 MHz (at the -3 DB roll off point).   Using the generally accepted formula of .35/Freq = RT, we have .35 divided by 400 MHz.   This = a rise time of .875 ns.

Should also point out that -3 DB in signal amplitude means the peak voltage at 400 MHz will read 29.3% less!   To maintain reasonable amplitude accuracy, of say -3%, the upper frequency limit would be about .30 x 400MHz, which brings the usable frequency (for amplitude accuracy) down to 120 MHz!   A good Tektronix article on this and the approximation of RT can be found at - http://www2.electron.frba.utn.edu.ar/~jcecconi/Bibliografia/06%20-%20Osciloscopios%20de%20Almacenamiento%20Digital/Understanding_Oscilloscope_BW_RiseT_And_Signal_Fidelity.pdf (http://www2.electron.frba.utn.edu.ar/~jcecconi/Bibliografia/06%20-%20Osciloscopios%20de%20Almacenamiento%20Digital/Understanding_Oscilloscope_BW_RiseT_And_Signal_Fidelity.pdf)

Ideally, to measure RT accurately, one needs a pulse generator with a RT of roughly 10x the .875 ns RT of the scope, or 87.5 ns.   Unfortunately, the best I could do was to borrow a Tek SG503 pulse generator.   It’s specifications give a rise time of 1 ns or better, which places it roughly equal to the scope.

When one begins to measure RT, a number of other questions arise.   Tektronix specifies it to be measured between the 10% & 90% of amplitude.   That’s easy in a perfect world where pulses have square clean corners.    But there is the “pre-shoot and overshoot of the leading edge of the displayed pulse.   I wrestled for some time with how to deal with that in making the RT measurement.   In the article above, they illustrate the answer which I like because it simplifies the measurement.

In order to minimize the leading edge distortions, I found the best results by connecting a 40 inch piece of 50 ohm coax directly between the SG503, using its internal 50 ohm output option, and the internal 50 ohm input to the scope.   When using a 50 ohm terminator feed through into the 1 meg ohm port, or a 300 MHz (unfortunately) scope probe into the 1 meg ohm port, the displayed pulse was not as clean.

All this wordiness was needed to qualify the following measurements.

The 1st photo below shows the displayed pulse with the amplitude adjusted to sit on the reticle 0% dotted line and the stabilized top on the 100% dotted line.   The under & overshoots pass outside those limits.

In the 2nd photo, the same pulse is shown with the sweep speed at max using the “x10 MAG”.   Measuring the time between the 10% & 90% crossings on the reticle, the cursors indicate 1.55 ns.   But the 1st photo shows the leading edge of the pulse rounding over before it plateaus across the top.   This will lengthen the measured RT.   Following some thought and experimentation, I came to the conclusion that, this distortion is coming from the source rather than the scope.   If so, then eliminating it would be fair.

The 3rd photo shows the elimination of the rounding and distortion across the top of the pulse.   This was done by reducing the pulse width to its minimum.   But this also shortens the height of the pulse.

The 4th photo shows where the pulse has been increased in height to again align with the 0% & 100% dotted lines.

In the 5th photo the sweep speed is increased to its max and the cursors are set on the 10% & 90% lines to indicate a rise time of 1.04 ns.

Letting the scope measure the rise time via the red “HELP” button, it indicates a rise time of .89 ns or .93 ns, depending on the repetition rate of the pulse generator.   A little discouraging, but again underscores the manually set cursors as being the most accurate.

Using the formula, .35 / 1.04 ns = 337 MHz.   But of course, that is the speed of the combined rise times including the scope, generator and cable.   But we can estimate the individual RT from the composite.   A published formula for this is - the square root of the sum of the individual squared rise times.

In this case – if we assume the cable is perfect for simplicity, it leaves us with 2 unknowns, the RT of the scope and the RT of the generator.   Since the scope RT is spec’d at .875 ns, and the generator is spec’d at equal to or better than 1 ns, we can further simplify by assuming they are both the same.   Using the formula above, then gives us an individual RT of .73 ns.   And since .73 ns is a safe margin below the spec’s of both instruments, I think it’s safe to say that the scope RT is equal to or better than .875 ns.   If we were to factor in something for the non-perfect cable, we would have an even larger margin.

This is not as perfect as I would like, but lacking a better pulse generator, it’s the best I can do.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: tautech on May 16, 2016, 05:46:35 am
When one begins to measure RT, a number of other questions arise.   Tektronix specifies it to be measured between the 10% & 90% of amplitude.   That’s easy in a perfect world where pulses have square clean corners.    But there is the “pre-shoot and overshoot of the leading edge of the displayed pulse.   I wrestled for some time with how to deal with that in making the RT measurement.   In the article above, they illustrate the answer which I like because it simplifies the measurement.
Tek are stating what is the common interpretation of rise time and what we most use.
However I believe one can overlook pre-shoots and overshoots and focus on measurement of the step function as mentioned in this Wiki article:

https://en.wikipedia.org/wiki/Rise_time

In electronics, when describing a voltage or current step function, rise time is the time taken by a signal to change from a specified low value to a specified high value.[1] These values may be expressed as ratios[2] or, equivalently, as percentages[3] respect to a given reference value. In analog or digital electronics, these percentages are commonly the 10% and 90% (or equivalently 0.1 and 0.9) of the output step height:

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on May 17, 2016, 01:16:43 am
tautech -

Yes, the link to the Tek article in my previous post clearly illustrates that the pre & overshoot on the leading edge of a pulse is to be ignored when making RT measurements.   Looking back, I neglected to actually state that.   That small difference can make a significant difference in the measurement outcome.

Getting into the sub-nanosecond arena, things starts getting rather spooky.   Things that have little or no effect at the lower frequencies, now can totally upset things.   And to make accurate measurements or properly functioning designs, those fine "spooky" points need to be addressed.

Thanks
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: nicnac117 on May 20, 2016, 08:31:13 pm
For information on the EAROMs in the 2445,2465, I opened  a thread  which may be of interest to the "A" and "B" guys....just search for EAROM
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: tautech on May 20, 2016, 09:12:09 pm
For information on the EAROMs in the 2445,2465, I opened  a thread  which may be of interest to the "A" and "B" guys....just search for EAROM
Editing your above post and inserting a link would be better.  ;)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: med6753 on May 21, 2016, 06:13:11 pm
For information on the EAROMs in the 2445,2465, I opened  a thread  which may be of interest to the "A" and "B" guys....just search for EAROM
Editing your above post and inserting a link would be better.  ;)

Here's the link....

https://www.eevblog.com/forum/testgear/tektronix-2445-2465-cal-settings-earom-er1400/ (https://www.eevblog.com/forum/testgear/tektronix-2445-2465-cal-settings-earom-er1400/)

I'm very interested in how this turns out.


More steady progress on getting everything on my 2465 DMS fully functional and calibrated. Since my last update on May 8th I've starting tackling getting the AC volts on the DMM calibrated. The “calibration constants” to calibrate the AC volts are:

0.19V @ 60Hz
1.90V @ 60Hz
19.0V @ 60HZ
19.0V @ 20KHz
190.0V @ 60Hz
500.0V @ 60Hz
(All RMS)

I used a function generator with a pot as a voltage divider to get the 0.19V and 1.90V constant. But the maximum output of the function generator is 20.0V p-p so it can't do the 19.0V. I'm in the early stages at looking at possible designs to boost the generator output to about 60V p-p and above. If someone has some ideas I'd like to hear them. I'm not going to try the 190.0V and 500.0V constants because those are insane p-p voltages.

Here's the DMM measuring a 1.0VAC Sine with the Fluke 87. Not bad but may require further tweaking. The dots on the screen are the DMM logic warning of a potential out of calibration condition. The dots do not appear when measuring DC volts or ohms.


Measuring mains voltage with the Fluke 87. Clearly needs more work. I think if I can get the 19.0V range calibrated it will be much better.


Follow on: I'm going to build a temperature probe since the DMM has temperature capability. And awaiting the results of the EAROM experiment so I can fix the Buffer Board check sum error.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MarkL on May 21, 2016, 08:00:13 pm
...
I used a function generator with a pot as a voltage divider to get the 0.19V and 1.90V constant. But the maximum output of the function generator is 20.0V p-p so it can't do the 19.0V. I'm in the early stages at looking at possible designs to boost the generator output to about 60V p-p and above. If someone has some ideas I'd like to hear them. I'm not going to try the 190.0V and 500.0V constants because those are insane p-p voltages.
...
Ok, here are some ideas...

You could drive a power transformer backwards with the function generator to step up the voltage.  You don't need any current to speak of for the DMM input, so 60V should be fairly easy to hit.  At 20kHz, a power transformer may not work well, but you could try a small audio transformer (like the kind in old transistor radio).

If your function generator does not have enough output power to reach the desired output voltages, you could add an audio amplifier to drive the transformer.  And if it's an amplifier with a high enough output, you might be able to dispense with the transformer altogether.

If using a transformer, use the scope input to make sure the sine wave is still clean before relying on it for RMS calibration.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on May 22, 2016, 04:27:14 am
MarkL reflected some of my thoughts on generating higher voltages.   Another thought might be to feed 120 v ac into a variac for voltage control, then feed that output backwards through a 24 volt doorbell transformer.   That would easily give you 500 volts.   I think the winding insulation is rated higher than that.   Cost on-line should be less than $10.

I recently used the same transformer to step up 120 v to 240 v by using the 120/240 volt primary as an auto transformer (120 into the center tap and one end - 240 out across both ends of the same primary).   The 24 v secondary leads were dead ended (not used).   Similar to your case, I was powering 2 digital panel meters that only draw milliamps.   $6.25 each on-line.

Question - How do you know if it's the scope or the Fluke (or both) that are in error?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: med6753 on May 22, 2016, 02:23:36 pm
Guys, thanks for the responses. Here I was trying to think of what was turning out to be a complex solution and a simple transformer solution was staring at me the whole time. Unfortunately this project is going to have to go on the shelf for a few weeks because I'll be involved in other pressing activities. But I'll provide an update when I get a chance.


Question - How do you know if it's the scope or the Fluke (or both) that are in error?

A very legitimate question and I'll try to provide a satisfactory answer. It goes back to the 1980's when I built a voltage/resistance “standard” based upon an article in an electronics magazine. It provides 10.00VDC, 1.000VDC, 100.0mVDC, 1.0VAC as well as some resistance “standards”. I used a borrowed and freshly calibrated Fluke 8050 to set it up. And documented the results. I also checked my then Fluke 77 and documented those results. I still have those documents to this day. And in the 30 years since building this unit I have never had the need to perform any further adjustments.

Around 1997 the Fluke 77 was damaged beyond repair by a leaking battery. So I purchased this current Fluke 87. I also documented how it compared to my “standard” and it was spot on. From about 1998 until very recently I was mostly inactive in this hobby and the equipment sat mostly unused. The 87 was rarely used and was never molested or damaged or overloaded. The only time it was opened was to replace the battery. So about 6 months ago when I got active again I compared the “standard” to the 87 to the 1997 readings and they were the same. I highly doubt both of them would have drifted the same amount so I trust what the 87 is telling me. And I often check both to make sure nothing has changed.

So I used the 87 as a reference point when applying the “calibration constants” to the 2465 DMM. Those constants do have a little bit of “wiggle” room but if it's too far out I get an “Out of limits” message on the CRT. Now will the 2465 DMM meet it's published specs? Of course not. But at least I know I'm close.

Now if I knew someone who had a Fluke 5101B and a Fluke 5205A I could have the entire 2465 DMM calibrated in about a half hour. But what's the fun in that? Redneck solutions are much more fun. “Hold my beer and watch this”.        ;D
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on May 22, 2016, 04:36:37 pm
“Hold my beer and watch this”.

Wasn't that the statement most often heard just before a car crash in redneck territory?  :)

Sounds like you have the cal issue pretty well nailed down as I assumed you did.   Just curious as to what route got you there.   Good work!
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on June 01, 2016, 05:50:50 pm
CHASING THE ILLUSIVE MILLIVOLT & NANOSECOND – PART IV

Looking further into the 2465B’s abilities, the scope can also function as a time domain reflectometer.   For those unfamiliar with this, the scope’s speed is fast enough to measure the transit time of signals traveling through conductors.
 
For this test, I connected a BNC T to the scope 50 ohm input at channel 1.   A 50 ohm cable connected one port of the T, to the 50 ohm output of the SG503 pulse generator.   The addition of the T was found to have no measurable effect on signal level or rise time.   The 1st picture shows the shortest pulse width out of the generator measuring 1.71 ns at 50% of amplitude.   The height of the pulse is adjusted to extend from the 0-100% markings on the scope screen.

Then a 41 inch piece of 50 ohm cable was connected to the remaining port on the T, and the other end of the cable was left open (no connection).
 
The pulse coming from the generator is split at the T which sends 50% of the total pulse power down the open ended coax, and 50% of the pulse power into the scope.   This results in the voltage at the scope dropping to .707 of the original voltage.   If we were reading the current, it would indicate the same drop.   Then when multiplying the reduced voltage x the reduced current, the pulse power would = ½ of the total from the generator.   In the meantime, the pulse going down the open ended coax finds an open (very high impedance).   This mismatch results in reflecting the pulse back toward the T where it splits again, sending 1/2 back to the generator and 1/2 to the scope input, but at a later time.   It is this time difference and relative voltage levels that can used to measure conductor characteristics.

The 2nd picture shows the time delay of 9.0 ns between the primary pulse and the reflected one, and the reduced voltages from each split at the T.   Again, the coax is 41" long.

So how does that calculate out?   Light & electricity travel at 186,000 miles per second, or 11.8 inches per nanosecond.   Therefore; 9.0 ns x 11.8” = 106.2” of electrical length.   But the pulse only travels a round trip through the cable of 82”.   The difference is the velocity factor.   That is; the pulse travels slower through the cable, because of the dielectric materials making up the cable, then it does through free space.   So if we divide 82” by 106.2” we get a velocity factor of .772.   That is; the signal is traveling through the coax at roughly ¾ the speed it would in free space.   Now that I know that number, I can determine the physical length of another piece of coax off the same spool, or find the point of damage along an existing coax, etc.

The same test with a 62 inch piece of coax gave a reflected delay of 15.80 ns.   This times 11.8 inches gives a round trip electrical length of 188.4”, which results in a velocity factor of .665.   Even though they are both 50 ohm coax, they are made up of different dielectric materials resulting in different velocity factors.   The 41” coax is stamped RG58/U, and the 62” coax is stamped RG58C/U.

Same test again with a 13 ¼” length of coax resulted in a reflected delay of 3.4 NS.   This calculates out to a velocity factor of .661.

Looking closer at the peak voltage of the pulses, as mentioned above, the primary pulse should be reduced to .707 of the original when adding a 2nd cable at the T.   In a perfect world, that would reduce the pulse height on the scope screen from 5 divisions (cm) to 3.54.   But the scope is actually displaying slightly less at 3.40 cm.   This difference can be from any number of minor dimensional errors in the coax or connectors.

The voltage of the reflected pulse indicates 2 cm high when it should be 2.5 cm.   The primary pulse power is first split when entering the T, and then the reflected pulse is split again.   That’s a voltage reduction of .707 x .707 which = .500, or 2.5 cm.   Part of that difference can be attributed to the cable attenuation at 400 MHz, and the remainder is probably caused from minor imperfections in the cable and connectors.   RG 58 coax gets fairly lossy at these frequencies, which is why they use RG 8 or better for any significant length.   For example, 100 feet of RG58C will lose (absorb) nearly 95% of the input power at 400 MHz.   RG8 will lose 45%.   A cable loss calculator can be found at - http://www.qsl.net/co8tw/Coax_Calculator.htm (http://www.qsl.net/co8tw/Coax_Calculator.htm)

I realize this is pretty basic stuff for many reading this, but hopefully others may find these tests interesting as I did.

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MarkL on June 01, 2016, 10:37:04 pm
You don't need to use power to calculate predicted amplitudes.

In the case of just the scope with its 50R termination, you have a 50R transmission line feeding the internal 50R resistor and measured at that junction.  The amplitude, as compared to open circuit (or 1M impedance setting) can be calculated as a simple resistor divider 50R/(50R + 50R).  So, when termination is turned on in the scope the amplitude is 50% of the unterminated setting.  Most people are familiar with this behavior and there are no lengthy stubs to observe pulse reflection behavior.

When you add the second coax transmission line, you're adding another 50R impedance at the scope's input (and also creating a discontinuity in impedance).  The amplitude of the pulse is now reduced because there's another impedance in parallel with the first two and creates a 3-way divider.  It is 50R/(50R + 50R + 50R), which 33.3% of the open circuit amplitude.  Or 66.6% if you want to use the terminated (50%) amplitude as the baseline.

The terminated pulse height you report as 5cm.  The pulse height with the second coax attached should be 5 * 66.6% = 3.33cm.  You report 3.40cm, which is within about 2%.  That's pretty good.

For the pulse on the way back, it is split again as you describe, but the amplitude should be 66.6% of 66.6% = 44.3%.  5cm * 44.3% = 2.21cm and you report 2cm.  Looking at the screen shots and using your 0 to 100% graticule, it looks like it might even be a little more than 40%, which again is exactly right.

When doing TDR with a scope, I usually leave the scope unterminated internally.  It's less confusing if you don't have the scope as a third impedance on the line.

More reading:

  http://cp.literature.agilent.com/litweb/pdf/5966-4855E.pdf (http://cp.literature.agilent.com/litweb/pdf/5966-4855E.pdf)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on June 01, 2016, 10:51:19 pm
Hmmm.   I'll give that some thought.

Thanks MarkL
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: med6753 on July 04, 2016, 01:11:15 am
Update from my last entry on May 22nd....

June was a busy month with other activities and finally got some time to do some additional work on the 2465 DMS.

The DMM option has temperature readout but I didn't have the Tek P6602 Temperature Probe. In checking E-bay and other sources it turns out this is a pretty rare animal and the prices reflect that. In other words...no way. Decided to build my own and the total cost was about $6 USD.

A scrap collapsible antenna, glued on rubber plug to make it immersible in liquids, Heraeus M1020 PT100 Class B sensor. Some banana plugs and done.


The results. Immersed in an ice bath. Sorry gang but this old school Yank prefers Fahrenheit over Celsius.


More updates to follow..stay tuned.       :D
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on July 04, 2016, 10:47:43 am
That is one hell of expensive thermometer  :o, considering how valuable this old gem is for that purpose.

But congrats on proofing it that its still performing very good, a temp reading using a scope.  >:D

Thanks for sharing.  :-+
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: med6753 on July 04, 2016, 12:15:37 pm
That is one hell of expensive thermometer  :o, considering how valuable this old gem is for that purpose.

But congrats on proofing it that its still performing very good, a temp reading using a scope.  >:D

Thanks for sharing.  :-+

You ain't kidding. The list price for a 2465 DMS in 1985 was $8400 USD.  :o More than the cost of a decent car at that time!
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: med6753 on July 08, 2016, 03:00:03 pm
As promised, more updates....


The DMM option on the 2465 DMS is calibrated as far as I can go with the equipment currently on hand. Thanks to MarkL's suggestion I used a power transformer connected secondary side to a function generator to get the 19.0V RMS@60Hz. Unfortunately the power transformer could not pass the required calibration constant of 19.0V RMS@50KHz. The best I could get out of it was about 7.0V RMS. So the ranges not done are:

500V DC
19.0V RMS 50KHz
190V RMS 60Hz
500V RMS 60Hz

So unless I can beg, borrow, or steal  :P a Fluke voltage calibrator at this point the DMM option is a done deal and I'm pleased with the results.

One issue left....the Buffer Board checksum error. I'm working it.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: med6753 on July 10, 2016, 12:17:44 am
The last issue on this Tek 2465 DMS:

BU TEST F1 FAIL 10
Buffer Board checksum error.

If I perform the DC Balance routine as defined on the attached troubleshooting chart I get some interesting results....


Upon immediate power up the scope comes up with all tests pass.
If I leave it off for about 10 minutes or so it still powers up all tests pass.
If I leave it off for about a half hour or longer the checksum error comes back.

To my simple mind I think this is telling me that the Buffer Board EAROM is defective and after a certain time frame it is dropping data.

In the reading thru the service manual it appears that EXER 02 will read the EAROM data out of both the A5 main board as well as the Buffer Board. Beyond that I'm a little ignorant (and perhaps a little fear of “fail”) as to what I can do with it. I have no experience in dealing with these types of circuits. And I'm not sure if I want to go thru the expense and learning curve to put together an ROM writer and write a new chip. Especially since it appears that this checksum error has no affect on other functions of the scope other than being an annoyance upon power up. So I'm tempted to leave it until it's a total crap out. Which may or may not ever happen. What say the group? Fix it or leave it? I'm open to suggestions.

So in summary this 2465 DMS has been an adventure since getting it (free) last year. Repaired or calibrated:

Noisy fan fixed.
Counter/Trigger option calibration power up fail fixed.
C/T and DMM option drift problem fixed after total recap of Inverter and Regulator boards.
DMM option fail fixed after self inflicted gun shot wound then calibrated.
2465 Mainframe all functions appear to be in spec to the limits to which I can test them.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MarkL on July 10, 2016, 02:55:39 pm
...
To my simple mind I think this is telling me that the Buffer Board EAROM is defective and after a certain time frame it is dropping data.

In the reading thru the service manual it appears that EXER 02 will read the EAROM data out of both the A5 main board as well as the Buffer Board. Beyond that I'm a little ignorant (and perhaps a little fear of “fail”) as to what I can do with it. I have no experience in dealing with these types of circuits. And I'm not sure if I want to go thru the expense and learning curve to put together an ROM writer and write a new chip. Especially since it appears that this checksum error has no affect on other functions of the scope other than being an annoyance upon power up. So I'm tempted to leave it until it's a total crap out. Which may or may not ever happen. What say the group? Fix it or leave it? I'm open to suggestions.
...
I also had an intermittent EAROM, but mine was on the main board.  The scope would sometimes power up with a checksum error.  I don't recall if it was dependent on how long it was off, but it could have been the same issue since data in the EAROM was being written when front panel settings were changed.

Properly done the EAROM should have been replaced, but I was able to change the supply voltage slightly and I got it to work without failure:

  https://www.eevblog.com/forum/testgear/tektronix-2445-2465-cal-settings-earom-er1400/msg927144/#msg927144 (https://www.eevblog.com/forum/testgear/tektronix-2445-2465-cal-settings-earom-er1400/msg927144/#msg927144)

It may be a long shot, but easy to try.  The supply for the buffer board EAROM (signal OEA35) is connected to the one on the main board, so it's the same zener.

EXER02 is harmless.  You can use it to make a backup copy of the contents in both EAROMs.  Getting the data back in there, however, is another matter.  It would have been nice for them to provide a "write" option in the diagnostics.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: tggzzz on July 10, 2016, 04:07:52 pm
Looking further into the 2465B’s abilities, the scope can also function as a time domain reflectometer.   For those unfamiliar with this, the scope’s speed is fast enough to measure the transit time of signals traveling through conductors.
 
For this test, I connected a BNC T to the scope 50 ohm input at channel 1.   A 50 ohm cable connected one port of the T, to the 50 ohm output of the SG503 pulse generator. 

If you think about it you can obtain the same information using an edge (not a pulse) and without using a 50ohm termination. The waveforms will look different, but the same information is easily available.

Sub-nanosecond pulses are easy to generate. In my experience, three parallel (74LVC1G14+140ohms) will drive a 50ohm load very cleanly to half the supply voltage with a risetime of, I believe, ~650ps.

A "high" impedance input will have the advantage of a higher amplitude, and the disadvantage of a marginally longer risetime.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: med6753 on July 11, 2016, 02:46:25 am
...
To my simple mind I think this is telling me that the Buffer Board EAROM is defective and after a certain time frame it is dropping data.

In the reading thru the service manual it appears that EXER 02 will read the EAROM data out of both the A5 main board as well as the Buffer Board. Beyond that I'm a little ignorant (and perhaps a little fear of “fail”) as to what I can do with it. I have no experience in dealing with these types of circuits. And I'm not sure if I want to go thru the expense and learning curve to put together an ROM writer and write a new chip. Especially since it appears that this checksum error has no affect on other functions of the scope other than being an annoyance upon power up. So I'm tempted to leave it until it's a total crap out. Which may or may not ever happen. What say the group? Fix it or leave it? I'm open to suggestions.
...
I also had an intermittent EAROM, but mine was on the main board.  The scope would sometimes power up with a checksum error.  I don't recall if it was dependent on how long it was off, but it could have been the same issue since data in the EAROM was being written when front panel settings were changed.

Properly done the EAROM should have been replaced, but I was able to change the supply voltage slightly and I got it to work without failure:

  https://www.eevblog.com/forum/testgear/tektronix-2445-2465-cal-settings-earom-er1400/msg927144/#msg927144 (https://www.eevblog.com/forum/testgear/tektronix-2445-2465-cal-settings-earom-er1400/msg927144/#msg927144)

It may be a long shot, but easy to try.  The supply for the buffer board EAROM (signal OEA35) is connected to the one on the main board, so it's the same zener.

EXER02 is harmless.  You can use it to make a backup copy of the contents in both EAROMs.  Getting the data back in there, however, is another matter.  It would have been nice for them to provide a "write" option in the diagnostics.


Mark, first....I want to publicly thank you for the prior assistance you've given me in getting this 2465 fully functional. It is greatly appreciated.  :-+

2nd, I saw your post in the other thread concerning lowering the voltage to the EAROM and I did wonder if perhaps it would help with mine. So I did some checking but I found a discrepancy in what you did vs what is currently in place and perhaps your memory of what you did 20 years ago is a little fuzzy.

I looked up A5 Board VR2003 and it's currently a 7.5 V Zener. You indicated that you lowered the voltage by 2 volts by installing a 9.1 V Zener. Isn't that actually RAISING the voltage by approx 2 volts? But you are correct. That line (OEA35) does supply the EAROM's on the both the A5 Board and the Buffer Board.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MarkL on July 11, 2016, 01:59:35 pm
Mark, first....I want to publicly thank you for the prior assistance you've given me in getting this 2465 fully functional. It is greatly appreciated.  :-+

2nd, I saw your post in the other thread concerning lowering the voltage to the EAROM and I did wonder if perhaps it would help with mine. So I did some checking but I found a discrepancy in what you did vs what is currently in place and perhaps your memory of what you did 20 years ago is a little fuzzy.

I looked up A5 Board VR2003 and it's currently a 7.5 V Zener. You indicated that you lowered the voltage by 2 volts by installing a 9.1 V Zener. Isn't that actually RAISING the voltage by approx 2 volts? But you are correct. That line (OEA35) does supply the EAROM's on the both the A5 Board and the Buffer Board.
You are most welcome!  I enjoy working on this old equipment and I'm usually looking for excuses to pop the lid off and get out the service manuals.  It's not something I get to do with more modern equipment I use on a daily basis for work.

On VR2003, note that it and CR2004 are used as a dropper from the +42V rail to supply the EAROM.  So, the end result to the EAROM is 42V - 9.1V - 0.7V = 32.2V.  The spec on the ER1400 says 35V +/- 8%, so the minimum happens to also be 32.2V.

I just verified the voltage on my EAROM (between pins 1 & 2) as 32.3V.  With the original 7.5V zener, this would be higher by 1.6V ( = 33.9V).
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: med6753 on July 12, 2016, 12:43:10 am
On VR2003, note that it and CR2004 are used as a dropper from the +42V rail to supply the EAROM.  So, the end result to the EAROM is 42V - 9.1V - 0.7V = 32.2V.  The spec on the ER1400 says 35V +/- 8%, so the minimum happens to also be 32.2V.

I just verified the voltage on my EAROM (between pins 1 & 2) as 32.3V.  With the original 7.5V zener, this would be higher by 1.6V ( = 33.9V).


D'OH  :palm:. You are absolutely correct. It's a dropper circuit from the +42V supply. I think I have a 9.1V Zener in my pile of parts. If not it will be on my next parts order. Gonna give it try and see what happens.  :-+
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: smgvbest on July 13, 2016, 11:31:36 am
Hello,

I have a 2467B that I have a GPIB interface for and I'm kind of stuck.   
It came with a A20 Buffer Board (i believe the correct name for it).   there are connections labeled C/D/E that I can find on the A1 board to connect to but also on the A20 is a 34pin connection that looks like it would go to the A5 Board but there is no 34 Pin connection available on the A5.   there is a 40Pin  my Serial Number is B053273.

So I take it this A20 Buffer Board is not compatible with my Serial Number.

Heres a few pics of my A1, A5 and A20 boards.

To use this GBIP board what am I looking for?   I could not find a A20 board in the service manual or in the option manual unless I'm totally blind

TIA

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: smgvbest on July 13, 2016, 11:45:26 am
More of the images

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: med6753 on July 13, 2016, 12:15:55 pm

To use this GBIP board what am I looking for?   I could not find a A20 board in the service manual or in the option manual unless I'm totally blind

TIA


I can't tell you specifically what you need to get the GPIB going but if you have the correct manuals the A20 Board is the Buffer Board. I have the 2465 options manuals and it shows it very clearly.

Artek Manuals has the 2467B Options Service Manuals on CD for $12.50 USD. If you don't already have that manual I would check it out.

Hope this helps.   
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Orange on July 13, 2016, 02:31:13 pm
Hello,

I have a 2467B that I have a GPIB interface for and I'm kind of stuck.   
It came with a A20 Buffer Board (i believe the correct name for it).   there are connections labeled C/D/E that I can find on the A1 board to connect to but also on the A20 is a 34pin connection that looks like it would go to the A5 Board but there is no 34 Pin connection available on the A5.   there is a 40Pin  my Serial Number is B053273.

So I take it this A20 Buffer Board is not compatible with my Serial Number.

Heres a few pics of my A1, A5 and A20 boards.

To use this GBIP board what am I looking for?   I could not find a A20 board in the service manual or in the option manual unless I'm totally blind

TIA
You need a GPIB board as well, see PDF excerpt
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MarkL on July 13, 2016, 02:37:26 pm
That 40-pin connector on A5 is J4241.

I don't have the 2467B options service manual, but on the other 2465/7 series scopes J4241 goes to the DMM option which is also a 40-pin connector.  A spot check on a bunch of signals on the 2467B J4241 connector shows they're the same as the DMM option pinout.

Without the manual I can't say for sure, but it's probably not coincidence.

That doesn't answer the basic question about your buffer board compatibility, though.

So, you obtained the buffer board and GPIB interface as an add-on?  (I.e., it didn't come with the scope?)

One seller on ebay (Qservice) has a listing for a 2467B GPIB retrofit kit:

  http://www.ebay.com/itm/381550986148 (http://www.ebay.com/itm/381550986148)

It looks like yours and is specifically for serial numbers < B50000.

So, it doesn't look too hopeful, but I agree with med6753 that obtaining the service manual is the next thing to do.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Orange on July 14, 2016, 01:22:52 pm
Hello,

I have a 2467B that I have a GPIB interface for and I'm kind of stuck.   
It came with a A20 Buffer Board (i believe the correct name for it).   there are connections labeled C/D/E that I can find on the A1 board to connect to but also on the A20 is a 34pin connection that looks like it would go to the A5 Board but there is no 34 Pin connection available on the A5.   there is a 40Pin  my Serial Number is B053273.

So I take it this A20 Buffer Board is not compatible with my Serial Number.

Heres a few pics of my A1, A5 and A20 boards.

To use this GBIP board what am I looking for?   I could not find a A20 board in the service manual or in the option manual unless I'm totally blind

TIA
Here is the interconnect diagram, it shows that there is no longer a buffer board in the 2467B (serials > 50000)

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: med6753 on July 15, 2016, 02:14:19 am
Hello,

I have a 2467B that I have a GPIB interface for and I'm kind of stuck.   
It came with a A20 Buffer Board (i believe the correct name for it).   there are connections labeled C/D/E that I can find on the A1 board to connect to but also on the A20 is a 34pin connection that looks like it would go to the A5 Board but there is no 34 Pin connection available on the A5.   there is a 40Pin  my Serial Number is B053273.

So I take it this A20 Buffer Board is not compatible with my Serial Number.

Heres a few pics of my A1, A5 and A20 boards.

To use this GBIP board what am I looking for?   I could not find a A20 board in the service manual or in the option manual unless I'm totally blind

TIA
Here is the interconnect diagram, it shows that there is no longer a buffer board in the 2467B (serials > 50000)


Wow! Those wiley Tek Engineers found a way to combine the Buffer functions on the A5 Board. Great for them but bad for us 30 years later when we are trying to figure out exactly what we have.  :-// 
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: smgvbest on July 15, 2016, 04:45:26 am
Thank you for replying
So the Buffer/GPIB and CTT boards I have will end up on eBay for sale as they do me no good as they are not supported by my serial number.

I do have the full service manual but had trouble understanding the A20 board and relation to my serial number.   This is when I really miss hardcopy.  sometimes it's easier to just have an open manual.



Title: Re: Tektronix 2465B oscilloscope teardown
Post by: med6753 on August 07, 2016, 04:51:06 pm
On VR2003, note that it and CR2004 are used as a dropper from the +42V rail to supply the EAROM.  So, the end result to the EAROM is 42V - 9.1V - 0.7V = 32.2V.  The spec on the ER1400 says 35V +/- 8%, so the minimum happens to also be 32.2V.

I just verified the voltage on my EAROM (between pins 1 & 2) as 32.3V.  With the original 7.5V zener, this would be higher by 1.6V ( = 33.9V).

D'OH  :palm:. You are absolutely correct. It's a dropper circuit from the +42V supply. I think I have a 9.1V Zener in my pile of parts. If not it will be on my next parts order. Gonna give it try and see what happens.  :-+

Today I changed VR2003 from a 7.5V zener to a 9.1V zener. Original EAROM voltage was 35.19V. After the zener change it was 33.19V. Unfortunately I still have the Buffer Board checksum error. So the mod didn't help. It's looking more and more like that chip is on it's last legs. Oh well. I'm going to leave it for now and consider this a completed project.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MarkL on August 07, 2016, 07:41:14 pm
Oh well - sorry the mod didn't work for you.  It was easy enough to be worth a try.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: jscgvnc on August 11, 2016, 08:20:39 pm
Hey guys and gals,

I just got a 2465b, Serial B012202, and so far the only thing wrong is what I've buggered up. I pulled some jumpers out, thinking it was a 4-pin connector, and it's really 2 2-pin connectors. They are J902 and J903 on the High Voltage Supply and CRT drawing 8 of the service manual. I can figure out their numbering system for the pins. Is one the "bottom" or the "top". There seems to be a small arrow printed on the board for those jumper pins, does that indicate the start of the numbering?

I've attached a photo. I didn't take a picture of them before I removed them, so I don't know which way they go on, which I know is a rookie maneuver.

I really don't want to have to pry the whole board off to see if the pins are numbered on the other side. Can anyone help?

Thanks,

Josh
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: guido on August 11, 2016, 11:10:01 pm
There is an arrow on the board. And an arrow on the connector. They need to allign  :)
It looks like one of your connectors is not alligned.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: MarkL on August 12, 2016, 02:37:16 am
The arrow points to pin 1 and an arrow on the connector housing also means pin 1.   It looks to me like you have the orientation right. 

If you want to double check, pin 1 on both J902 and J903 are ground, so you can check for continuity to ground on both pin 1's (cables unplugged).

If your question is which cable is which, you'll have to trace where they go if they're not labeled on the wire.  P902 goes to a coil near the front of the CRT and P903 goes to a coil further back on the neck.

If you have anything wrong with these connectors the scope is not going to blow up, but the beam alignment will be a mess.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: jscgvnc on August 12, 2016, 12:51:10 pm
MarkL,

Thanks for the info. Exactly what I was looking for.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: guido on August 12, 2016, 05:09:33 pm
Looks like the connector/wire was replaced. Not the usuall style with the arrow. Got me on the wrong track.
Google usually is your friend. First hit with 2465b high voltage supply in pictures:

(https://www.eevblog.com/forum/index.php?action=dlattach;topic=5397.0;attach=16699;image)

On this forum  ;D

Note i said usually. A two pin connector to the pcb on the HV supply in the 7603 has been swapped between revisions. Including the cable (from cross wired to straight or vzv). If you do not swap the cable and pcb at the same time it doesn't work if you have two versions of the board/cable.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on August 15, 2016, 03:31:19 am
Just realized that I still have the close-up photo on those J902 and J903 connectors orientation, and it's arrow (or pin 1) markings, put here as a reference for future owners that may experience the same problem again.  ;D
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: jscgvnc on August 15, 2016, 01:12:59 pm
Thanks guido and BravoV, very helpful!

I had made the leap that they had replaced the cable and therefore had different connector markings, but this is great info. I appreciate it.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: GasGas on August 22, 2016, 02:58:36 pm
Hello.

This is my first participation in the Forum. I just buy a 2467B to 2465B to my company. I still have it in my hands, which happened soon, because I need to go search it in another state. Well, I want to accomplish the exchange of his Nvram because the photos I received from the seller, the date of Nvram is 1991 .... here in Brazil I am not finding the Nvram with DS1225Y-200 specification, only DS1225Y- 150.

Could someone tell me if this DS1225Y Nvram-150 can be used? I want to be with everything at hand at the time of exchange of the same.

Sorry for bad english, I'm using Google Translate.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on August 22, 2016, 03:17:18 pm
Could someone tell me if this DS1225Y Nvram-150 can be used? I want to be with everything at hand at the time of exchange of the same.

The DS1225Y-150 will work fine; it is just a little faster than the DS1225Y-200.  The DS1225AD is the replacement for the DS1225Y and can be used also.

Make sure to buy the DS1225Y or DS1225AD from a reputable seller and not on Ebay; they are commonly counterfeited.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: GasGas on August 22, 2016, 04:19:19 pm
Thanks for the quick response.

About where to buy Nvram, this is a big problem for me here in Brazil, because there are no reliable distributors like Digikey and others.

One way to check if the Nvram to buy in Brazil will work, would record data from Nvram posted several users in this topic? I have a TL 886. recorder If you can record it on the TL886 is likely to work after being installed in scope, right?

Thank you.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on August 22, 2016, 09:01:36 pm
A TL886 programmer is a good start.

The major problem is counterfeiters remarking old Dallas/Maxim NVSRAMs with current date codes and selling them so while programming the NVSRAM might indicate that it works, it may not last long because the battery is almost dead.  NVSRAMs are a good target because individually they are expensive.

So you do not have *any* distributors for Maxim's products?  I tried looking up their distributors for Brazil but Maxim's web site is broken; I cannot even order parts directly from them or contact sales.  I have always tried to avoid them because of poor support and it seems they are continuing that tradition.

If it helps, the ST Microelectronics M48Z18 or M48Z58Y NVSRAMs could also be used.

Maybe someone in the forum could recommend a reputable Ebay seller for these parts.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: GasGas on August 23, 2016, 12:00:06 am
I am very grateful for the help. I'll probably end up importing the Nvram via Digikey, however sending so are U$ 40.00 + taxes in Brazil.  :-[ :-[ :-[

You are right about buying a fake Nvram with the old manufacturing date, which will have its useful life much less than expected, however my biggest fear is loss of data at the time of withdrawal of the same, as in some cases reported in this topic. I will take care of maximum, with the help of Hakko 474 station.

I will copy all data via Exer 02 even without making sure someone could manually enter the data into the new Nvram.

I look forward to put the hand in the new scope, so that I could verify via Exer 05 it has only 1193 hours of use and 867 power on ... 8)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on August 23, 2016, 04:25:49 am
When I replaced the NVSRAMs in my Tektronix 2440, I was not able to read the data even though I did everything correctly.  It is possible that my programmer had problems with them but it worked fine on the replacements that I used.  Luckily doing the external calibration on a 2440 is much easier than on a 2465 series oscilloscope and I was prepared for that.

I now have a 2445B to worry about but I have not inspected it yet to check the NVSRAMs.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: GasGas on August 23, 2016, 02:04:13 pm
It is a worrying situation know that Nvram this in his last days and not be sure that I will be successful in your replacement. I do not have the necessary equipment to perform a recalibration (basically I have an HP 3324A signal generator and DMM Fluke 189).

I will have positive thinking that nothing goes wrong at the time of exchange ...

Thanks for everything. :-+
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on August 23, 2016, 04:39:41 pm
Now I am looking into the same thing for my 2445B.

The currently produced 8k x 8 STK11C68 should work as a direct replacement but its SOIC package will require an adapter.  The older but discontinued 32k x 8 STK16C88 should also work and I have a couple in DIP packages so I may try one of these first.  The STK16C88 is 32k instead of 8k but the pinouts are compatible; the extra two address lines need to be permanently tied to ground or Vcc.

These parts are made by Cypress Semiconductor and are SRAM memories backed up by EEPROM memory so they have no batteries to run down.  I used a pair of STK16C88s to replace the DS1230ABs in my 2440.

Unfortunately you will probably have just as much of a problem if not more trying to find these parts.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: GasGas on September 14, 2016, 01:03:21 am
As I had commented seek 2467B he had bought, for it was necessary to conduct a 1300Km travel round-trip, I was afraid that it was damaged in transit by using a carrier service.

When I arrived at the residence of the former owner, I did a quick test and everything seemed to function normally. When I arrived at my house, the first offers was to change the 110V voltage selector switch to 220V, which was promptly done. Well, after that I called the same and my joy did not last 30 seconds .... this was the time to listen to the sound of something frying and witness a beautiful cloud of smoke coming from within the scope .... I wanted to cry after an exhausting trip down a lot of rain witness that was very disappointing ....

The other day, I opened the scope to see what had happened and the first offers was to remove the power supply of your site and survey the damage. All it took was a quick visual inspection to realize that the film capacitor 68nf x 250V was broken out, which made me more relaxed because provavelmete replacement and more few components establish a fully functioning scope. As was already aware of the need for NVRAM and not finding any in Brazil dated back manufacturing to 2010 I decided to book with NVRAM socket, and all capacitors for Reconstruction the inverter board, power supply and A5 board, I also did not find quality electrolytic capacitors in Brazil. I made the purchase in the online store Digikey and requested shipping via Fedex which took exactly 7 consecutive days, yesterday received the box with all components:

(http://i1202.photobucket.com/albums/bb376/gasgas08/20160912_170741.jpg)

I started the exchange by film capacitors and you can see small cracks in the capacitor body what I believe is the cause for it to absorb moisture over the years:

(http://i1202.photobucket.com/albums/bb376/gasgas08/20160912_181606_1.jpg)

After finishing the exchange of film capacitors, the next step was the subsitution of electrolytic capacitors, which did not fail to cause surprises, as many original electrolytic capacitors (Nichicon Green) had a lower ESR than the new Panasonic and Nichicon...

Original Nichicon:

(http://i1202.photobucket.com/albums/bb376/gasgas08/20160912_173749_1.jpg)

New Panasonic:

(http://i1202.photobucket.com/albums/bb376/gasgas08/20160912_173818_1.jpg)

The capacitors showed fullness at the bottom of the body were changed, although its capacitance and ESR were perfect when compared to new:

Original:

(http://i1202.photobucket.com/albums/bb376/gasgas08/20160912_183348_1.jpg)

New:

(http://i1202.photobucket.com/albums/bb376/gasgas08/20160912_183602_1.jpg)

The only original capacitor which really had a high ESR was this 3.3 UF 350V.

Original:

(http://i1202.photobucket.com/albums/bb376/gasgas08/20160912_180004_1.jpg)

New:

(http://i1202.photobucket.com/albums/bb376/gasgas08/20160912_180036.jpg)

All capacitors replaced:

(http://i1202.photobucket.com/albums/bb376/gasgas08/20160912_224053.jpg)

After the exchange made the scope back to life!

(http://i1202.photobucket.com/albums/bb376/gasgas08/20160912_224022.jpg)

Now came the part that caused me concern, which was the exchange of NVRAM because lí some reports on this topic failures and loss of data at the time of replacement. Before replacing the NVRAM, I filmed with my phone all andress via Exer from the service menu. Not leaving anything to do, I removed the old NVRAM with 1991 manufacturing date and copied the data from it using a TL recorder 886 and after that the data was copied to the NVRAM with 2016 manufacturing date, which was embedded in a socket to intervene in a very distant future!

Old NVRAM:

(http://i1202.photobucket.com/albums/bb376/gasgas08/20160913_102753.jpg)

New NVRAM:

(http://i1202.photobucket.com/albums/bb376/gasgas08/20160913_102656.jpg)

This tool is essential for the success of the service:

(http://i1202.photobucket.com/albums/bb376/gasgas08/20160913_104335.jpg)

Very happy with my 2467B with very little use and no burn mark in the CRT!

(http://i1202.photobucket.com/albums/bb376/gasgas08/20160913_114007_resized_1_1.jpg)

(http://i1202.photobucket.com/albums/bb376/gasgas08/20160913_114019_resized.jpg)

Thanks for the help and information  :-+ :-+

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: cheeseit on October 17, 2016, 08:46:25 pm
This is a great thread - thanks to you all  for contributing with so much valuable information and knowledge! I've read more or less everything in the last few days and have bookmarked plenty of further reading but I haven't yet really gone beyond this thread.

Quick question while I await the arrival of a 2465B, which I bought for €53/$60 (my first Tek scope - yay), that is supposedly defective. The seller stated that it arced in either the tube or the HV-supply but was otherwise in perfect working condition and in calibration until that day. I know that it is kinda hard to speculate on without more information, and he did mention that a new tube might be needed which seems plausible, but any ideas what might be the source of this arcing?

I know nothing about its vintage, serial or what, if any, repairs have been done to it. The seller seems very honest, and even turned down several bids that were a lot higher since I was the first, and I don't believe that he has even checked what it might be so I'm hoping it might be simple but fear that it could be expensive.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: med6753 on October 18, 2016, 01:02:55 am

Quick question while I await the arrival of a 2465B, which I bought for €53/$60 (my first Tek scope - yay), that is supposedly defective. The seller stated that it arced in either the tube or the HV-supply but was otherwise in perfect working condition and in calibration until that day. I know that it is kinda hard to speculate on without more information, and he did mention that a new tube might be needed which seems plausible, but any ideas what might be the source of this arcing?

The chances of the CRT being the source of the HV issue is rather remote, unless it's been subject to damage or shock. The best way to find the source of the arcing is to remove the case, darkened room, and look for the source. But keep your hands behind your back.  :P
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on October 18, 2016, 03:08:41 am
The seller stated that it arced in either the tube or the HV-supply but was otherwise in perfect working condition and in calibration until that day. I know that it is kinda hard to speculate on without more information, and he did mention that a new tube might be needed which seems plausible, but any ideas what might be the source of this arcing?

The AC line safety capacitors may have failed which is a common and easily repairable problem.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: tggzzz on October 18, 2016, 12:31:48 pm
The seller stated that it arced in either the tube or the HV-supply but was otherwise in perfect working condition and in calibration until that day. I know that it is kinda hard to speculate on without more information, and he did mention that a new tube might be needed which seems plausible, but any ideas what might be the source of this arcing?

The AC line safety capacitors may have failed which is a common and easily repairable problem.

Yes, but some of those capacitors are "hidden"; in the last week I've "done" a 2465 and 2445B, and while the "hidden" caps hadn't failed, they were crazed. FFI, see http://www.condoraudio.com/wp-content/uploads/Projects/Tektronix-2465B-Oscilloscope-Restoration-Repair.pdf (http://www.condoraudio.com/wp-content/uploads/Projects/Tektronix-2465B-Oscilloscope-Restoration-Repair.pdf)

And don't forget the infamous control board caps, q.v.

The HV supply arcing may simply be neons flashing.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on October 18, 2016, 05:25:54 pm
The seller stated that it arced in either the tube or the HV-supply but was otherwise in perfect working condition and in calibration until that day. I know that it is kinda hard to speculate on without more information, and he did mention that a new tube might be needed which seems plausible, but any ideas what might be the source of this arcing?

The AC line safety capacitors may have failed which is a common and easily repairable problem.

Yes, but some of those capacitors are "hidden"; in the last week I've "done" a 2465 and 2445B, and while the "hidden" caps hadn't failed, they were crazed. FFI, see http://www.condoraudio.com/wp-content/uploads/Projects/Tektronix-2465B-Oscilloscope-Restoration-Repair.pdf (http://www.condoraudio.com/wp-content/uploads/Projects/Tektronix-2465B-Oscilloscope-Restoration-Repair.pdf)

And don't forget the infamous control board caps, q.v.

The HV supply arcing may simply be neons flashing.

Those paper capacitors all seem to be universally bad having either physically degraded do to age like you describe or shorted out.  I think they have been changed in my 2445B but I have a few junked 22xx main boards where they are crazed and I do not bother pulling them for spares.

The reason I suggested them is that they do not always go out with a bang and their arcing may have been mistaken for a high voltage problem while not disabling the oscilloscope.  They are just something else to check.

I do not know of any reason they cannot be replaced with modern film or ceramic safety capacitors and of course they can always be derated.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: tggzzz on October 18, 2016, 06:50:22 pm
The seller stated that it arced in either the tube or the HV-supply but was otherwise in perfect working condition and in calibration until that day. I know that it is kinda hard to speculate on without more information, and he did mention that a new tube might be needed which seems plausible, but any ideas what might be the source of this arcing?

The AC line safety capacitors may have failed which is a common and easily repairable problem.

Yes, but some of those capacitors are "hidden"; in the last week I've "done" a 2465 and 2445B, and while the "hidden" caps hadn't failed, they were crazed. FFI, see http://www.condoraudio.com/wp-content/uploads/Projects/Tektronix-2465B-Oscilloscope-Restoration-Repair.pdf (http://www.condoraudio.com/wp-content/uploads/Projects/Tektronix-2465B-Oscilloscope-Restoration-Repair.pdf)

And don't forget the infamous control board caps, q.v.

The HV supply arcing may simply be neons flashing.

Those paper capacitors all seem to be universally bad having either physically degraded do to age like you describe or shorted out.  I think they have been changed in my 2445B but I have a few junked 22xx main boards where they are crazed and I do not bother pulling them for spares.

The reason I suggested them is that they do not always go out with a bang and their arcing may have been mistaken for a high voltage problem while not disabling the oscilloscope.  They are just something else to check.

Those directly across the mains in my 2465 "expanded rapidly" after 30s, and one of the associated series resistors disintegrated - leaving carbon across the board and the PCB's glass fibre weave exposed without prepreg :)

Quote
I do not know of any reason they cannot be replaced with modern film or ceramic safety capacitors and of course they can always be derated.

I just followed the information in the pdf I referred to, replacing them with X*/Y* caps as appropriate.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: cheeseit on October 18, 2016, 08:22:50 pm
The chances of the CRT being the source of the HV issue is rather remote, unless it's been subject to damage or shock. The best way to find the source of the arcing is to remove the case, darkened room, and look for the source. But keep your hands behind your back.  :P

According to the seller he just powered it up and somehow experienced arcing, that is all I know for the moment, so I don't think it was damage or shock. A good idea I hadn't thought of with the darkened room, and good advice too. :)

The AC line safety capacitors may have failed which is a common and easily repairable problem.

That was my first thought too but I shuck it off as wishful thinking so I am glad that you suggest this. Those will be the first I examine after having looked for anything obvious.

The HV supply arcing may simply be neons flashing.

Flashing as in worn out? As far as I know the scope does not work anymore, could these cause that if they are broken and/or kill other components?


Thanks all, you've raised hopes that it could be simple and less expensive to repair. I will surely post when I get it and most likely seek your advice and help again. :)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: tggzzz on October 18, 2016, 08:30:36 pm
The chances of the CRT being the source of the HV issue is rather remote, unless it's been subject to damage or shock. The best way to find the source of the arcing is to remove the case, darkened room, and look for the source. But keep your hands behind your back.  :P

According to the seller he just powered it up and somehow experienced arcing, that is all I know for the moment, so I don't think it was damage or shock. A good idea I hadn't thought of with the darkened room, and good advice too. :)

The AC line safety capacitors may have failed which is a common and easily repairable problem.

That was my first thought too but I shuck it off as wishful thinking so I am glad that you suggest this. Those will be the first I examine after having looked for anything obvious.

The HV supply arcing may simply be neons flashing.

Flashing as in worn out? As far as I know the scope does not work anymore, could these cause that if they are broken and/or kill other components.

They prevent the cathode-grid voltage from becoming dangerous. Normally that only happens after the power is turned off. Some Tek scopes also have a neon in the main PSU that flashes continually, but IIRC the 2465 doesn't.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on October 18, 2016, 08:45:21 pm
Flashing as in worn out? As far as I know the scope does not work anymore, could these cause that if they are broken and/or kill other components.

They prevent the cathode-grid voltage from becoming dangerous. Normally that only happens after the power is turned off. Some Tek scopes also have a neon in the main PSU that flashes continually, but IIRC the 2465 doesn't.

Exactly, they are used as zero leakage surge suppressors to protect various elements of the CRT and sometimes other circuits.  They usually only flash when power is first applied or when it is removed.  I have never seen them go bad.

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: cheeseit on October 20, 2016, 11:28:23 pm
My 2465B has arrived. Frontcover but no probes, manuals or CRT filter. It looks great and has no nicks or scratches, is only slightly dirty and the BNC connectors could use a bit of polishing. A bit of dust inside in places but nothing that a bit of compressed air can't remove.

1989 vintage, all through hole and the serial is 134xxx and is from Guernsey in the Channel Islands. GPIB and TV trigger options.

No RIFA caps on the regulator board and no leaking or bulging caps or anything obvious burned or broken. The battery date code is 0589 and measures 3.696V at the terminals so cal data should be safe for now, right? I find that incredible for a 27 year old battery?

Still haven't turned it on an and worryingly, something rattles when I turn it around. I'm pretty sure it's from within the CRT metal shield in the wide part behind the front of the tube - a loose lamp? Is there anything in there that could short from a lamp rattling around and explain what the seller called arcing..?

(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=263876;image)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: cheeseit on October 23, 2016, 02:47:45 pm
Well, of course it wasn't a lamp and there was no way one of those could come loose and rattle between the CRT shield and tube. But something is in there. I tried to make sure that it was lodged towards the front of the tube, away from any connections, and turned the scope on.
Good news is that it boots but bad news is that there is nothing on the screen and - worse - that something sure arcs in there somewhere. I only had it on a few times for 10-15 sec. max but the arcing started a few seconds into booting, with what sounded like an arc welder and the strong smell of ozon.
Unfortunately no blue glow to see anywhere through holes, between boards and so on, not even in a darkened room. I noticed though that the fuse on the HV-board started glowing the instant the arcing started.

Next step is to pull the A9-board and CRT out and see if I can locate where it is - there just has to be signs with that much noise and ozon - and get whatever is rattling out. Ideas, suggestions and advice is most welcome. :)

I'm unsure if I should start my own thread or continue in this one?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on October 23, 2016, 03:10:16 pm
Cheeseit, sorry to hear the progress, please just continue in this thread in you don't mind.

Curious as well how will this end up.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: med6753 on October 23, 2016, 06:56:03 pm
Agreed, keep posting in this thread. It has become a "catch all" thread for 24XX issues in one convenient location.

Can't offer any advice at this point until you find out what the rattle is and you inspect the HV board. 
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: cheeseit on October 24, 2016, 08:51:54 pm
Well, there's your problem.. And, sometimes you win, sometimes you lose.

(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=264741;image)

Good news; I found the source of the rattling, and the source of the arcing.. Bad news; the tube is very much broken and it was two pieces of glass.  |O I kinda knew it as I was pulling off the CRT connector at the back since the tube was moving around as I was prying it off.

How are my chances that nothing else is damaged from this broken tube? Everything else looks totally undamaged and in excellent condition. After all, it has been turned on with the tube in this state.

I was contemplating posting images of the boards but decided that there is plenty throughout the thread. Let me know if you want images of something.

I have been looking at this sellers (http://stores.ebay.co.uk/Qservice-tech-shop/Tektronix-CRT-/_i.html?_fsub=4841171&_sc=1&_sid=75705061&_sop=3&_trksid=p4634.c0.m322) ebay shop and they have a lot of good stuff, and very good feedback. I've found a few other tubes on ebay, but haven't yet decided if I should wait for a for-parts scope which may have a bad and/or burned tube, or just buy this (http://www.ebay.co.uk/itm/Tektronix-154-0850-01-CRT-2445-2465-2445A-2465A-2445B-2465B-770662-/141862702361?hash=item2107ad0d19) which would cost me €134/$146 including shipping. It would still be a cheap 2465B in the end, if nothing else is damaged.

Any other sources for a good tube or for-parts scope? Or anyone that has a suitable tube or donor scope? Has to be within EU because of tax and shipping.

Tubes from 2445, 2445A, 2445B, 2465, 2465A, 2465B,2430, 2430A, 2432, 2432A and 2440 are all suitable, right?

I don't need this scope now but I really want it now. It would also be the fastest scope in my possession. ;) A good thing about waiting for a donor scope is having spare parts/boards if something else is broken. Or parts to sell once this one works - that could perhaps pay for the majority or the whole thing in the end.

To end on a positive note, this does give me time to order caps and recap the A5/A2A1/A3 boards. :)


Edit: I think the seller must have known, since he mentioned the tube might need replacing, and suspect that he dropped it. Oh well, he did warn me..
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: tggzzz on October 24, 2016, 09:04:24 pm
Well, there's your problem.. And, sometimes you win, sometimes you lose.

How are my chances that nothing else is damaged from this broken tube? Everything else looks totally undamaged and in excellent condition. After all, it has been turned on with the tube in this state.

Been there, done that, ended up with: https://entertaininghacks.wordpress.com/2016/03/09/rescuing-a-broken-tektronix-465-crt/ (https://entertaininghacks.wordpress.com/2016/03/09/rescuing-a-broken-tektronix-465-crt/)

Quote
Tubes from 2445, 2445A, 2445B, 2465, 2465A, 2465B,2430, 2430A, 2432, 2432A and 2440 are all suitable, right?

See http://www.reprise.com/host/tektronix/reference/crt.asp (http://www.reprise.com/host/tektronix/reference/crt.asp)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: med6753 on October 25, 2016, 05:49:40 am
Wow, that's a hell of a mess. Obviously the seller did drop it, or it fell off a bench. I'm sure he knows exactly what happen and doesn't want to admit it. And it's hard to say if there's other damage until after you install a replacement CRT.

But it is neat to see Tek's innovative and at the time leading edge process that combined a ceramic bell of the CRT with the glass gun and faceplate. As far as I know no else attempted that. But I did read somewhere that Tek shared some of their CRT technology with Sony which directly influenced the design of the Trinitron CRT.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on October 25, 2016, 07:39:37 am
But it is neat to see Tek's innovative and at the time leading edge process that combined a ceramic bell of the CRT with the glass gun and faceplate. As far as I know no else attempted that. But I did read somewhere that Tek shared some of their CRT technology with Sony which directly influenced the design of the Trinitron CRT.

Tektronix started using ceramic CRT envelopes in 1962 with the 561A (http://w140.com/tekwiki/wiki/561A) and this also allowed marking the graticule on the inside removing parallax error.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on October 25, 2016, 05:56:22 pm
What a bummer  |O, really sorry to hear that cheeseit.  :'(

Please, once you have the replacement tube, share your journey here please, that will be really interesting.

PS : The broken tube, have you dump it yet ? I really love to own it if you're going to toast it, as the gun and metal parts inside looks artistic, at least to my eyes. I will pay for the shipping cost.

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: tggzzz on October 25, 2016, 06:23:25 pm
... the gun and metal parts inside looks artistic, at least to my eyes.

And mine.

I was lucky to have access to a glass bandsaw. If I hadn't I would have had to experiment with heated nichrome wires.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: cheeseit on October 25, 2016, 08:16:48 pm
Been there, done that, ended up with: https://entertaininghacks.wordpress.com/2016/03/09/rescuing-a-broken-tektronix-465-crt/ (https://entertaininghacks.wordpress.com/2016/03/09/rescuing-a-broken-tektronix-465-crt/)

I had seen that before and it was the second thing that came to mind after pulling only the top half out of the scope, right after "#&!$ hell". :D It looks awesome!

I've been emailing with the seller and he insists that it was not dropped and he does sound sincere. He called it his dear scope and talks about how he would hate to see it trashed and that he really hope I will try to find a replacement tube. I don't know, seems implausible that it would snap in two without an external force so maybe it happened in transit and something else is arcing too.. :-DD Whatever it is, it needs a new tube now so time will tell if it holds any other surprises.

Such a tube is a technical marvel IMHO and deserves to be displayed, though SWMBO had the ".. yes, very cool.."-look on her face when I showed her. ::)

PS : The broken tube, have you dump it yet ? I really love to own it if you're going to toast it, as the gun and metal parts inside looks artistic, at least to my eyes. I will pay for the shipping cost.

I feel the same about its looks so I hope you can find another tube somewhere. :) Any ideas for making something of the envelope funnel? And sure, I will update once I make some progress.

----

I didn't realize that the tube I linked to was on sale and that the sale ended a few hours ago. So, having spent some time searching for scopes and tubes that was reasonably priced I wrote the seller asking if there was a chance that I could get the 12% off sale price. There was and the tube will be on its way in a couple of days. They say it is an 8 on a scale from 0 (dead) to 10 (brand new) so I figured that it was worth it, especially considering the 30-day warranty. The seller even gave me a 15% discount instead.
Now I just need to decide whether to try the tube in the scope in its current condition, or order new caps and recap it first. I'm leaning towards testing it before recapping, in case something else is damaged.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: cheeseit on November 07, 2016, 07:51:28 pm
My new tube has finally arrived and is still in one piece. Qservice (http://www.qservice.eu/default.asp) had packeged it real good using loads of bubble wrap, foam and tape. It came in a cardboard box with British American Tobacco Group logos. Wonder if that triggered an inspection or x-raying along the way.. ;D
(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=268441;image)

Date code is from week 15 in 1993 and it looks good, with no soot but that could of course just have been cleaned off. I trust the seller though and hope it is as good as the service he provided.
(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=268443;image)

I have decided to just recap it before installing the tube as it seemed likely that the only problem was the broken tube. I ordered caps from Mouser late last week which is scheduled to arrive tomorrow so hopefully this lovely scope will be up and running soon once time permits. Should be later this week or the next.

This is my first time replacing a CRT but I'm guessing that I will likely have to do some or all of the adjustments outlined in the "CRT Adjustments"-section of the SM, right?


Edit: this is the old tube, disregard the light specs and what looks like (and is) a brush stroke. That Lichtenberg-looking burn, does that perhaps indicate that the tube was powered when it had its catastrophic failure?
(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=268447;image)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on November 07, 2016, 10:08:54 pm
This is my first time replacing a CRT but I'm guessing that I will likely have to do some or all of the adjustments outlined in the "CRT Adjustments"-section of the SM, right?

Yes and the horizontal and vertical deflection will probably need to be adjusted as well.  The transient response may be affected but if you do not have a suitable signal source, leave it alone.

Quote
Edit: this is the old tube, disregard the light specs and what looks like (and is) a brush stroke. That Lichtenberg-looking burn, does that perhaps indicate that the tube was powered when it had its catastrophic failure?

That is what happens when debris gets lose inside the CRT envelope (no surprise here) and contacts the phosphor which is very delicate.  It is a bad idea to move or store CRTs face down.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: BravoV on November 08, 2016, 03:24:02 am
cheeseit, readying pop corn to watch your journey, please share it here along with photos, thanks in advance.  :popcorn:  :clap:
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Fateh Singh on November 10, 2016, 05:00:30 pm
I have been reading the messages on this topic and find them enlightening.
On my own machine -2465B- I have  changed the capacitors as already advised by many experts here, and has the supply
voltages are under specs. For a few days , I was confounded by  very high voltages on all lines, when PSU was powered outside
the machine. Then somewhere, I read that the supplies have to be loaded to be tested. On loading the supplies settled OK.
Now, the machine has the following problems-  It shows   Fail Test 05 -44.  Presumeably,  the DAC312 and the Comparator 311 on A5 has something wrong.
The 311- pin 7 output shows fluctuating 0.8V when the test is looping.  Grid bias is active. Focus is acive. Intensity pot has no effect. Beam find brings the beam into a small rectangle in the screen center. Otherwise the beam is off screen with only spots on screen. I will continue the search for faults, because i want this wonderous machine to help me in my many projects.
Kindly help with your questions and suggestions. I would like to post a small video of what the screen looks like, but just now, i dont know how.
Many thanks .
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: med6753 on November 11, 2016, 01:37:58 am
Now, the machine has the following problems-  It shows   Fail Test 05 -44.  Presumeably,  the DAC312 and the Comparator 311 on A5 has something wrong.

If this fail occurred after you replaced the caps and reassembled the scope go back and check the ribbon cables that plug on the underside of the top plate. It is very easy to plug them one pin off or they aren't fully seated. We've all done it and it causes those trigger level fails.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Fateh Singh on November 11, 2016, 02:49:36 pm
The ribbon cable is on A5 and it is going to many front panel switches. Did you mean this? It seems very secure. I have not touched it.
I have another scope, and will look into the signals from Comp311, and will revert. Meanwhile , the status quo. Error test 05  44.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on November 11, 2016, 08:04:45 pm
Just as a double cre you positive the voltages are in spec and you have checked for ripple using another scope. Can do funny things when not in spec.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Fateh Singh on November 12, 2016, 10:50:06 am
I am checking with  TDS7104- dig. scope- using it first time. The trace appears a bit noisy- unlike smooth lines in analog scopes.
Supplies + _5V, +_15V appear OK. 42V and 87V  not seen yet.
On A5 board  Test pin wave forms  1 , 2 , 4  appear OK.  no. 3 on U2540 hex inverter pin 10 , is not there ( remains high ) pin 11 is remains low.
So this chip is innocent.
The comparator 311, appears to give out on pin 7-  some pulses longer than others.Why?
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on November 12, 2016, 11:12:36 am
What do you mean the 42v and 87v are not seen?. Are the voltages not present or you haven't measured.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Fateh Singh on November 13, 2016, 10:12:43 am
Mr Bryan,  I have checked the 87V and 42V supplies with scope. They look OK. DMM measures only 15 mv ripple.
On checking the high voltage A9 card- I find an anamoly. The sinewave oscillation  on Pin7 ,T1970- is not a steady amplitude
+_150V AC.  Its amplitude is modulated- the oscillation builds up and dies down.Each cycle is 5-6 waves. The behavior is the same at  pins 5 and 6.
Because the oscillator is under feedback control with U1956, trying to stabilise -1900V- the IC pin7 has the same modulation at low amplitude.
R1973 is listed as 16K, but actually it was 120K. The layout seems different here, and i am trying to see if any C or R is open /short/out of specs.
My suspicion is on U1956- dual op amp. Its supplies are ok.    -300V supply from doubler fed by pin 7 T1970 is OK- possibly due to filtering
and low load. But this behavior from pin7 must be doing funny things to Control grid voltage and the -1900 V cathode bias.
Thanks for your interest in my woes.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on November 13, 2016, 10:32:23 am
Fateh:  Do you have the comprehensive service manual for the scope. Sounds like there is some issues with the scope and the A9 board is definitely a area that I am not familiar with. I can send you a copy if you do not have one. You may want to join the Yahoo group Tekscopes. This is where all the experts in teak scopes hang out, if they can't help no one can<g> Takes a couple days to join as the memberships are moderated.

https://groups.yahoo.com/neo/groups/TekScopes/info (https://groups.yahoo.com/neo/groups/TekScopes/info)

Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Fateh Singh on November 13, 2016, 12:15:53 pm
Bryan, I have one downloaded copy with me- and I have all circuit schematics in A3 and A2 sizes.
I am reasonably good at trouble shooting electronic equipment. It is my hobby and my profession now.
We are designing an EV motor and and Inverter. Stuck with the inverter, that requires 4 isolated 20 V /0.5A
supplies. Hence the requirement of good quality Oscilloscopes.
Please send your copy of the service manual by mail-  fs_monder@yahoo.com.

Many thanks.
Fateh
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on November 14, 2016, 10:27:21 am
E-mail sent
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Fateh Singh on November 15, 2016, 06:28:02 am
Bryan,

We have got it RIGHT, after much hair splitting. The error message  Fail  Test 05  44   passed after change R2013. I dont know stable or accurate
that is.  The HV control system loop oscillation, went away,  after some prying  about U1956. I tried putting another capacitor across pins 1 and 2 . No change except a little lower modulation frequency.  Possibly, some dry solder point got set right.

Now, all four channel traces are on screen , and they can be moved about. Intensity control OK. Focus OK. Checking calibration can wait.
Replacing electrolytics on A1 card can also wait. It looks like a difficult maneuver just  now. May be NV RAM data transfer to another compatible
chip later on. Breathe easy now.

Thanks everybody here, especially about clearing doubts about DAC functioning.

Fateh
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Bryan on November 15, 2016, 06:45:49 am
That is good news that you got it fixed, or at least hope so. One thing I would do as a priority is get the Dallas NVRAM changed sooner than later or risk losing your calibration data. The battery on the chip is probably close to 25-30 years old by now. Lot's of threads on how to replace.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: cheeseit on November 15, 2016, 09:40:37 pm
It's alive! No more arcing and now with squiggly lines on the tube! ;D
(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=270676;image)

Apart from the missing adjustment everything seems to work as far as I can tell. (?) The image looks a bit more fussy than IRL but it definitely needs adjustment - I assume that it is possible to adjust it to a much sharper image? ATM this is the best I can achieve using the front panel adjustments.

The PS has been recapped and I replaced the single electrolytic and the fuse on the HV-board. Two 15R resistors (R1010 and R1019) on the regulator board were replaced with beefier ones. One measured open and had visible cracks, and the other measured 68K and had tiny scorch marks, both out of circuit.

Handling and installing the tube was a bit scary since this is the most expensive single part I have ever replaced, and of course, because of the fragile glass. The tube also didn't line up to the holes in the shield as well as the old one did. The ground pin was so crooked that it was impossible to use so I had to pull the tube out again and straighten the pin with flat nose pliers. I took great care not to bend it and just hope that I didn't damage the seal but it was unfortunately necessary.

No error codes on boot and the battery is healthy at 3.56V measured on the SRAM supply pins so calibration is safe for the time being. I already bought a new battery and will be replacing the current one. 15592 hours on and 2619 power cycles logged.

I'm not sure how to proceed with the adjustments but will study the relevant parts of the SM and try to figure out what exactly needs to be done and what my options are, given the equipment I have and my limited budget. I will return once I make further progress and/or if (when) I need help. Thanks so far. :)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: tggzzz on November 15, 2016, 11:14:09 pm
I'm not sure how to proceed with the adjustments but will study the relevant parts of the SM and try to figure out what exactly needs to be done and what my options are, given the equipment I have and my limited budget.

Congratulations, and that's the right attitude :)

I presume you replaced those blasted (pun intended) mains filter caps.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: cheeseit on December 13, 2016, 09:39:17 pm
I was searching for higher bandwidth probes for my 2465B above and ended up buying another (working) 2465B on my local craigslist. :D The seller obviously didn't really know what he was selling since his reply to me asking for probes was "please explain what probes are and where I can find them". :P Turned out that it included four P6137 400MHz probes and a single P6105A 100MHz. He also had a manual, quick start guide and a few other bits. He was asking for €270, I courageously (since others were interested too) offered him €148, and got it for €161. Total cost including shipping €180, which to me is a score considering that sold listings on ebay shows the P6137 selling for about €60 a piece plus shipping. >:D

This is what I got:
(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=277824;image)

It looks like it has been stores upright somewhere dirty, or for a very long time. I know that it is trivial to reset but only 3454 hours on and 658 power cycles so I'm hoping that it has just been stored for a long time. Perhaps the inside will give some clues. The three probe instruction sheets I got have revision dates from 1991 to '93 so the scope likely is from this period.
All the probes appear to work. The tube has no burns and is very bright. The 2nd and 4th channel (I think) did show a bit of noise when the scope was cold but that went away after warming up. The readout and traces shimmers a tiny bit randomly from time to time. Otherwise everything appears to work fine but I haven't yet done much testing.
(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=277828;image)

(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=277826;image)

I will open it up tomorrow and see what it looks like inside and what needs to be done but PSU and A5 is likely to need work I would guess. I seem to recall that recapping the PSU has solved issues similar to the shimmer I'm seeing. I'll post once I have opened it and had a look around. :)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: med6753 on December 13, 2016, 11:13:53 pm
That is one heck of a good score!  :clap: :-+
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: David Hess on December 14, 2016, 12:34:12 am
I got similar deals on a Tektronix 2440 and 7854 which apparently sat in storage for many years and were in excellent condition.  Later I hunted down a front cover for the 2440 so it remains clean and protected.

The 2nd and 4th channel (I think) did show a bit of noise when the scope was cold but that went away after warming up.

Warming up usually results in better performance from aluminum electrolytic capacitors so this might indicate that they are at the end of their useful life.

I am fussy on exactly which 2465 series oscilloscopes had problems with leaky surface mount aluminum electrolytic capacitors but I do not think the early and late ones did but it is still worth checking.

Quote
The readout and traces shimmers a tiny bit randomly from time to time. Otherwise everything appears to work fine but I haven't yet done much testing.

Check to see if this is just an artifact of the beam multiplexing needed to display the readout by disabling the readout.  Sometimes the readout will momentarily synchronize with the sweep to produce visible artifacts.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: razberik on December 14, 2016, 08:35:18 am
The seller obviously didn't really know what he was selling since his reply to me asking for probes was "please explain what probes are and where I can find them". :P
Use word "cables". ;D "Cable" is more explaining that "probe".
Quite funny in situations where "cables" are more valuable than the instrument itself.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: cheeseit on December 14, 2016, 09:33:41 pm
I got similar deals on a Tektronix 2440 and 7854 which apparently sat in storage for many years and were in excellent condition.  Later I hunted down a front cover for the 2440 so it remains clean and protected.

The 2nd and 4th channel (I think) did show a bit of noise when the scope was cold but that went away after warming up.

Warming up usually results in better performance from aluminum electrolytic capacitors so this might indicate that they are at the end of their useful life.

I am fussy on exactly which 2465 series oscilloscopes had problems with leaky surface mount aluminum electrolytic capacitors but I do not think the early and late ones did but it is still worth checking.

Quote
The readout and traces shimmers a tiny bit randomly from time to time. Otherwise everything appears to work fine but I haven't yet done much testing.

Check to see if this is just an artifact of the beam multiplexing needed to display the readout by disabling the readout.  Sometimes the readout will momentarily synchronize with the sweep to produce visible artifacts.
I was thinking electrolytic caps warming up too so great that you mention this. And this one unfortunately does have leaky surface mount caps but it still haven't caused that much damage.
I will look into the part about beam multiplexing and synchronization. Thank you!

The seller obviously didn't really know what he was selling since his reply to me asking for probes was "please explain what probes are and where I can find them". :P
Use word "cables". ;D "Cable" is more explaining that "probe".
Quite funny in situations where "cables" are more valuable than the instrument itself.
Cables might have made more sense to him but I would expect him to answer that there is a power cord included.. :D I don't know about the probes being more valuable than the instrument but it sure was a nice bonus having a working 2465B thrown in when purchasing probes. I'm thinking of selling it once refurbed and perhaps use the money to finally buy a modern scope. I've been wanting a Rigol 1054Z for a while.

Update:
Just a few images for now since I'm of to bed but I've taken the case of and it looks both good and bad. Good because it is really clean, and bad because the surface mount caps have leaked. The damage is not that bad and some scrubbing with alcohol and a brush should take care of it. This is my first time removing corrosion like this so I will have to read up on it using this thread. I thinking replacing the affected resistors and caps, or what? I will at least remove the other components to scrub thoroughly.

I have some side-by-side images of this 1993 next to my 1989 vintage, if anyone is interested? There are a few differences, besides the obvious A5 boards, like different bodges and such.

Corrosion:
(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=278027;image)

(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=278029;image)

The U800 has a strange concave and roughed up mark. Is this a sign that its been cooked? I hope not and would think that it would be convex and not working if so, judging by its looks.
(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=278031;image)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on December 24, 2016, 06:52:25 pm
Taking a scope break –

While still curious about where the upper frequency limit is, I’ve had daydreams of actually seeing 500 MHz displayed.   The 2465B is rated for 400 MHz, which is quite respectable.   But the scope spec’s say it will display 500 MHz!

To find that upper limit, thought I would use my Baofeng handheld radio as a signal source.   This is one of the many slightly different variations of the well known UV-5R which is spec’d up to 520 MHz.   Tested this one to find the upper limits and was pleased to see it top out at 570 MHz.   So that should do well in finding the upper limit of the scope.

The connection was made by simply hooking the scope probe onto the insulated antenna and pressing the transmit button.

Plan was to start out at 570 MHz, then reduce the frequency until the scope was able to lock on to it.   But the scope locked on to the first test at 570 MHz.   And everything was very stable at that frequency.   Wow!

Next test was to see how the frequency readouts worked.   Pressing the delta V & delta T buttons displays the vertical cursor lines that indicate frequency.   For this test the cursors were spread over 10 cycles which read 57 MHz, which = 570 MHz for the waveform.   And again, all was stable and reading correctly.   See photos below.

Repeated the test using the 10x button and adjusted the cursor to cover just one cycle.   And again, everything was stable and accurate.

Then I let the scope determine the frequency by pressing the lower red “HELP” button followed by the channel 1 button.   And as can be seen in the 3rd photo, it easily read out the frequency as 576.9 MHz, while the Baofeng can be seen indicating570.000 MHz on the top indicated frequency, which amounts to a 1% error.   Wow again!

While these frequencies are impressive, they say nothing about the voltage levels that have rolled off quite significantly.   And the scope probe I used was only rated for 100 MHz.   But the same argument could be made for signals at 400 MHz where the scope gain has rolled off by 3 DB, plus probe losses.

The only bad news here is that I still don’t know where the upper frequency limit is.   But, that’s ok, I’ll take what is until I find a higher frequency signal source.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: cheeseit on December 30, 2016, 12:24:51 am
Taking a scope break –

Very interesting - I hope you find a higher frequency source!

Update

Now that Christmas is over I finally found some time to continue work on my second 2465B. It cleaned up real nice, except for the BNC's. I took the front panel out and disassembled it and then washed the face plate in warm water and soap. The buttons were washed and then whitened with hydrogen peroxide. The image below doesn't really do it justice but they are gray now, not that brownish-gray like before.
As a pleasant surprise both the implosion shield and the blue filter cleaned up nice too and has hardly any scratches, only a few tiny ones that are only barely visible when viewed from certain angles and in the right light. Combined with the generel cleanliness inside and lack of dust on the fan and on the boards, I'm inclined to believe that the low number of hours on and power cycles are indeed true and haven't been reset.
(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=281758;image)

What unfortunately didn't just clean up is the badge, which is a minor annoyance for now, and the BNC's. It looks like the plating on the BNC's have been eaten through by corrosion. They of course work no problem but their appearance bothers me. The image below is after polishing them once. I would like the scope looking mint if I resell it, so, I've found a source for somewhat cheap (NOS I think) BNC's but am wondering if desoldering and replacing them will affect anything? It's heating up the associated components twice after all. Or are they salvageable, and if so, using what? I've used what I had, which is a product called Silvo, that has worked fine before.
(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=281760;image)

(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=281762;image)

I've started recapping the power supply with the components I had in stock using my new ZD-915 - what a joy it is to finally have a desoldering station. My TL866 has arrived so now I await the arrival of an order from Mouser so I can finish recapping and replace the DS1225Y with FRAM.
Doing this I found some more corrosion, this time under the four 250µF 20V caps on the A3 board. All four have some black gunk around the positive lead but it fortunetly didn't spread that far and cleaned up nicely using a glass fiber brush, alcohol and q-tips. No visible damage after it has been removed.
(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=281764;image)

(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=281766;image)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: Old-E on December 30, 2016, 03:26:47 am
Very nice looking scope cheeseit!   Thanks for sharing.   It's amazing what a little soap & water or other cleaners can do.   Certainly increases the perceived value.

My scope arrived very clean inside and out, except for the BNC's that are tarnished.   like yours, they all work just fine, but some cleaning would help the appearance.   You said you used Silvo to clean the BNC's.   Is that a silver polishing compound?

Interesting that you used hydrogen peroxide on the knobs which might brighten mine up too.   Never heard of using it for that.

Your BNC's appear to be pitted, which probably means there is nothing that can be done to fill in the pits.   Appears that your scope may have been stored in a higher humidity environment.

Also have been wanting to suggest that you replace the 4 electrolytic caps on the A5 board ASAP, because they leak, as yours are just starting too.   C 2965 appears to be corroding the adjacent screw head.   Mine was worse and an adjacent IC, U2890, had absorbed the acid which caused it to fail.   Thought those IC's were totally sealed, but this one had a corroded interior when I opened it up, along with signs of corrosion on the exterior solder connections.   So where the corrosive gases migrate to, can be a challenge to forecast.   Other board connections were thinned, but still ok.   Also replaced several other suspected components adjacent to those cap's.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: lordvader88 on December 30, 2016, 04:09:35 am
why does this thread have some many views/replies for some random scope ?

Anyways I own a Tektronix 2430A, got it for a decent price (I guess) on fleabay, but as it turns out CH1 has a big problem in the vertical gain. But all and all good enough for now.
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: tautech on December 30, 2016, 04:36:22 am
@ cheeseit and Old-E
There's some good restoration tips in this sticky thread including polishing BNC's.
https://www.eevblog.com/forum/repair/vintageclassic-renovation-techniques/ (https://www.eevblog.com/forum/repair/vintageclassic-renovation-techniques/)
Title: Re: Tektronix 2465B oscilloscope teardown
Post by: cheeseit on December 30, 2016, 11:26:06 am
@ cheeseit and Old-E
There's some good restoration tips in this sticky thread including polishing BNC's.
https://www.eevblog.com/forum/repair/vintageclassic-renovation-techniques/ (https://www.eevblog.com/forum/repair/vintageclassic-renovation-techniques/)

Thanks, don't know why I forgot about that sticky and I remember seeing robrenz fantastic results and thinking that would come in handy sometime. I will try to find what he used but what about replacing the BNC's, I know how to do it but will it affect anything?

why does this thread have some many views/replies for some random scope ?

Because it is a great scope. :)

My scope arrived very clean inside and out, except for the BNC's that are tarnished.   like yours, they all work just fine, but some cleaning would help the appearance.   You said you used Silvo to clean the BNC's.   Is that a silver polishing compound?

Yes it's primarily for silver polishing but also works on gold, aluminium and chrome. I once gave it a try on some BNC's that were tarnished and it worked great. I'll try some other products but they do appear pitted and had green oxide spots so I think they are too far gone for just polishing.

Interesting that you used hydrogen peroxide on the knobs which might brighten mine up too.   Never heard of using it for that.

It works wonders. Google whiten yellow plastic and you'll find many guides but it's basically about submersing it in a 3%-10% solution and exposing it to UV. Many just place it out in the sun but I've found that using a desk lamp lowered down over the glass jar that I use works great. The LED bulb I use and the little heat from it is enough. I just stir it vigorously from time to time to remove the bubbles that form and rinse it once it looks nice. The aluminium inserts in some of the knobs on the 2465 is not a problem in a low solution but other metals very much react in hydrogen peroxide so remember to remove the set screws.
Some suggest using a UV-sealant afterwards might be a good idea.

Also have been wanting to suggest that you replace the 4 electrolytic caps on the A5 board ASAP, because they leak, as yours are just starting too.   C 2965 appears to be corroding the adjacent screw head.   Mine was worse and an adjacent IC, U2890, had absorbed the acid which caused it to fail.   Thought those IC's were totally sealed, but this one had a corroded interior when I opened it up, along with signs of corrosio