Buy RAM chip heatsinks on eBay and use thermal epoxy to glue them right to the IC
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.
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.
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.
60 celsius is NOT hot. 90 celsius is not hot. 100 celsius is not hot.
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.
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.)
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
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
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.
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.
It looks that scope need service calibration.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. :'(
If do adjustments it need follow _exactly_ Tektronix service manual. There are not words without meaning (even if it feels stupid..).
How is measurement accuracy?
(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.
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?
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?
(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.
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).
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
<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.
<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. ;)
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 !
Looks like all analog Tek 24xxB scope's SRAM image are compatible each other, never expected that, great finding.
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.
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
I just bought another 10-20 years of cal data ;) and the next guy does not have to unsolder that crazy chip.
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)
anyway, it seems done now. I'd like to get it professionally calibrated but at least its rejuvinated.
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?
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.
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.
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?
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!).
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.
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.
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.
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
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?
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?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.
Is this process documented/detailed anywhere?
Dom
Does this effect ALL 2465 models?
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) :oDoes this effect ALL 2465 models?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.
Is this process documented/detailed anywhere?
Dom
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).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.
The A5 logic and control board is the one the outside right of the scope looking from the front right?
Dom
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.
I'll drop a photo of the board here after lunch (about 3 hours from now).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.
The A5 logic and control board is the one the outside right of the scope looking from the front right?
Dom
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
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 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)
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
.... 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.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.
Dom
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).
[...]
I just need to find two small replacement knobs for the intensity and focus controls.
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?
.... 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....
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.
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.
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!
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. .............
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).
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.Straight from the horse's mouth, thanks Alan for clarifying this. :-+
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.
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.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.
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.
Yep, but they don't leak overtime and I think they should be pretty reliable.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.
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.
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)!
Turn off ID check and tell it it is a DS1225 and it probably will write to it.
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.
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 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.
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?
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?
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. :-+
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.
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.
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??
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??
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?
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.
This time I will take some shots with my TIC.
I thought crest factor also had to be taken into consideration.
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)
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.
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 :)
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.
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).
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.
Guido, that heatsink looks like a stacked coins to me. ;D
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 ? :-//
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.
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
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.
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.
Looks like to perform the differential comparator measurement as above a differential probe is needed?.
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.
How would you test to see if the U800 is having any issues?
I have no available this ICs on easy :(Really ?
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.
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.
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".
@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?
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...
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.
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!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?
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.
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).
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? :)
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.
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.
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.
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.
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
>
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
>
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.
.... 16k years to wear the device out.
Yes, I am.
Are you sure...
Both are rated for 1014 operations.No, they aren't. Look again.
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)
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?
But it didnt work in BravoV's case. ?
Now, go to eBay, seek for "FM1608", and all the parts you will get will be Ramtron ones.I'll agree with you as far as "from eBay, you cannot know what exactly you are buying" :)
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?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.
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. :)
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?
Finished my U800
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
Wikipedia notes 01E is for joining two scopes with one sync pulse.
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.
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!!!
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).
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.
The other thing that happened, was I found out I need an angiogram, maybe a stent, or even bypass surgery.Well at least the stress of the Tek has passed now.
Maybe it's a really good thing... I might live to use the damn thing! :)
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!
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
The calibration constants from exercise 2 are located at addresses 1E00 - 1FFF in the NVRAM.
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
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. :)
All, Im going to move my posting over to the Repair section under a different thread so I am not hijacking this one.
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.
Howardlong I sent you a PM.I cant make the PM work. :(
Howardlong I sent you a PM.I cant make the PM work. :(
Dont worry about what the Rigol fundamentalists say, they dont know quality when they see it.
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.
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.
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.
...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.
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
MarkL,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 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.
MarkL,Hi Mitch,
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
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.
Everybody take note, make a note and stick it to your scope. Ohh shit it rhymes. :palm:OK I couldnt stand it anymore. I took my 2445B apart and this is what I found.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.
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.
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.
MarkL,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.
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.
...
MarkL,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.
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
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
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...
knobs, shaft extenders, and pots. How much???
Sent the PM. not seeing responses... :-/O
Anyone have the Digi-Key parts list handy for a power supply re-cap?
Sent from my Tablet
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.
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.
...<snip>... I managed to get it for free.
...<snip>... I managed to get it for free.
I hate you. LOL ...j/k >:D
Congrats on the score. :clap: :-+
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.
Sent from my Tablet
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
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 (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.
Why not just zip it and attach here, it will be useful reference for others in the future, sorry , don't have dropbox account.
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*
Sent from my Tablet
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.
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.
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 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 :-+
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.
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.
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.
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.
It's good to 200MHz, not 150MHz.
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 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.
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.
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.
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.
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.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.
Hello,There's a good Tek pdf with a section on troubleshooting SMPS in this thread:
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..
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..
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.
Here is the damage, apparent bad components and recapping of the A3 Inverter board for my 2465B CT scope.
You have hidden all the brand names. :-// On purpose?
Replaced capacitors
(http://imgur.com/GlV9bub.jpg)
RIFA, Nichicon, Sprague and Cornell Dublier is my guess.Sure, but why guess?
You have hidden all the brand names. :-// On purpose?
Replaced capacitors
(http://imgur.com/GlV9bub.jpg)
How many were faulty?
Care to list them for us?
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:
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)?http://www.sphere.bc.ca/ (http://www.sphere.bc.ca/)
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.
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?
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)
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.
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)
Welcome to the forum.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.
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.
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. :-+
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?
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 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?
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?
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.
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?
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
Is the fan supposed to blow into the case or out of it? Normally, a fan will blow into the case.
....<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.
[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.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 -You've nearly got it.....
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.
[img]url link to picture on the web or attachement[/img]
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.
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.
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.
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!LOL
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.
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?
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.
Baddies.Quite common in X and Y rated caps, they can survive for years in this condition in a dry climate.
All of these probably, hairline cracks on case likely ballooned caps
(http://i.imgur.com/TuZayZo.jpg?1)
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.
Another tell tale sign is the caps will give off a horrible fishy smell once unsoldered.
Baddies.Quite common in X and Y rated caps, they can survive for years in this condition in a dry climate.
All of these probably, hairline cracks on case likely ballooned caps
(http://i.imgur.com/TuZayZo.jpg?1)
When they finally let go...poof, it's more of an inconvenience than anything else plus the mess they can make. :palm:
Of course and humidity/and or time spent unplugged will allow ingress, then pop.Baddies.Quite common in X and Y rated caps, they can survive for years in this condition in a dry climate.
All of these probably, hairline cracks on case likely ballooned caps
(http://i.imgur.com/TuZayZo.jpg?1)
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?
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. :)
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.
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.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.
You may already know much of this. If not, hope this helps.
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.
Just for the fun I've also made a few thermal images, enjoy!
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.
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.
.....<snip>...
And I have a hard copy of it stored in the scope binder. ...
Do consider Edit or Modify to a previous post so your great info reads correctly in that one post.
Correction - In my previous entry, I wrote -.........
I'll write more later.
Can someone please tell me how to get to the information on 'Switch on off times' and 'Number of Operation Hours'? Thanks!
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!
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.
...Here's the 2445/2465 (plain, not A or B) of the CT and WR service manual if you want it:
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:
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.
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)
...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".
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?
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.
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?
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.
Hi everybody!The absolute value is not as critical as the X2 and voltage ratings that must be maintained.
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?
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.
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 EAROMEditing your above post and inserting a link would be better. ;)
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 EAROMEditing your above post and inserting a link would be better. ;)
...Ok, here are some ideas...
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.
...
Question - How do you know if it's the scope or the Fluke (or both) that are in error?
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. :-+
...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.
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.
...
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.
...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.
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.
...
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. :-+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.
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.
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).
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
Hello,You need a GPIB board as well, see PDF excerpt
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
Hello,Here is the interconnect diagram, it shows that there is no longer a buffer board in the 2467B (serials > 50000)
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
Hello,Here is the interconnect diagram, it shows that there is no longer a buffer board in the 2467B (serials > 50000)
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
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. :-+
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.
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 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 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.
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.
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.
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
The AC line safety capacitors may have failed which is a common and easily repairable problem.
The HV supply arcing may simply be neons flashing.
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.
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.
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.
Tubes from 2445, 2445A, 2445B, 2465, 2465A, 2465B,2430, 2430A, 2432, 2432A and 2440 are all suitable, right?
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.
... the gun and metal parts inside looks artistic, at least to my eyes.
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/)
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.
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?
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.
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.
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.
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". :PUse word "cables". ;D "Cable" is more explaining that "probe".
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.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.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.QuoteThe 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.
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.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". :PUse word "cables". ;D "Cable" is more explaining that "probe".
Quite funny in situations where "cables" are more valuable than the instrument itself.
Taking a scope break –
@ 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/)
why does this thread have some many views/replies for some random 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?
Interesting that you used hydrogen peroxide on the knobs which might brighten mine up too. Never heard of using it for that.
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.
That would be up to you. Sure if you want her looking like new then replace them, personally I wouldn't bother.@ 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?
I take it that replacing them doesn't pose any problems, apart from quite possibly being a bit laborious.It could be worse than just laborious, especially the Gnd connection pins. If the Gnd plane is substantial, as it likely will be as to not fuse if a connection is made that makes a Gnd loop, then desoldering the BNC Gnd pins will require an iron with good thermal mass. These can be tricky but not impossible with a good iron and is one of the reasons why I said if they are functional just leave them be.
I have a number of Tek scopes, including a 2465B and 2467. My favorite is a 545B but that's another era. The 2467 is in storage and the 2465B is on the rack and I use it. How concerned should I be about the battery?, tant's and, electrolytics?
I have a number of Tek scopes, including a 2465B and 2467. My favorite is a 545B but that's another era. The 2467 is in storage and the 2465B is on the rack and I use it. How concerned should I be about the battery?, tant's and, electrolytics?
The infamous mains X/Y film caps can be "entertaining" when they fail; in my 2465 a series resistor rapidly dissociated itself and took some of the PCB prepreg with it.
The control board caps are also infamous for venting their spleen over nearby components. Seen that in my 2445B.
A protection against battery failure would use the test routine to examine the nonvolatile memory's contents, and to make a video as you step through each location. Then, if necessary, you could reprogram another memory with the old calibration constants.
I have a number of Tek scopes, including a 2465B and 2467. My favorite is a 545B but that's another era. The 2467 is in storage and the 2465B is on the rack and I use it. How concerned should I be about the battery?, tant's and, electrolytics?
The infamous mains X/Y film caps can be "entertaining" when they fail; in my 2465 a series resistor rapidly dissociated itself and took some of the PCB prepreg with it.
The control board caps are also infamous for venting their spleen over nearby components. Seen that in my 2445B.
A protection against battery failure would use the test routine to examine the nonvolatile memory's contents, and to make a video as you step through each location. Then, if necessary, you could reprogram another memory with the old calibration constants.
I've been hesitant to touch the 2465B and 2467 but I'm thinking about recapping the PSU as a precautionary measure. Maybe the control board too (now). I'll look into running the test routine
A protection against battery failure would use the test routine to examine the nonvolatile memory's contents, and to make a video as you step through each location. Then, if necessary, you could reprogram another memory with the old calibration constants.
I haven't found a test routine that shows the NVRAM contents. It passes the tests I ran with the ?T/?V menu selection but no data is displayed. From what I've read the battery doesn't warn you when it dies...
Thanks for the parts list. Everything is ordered. $30-ish for a little peace of mind.QuoteA protection against battery failure would use the test routine to examine the nonvolatile memory's contents, and to make a video as you step through each location. Then, if necessary, you could reprogram another memory with the old calibration constants.
I haven't found a test routine that shows the NVRAM contents. It passes the tests I ran with the ?T/?V menu selection but no data is displayed. From what I've read the battery doesn't warn you when it dies...
Much appreciated. I checked the service manual and was able to figure out how to retrieve the cal data. I video'd it and put it on YouTube. I don't know if it's useful for anyone else. If it is I'll post a link.
Good deal. :-+ When you get ready to replace the caps on the Regulator and Inverter boards do NOT do a mass remove then go back and do a mass install. There are minor differences between the 2465, 2465A, and 2465B. Plus there are discrepancies with the board lettering and the schematics which Tektronix never fixed. Doing a mass replace then install will result in aggravation and magic smoke. Do one or two caps at a time and compare value, orientation, and voltage rating as you replace them. Granted that's inefficient but it will be accurate.
Also you'll notice that C1110, 1111, 1113, 1114, 1115, 1116 have all been "upgraded" to 330uf. I followed that recommendation and everything works fine.
...Take a look at page 6-15. It describes the format of the line and the codes that show up for Exerciser 01.
Page 461 (front panel troubleshooting flow chart) seems relevant. I entered the Exerciser 01 mode and all the switches and pots are getting picked up. However, I can't find anything in the manual on the switch codes referred to on that page. Also the four 2-digit hex values seem to change in a funny way. Hard to describe without doing a movie but pressing a given switch once registers on the switch code display (in the first two groups), pressing it again registers too (this time in the second two groups) and subsequent presses don't change anything. This may well be right but it's not what I would expect from a keypad scanned in the usual matrix way. Why the two button presses?
...
Much appreciated. I checked the service manual and was able to figure out how to retrieve the cal data. I video'd it and put it on YouTube. I don't know if it's useful for anyone else. If it is I'll post a link.
Wish I ran the test and recorded the data before replacing my Dallas. Something went wrong and I lost all the calibration data. @#$*$*($. Why don't you go ahead and post the link
Wonder if those hybrids could be replicated by modern SMD components on a small PCB?
I did find that switch code table - thank you. I reckon there is something wrong with the switches. As I posted, pressing a button once shows up as a change in the four 2-digit values (only the left two change) and pressing it again shows up as another change (only the right two change). Subsequent presses don't change anything. I would be amazed if that was right. Can anyone confirm this? I can do a little video later.
...It's not the case on this scope. Take a look at schematic <3>. There are 6 cascaded 74F164 shift registers that drive the LEDs directly and are loaded by LED CLK and LED DATA.
It would be fairly common to use the same lines as are used to scan the switches for driving (multiplexed) LEDs. In fact I am using an ST LED display driver chip right now which does exactly that.
Wonder if those hybrids could be replicated by modern SMD components on a small PCB?
Apparently one of the hybrids was. I believe the U800 I think...for awhile could be returned to a company in Japan that was able to fix them.
Will keep you all posted,
I couldn't help myself, I just bought a second 2465B to repair... :palm: :palm: :palm:
I couldn't help myself, I just bought a second 2465B to repair... :palm: :palm: :palm:
No ... not that face palm ... infact its good and good news only, no bad news at all. ::)
Now, visit here for the stress relief amongst brother & sisterhood of -> TEA ... (https://www.eevblog.com/forum/chat/test-equipment-anonymous-(tea)-group-therapy-thread/) >:D
It has the same basic HW as the 2465A.
As for the RAM, it has the "Keeper" Li battery. I plan to replace it with a socket and a CR123 Li cell.
My question is what happens if you lose RAM data ? If you do a CAL procedure (steps in the manual), will this refresh the BB RAM and generate a checksum ?
Since there is no way to remove the RAM to read the contents, without losing the data, there must be a method for the scope to "restore" itself from a dead battery.
I don't know about the 2565A/2467, but the EAROM in the 2456 can dumped via GPIB. By examining the EPROMs on the GPIB board I was able to figure out the following. It may be extensible to other models.Since there is no way to remove the RAM to read the contents, without losing the data, there must be a method for the scope to "restore" itself from a dead battery.
This might be possible through the GPIB interface; I do not remember. One of the 2465 series experts will know.
Now I want to improve the cooling of U800 and replace the Dallas chip.
Now I want to improve the cooling of U800 and replace the Dallas chip.
I am not convinced the U800 needs to cooled, yes it gets hot, but I am sure Tek took this into account when engineering. I suspect failures are due to a fan that stops working or the cooling vents at the bottom are plugged with lint, or maybe it's used in a environment that is beyond it's ambient temperature specs.
And now the final part: cooling of the U800.
The consensus seem to be, that the TekTronix made chips are "better" in terms of failing on the long term.
Mine is not getting hot, but it may have to do whem touching the chip is is just doing almost nothing?
Maybe when the scope is running on a very high frequency with a high repetition rate, it may get hot due to more capacitive load??
Anyway, I decided to help this little chip a bit.
What I did was, I removed the nut where the metal tab from under the chip is, and made a brass (for thermal conductivity) bushing the same height as the remaining part of the chip.
So basically, I try to guide the heat through this bushing to the top, and there transfer it to a cooling element.
I also put some thermal conductive grease on top of the chip, although this may be of little effect.
The cooling I found at Mouser's, it is a double to-220 part.
I will start adding pictures to show what I did.
Un saudo,
Satbeginner (Leo)
I thought the Maxim dies were not specific to the U800 but for the other custom chips, U400's maybe
and funny enough, one of the 15 Ohm resistors went up to 4968 Ohm!! without any markings or change of color.
Be careful. The studs that secure U800 are NOT at ground potential. I may be mistaken but I think each stud is at a different potential. So you could easily cause a short. The heatsink modifications I've seen for U800 are glued to the top of the chip away from the studs. So check what you've done very carefully or you might have magic smoke.
Be careful. The studs that secure U800 are NOT at ground potential. I may be mistaken but I think each stud is at a different potential. So you could easily cause a short. The heatsink modifications I've seen for U800 are glued to the top of the chip away from the studs. So check what you've done very carefully or you might have magic smoke.
That studs (or embedded bolts ?) is -5 (negative five) volts.
Posted this at -> post #2 (https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg70295/#msg70295) at the beginning of this thread, yep, I measured it with DMM.
And now the final part: cooling of the U800.
The consensus seem to be, that the TekTronix made chips are "better" in terms of failing on the long term.
Mine is not getting hot, but it may have to do whem touching the chip is is just doing almost nothing?
Maybe when the scope is running on a very high frequency with a high repetition rate, it may get hot due to more capacitive load??
Anyway, I decided to help this little chip a bit.
What I did was, I removed the nut where the metal tab from under the chip is, and made a brass (for thermal conductivity) bushing the same height as the remaining part of the chip.
So basically, I try to guide the heat through this bushing to the top, and there transfer it to a cooling element.
I also put some thermal conductive grease on top of the chip, although this may be of little effect.
The cooling I found at Mouser's, it is a double to-220 part.
I will start adding pictures to show what I did.
Un saludo,
Satbeginner (Leo)
Be careful. The studs that secure U800 are NOT at ground potential. I may be mistaken but I think each stud is at a different potential. So you could easily cause a short. The heatsink modifications I've seen for U800 are glued to the top of the chip away from the studs. So check what you've done very carefully or you might have magic smoke.
and funny enough, one of the 15 Ohm resistors went up to 4968 Ohm!! without any markings or change of color.
Leo, which resistor is that ?
No markings ? You still have it ? Photo please.
Must be either R1010 or R1019. Both were bad in one of my 2465B, one was open and the other measured 68K, but both had visible signs although not that easy to see.
Must be either R1010 or R1019. Both were bad in one of my 2465B, one was open and the other measured 68K, but both had visible signs although not that easy to see.
And now the final part: cooling of the U800.
The consensus seem to be, that the TekTronix made chips are "better" in terms of failing on the long term.
Mine is not getting hot, but it may have to do whem touching the chip is is just doing almost nothing?
Maybe when the scope is running on a very high frequency with a high repetition rate, it may get hot due to more capacitive load??
Anyway, I decided to help this little chip a bit.
What I did was, I removed the nut where the metal tab from under the chip is, and made a brass (for thermal conductivity) bushing the same height as the remaining part of the chip.
So basically, I try to guide the heat through this bushing to the top, and there transfer it to a cooling element.
I also put some thermal conductive grease on top of the chip, although this may be of little effect.
The cooling I found at Mouser's, it is a double to-220 part.
I will start adding pictures to show what I did.
Un saludo,
Satbeginner (Leo)
Be careful. The studs that secure U800 are NOT at ground potential. I may be mistaken but I think each stud is at a different potential. So you could easily cause a short. The heatsink modifications I've seen for U800 are glued to the top of the chip away from the studs. So check what you've done very carefully or you might have magic smoke.
Hi,
thanks for your response, in the picture you can see this cooler stays far away from any surrounding part, I also have like 8-9 mm from the case.
Although my U800 stayed cool, I just wanted to help it a little by conducting heat away from the chip.
The spring washers are no good in doing this, but -my thoughts- a solid brass ring might help, and also cooling the chip -although plastic- itself a bit.
I never liked glue and heatsinks, in my book they always end up somewhere loose in the device... ;-)
Un saludo,
satbeginner (Leo)
I have open up mine at last. Some chips are date coded 1997. The battery backed up SRAM is 1995.You're constrained by the forum 1Mb file size limit, compress the size of your pics to under 1 Mb and much less unless great detail is needed. In most cases 100Kb is plenty big enough.
I believe this scope was "overhauled" in some way about 10 years ago, by the refurbish company which I bought it from.
Some pics here - the site crashes when I try to upload anything sizeable.
http://peter-ftp.co.uk/screenshots/2017-03-28_225205.jpg (http://peter-ftp.co.uk/screenshots/2017-03-28_225205.jpg)
http://peter-ftp.co.uk/screenshots/2017-03-28_225239.jpg (http://peter-ftp.co.uk/screenshots/2017-03-28_225239.jpg)
I have open up mine at last. Some chips are date coded 1997. The battery backed up SRAM is 1995.
I believe this scope was "overhauled" in some way about 10 years ago, by the refurbish company which I bought it from.
Some pics here - the site crashes when I try to upload anything sizeable.
http://peter-ftp.co.uk/screenshots/2017-03-28_225205.jpg (http://peter-ftp.co.uk/screenshots/2017-03-28_225205.jpg)
http://peter-ftp.co.uk/screenshots/2017-03-28_225239.jpg (http://peter-ftp.co.uk/screenshots/2017-03-28_225239.jpg)
Now I need to find out where to check the supply voltages,
...When you say you "can't find" it, do you mean there's no signal or you can't locate it on the schematic? LED DATA is on the snippet you posted; outlined below.
but can't find the LED DATA signal.
Is the LED clock definitely pin 16 J652?I think so. I would believe the schematic before the troubleshooting chart. The J652.13 referenced in the chart is already spoken for as ROW 0 at the bottom right corner of schematic <2>.
How do you get to the front panel? I can see some screws on the bottom, but there are many buttons etc to remove. At that point I would rather pay someone who has done this before, a couple of hundred GBP... I am in the UK.There are step-by-step instructions starting on page 6-28 in the maintenance section. I've never had the privilege of needing to remove the front panel. If there are any tricks to it perhaps someone who has done it can post.
You can see the yellow wire bringing the +5V from the CPU board, in the top right.Great; glad you got it working!
Now I have to put this damned thing together :)
One unrelated thing: is there any adjustment for the focus between the upper and lower part of the CRT? This photo doesn't show it too well but the upper stuff is less focusedThere's some interplay between the front panel ASTIG and FOCUS controls. I would try those first.
One unrelated thing: is there any adjustment for the focus between the upper and lower part of the CRT? This photo doesn't show it too well but the upper stuff is less focused
Yeah DSOs are expensive, but I was under the impression you already had the TDS scope? I've always been an analog scope guy myself but since acquiring a really good older Tek DSO it has become my primary scope. Being able to capture and examine waveforms is just incredibly useful.
Obviously you have some junk units laying around. By any chance do you have a 2465 Buffer board with Option 01 (DMM) and any combo of options 06, 09, 10? Tek P/N 670-7830-05 or 670-7830-09. I'd salvage the EAROM off it to try to fix a checksum error on mine.
Probably not...it's not very common but I figured I'd ask. :-+
Obviously you have some junk units laying around. By any chance do you have a 2465 Buffer board with Option 01 (DMM) and any combo of options 06, 09, 10? Tek P/N 670-7830-05 or 670-7830-09. I'd salvage the EAROM off it to try to fix a checksum error on mine.
Probably not...it's not very common but I figured I'd ask. :-+
Wish I have that, sorry. :-//
No, I'm not the one who butchered those A1 boards, no way in hell I would do that. :'(
Actually they're sort of "souvenir" gift from a friend who visited abroad, and brought me these as he aware of the U800 obsession, at least me as a 2465B owner. :palm:
At least with the sawn board you can be sure the U800 is not a fake chip with more certainty, but the bigger question is if they work still, and if not if they are repairable with new package and leadwires after they are decapped.
When I saw how Tektronix mounted these parts, I concluded that somewhere they screwed up the engineering. The shoulder of the pins prevents the DIPs from sitting flush and even if they did not, DIP leads do not allow enough strain relief for good reliability. DIP packages designed for heat sink attachment have a very different configuration. What I think might have worked is a thermally conductive spacer between the package and the board and the right kind of low profile collet socket.I read somewhere that the original intent was to have the tab in contact with the PCB to provide heatsinking but this didn't work given the stand-off provided by the DIP leads.
Maybe what they did was sufficient though. What was the failure rate for these parts while under warranty?
When I saw how Tektronix mounted these parts, I concluded that somewhere they screwed up the engineering. The shoulder of the pins prevents the DIPs from sitting flush and even if they did not, DIP leads do not allow enough strain relief for good reliability. DIP packages designed for heat sink attachment have a very different configuration. What I think might have worked is a thermally conductive spacer between the package and the board and the right kind of low profile collet socket.
Maybe what they did was sufficient though. What was the failure rate for these parts while under warranty?
I read somewhere that the original intent was to have the tab in contact with the PCB to provide heatsinking but this didn't work given the stand-off provided by the DIP leads.
Has anyone tried thermal pads under U800?
Whelp, I just got gifted a vanilla 2445, thankfully in relatively good working order. There does seem to be something a little wonky in the input coupling relays. looks like I have some work ahead of me curating this. Only just started reading but just with a cursory assay of the literature;
>electrolytic and some film caps
>heatsink U800
>construct interface and read out cal data
>develop strategy for eventual memory replacement and reprogramming
I have just pulled my 2465B out of storage to use it after almost 30 years. I had forgotten that I even had it. As I was the original purchaser and the only user, I know when I last used it, it worked flawlessly.
So I am in the process of getting her cleaned up a bit before hitting the on button. I have 4 of the original probes, 2 of which are still in the factory sealed pouches. Plus the ops manual, the Polaroid camera shroud, and the added reticules.
I'll love getting her back to operating condition. Thanks for starting this thread, it will come in handy.
Ok in case anyone is still interested I found the issue. The unit has a bad A&B Trigger chip - 155-0239-02
Hi everyone,
very good thread about the 2465B Scope. I got mine some years ago from ebay, a 2465BDV, which hat some options included (01, 05, 06, 09, 10), TV triggering, CTT, Word Recognizer Probe, DVM, GPIB). It came frome a production site, a lot of opreation hours, very few on/off cycles.
Just replaced all caps in the power supply, and the Dallas chip and the already leaking electrilytics on the A5 boards. Without this thread, I would never have noticed that, thanks!
I bought a Dallas chip from china, which was an old one with reprinted date code. And then one from a local distributor, which was fresh.
Because there were no pics of a BDV in this thread ( I think), I will post some:
Next post will be about my new scope, a 2445B.
Any suggestions? I did check the supply voltages (J119 on Board A1), all stable from the beginning.Focus (excuse the pun) investigations on componentry in the EHT supply for the CRT, that's where these sorts of problems are normally found IME.
Now to my new scope, a 2445B (same as a 2465B except bandwith), Serial below 050000, so it has the old-style A5 board without SMD and without the leaking caps.
It looks almost like new, has below 900h of operation, came from a broadcasting station (sfb, Sender Freies Berlin) here in Germany. I did the bandwith "hack" on the A1 board (seems to work very close to my 2465B).
But it has a focus problem: When cold, it is extremely out of focus (and astig as well), it takes 5 to 10 minutes to get a sharp image. My other 2465BDV is perfect from the first second.
I did replace all caps in the power supply. But I am not sure if this problem was there before the re-cap, because this was one of the first things to do after getting the scope.
Any suggestions? I did check the supply voltages (J119 on Board A1), all stable from the beginning.
Now to my new scope, a 2445B (same as a 2465B except bandwith), Serial below 050000, so it has the old-style A5 board without SMD and without the leaking caps.
It looks almost like new, has below 900h of operation, came from a broadcasting station (sfb, Sender Freies Berlin) here in Germany. I did the bandwith "hack" on the A1 board (seems to work very close to my 2465B).
But it has a focus problem: When cold, it is extremely out of focus (and astig as well), it takes 5 to 10 minutes to get a sharp image. My other 2465BDV is perfect from the first second.
I did replace all caps in the power supply. But I am not sure if this problem was there before the re-cap, because this was one of the first things to do after getting the scope.
Any suggestions? I did check the supply voltages (J119 on Board A1), all stable from the beginning.
Attached is a partial schematic of the 2465 focus/astig circuit. The 2445 should be similar. The first thing I would check is that -300V to Q1851 and Q1852. With the scope "cold" and power off hang your probe on that supply and see what it does as the scope powers up and warms up. Of course be VERY CAREFUL working around the high voltage supply. It can really hurt. :scared:
Now to my new scope, a 2445B (same as a 2465B except bandwith), Serial below 050000, so it has the old-style A5 board without SMD and without the leaking caps.
It looks almost like new, has below 900h of operation, came from a broadcasting station (sfb, Sender Freies Berlin) here in Germany. I did the bandwith "hack" on the A1 board (seems to work very close to my 2465B).
But it has a focus problem: When cold, it is extremely out of focus (and astig as well), it takes 5 to 10 minutes to get a sharp image. My other 2465BDV is perfect from the first second.
I did replace all caps in the power supply. But I am not sure if this problem was there before the re-cap, because this was one of the first things to do after getting the scope.
Any suggestions? I did check the supply voltages (J119 on Board A1), all stable from the beginning.
Attached is a partial schematic of the 2465 focus/astig circuit. The 2445 should be similar. The first thing I would check is that -300V to Q1851 and Q1852. With the scope "cold" and power off hang your probe on that supply and see what it does as the scope powers up and warms up. Of course be VERY CAREFUL working around the high voltage supply. It can really hurt. :scared:
I checked all voltages around Q1851 and Q1852, all very stable from the beginning. -300V is stable. Focus can also be bad if other voltages of the tube are wrong, so I have to look elsewhere.
There is a test point "74" with a warm-up voltage raising from zero to 15V (around U1890), I will try to understand what is done with this circuit.
Yep, that circuit is the grid bias to the CRT. If that's not correct it will affect the focus. Section 5-4 of the Service Manual describes the adjustments. If you have a slowly rising voltage at the output of that Op-amp concurrent with better focus I would check for leaky capacitors in that area.
Thinking out loud....try swapping the HV supplies between the 2 scopes. I believe they are the same part number. I've never pulled the supply in a 24XX so I don't know how difficult it would be.
If that doesn't fix it you basically only have one thing left. The CRT itself. If it were "gassy" (loosing it's vacuum) or has low emission it could cause an extended warm up time.
Thinking out loud....try swapping the HV supplies between the 2 scopes. I believe they are the same part number. I've never pulled the supply in a 24XX so I don't know how difficult it would be.
If that doesn't fix it you basically only have one thing left. The CRT itself. If it were "gassy" (loosing it's vacuum) or has low emission it could cause an extended warm up time.
Swapping the A9 (HV) boards did not change anything. 2465B sharp as ever, 2445B sharp 10 minutes from start. And it takes about one hour switched-off to get it fully out of focus again.
I have never heart of a bad 2465 CRT up to now. And it is bright from the first moment.
I will check the power supply again, because I think it was not having this problem before i replaced the caps in it, or at least not so bad. I think I would have noticed that.
...If you're not already doing so, use a scope in addition to a DMM to make sure there's nothing strange happening on any of the supplies. (Maybe something with the +87V supply? It supplies CRT ANODE #1 directly.)
I will check the power supply again, because I think it was not having this problem before i replaced the caps in it, or at least not so bad. I think I would have noticed that.
I don't know about the 2565A/2467, but the EAROM in the 2456 can dumped via GPIB. By examining the EPROMs on the GPIB board I was able to figure out the following. It may be extensible to other models.Since there is no way to remove the RAM to read the contents, without losing the data, there must be a method for the scope to "restore" itself from a dead battery.
This might be possible through the GPIB interface; I do not remember. One of the 2465 series experts will know.
First, you have to enable the "special" commands:
key 0
Then you can dump the EAROM with the following command:
earom? <address to dump>[,<address to dump>,<...>]
This allows reading out of multiple locations in one command. For example, to dump the first 10 addresses:
earom? 0,1,2,3,4,5,6,7,8,9
Then the next 10:
earom? 10,11,12,13,14,15,16,17,18,19
And so on, until address 199. The first 100 locations are the EAROM on the main board, and the second 100 is the EAROM on the buffer board. This is the same as in the exerciser. The values should match.
The above commands return a line in the form (from the above example 0 to 9):
EAR 0:84,1:1993,2:10102,3:1893,4:10091,5:1798,6:1494,7:1420,8:9608,9:1431;
The return format is <address>:<value> and everything is in decimal. You can set an EAROM value by using the same format:
earom <address>:<value>
Trying to write multiple values in one line didn't work for me and crashed my scope. YMMV.
It would be interesting if someone could try this on a model other than a 2465(plain).
WARNING!! If you want to play with any of this, be careful not to overwrite overwrite the EAROM values until you've saved them with a screen capture! On my 2465 it DOES NOT MATTER if you have the the cal jumper set to off. These commands are surely hidden for a reason!
If you're even braver, there's another hidden query I've discovered called "BYTE?". It takes one argument and dumps that number of bytes from somewhere. I can't figure out what it's dumping, and I can't make it repeat itself except after a reboot. Eventually after several hundred bytes it causes my 2465 to reboot. I'm mentioning it because maybe that command will be useful on other models without EAROMs.
If anyone decides to try anything, please post your results. Obviously this needs a GPIB interface. I haven't found any equivalent method to write EAROM/NVRAM values from the screen, although now that I found it via GPIB it makes me suspect it's possible.
First thanks for your help here a small VideoThanks, that was a great video of the problem. It wasn't too clear because your hand was blocking the control, but it looks like the Intensity control is also affected. That would be consistent with the issue on the other controls.
...
the next days i will test the scope
OK, google is your friend, right from the source - https://www.tek.com/manual/2445-service-manual (https://www.tek.com/manual/2445-service-manual) - if you don't mind giving up your email address :)Thanks, but that's for the 2445. We need the schematics pages for the 2445B, emphasis on the B.
All, just a tip for anyone working on the A5 board due to capacitor leakage, don't forget to check R2010 20K trim pot. Mine was reading close to 30K so that's a big difference!!! They are easy to get from DigiKey.
Thanks, but that's for the 2445. We need the schematics pages for the 2445B, emphasis on the B.You could use the manual for the 2465B, the 45s are said to be mostly the same as the 65s. Search for the filename: 070-6873-00_2465bSvc_Sep89.pdf
There might be other differences but, from memory, the firmware limits the fastest timebase slightly in the '45 and there is some filtering on the input to the final Y amp - after the delay line, to limit bandwidth slightly. At least some of the implementation is with PCB traces to form inductors.Thanks, but that's for the 2445. We need the schematics pages for the 2445B, emphasis on the B.You could use the manual for the 2465B, the 45s are said to be mostly the same as the 65s. Search for the filename: 070-6873-00_2465bSvc_Sep89.pdf
http://www.ko4bb.com/getsimple/index.php?id=manuals&dir=Tektronix (http://www.ko4bb.com/getsimple/index.php?id=manuals&dir=Tektronix)Been there. In the 2445B directory, right? Like I said previously, the service manual is there, and in many other places around the net, but they are all missing the schematics.
:-//
I just uploaded a better scanned 2465B service manual to the http://www.ko4bb.com/ (http://www.ko4bb.com/) site
It is a 1993 manual, with schematics on one page, good quality, 35 Megs
Thanks, got it ! :-+Even better, did not even noticed this
Found an interesting date in there, highlighted in red.
Thanks, got it ! :-+Even better, did not even noticed this
Found an interesting date in there, highlighted in red.
There is a bit of a vertical jitter in the readout on some horizontal ranges and the tube goes out of focus if I go all the way up with the intensity but I guess this is mostly related to the aging of the tube?A little bit of jitter is normal. There are adjustments to tweak the vertical and horizontal readout jitter, R805 and R618. It's in the service manual in the "DC Balance, And X-Y Phase Differential" section.
I've got my FRAM FM6W08 from ebay and it doesn't work. I can program it with Xeltek SP5000, it passes verification, but once inserted in the scope I get TEST 04 FAIL 11. It's either a faulty rejected chip, I wouldn't be surprised considering it was only $4.39, or maybe it doesn't work in 2445B. I would expect the addressing mode to be identical between 2445, 2465, 2467. Any experience?No experience, but one thing you could do is use Exerciser 02 to scroll through the calibration data you programmed into the FRAM. As discovered in another thread, RAM locations 0x1e00 - 0x1fff should be the 16-bit calibration constants visible through the exerciser, big endian.
Unless the jitter and focus really bothers you, I would probably leave everything alone.
No experience, but one thing you could do is use Exerciser 02 to scroll through the calibration data you programmed into the FRAM. As discovered in another thread, RAM locations 0x1e00 - 0x1fff should be the 16-bit calibration constants visible through the exerciser, big endian.
Maybe the values (or lack of) would provide some clues.
Is that part number right? Did you mean FM16W08?
What I suspect is that it is a part that failed in production. I works in the programmer, probably it is programmed at low speed, but once it is addressed at full speed, it doesn't keep up. Don't know.Seems like a good theory. The cycle time of the 2445B and others in the series is a leisurely 800ns, so the FRAM must be in pretty bad shape to not work at that speed. Either that or some setup/hold times are on the edge since it works some of the time. It might be better to get a fresh, known good FRAM from Digikey or Mouser before investing more time in it.
It's possible that it's a fake that is not even a real FRAM inside. It could even be something like a microcontroller paired with a serial EEPROM, you never know with random Chinese parts. I got several Dallas SRAM modules that were obvious fakes.
It's possible that it's a fake that is not even a real FRAM inside. It could even be something like a microcontroller paired with a serial EEPROM, you never know with random Chinese parts. I got several Dallas SRAM modules that were obvious fakes.
It is possible but I would think is too much trouble, does it even make economic sense? I'll give it an X-Ray one day to see how many dies are inside.
I've read somewhere but forgot where, for those dodgy ones especially Maxim/Dallas BBSRAM products, actually they're genuine, but re-cycled and re-labelled.
any feedback from you guys? :(They do just pull off, but maybe after being on there for so long they are stuck.
any feedback from you guys? :(They do just pull off, but maybe after being on there for so long they are stuck.
Maybe warm the knob up a little (like with hair dryer, not a heat gun) before pulling on it?
It's possible that it's a fake that is not even a real FRAM inside. It could even be something like a microcontroller paired with a serial EEPROM, you never know with random Chinese parts. I got several Dallas SRAM modules that were obvious fakes.
It is possible but I would think is too much trouble, does it even make economic sense? I'll give it an X-Ray one day to see how many dies are inside.
I've read somewhere but forgot where, for those dodgy ones especially Maxim/Dallas BBSRAM products, actually they're genuine, but re-cycled and re-labelled.
Does anyone here has a working U950 (155-0242-01) chip for sale? Preferred in Europe?At the foot of this page there's a link to a 27 MB cross ref file of Tek parts.
Does anyone here has a working U950 (155-0242-01) chip for sale? Preferred in Europe?At the foot of this page there's a link to a 27 MB cross ref file of Tek parts.
http://www.sphere.bc.ca/test/tekequiv.html (http://www.sphere.bc.ca/test/tekequiv.html)
It might be commonly available so check what it is. ;)
Anyone know what it means when a 2465B bleeps its front lights? Fan's running and it starts up like normal until it starts that, the blinking of it's front light i mean.
Anyone know what it means when a 2465B bleeps its front lights? Fan's running and it starts up like normal until it starts that, the blinking of it's front light i mean.
Start with the basics and work from there. Make absolutely certain all your supply voltages are within spec as far as voltage and ripple. J119 on the main board is a convenient location to check them. I don't have the manual in front of me at the moment so I can't tell you what page it's on.
I recently started working on my late model 2445B. It had the usual leaking caps on the A5 board, plus some open traces. I've taken care of those problems, and it's basically working, but there's one peculiarity.
If I use auto scale, or any of the auto measurements, it momentarily blanks the trace (I assume this is normal), but when it's done, the trace is either very dim, or invisible. I can get the trace back by turning up the intensity, but the same thing happens again if I repeat the auto operation. After enough times, it needs to be near maximum to get a visible trace. Reducing the intensity control to minimum, and turning it up restores its normal range. I assume this isn't normal.
I recently started working on my late model 2445B. It had the usual leaking caps on the A5 board, plus some open traces. I've taken care of those problems, and it's basically working, but there's one peculiarity.
If I use auto scale, or any of the auto measurements, it momentarily blanks the trace (I assume this is normal), but when it's done, the trace is either very dim, or invisible. I can get the trace back by turning up the intensity, but the same thing happens again if I repeat the auto operation. After enough times, it needs to be near maximum to get a visible trace. Reducing the intensity control to minimum, and turning it up restores its normal range. I assume this isn't normal.
If I use auto scale, or any of the auto measurements, it momentarily blanks the trace (I assume this is normal), but when it's done, the trace is either very dim, or invisible. I can get the trace back by turning up the intensity, but the same thing happens again if I repeat the auto operation. After enough times, it needs to be near maximum to get a visible trace. Reducing the intensity control to minimum, and turning it up restores its normal range. I assume this isn't normal.
Anyone know what it means when a 2465B bleeps its front lights? Fan's running and it starts up like normal until it starts that, the blinking of it's front light i mean.
Start with the basics and work from there. Make absolutely certain all your supply voltages are within spec as far as voltage and ripple. J119 on the main board is a convenient location to check them. I don't have the manual in front of me at the moment so I can't tell you what page it's on.
So then, the blinking points to nothing specific then, therefore the long way it is. Thank you that is exactly what i wanted to know, the 70s were easier to work on :-DD
https://www.eevblog.com/forum/repair/tektronix-2465b-repair/ (https://www.eevblog.com/forum/repair/tektronix-2465b-repair/)
Anyone know what it means when a 2465B bleeps its front lights? Fan's running and it starts up like normal until it starts that, the blinking of it's front light i mean.
Start with the basics and work from there. Make absolutely certain all your supply voltages are within spec as far as voltage and ripple. J119 on the main board is a convenient location to check them. I don't have the manual in front of me at the moment so I can't tell you what page it's on.
So then, the blinking points to nothing specific then, therefore the long way it is. Thank you that is exactly what i wanted to know, the 70s were easier to work on :-DD
https://www.eevblog.com/forum/repair/tektronix-2465b-repair/ (https://www.eevblog.com/forum/repair/tektronix-2465b-repair/)
i think I might have found a clue for you, Neo. Having just built a dim-bulb tester recently I was keen to use it to power up the 2465B I mention above. It didn't like it. The bulbs brightened, fans on, the leds on the 'scope all came on, then all went off, fan off, then it tries to do it again. It starts as normal (barring the missing display) when plugged directly into the mains. I'm thinking that the cold resistance of the filaments in series with the inrush current limiters, which are NTC thermistors, is stopping the switching psu from starting, and that may be the issue that is affecting your 'scope.
On my 2467B the larger thermistor (RT1010) had drifted high and the resistor in parallell (R1010) with it had opened. If your R1010 has drifted high rather than opened it could be having a similar effect to my dim-bulb tester and not allowing enough current through to get the switcher started.
I tested it on a late 2465B and a late 2445B, both set the intensity to the same intensity as adjusting the intensity knob to the mid-position. On one this is fine, on the other it is to dark. But both are equal to the mid-position if adjustet by hand.
Re-adjusting grid bias and the other intensity adjustments (see the service manual) so that mid-position of the intensity pot gives a "normal" intensity will help.
Hi all, just received a very clean 2465B with a perennial problem: Start-up proceeds right up until the ADD led comes on and it stops. A/B TRIG brings about normal front-panel operation but no display or trace on the CRT, but it is glowing. So I have a look at A5 around the DAC area and look what I find! Green pins, and one corroded torx bolt are the only real evidence of electrolyte release, but thankfully I took pictures, and I'll lay ten-to-one that that resistor there has opened, or one near-by.
One question I have: does anyone know when these SMD control boards first started failing? This machine was last cal'd (by Tek, no less, it was owned by Sony Europe) in '09, when this particular A5 board was already 19 years old. Considering SMD hadn't been around that long in 1990 that's really not bad going.
With any luck that will be the only issue (apart from the dreaded cracked Rifas of course) this baby has!
I tested it on a late 2465B and a late 2445B, both set the intensity to the same intensity as adjusting the intensity knob to the mid-position. On one this is fine, on the other it is to dark. But both are equal to the mid-position if adjustet by hand.
Re-adjusting grid bias and the other intensity adjustments (see the service manual) so that mid-position of the intensity pot gives a "normal" intensity will help.
It's good to know it's normal. I'll readjust it to provide usable intensity at mid range. It seems strange that it couldn't just remember the previous intensity value and recall it when it's done.
This may be a redundant question, but would you guys change the Dallas NVRAM while you had the board off. I'm really hoping someone is going to say: "No, Gerry, you don't need to learn how to read and program cal data just yet." Anyone?
I was always to chicken to get one of these great scopes (and part of me would still like one) for the risk of losing the Cal data but the above is excellent advice. :-+This may be a redundant question, but would you guys change the Dallas NVRAM while you had the board off. I'm really hoping someone is going to say: "No, Gerry, you don't need to learn how to read and program cal data just yet." Anyone?
Most definitely. At the very least get a backup of your cal data, either by using the exerciser and record the data or by reading its content. That will be far easier than going through calibration if you lose your data.
One question I have: does anyone know when these SMD control boards first started failing? This machine was last cal'd (by Tek, no less, it was owned by Sony Europe) in '09, when this particular A5 board was already 19 years old. Considering SMD hadn't been around that long in 1990 that's really not bad going.
I was always to chicken to get one of these great scopes (and part of me would still like one) for the risk of losing the Cal data but the above is excellent advice. :-+
Once upon a time (fairy tale starting ::)) I did relish fixing scopes but the demands of what I do now takes away all that spare time. :(I was always to chicken to get one of these great scopes (and part of me would still like one) for the risk of losing the Cal data but the above is excellent advice. :-+
Still waiting you to join the club Rob. :P
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:
(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=426241;image)
Corrected:
(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=426247;image)
One question I have: does anyone know when these SMD control boards first started failing? This machine was last cal'd (by Tek, no less, it was owned by Sony Europe) in '09, when this particular A5 board was already 19 years old. Considering SMD hadn't been around that long in 1990 that's really not bad going.
There is post few pages back, similar to your problem, that the leaked liquid from the electrolytic cap also ruined the PCB traces and pins under and surrounding components :(, here is the affected board photo and the description, just beware.
(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?
action=dlattach;attach=137900;image)
I think more than those with arrows need attention, like the cap to the left of the upper tantalum. And possibly those rows of three vias in the upper left, some of them looks corroded.
This may be a redundant question, but would you guys change the Dallas NVRAM while you had the board off. I'm really hoping someone is going to say: "No, Gerry, you don't need to learn how to read and program cal data just yet." Anyone?
It seems that I have issues with U500, the A/B trigger hybrid. The readout got fainter as I put the 'scope through its paces, and I found that the A/B trigger button wasn't working properly.
Now I get no readout at all apart from a brief flash on start-up telling me it has failed "Test 05 40", which is the main board, a positive peak that is too positive, possibly a problem with the line trigger, but definitely something to do with U500. The readout issue may be related, as the trigger hold-off time or time spent waiting for a trigger event is used (2nd priority, I think) to display the readout, or completely separate. The main board is implicated in the readout troubleshooting chart at one point, but I can't get to that point without a scope to check for a 425mV sine wave. I'll let everyone know what I find, as all this is applicable to the 2465B.
In order to expand and preserve the knowledge base on the 24XX series in one place without attempting to cross post please refer to the Test Equipment Anonymous (TEA) thread pages 422 to 424. My saga of scoring a pristine 2465 for the pauper's sum of $60 USD. :-/O
Entirely depends of your forum view settings for posts/page. ;)In order to expand and preserve the knowledge base on the 24XX series in one place without attempting to cross post please refer to the Test Equipment Anonymous (TEA) thread pages 422 to 424. My saga of scoring a pristine 2465 for the pauper's sum of $60 USD. :-/O
Could you provide links to the specific start/end messages, please. That thread only has 213 pages in it - see screenshot.
(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=431732)
Just mention the post number instead of page number.
Still not fool proof though, if someone deleted their post before and screw up the sequence number.
It seems that I have issues with U500, the A/B trigger hybrid. The readout got fainter as I put the 'scope through its paces, and I found that the A/B trigger button wasn't working properly.
Did you run the scope for extended periods without a fan keeping everything cool while the case was off? If so that may explain any issues with the hybrids but hopefully it's just a bad contact.
Just bought this really nice 2465B, in excellent cosmetic condition and with only 750 working hours. It works superb. Being in such good cosmetic shape and working so flawlessly, I'm a bit reluctant to open it for a recap
and cal RAM refreshment, what do you think about postponing such maintenance? Serial is 134xxx.
I've recorded a video with the cal data thru EXER 02, is this enough to recover the cal data in an eventual backup battery drain?
...
I've recorded a video with the cal data thru EXER 02, is this enough to recover the cal data in an eventual backup battery drain?
My attitude is to record the data and replace the NVRAM iff it fails. But I haven't verified that is sufficient strategy.
Thanks to all that answered my question.
So, well, I'll open it and perform the update, focusing on the RIFAs, PSU and the three electrolytic ones. Recently I updated the battery backed Dallas RAM in some hp54600 scopes (that was easy. All they were suffering from the vertical deflection cap syndrome), so I will also try to update it. Once opened there's no big reason to not to try a more ample overhaul, maybe including some heatsink for the U800. I'm wondering if Berillyum Copper may be a good choice for such custom made heatsink.
Thanks again and regards.
Once opened there's no big reason to not to try a more ample overhaul, maybe including some heatsink for the U800.
...The 256 values should match what you see in EXER 02, in which case, yes, it has all of your calibration data.
It also seems like the 2465A only has entries from 0-254. 255 is zero and from 256 onwards the values wrap around. Is that enough to back up all of my calibration data?
I don't feel like experimenting with restoring the settings, but I'm happy to write another script that does this over GPIB in one go if someone is willing to test.
...
The 256 values should match what you see in EXER 02, in which case, yes, it has all of your calibration data.A spot check of a few memory locations (including the start and end) indicates that the data does match up.
Putting the calibration data back via GPIB works on a 2465(plain), but I haven't heard of anyone trying it yet on an A or B.
Also I'd like to replace the Keeper battery at some point but I cannot find a source for it on this side of the pond. There is an LTC-7PN sold on Ebay UK (https://www.ebay.co.uk/itm/EVE-EF651625-LTC-7PN-Size-750mAh-Lithium-Battery-Cell-3-6V-PCB-Pin-232542/142821167102 (https://www.ebay.co.uk/itm/EVE-EF651625-LTC-7PN-Size-750mAh-Lithium-Battery-Cell-3-6V-PCB-Pin-232542/142821167102)) under a (rather convincingly named) brand called EVE or "Energy Very Endure". Has anyone used one of them? Looks like the difference is that the casing is metal rather than plastic. The US sellers I've looked at either won't ship overseas or charge an arm and leg.Yes, the availability of the original battery in Europe is limited. Mouser sells it, sadly only in the US.
Also, the intensity knob is cracked. Do you know where I can get one without having to sell the scope to buy it?You could check Qservice (https://www.qservice.tv/vpasp/), they sell various Tek parts. No affiliation, just a happy customer.
I've got my 2445B few years ago and it was waiving like crazy. I knew there must be something wrong with the PS and I found this 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.) I recapped the power supply with the exception of the two big Sprague 290uF and the Rifa caps. Last week I ordered two 330uF Nichicon PW and the Rifa caps (well most of them, I missed two) and I opened it up to replace them. To my surprise, the Sprague ESR was better than the new Nichicon, 25mOhm Sprague and 100mOhm Nichicon so I didn't replace them. Sure enough, the Rifa caps were all micro cracked.
One relatively annoying issue that I have is that I can see a small flicker, a tiny fluctuation of the intensity. Do you know where it can come from? It has over 40K hours so I may need to recap the main board?
Also, the intensity knob is cracked. Do you know where I can get one without having to sell the scope to buy it?
I've got my 2445B few years ago and it was waiving like crazy. I knew there must be something wrong with the PS and I found this 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.) I recapped the power supply with the exception of the two big Sprague 290uF and the Rifa caps. Last week I ordered two 330uF Nichicon PW and the Rifa caps (well most of them, I missed two) and I opened it up to replace them. To my surprise, the Sprague ESR was better than the new Nichicon, 25mOhm Sprague and 100mOhm Nichicon so I didn't replace them. Sure enough, the Rifa caps were all micro cracked.
One relatively annoying issue that I have is that I can see a small flicker, a tiny fluctuation of the intensity. Do you know where it can come from? It has over 40K hours so I may need to recap the main board?
Also, the intensity knob is cracked. Do you know where I can get one without having to sell the scope to buy it?
I think the light flicker is normal and part of the design. All of my three scopes have it, one has only 800 hours of operation. Also the flickering of the LEDs on the front panel when You press buttons seems to be normal. Did not change with replacing all caps in the power supply at all.
Now there's a nice little challenge for you !I've got my 2445B few years ago and it was waiving like crazy. I knew there must be something wrong with the PS and I found this 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.) I recapped the power supply with the exception of the two big Sprague 290uF and the Rifa caps. Last week I ordered two 330uF Nichicon PW and the Rifa caps (well most of them, I missed two) and I opened it up to replace them. To my surprise, the Sprague ESR was better than the new Nichicon, 25mOhm Sprague and 100mOhm Nichicon so I didn't replace them. Sure enough, the Rifa caps were all micro cracked.
One relatively annoying issue that I have is that I can see a small flicker, a tiny fluctuation of the intensity. Do you know where it can come from? It has over 40K hours so I may need to recap the main board?
Also, the intensity knob is cracked. Do you know where I can get one without having to sell the scope to buy it?
I think the light flicker is normal and part of the design. All of my three scopes have it, one has only 800 hours of operation. Also the flickering of the LEDs on the front panel when You press buttons seems to be normal. Did not change with replacing all caps in the power supply at all.
Mine does that too.
Read this somehere that its common for B model (2445B & 2465B), to have that annoying whole panel's faint LEDs flickering everytimes when any button was pressed.
I've got my 2445B few years ago and it was waiving like crazy. I knew there must be something wrong with the PS and I found this 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.) I recapped the power supply with the exception of the two big Sprague 290uF and the Rifa caps. Last week I ordered two 330uF Nichicon PW and the Rifa caps (well most of them, I missed two) and I opened it up to replace them. To my surprise, the Sprague ESR was better than the new Nichicon, 25mOhm Sprague and 100mOhm Nichicon so I didn't replace them. Sure enough, the Rifa caps were all micro cracked.
One relatively annoying issue that I have is that I can see a small flicker, a tiny fluctuation of the intensity. Do you know where it can come from? It has over 40K hours so I may need to recap the main board?
Also, the intensity knob is cracked. Do you know where I can get one without having to sell the scope to buy it?
I think the light flicker is normal and part of the design. All of my three scopes have it, one has only 800 hours of operation. Also the flickering of the LEDs on the front panel when You press buttons seems to be normal. Did not change with replacing all caps in the power supply at all.
Mine does that too.
Read this somehere that its common for B model (2445B & 2465B), to have that annoying whole panel's faint LEDs flickering everytimes when any button was pressed.
Now there's a nice little challenge for you !I've got my 2445B few years ago and it was waiving like crazy. I knew there must be something wrong with the PS and I found this 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.) I recapped the power supply with the exception of the two big Sprague 290uF and the Rifa caps. Last week I ordered two 330uF Nichicon PW and the Rifa caps (well most of them, I missed two) and I opened it up to replace them. To my surprise, the Sprague ESR was better than the new Nichicon, 25mOhm Sprague and 100mOhm Nichicon so I didn't replace them. Sure enough, the Rifa caps were all micro cracked.
One relatively annoying issue that I have is that I can see a small flicker, a tiny fluctuation of the intensity. Do you know where it can come from? It has over 40K hours so I may need to recap the main board?
Also, the intensity knob is cracked. Do you know where I can get one without having to sell the scope to buy it?
I think the light flicker is normal and part of the design. All of my three scopes have it, one has only 800 hours of operation. Also the flickering of the LEDs on the front panel when You press buttons seems to be normal. Did not change with replacing all caps in the power supply at all.
Mine does that too.
Read this somehere that its common for B model (2445B & 2465B), to have that annoying whole panel's faint LEDs flickering everytimes when any button was pressed.
Is more front panel bulk capacitance needed for the LED supply rails or is it a digital glitch affecting the the switching for the LEDs ?
It is not front panel LED flicker, it is CRT flicker. Tiny but noticeable and random, not following a pattern.How can they be one in the same ? :-//
One relatively annoying issue that I have is that I can see a small flicker, a tiny fluctuation of the intensity. Do you know where it can come from? It has over 40K hours so I may need to recap the main board?
I think the light flicker is normal and part of the design. All of my three scopes have it, one has only 800 hours of operation. Also the flickering of the LEDs on the front panel when You press buttons seems to be normal. Did not change with replacing all caps in the power supply at all.
Mine does that too.
Read this somehere that its common for B model (2445B & 2465B), to have that annoying whole panel's faint LEDs flickering everytimes when any button was pressed.
Now there's a nice little challenge for you !
Is more front panel bulk capacitance needed for the LED supply rails or is it a digital glitch affecting the the switching for the LEDs ?
One relatively annoying issue that I have is that I can see a small flicker, a tiny fluctuation of the intensity. Do you know where it can come from? It has over 40K hours so I may need to recap the main board?
Is the flicker still there when the readouts are turned off, i.e. the readout control in the central position? The readouts "steal" time from the main trace, and that can cause intensity variations depending on the sweep time.
Also, the intensity knob is cracked. Do you know where I can get one without having to sell the scope to buy it?You could check Qservice (https://www.qservice.tv/vpasp/), they sell various Tek parts. No affiliation, just a happy customer.
One relatively annoying issue that I have is that I can see a small flicker, a tiny fluctuation of the intensity. Do you know where it can come from? It has over 40K hours so I may need to recap the main board?
Is the flicker still there when the readouts are turned off, i.e. the readout control in the central position? The readouts "steal" time from the main trace, and that can cause intensity variations depending on the sweep time.
Wow .. thanks for sharing med6753 ! :-+ :clap:
PS : All your images are saved, just in case Imageshack acting up in the future, hope you don't mind.
One thing I am nervous about though - this removal of the fan/mandrel. Are there any other tips anyone can give apart from 'go gently and glue back up if you have to'? I've read elsewhere that you can also push a bit on the mandrel, after loosening the nut a little. I also wondered about making some sort of jug to apply pressure in the right place. Can anyone give me advice or reassurance here?
Thanks a lot from the UK
Jon N
I wonder why they used such a complex fan instead of just putting a muffin fan in the panel like practically every other instrument out there.
One thing I am nervous about though - this removal of the fan/mandrel. Are there any other tips anyone can give apart from 'go gently and glue back up if you have to'? I've read elsewhere that you can also push a bit on the mandrel, after loosening the nut a little. I also wondered about making some sort of jug to apply pressure in the right place. Can anyone give me advice or reassurance here?
Thanks a lot from the UK
Jon N
Your concern about the fan assembly is certainly understandable. If you apply pressure incorrectly you could break the fan itself. That would be a difficult repair.
I haven't heard about pushing the assembly forward slightly and I'm not sure if it would help because the mandrel is tapered. And all those years assembled has resulted in the fan and the mandrel "cold fusing" together. That's where the deoxit or some other penetrating oil would help. A long thin pair of needle nose pliers against the rear hub and carefully pry forward seems to be the best method that I found. The point is....don't be afraid of it....just work carefully and chances are it will come apart.
I wonder why they used such a complex fan instead of just putting a muffin fan in the panel like practically every other instrument out there.
Apparently some over zealous Tek engineer thought that the 2465 required a complex variable speed fan as shown in this schematic. And apparently later on it was discovered that a standard $20 computer type fan would do the job just as effectively.
It is similar how a bicycle steer is fixed.
To loosen: undo the nut a few turns, before any pulling!!, slightly tap the nut inwards, this will loosen the collet and the fan from the shaft.
Now pull the fan from the shaft.
To tighten: place the fan on the shaft, carefully tighten the nut. (A bit)
Here's the best picture I have of the fan removed. I was mistaken when I said you could pry from the back hub. You can't. The hub of the fan extends internal to the case. But the thin needle nose can get between the case and the shaft piece and carefully pull forward. What you call a mandrel and I call a collet you can barely see extending slightly out from the end of the fan. When you tighten the nut it pulls forward and compresses against the motor shaft and also tightens it against the fan itself.
(...Image URL elided)
I was mistaken when I said you could pry from the back hub. You can't. The hub of the fan extends internal to the case.I'm not sure I fully understand you here...
But the thin needle nose can get between the case and the shaft piece and carefully pull forward.
To loosen: undo the nut a few turns, before any pulling!!, slightly tap the nut inwards, this will loosen the collet and the fan from the shaft.
Now pull the fan from the shaft.
Update - managed it!
Well, more or less. I packed some cardboard between the rear of the fan and the chassis, then got a small-ish hanner and tapped the screw head of the collet.
It took a bit more force than I was expecting but then it loosened and I was able to remove the fan.
The collet was still holding inside the fan assembly; I wanted to get it out and may have made a slight error there. I turned the collet and it started coming out; however now that I have it out I see that it has a break in the middle, just where the metal screw stops. I am guessing this is a common place for it to break; it is not all the way through and I am pretty confident that a bit of epoxy resin will hold it OK once I have degreased the thing.
So now I am on with the next stage. I just have to puzzle out how to remove the black plastic mains shield. That should be easy, but...
Cheers, J^n
Apparently some over zealous Tek engineer thought that the 2465 required a complex variable speed fan as shown in this schematic. And apparently later on it was discovered that a standard $20 computer type fan would do the job just as effectively.
Apparently some over zealous Tek engineer thought that the 2465 required a complex variable speed fan as shown in this schematic. And apparently later on it was discovered that a standard $20 computer type fan would do the job just as effectively.
I replaced the "complex variable speed fan" with a "$20 computer type fan" in my 2465 because the bearings were worn and the motor squealed like <insert wounded animal here>. After suffering this abomination for a couple of months, I took the trouble to find a NOS motor to reverse the mod. I'm also fortunate enough to own a 2467, so I've had occasion to compare the two kinds of fans.
So, from experience, the 2465 is as near silent as makes no difference - as is my 485, which has the same kind of fan. The 2467, by comparison, while perhaps not as loud as a 747 at takeoff, is annoyingly loud enough that it's only turned on at need.
All this to say that I take umbrage at the "do the job just as effectively" statement, and I'd wager you haven't had the opportunity to compare the two.
I'd also guess the squirrel cage fan design goes back a ways (witness the 485, introduced in 1972), and so was inherited by the 2465 as a tested design. There was plenty of other innovation in that scope for its time, and perhaps the "$20 computer type fan" wasn't all that common or inexpensive back in 1984 when the 2465 was introduced.
Your umbrage is misplaced. I'm only speaking from a historical perspective and reality. When the 2465A was introduced the cage fan was dropped in favor of a conventional design. If the Tek engineers felt it wouldn't do the job they would have continued with the cage fan.
I have a 2465 DMS with the cage fan that does the same shenanigans for about 20 minutes to about a half hour after initial power on. Then it calms down but is never whisper quiet and it makes itself known but isn't annoying.My 485's fan did the same thing. Before you replace the motor, try flushing it with IPA, then lubricating it with something like 5W-30 synthetic motor oil. It might be enough to silence it for a couple of more decades :). This is a bit of a pain to do, as if memory serves, you need to desolder the motor from the PCB it's mounted on to gain access to the thrust bearing screw. Once that's out, you can pour IPA through the motor a couple of times to flush out the gunked up old dust-in-oil.
Your umbrage is misplaced.Maybe umbrage is the wrong word, I just feel my 2467 is unreasonably loud in comparison to the 485 and the 2465.
The 2465BCT has Option 09, which is the Counter/Trigger. See attached. This is from the 1986 Product Catalog and it's the 2465 Option 09 but the 2465B is essentially the same. I have this option on my 2465 DMS and it comes in quite handy.
I have a copy of the 2465B Options Operating Manual in PDF if you want it. Send me an e-mail at seanfinn999@gmail.com. I don't have a copy of the 2465B Options Service Manual but Artek Manuals does have it for sale.
But from what I now read this option 09 just -increases- the accuracy of the frequency and time measurement of the displayed waveform by using crystal-controlled reference. So my question here is, how does the plain 2465B take time/freq measurements without option 09? What kind of reference does it use? Or is the plain B not capable of taking frequency readings and display them on screen? I'm probably wrong but cannot understand why a sophisticated instrument like a 2465B does not have an internal high precision crystal-controlled reference to begin with. I understand the frequency counter on the B version is good up to 150-200MHz, so if its not going to be very accurate it does not make much sense to display the measurement numerically on screen.
As a comparison, in my 2247A everything time/frequency measurement based is related to the 10MHz internal oscillator, with an option to connect an external high precision 10MHz (Rubidium, etc) signal to substitute the internal one. By doing just two button presses I get dead on frequency (or time) measurements shown numerically on screen with 6 decimal places from a displayed waveform even it is only maybe half a division in amplitude, and up to 100MHz. Granted the internal 10MHz is not a OCXO and takes about 30 min to fully stabilize, but will be rock solid after that.
Does the 2465B also do frequency measuring like this?
But from what I now read this option 09 just -increases- the accuracy of the frequency and time measurement of the displayed waveform by using crystal-controlled reference. So my question here is, how does the plain 2465B take time/freq measurements without option 09? What kind of reference does it use? Or is the plain B not capable of taking frequency readings and display them on screen? I'm probably wrong but cannot understand why a sophisticated instrument like a 2465B does not have an internal high precision crystal-controlled reference to begin with. I understand the frequency counter on the B version is good up to 150-200MHz, so if its not going to be very accurate it does not make much sense to display the measurement numerically on screen.
As a comparison, in my 2247A everything time/frequency measurement based is related to the 10MHz internal oscillator, with an option to connect an external high precision 10MHz (Rubidium, etc) signal to substitute the internal one. By doing just two button presses I get dead on frequency (or time) measurements shown numerically on screen with 6 decimal places from a displayed waveform even it is only maybe half a division in amplitude, and up to 100MHz. Granted the internal 10MHz is not a OCXO and takes about 30 min to fully stabilize, but will be rock solid after that.
Does the 2465B also do frequency measuring like this?
You are actually asking something I have wondered about but nobody has been able to answer. I have a 2247A and more recently acquired a 2445B so I can only answer part of your question.
The 2247A has the normal A and B triggers but also a C trigger and universal timer/counter IC which is used to make voltage and timing measurements continuously in real time. The 2445B does the same thing using its A or B trigger (so the display blanks during measurement) and some form of microprocessor control which results in equally good voltage measurements but much lower resolution timing measurements and measurements are *not* made in real time with continuous updates; it makes a single measurement and then displays it along with the sweep.
I have no idea how the timer/counter variants of the 2465B series operate other than providing higher resolution and I have never seen a video showing them in operation.
Thanks for the input David. Lets hope one of the Tek gurus on this post can answer our question.
BTW, don't you love your 2247A? I know I do! (Disclaimer: no intention on hijacking this thread, not that it would even be possible) ;-)But from what I now read this option 09 just -increases- the accuracy of the frequency and time measurement of the displayed waveform by using crystal-controlled reference. So my question here is, how does the plain 2465B take time/freq measurements without option 09? What kind of reference does it use? Or is the plain B not capable of taking frequency readings and display them on screen? I'm probably wrong but cannot understand why a sophisticated instrument like a 2465B does not have an internal high precision crystal-controlled reference to begin with. I understand the frequency counter on the B version is good up to 150-200MHz, so if its not going to be very accurate it does not make much sense to display the measurement numerically on screen.
As a comparison, in my 2247A everything time/frequency measurement based is related to the 10MHz internal oscillator, with an option to connect an external high precision 10MHz (Rubidium, etc) signal to substitute the internal one. By doing just two button presses I get dead on frequency (or time) measurements shown numerically on screen with 6 decimal places from a displayed waveform even it is only maybe half a division in amplitude, and up to 100MHz. Granted the internal 10MHz is not a OCXO and takes about 30 min to fully stabilize, but will be rock solid after that.
Does the 2465B also do frequency measuring like this?
You are actually asking something I have wondered about but nobody has been able to answer. I have a 2247A and more recently acquired a 2445B so I can only answer part of your question.
The 2247A has the normal A and B triggers but also a C trigger and universal timer/counter IC which is used to make voltage and timing measurements continuously in real time. The 2445B does the same thing using its A or B trigger (so the display blanks during measurement) and some form of microprocessor control which results in equally good voltage measurements but much lower resolution timing measurements and measurements are *not* made in real time with continuous updates; it makes a single measurement and then displays it along with the sweep.
I have no idea how the timer/counter variants of the 2465B series operate other than providing higher resolution and I have never seen a video showing them in operation.
The 2465 does not have the capability to tie in an external reference like your 2247A. And I doubt the 2465A & B have that capability either.
The 2465 does not have the capability to tie in an external reference like your 2247A. And I doubt the 2465A & B have that capability either.
Option 1E on an oscilloscope with timer/counter option 06 or 09 adds an external reference input which accepts any of 1.000000, 3.579545, 4.433185, 5.000000, or 10.000000 MHz as a reference.
Option 1E on an oscilloscope with timer/counter option 06 or 09 adds an external reference input which accepts any of 1.000000, 3.579545, 4.433185, 5.000000, or 10.000000 MHz as a reference.
OK, that must apply to the 2465A or B. I have the complete option list for the 2465 and Option 1E is not listed.
I see answers so far have been focusing on the external reference input BNC option 1E. But that still leaves the real question unanswered as to why a sophisticated instrument like the 2465 (inc A&B) did not come with a high precision internal reference to begin with (not to mention a standard external input), but instead the buyer had to add options 06 and or 10 to get a higher degree of accuracy.
I wonder if it is possible Tektronix was mainly focusing on developing a higher bandwidth scope, and not so much on other (useful in my opinion) features that could have been easily added? Which features? again, take a look at the 2247A real-time on-screen measurements (frequency, time, volts, etc).
If this is the case, I for one am disappointed. I only rarely push my scope bandwidth needs beyond 100MHz, but I was instead looking forward that getting a 2465B would be (or almost) like a 2247A on steroids with 400MHz bandwidth and a somewhat nicer updated front panel functionality and design. Seems now to me that this is not quite the case, so unless someone can maybe disprove this, and with all due respect to the 2465, but I think I rather stay with my 2247A for now. No dying NVRam, no Hot deflection hybrid, and virtually no unobtanium parts.
Perhaps it worked better with a scope camera to not have the filter? Seems like the filter is easily removable on my 465 too, looks better with it on though.
Especially the front covers, they all seem to end up as pencil cases in some deskdrawer.
Maybe we need to start using different search terms on ebay, like "Blue Pencil Tray" or "holder". Some time ago, just to see what came up, I tried looking for a 2465 front cover, but not one positive result came back.
I have a 2465B with option 06 (I believe that is the CT).
Obviously there is no guarantee that your scope will be close to it's normal function when you use my caldata.
Perhaps it worked better with a scope camera to not have the filter? Seems like the filter is easily removable on my 465 too, looks better with it on though.
To my eyes, on camera its better with filter on, shot this while ago.
(https://www.eevblog.com/forum/beginners/oscilloscope-training-class-(long)/?action=dlattach;attach=22223;image)
Perhaps it worked better with a scope camera to not have the filter? Seems like the filter is easily removable on my 465 too, looks better with it on though.
To my eyes, on camera its better with filter on, shot this while ago.
(https://www.eevblog.com/forum/beginners/oscilloscope-training-class-(long)/?action=dlattach;attach=22223;image)
The camera used in that case is a camera that was directly positioned over the CRT, where the little groove is for.
Polaroid and Kodak made the films I believe.
Often used in old school labs where stuff was mostly Single Shot, like short laser pulses etc.
Like these:
https://www.google.de/search?biw=1745&bih=892&tbm=isch&sa=1&ei=K9l5W5ONO4_uaYKbrsgF&q=tektronix+crt+camera&oq=tektronix+crt+camera&gs_l=img.3...0.0.0.7878.0.0.0.0.0.0.0.0..0.0....0...1c..64.img..0.0.0....0.FDak53Igd1A (https://www.google.de/search?biw=1745&bih=892&tbm=isch&sa=1&ei=K9l5W5ONO4_uaYKbrsgF&q=tektronix+crt+camera&oq=tektronix+crt+camera&gs_l=img.3...0.0.0.7878.0.0.0.0.0.0.0.0..0.0....0...1c..64.img..0.0.0....0.FDak53Igd1A)
Un saludo,
satbeginner (Leo)
So getting back to my other question, what do you guys think about an early serial (under 50K) 2465A version scope, possibly showing an error message on screen at power up, but that otherwise seems to properly display traces and cursors, a bit dusty on the outside but no broken shafts or missing knobs buttons, or any other obvious damage, etc, no front cover or probes, but yes it has the blue screen filter. I have not had a chance to see it personally, but this is what i have so far been able to glean into the situation, and I am still haggling with the owner over a compromise price given probable problems. Just like trying to buy a car without even test driving it first, so how much trouble could I possibly get into....? Ha!
I am asking him to send me a picture of the error message, but he really doesn't know much about scopes. I am not sure of the procedure to bring up the error message myself, but I assume telling him to just turn on the scope and then taking a picture of the first screen he will see would be enough to capture the error message? Thanks for the input.
Another useful bit of information at this point while looking for a 246x scope would be if there is an error code specific to an instrument that has lost its calibration constants? Is there such error message, or is there anything else I would need to look out for to know for sure that the calibration is gone? Thanks.
But it is the Lithium cell what worries me. Its timestamp is from 1988Q1, so it has more than 30 years on it. Its voltage is now 3.67 V.
Does anybody changed this battery not losing the battery cal. data? I'm thinking on powering the RAM from an external battery; remove the old one; solder a pair of wires to the PCB holes of the removed battery; and connect a new battery to such wires, in case I need to replace the battery again in the future. Comments on this? Any other EEVblog-approved procedure?
Also, the battery (a Eagle-Picher Keeper LPC-7P) seems to be unobtanium in EU, any replacement?
Thanks a lot & regards.
Another useful bit of information at this point while looking for a 246x scope would be if there is an error code specific to an instrument that has lost its calibration constants? Is there such error message, or is there anything else I would need to look out for to know for sure that the calibration is gone? Thanks.
You can download a copy of the 2465A service manual here...
https://elektrotanya.com/tektronix_2465a_2467.pdf/download.html
Starting at section 6-10 it lists all the diagnostic routines.
But it is the Lithium cell what worries me. Its timestamp is from 1988Q1, so it has more than 30 years on it. Its voltage is now 3.67 V.
Does anybody changed this battery not losing the battery cal. data? I'm thinking on powering the RAM from an external battery; remove the old one; solder a pair of wires to the PCB holes of the removed battery; and connect a new battery to such wires, in case I need to replace the battery again in the future. Comments on this? Any other EEVblog-approved procedure?
Also, the battery (a Eagle-Picher Keeper LPC-7P) seems to be unobtanium in EU, any replacement?
Thanks a lot & regards.
Yes, that's been done. A backup voltage provided while the battery is changed out. If I recall correctly that procedure is buried somewhere way back in this thread. Got a few hours to do some reading/searching? :-DD
Why remove the capacitor? Can't you just tack solder some wires to the pads with the capacitor in place?
Hi again,
Finally managed to fix it. As there was no image at all, but the controls seem operative, I decided to check the HV board. Soon noticed that all HV voltages were dead, because the HV oscillator was also dead, as the unregulated -15 V tension was not present. Such voltage comes from the A2A1 regulator board via the J121 connector in the center of the image.
(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=525008)
The problem was that I inserted the connector badly, in such a way that pin 1 from the PCB (the unregulated -15 V) was not inside the plastic connector, but below it |O, where it cannot be seen . This was possible (apart for my clumsiness) because pin 2 is not present, so it is possible to push the connector slightly tilted, so pin 1 goes outside its place.
The unregulated -15 V source seems not to be used in any place, but in the HV oscillator, and it is also not monitored by the processor, so the remaining circuitry worked flawlessly and all tests passed OK.
It's working now, waiting for the AA sized Li-SOCl2 cell I will use to replace the PCB mounted RAM backup battery.
Regards.
Hi again,
Finally managed to fix it. As there was no image at all, but the controls seem operative, I decided to check the HV board. Soon noticed that all HV voltages were dead, because the HV oscillator was also dead, as the unregulated -15 V tension was not present. Such voltage comes from the A2A1 regulator board via the J121 connector in the center of the image.
The problem was that I inserted the connector badly, in such a way that pin 1 from the PCB (the unregulated -15 V) was not inside the plastic connector, but below it |O, where it cannot be seen . This was possible (apart for my clumsiness) because pin 2 is not present, so it is possible to push the connector slightly tilted, so pin 1 goes outside its place.
The unregulated -15 V source seems not to be used in any place, but in the HV oscillator, and it is also not monitored by the processor, so the remaining circuitry worked flawlessly and all tests passed OK.
It's working now, waiting for the AA sized Li-SOCl2 cell I will use to replace the PCB mounted RAM backup battery.
Regards.
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)
Hi all,
Just started to open my pristine 2465B for a recap and cal. backed memory update, just to discover that mine has the old style A5 board (insertion components) that, to hold the cal. data, has a separate RAM chip and a PCB mounted Lithium battery, as seen here:
The top plate is now accessible. Looks innocent enough, doesn't it? The real fun is yet to begin in Part 2.
med6753, gorgeous machine :clap: and thanks for sharing the nicely shot detail photos. :-+
Is there any reason you don't use the forum's attachment instead of hosting them at imageshack ?
Really worry if someday imageshack acting up, all of this great photos with details will be lost, as we already have few valuable post that had photos gone at earlier posts in this thread alone. :'(
What were my results? The fan motor for the first time since I've owned this scope is totally silent. So far the repair has worked and I've run it several hours. Will it last? Hard to say. I think this motor is potentially on it's last legs. But so far it's a thumbs up. :-+
Four items totaled are listed on the can. (1) Hydrotreated light naphtha is a light petroleum. (2) 1,1Difuorethane is a propellant listed as safe to use by the EPA for food. (3) Polydmethylsiloxane is a type of silicone. (4) n-Hexane 110-54-3 is a crude oil product that evaporates very quickly into the air and is used to extract vegetable oils from crops like soybeans. I use this product on my Cabela's meatgrinder after I've cleaned it, dried it, and before I put it away. It keeps away the rust while keeping the product lubricated between uses. Also never use this product near an open flame as it is very flammable.
...The 256 values should match what you see in EXER 02, in which case, yes, it has all of your calibration data.
It also seems like the 2465A only has entries from 0-254. 255 is zero and from 256 onwards the values wrap around. Is that enough to back up all of my calibration data?
I don't feel like experimenting with restoring the settings, but I'm happy to write another script that does this over GPIB in one go if someone is willing to test.
...
Putting the calibration data back via GPIB works on a 2465(plain), but I haven't heard of anyone trying it yet on an A or B. There's no reason to think it would operate differently, but until someone tries it I guess we don't know for sure. I've been watching for an A or B junker on ebay for some time now to do this experiment.
Nice find on the "f" option to the EAROM command, thanks!
I've had my Tek 485 display a stable >1GHz signal. Not bad for a 350MHz scope :)
The limitation wasn't the frequency, but the amplitude of the signal; the limit was set when the amplitude fell to <0.2 divisions. That is a good illustration of the quality of Tek's tunnel diode trigger circuits.
I've had my Tek 485 display a stable >1GHz signal. Not bad for a 350MHz scope :)
The limitation wasn't the frequency, but the amplitude of the signal; the limit was set when the amplitude fell to <0.2 divisions. That is a good illustration of the quality of Tek's tunnel diode trigger circuits.
I've had my Tek 485 display a stable >1GHz signal. Not bad for a 350MHz scope :)
The limitation wasn't the frequency, but the amplitude of the signal; the limit was set when the amplitude fell to <0.2 divisions. That is a good illustration of the quality of Tek's tunnel diode trigger circuits.
Wow! What probes did you use for that?
Plugged in, power on, but no trace or readout on screen. Self test stops at the "ADD" label, which means a Test 05 Error of some kind. Seller's description stated that the scope was showing an Error 05 Fail 40, which means "Positive Level too positive", and I assumed most probably due to corrosion on the A5 board due to well known leaky caps, which now is already confirmed ->detailed pictures of clean-up to follow as well. Seller also stated that trace had a lot of vertical jitter, and after a while it would move off screen towards the bottom. Not sure how long ago this scope still had a visible trace upon power up.
Anybody has any ideas/suggestions on why there is no trace?
Oh, and yes, I will definitively check all the voltages at J119 once I get the mess cleaned up on A5.
Plugged in, power on, but no trace or readout on screen. Self test stops at the "ADD" label, which means a Test 05 Error of some kind. Seller's description stated that the scope was showing an Error 05 Fail 40, which means "Positive Level too positive", and I assumed most probably due to corrosion on the A5 board due to well known leaky caps, which now is already confirmed ->detailed pictures of clean-up to follow as well. Seller also stated that trace had a lot of vertical jitter, and after a while it would move off screen towards the bottom. Not sure how long ago this scope still had a visible trace upon power up.
Anybody has any ideas/suggestions on why there is no trace?
Oh, and yes, I will definitively check all the voltages at J119 once I get the mess cleaned up on A5.
Your scope sounds almost exactly like mine. The problem is almost certainly just the DAC circuit on A5 due to the capacitor corrosion. That DAC circuit is used for controlling pretty much everything in the scope. ADD being illuminated also suggests you have a DAC problem. Fix A5 and you'll be good to go.
I say this from experience -- a couple weeks ago I purchased a SN005xxxx 2465B, datecodes ~1990, with no trace (advertised as "HV collapses") for not much money. Finished fixing it the other day (have not recapped the power supply or replaced the NVRAM yet; those are next on the list). I haven't yet gotten around to writing it up for this thread and posting my pictures, but here's the abridged version for you & posterity.
I've had my Tek 485 display a stable >1GHz signal. Not bad for a 350MHz scope :)
The limitation wasn't the frequency, but the amplitude of the signal; the limit was set when the amplitude fell to <0.2 divisions. That is a good illustration of the quality of Tek's tunnel diode trigger circuits.
Wow! What probes did you use for that?
None! BNC coax, 50ohm termination in the scope.
The 485 has two attenuators, one 50ohm and one 1Mohm. None of this "stuff a 50ohm resistor across the 1Mohm//20pF input and call it 50ohm" crap :)
Quick question: what would you say are the easiest access points to check on the +1.36V and -1.25V DAC reference voltages? Wanted to do a quick "1-2-3" check on that to see at what level those voltages are actually now, before and after the board wash of the two separate affected areas. And eventually after the required parts are replaced. Kind off to keep track of those voltages, mostly out of curiosity. Are there any easy access test points on the A5 board itself, or maybe some pins on one of the on board connectors? I do have the service manual but have been kind of overwhelmed a bit between some lack of time and all the huge amount of technical information in there, so at times one tends to loose track of what is where. Guess it will get better after I have gone through it enough times to familiarize myself with the content on a greater extent.I’m out of town for the weekend so unfortunately I can’t provide specifics or take a picture of the schematic where I circled my test points for the reference voltage. However they should be straightforward to find if you compare the schematic and layout view. On the SMT A5 board, there are no explicit test points for the reference voltage, but they are easy to access on component terminals, I just don’t remember which components. First find the reference voltages in the analog control schematic (they’re labeled clearly), then identify which components have those voltages on them (for each there should be an op amp and probably an analog mux and maybe a capacitor). Then identify the components on the layout diagram. The voltages are also available on some of the front panel pots — intensity for sure, don’t remember which others. The schematic is clear on this though. They are undoubtedly on some headers/cable assemblies as well but I don’t know which and I didn’t investigate carefully.
BTW by any chance do you (or anyone else out here) would have handy an already made list of specific Mouser PNs of the usual parts that need to be replaced in the DAC area? I've come across a list with Digikey PNs for some of the caps and resistors, which is a start but would also like to order the DAC trimmer resistor as well, just in case. And for several reasons, including the above and beyond easy and friendly quality user experience, my preferred go to parts place for years now has always been Mouser.
Thanks again for the great write up. I will send in some more updates of progress on the board wash hopefully in the next couple of days, as time and other occupations pressing for attention as well do permit.
Try to find 070-6863-01 which is newer, preferably the searchable version.
Ok dried the board for a while and popped in temporary elco subs for the removed leaky caps so I could take some measurements around the DAC. Please see attached image with schematic of the DAC input resistor network. All voltages in red taken with a HP974A DMM. I have not checked yet any of the resistor values, which I assume cannot be checked in-circuit anyhow.
Not sure if anyone has records of what the correct voltages should be around these nodes so as to compare and try to figure out which ones are probably bad without having to pull one by one to test them. For me once a SMD part out it will probably stay out and a new replacement will go in instead. So i rather will try to keep as many as possible of the undisturbed originals and try to deduce which might be bad with these voltage measurements.
The +1.36V out at the + side of C2420 only measures a mere +0.25V or so (all measurements where a bit jumpy and dance around 0.1-0.2V). Likewise the -1.25V output has only 0.23V (at pin 13 of IC2420).
Anyone out there that has done these same measurements on a good scope?
So I build a simulation of the resistor divider of the DAC input with 5% resistors on a protoboard so I could make some voltage reading comparisons. I am assuming that the two DAC reference inputs are high impedance and do not account for much if any change on the actual resulting voltages (please correct me if I am wrong on this). I also adjusted the 10V input voltage to match the 9.988V actually seen on the scope, and adjusted the wiper of the 20K trimmer to match 5.51V as seen on the scope as well. The results are on the attached picture.
The total series resistance of this network measured roughly about 38~39K (I left out the 15uF C2010 capacitor on purpose to be able to measure this resistance). I measured about 268uA current flowing through the divider, which I calculated taking the voltage across the 1K R2016 resistor, the upper leg of the divider, which is 9.988v - 9.72v = 268mV / 1K = 268uA. Again, these are 5% resistors, so readings will be slightly off here and there, but should definitively be good enough for a general comparison.
Now going back to my original readings on the scope (I re-posted the picture showing those readings as well), the voltage difference on the 1K R2016 resistor is only 9.988-9.926 = 62mV, which if I assume the 1K resistor is still within its value, there are only 62uA of current flowing into the resistor network. Way too low. This I would think would mean that one or more resistors have gone high (or open). My first suspect would be R2012 10K, as the voltage on pin 15 of the DAC (-Ref) is more than twice as high as expected, and this resistor is the lower leg of the voltage divider. Then again, maybe R2013 has gone high (or open), as the +Ref voltage is about 2.25v low compared to my simulation.
I could try to further tweak my breadboard simulation to see if I can find a combination that would arrive at the actual voltages read on the scope. That would of course only be practical if one assumes that only one or maybe two resistors have sustained damage, but given that more than two might be bad, it might be a futile exercise.
Time now for a break, get some Zzzzs.... its almost 4am.
@AMR Labs
Wouldn't you just measure a few of your 5% resistors on hand to find some that fall within a 1% tolerance and use those ?
My 2465B bought in 2011 had 292 on hours & and on/off counter at 349, I guess that depends on previous owner usage, but yours look pretty low count, assuming its not tampered.
My 2465B bought in 2011 had 292 on hours & and on/off counter at 349, I guess that depends on previous owner usage, but yours look pretty low count, assuming its not tampered.
I guess that must be the scope that started this thread? I saw you also got lucky that the front cover and a storage pouch where included, mine came with those as well, but no probes. Very hard to get those accessories included nowadays on a low or even mid priced 2465x on ebay, specially the front cover. I have seen these sold separately for $100, just for the cover. And you also have a TEK made U800. In what serial number group is yours? Mine is 55xxx and most chips inside have a 1990 date code, including the NVRAM. From the inscriptions and labels on the front cover and on one side, this might have been a field unit that was not really taken out that much, and who knows maybe even less once the problems created by the leaky caps started to show up. The inside is almost pristine, very little dust only in a few places, if any at all. No signs of anyone tampering inside either.
Actually that kind of socket fits the DS1225 poorly, at least the ones I have, but the pins on the converter (standard pin headers) fits very well. They may damage the socket because of sharp edges but I don't plan on removing it again so no problem. The same is true for machined sockets I believe.
Yes the 2467B is nice, but since they are in great demand prices are through the roof, compared to the 2465B. Lots of people looking to get one, but waiting for the right/fair price.
I agree the front cover is very important to have, more so to get it with the scope in the first place, and yes definitively makes it easier to rest the scope on its face upside down to safely remove the back panel. I was even feeling a bit apprehensive of buying a scope like this without the front cover, as it is a very effective layer of protection against bent/broken controls due to shoddy packaging or in-transit mishandling. More than a few horror stories out there of mangled front panels.
Was going back to page one and looking at your pictures of the scope, very nice indeed. Which reminds me, at some point I will probably have to check on the power supply caps, and wrestle with those two boards to get them out.
BTW looking at you options sticker in the back, mine is a bit different, and the only option marked on this one is numbered 46, which I still have not been able to figure out what it is. Do you (or anyone ) know what option 46 is for? Asked before but no answers, so give it another try.
So from the origin of your scope I assume you are located on the other side of the "pond". Bet you never thought about this thread lasting so many years.
I normally wouldn't clutter a technical thread with such stuff, but since this is the definitive 2465 thread, I'll mention I've posted a probe pouch and a front cover over in the buy/sell forum:
https://www.eevblog.com/forum/buysellwanted/fs-(canada)-tek-2465-2467-front-cover-and-probe-pouch/ (https://www.eevblog.com/forum/buysellwanted/fs-(canada)-tek-2465-2467-front-cover-and-probe-pouch/)
Good deal on getting your DAC issues straightened out. :-+ And yes, recapping the Regulator and Inverter boards should be next on the agenda. You can follow my post back in July on getting those boards out with minimal hassle.
Edit, starts at reply 1091.
Already have 2 probe pouches and while I'd really like to have a front cover for my 2465 I think $76 USD plus shipping is a little (no, a lot) too much. :-- (And yes, I understand they are rare and sell at a premium which is why mine will remain naked)
Good deal on getting your DAC issues straightened out. :-+ And yes, recapping the Regulator and Inverter boards should be next on the agenda. You can follow my post back in July on getting those boards out with minimal hassle.
Edit, starts at reply 1091.
Thanks for the heads up Med, will certainly take a look at it! The traces seem a bit fuzzy under certain conditions, specially while using the 10x horizontal magnification, and most probably recapping the PS might help cleaning up the traces. On the other hand, it really helps using the 20MHz BW limit, it makes the traces much sharper. That tells me there must be HF noise probably creeping in through the power supply.
Here is a pic of the scope still triggering on a 800.000MHz signal, even tough at this point the trace looks quite fuzzy due to the vertical input amp gain running way out of bandwidth (the input signal was 400mV). The automatic counter would only read up to 650MHz. But in general the counter doesn't seem to be very accurate, always seems to be off by 10% or so. Even with an accurate 10MHz signal the 2465B was showing a counter best reading at something like 10.173 MHz. I guess that is what that 2465B C/T option is all about to tighten up the counter accuracy. My 2247A was effortless counting the same signal as 10.000071MHz (yes the scope counter calibration is actually off by about 71Hz), and counter is good and stable to about 300-350MHz.
BTW the traces look much brighter on this picture than they actually where, was trying to avoid using a flash, so the camera opened way up. Nowhere near what looks like CRT melting levels.
Already have 2 probe pouches and while I'd really like to have a front cover for my 2465 I think $76 USD plus shipping is a little (no, a lot) too much. :-- (And yes, I understand they are rare and sell at a premium which is why mine will remain naked)
Not too long ago a 2465B cover (new style with the indentation) sold on ebay for a cool 100 bucks plus shipping from the Philippines. But it took quite some time to sell. Supply and demand market, unfortunately. I was looking for these for some time anticipating my future scope would not have it, and not even one other ever came up. I'm glad I actually got lucky, makes me think the scope alone actually sold for a mere $110, plus the cover (and a pouch).
Was going back to page one and looking at your pictures of the scope, very nice indeed. Which reminds me, at some point I will probably have to check on the power supply caps, and wrestle with those two boards to get them out.
BTW looking at you options sticker in the back, mine is a bit different, and the only option marked on this one is numbered 46, which I still have not been able to figure out what it is. Do you (or anyone ) know what option 46 is for? Asked before but no answers, so give it another try.
So from the origin of your scope I assume you are located on the other side of the "pond". Bet you never thought about this thread lasting so many years.
Does your 2465B have the Counter/Trigger option? If yes and you don't have the equipment as per the manual to calibrate it I have an alternate procedure that came from an old gray bread on the Yahoo Tek group that is simple and will get it dead nuts.
Does your 2465B have the Counter/Trigger option? If yes and you don't have the equipment as per the manual to calibrate it I have an alternate procedure that came from an old gray bread on the Yahoo Tek group that is simple and will get it dead nuts.
I would be interested to see it if you don't mind sharing.
Could someone please explain how one does put the values gathered with the EXER 02 routine into a BIN file?Here, try this explanation...
...
Any explanations, pointers, or even links to other already existing clear explanations for a newbie in this procedure will be much appreciated.
MarkL:Yes, you are right that the leading zeros don't matter.
OK I started trying some things on the Hex Editor program and found that by changing the bytes per row from 16 to 10 (DOH) it will give me the correct row length that matches your example. I still get the four zeros in front of the 4 digit address, I assume this the usual way to look at the addresses and just ignore the leading zeros?
Could you please check the updated attached image and let me know if this would be correct in accordance to your example from your post above?
Thanks again.
One last question if you don't mind, when you refer to a line by labeling it as "0x1E00", what is the meaning of the "x" in it? Is this a common convention just to save not having to write it with all the leading zeros as in 00001E00, or does it have another meaning?
MarK, thanks very much for the template and additional clarification. I will work on rewriting my own Exer02 data into it. That was very helpful. Maybe I could even post my finished BIN file and if someone out here in the US with a programmer would be willing to write the data for me into a fresh DS1225AD-150 and mail it to me to FL zip 33152, I would be more than willing to pay for the efforts and cost of shipping. That way once I pull my original NVRAM and install a socket I could compare them and verify that it actually works to copy the exer02 values into a chip and put to rest that this might not be feasible as some members of the TekIO group stated in older messages I found. Or maybe in the end they will be proven right, but at least we will know.Glad it worked out for you!
...
My Tek 2445B developed an interesting belly dance at first power up when cold. I think it is the capacitors on the main board. What do you masters think? It stabilises after 2 - 3 minutes and it is stable after that.
I tried to remove two of the knobs from the front panel and both broke, that's how brittle they are. Without removing those knobs there's no way to get to the main board. Anyone has a set of brightness, focus, etc knobs?
As requested here is an alternate procedure for calibrating the Counter/Trigger option. First, here is the copy of the cal procedure from the 2465 Options Service Manual. I assume the procedure is the same or similar for the 2465A/B.
(https://imagizer.imageshack.com/v2/xq90/924/KPrSnZ.jpg) (https://imageshack.com/i/poKPrSnZj)
(https://imagizer.imageshack.com/v2/xq90/922/YOeXJM.jpg) (https://imageshack.com/i/pmYOeXJMj)
The alternate procedure was from a gray beard on the Yahoo Tek Group who's name I forget and I take no credit for developing this procedure. But I can tell you from experience that it does work. You can use a function generator, oscilloscope calibrator, or home made pulser with the following requirements:
Square wave must be exactly 1 MHz.
Rise time of 1ns or less.
0.8 to 1 volt peak to peak.
Preferably as close to 50% duty cycle as possible but not absolutely necessary.
Must not have an either positive or negative offset. In other words, must be equally above and below 0 (GND) centerline. See first trace example. I have a Heath IG-4244 Oscilloscope Calibrator which meets all the requirements except it has a fixed negative offset as shown. If your signal source has an adjustable offset set it for approx .4V to .5V p-p above and below centerline (.8V to 1 V p-p total). Then set up your scope as per the cal instructions and proceed right to step F and do the cal. As long as your source is exactly 1 MHz it should work. If you have an offset issue see next step.
Negative offset:
(https://imagizer.imageshack.com/v2/xq90/923/iQzh3E.jpg) (https://imageshack.com/i/pniQzh3Ej)
What you'll need:
BNC “T” connector.
6dB inline attenuator.
DC supply that goes down to 0 volts.
50 ohm coax.
Connect the signal source to the left. Connect the power supply to the attenuator. If your source is a negative offset connect positive to center pin. If the source is a positive offset connect negative to the center pin. Slowly increase the voltage until you obtain a waveform similar to the 2nd pix. .8 volt - 1 volt p-p equal to centerline. Then proceed to step F and do the cal. It should take. If not go back and check your setup.
(https://imagizer.imageshack.com/v2/xq90/922/2WMwLb.jpg) (https://imageshack.com/i/pm2WMwLbj)
(https://imagizer.imageshack.com/v2/xq90/924/a8FQZU.jpg) (https://imageshack.com/i/poa8FQZUj)
My Tek 2445B developed an interesting belly dance at first power up when cold. I think it is the capacitors on the main board. What do you masters think? It stabilises after 2 - 3 minutes and it is stable after that.
I tried to remove two of the knobs from the front panel and both broke, that's how brittle they are. Without removing those knobs there's no way to get to the main board. Anyone has a set of brightness, focus, etc knobs?
Agree with tautech. Try cleaning the horizontal position pot.
Knobs....mnementh had a spare focus knob for my 2465. He may have some additional. PM him and make sure you tell him I sent you.
If he doesn't, Google is your friend. There are multiple sites selling Tek parts. I'm sure you can find them.
Next step then is to monitor the supply voltages at J119 on the main board and see if one of them is bouncing around. And with that many hours have the Inverter and Regulator boards ever been recapped? If not I highly recommend it be done.
Maybe the picture below will clarify some things... ;D
Next step then is to monitor the supply voltages at J119 on the main board and see if one of them is bouncing around. And with that many hours have the Inverter and Regulator boards ever been recapped? If not I highly recommend it be done.
I recapped the power supply few years ago with good Nichicon PW series caps.
Glad it worked out for you!
If your goal is to prove that writing the EXER 02 values into the NVRAM works, that's already been verified.
There have been multiple conversations about it on TekScopes groups.io. Which one are you referring to? The last one I recall was the thread "tektronics 2465b 400mhz nvram battery info" where someone verified it with a 2467B in April.
Although I didn't mention it in a post a couple of weeks ago (reply #1182), I also verified that both the EXER 02 and the GPIB dump of the cal data was an exact copy of what's in the NVRAM on a 2445A. But I didn't bother mentioning it because it had been done before.
It's also been verified on a 2465, although that scope is a little different since it doesn't use a Dallas NVRAM.
So, we have all the versions covered for this series (A, B, and plain).
More verification is always nice, but it may not be worth the extra hassle if you don't already have a programmer or other equipment to do it.
That being said and you still want to experiment, I'm willing to drop your BIN data in a fresh DS1225AD-150 for you for free, if you want to send me the chip and a self-addressed, pre-paid return envelope. PM me if you want to set this up.
I tried to remove two of the knobs from the front panel and both broke, that's how brittle they are. Without removing those knobs there's no way to get to the main board. Anyone has a set of brightness, focus, etc knobs?
Maybe the picture below will clarify some things... ;D
Wow, 41K plus hours of operation? Have you owned the scope since new or for a long time? Looks like during its life it might not have been officially recalibrated either, at least not at an accredited lab. The tech that performs the cal is supposed to also reset this counter after each calibration, so the next tech guy that has to deal with the instrument will know the elapsed time. But if just left to run it also can give a ballpark idea of the usage, but then again, it may have more than 41K hours on the clock, with one or more resets along the way.
Are you sure that counter is resettable? It is the ON counter and probably it is stored in the same infamous NVRAM that I replaced this summer.
Next step then is to monitor the supply voltages at J119 on the main board and see if one of them is bouncing around. And with that many hours have the Inverter and Regulator boards ever been recapped? If not I highly recommend it be done.
I recapped the power supply few years ago with good Nichicon PW series caps.
OK, but I would still monitor the PSU voltages at initial power up and see if something is amiss. Rule that out first before digging into it further.
I tried to remove two of the knobs from the front panel and both broke, that's how brittle they are. Without removing those knobs there's no way to get to the main board. Anyone has a set of brightness, focus, etc knobs?
I read somewhere that carefully warming up the knobs with a heat gun really helps to remove the stuck ones (after so long most of them will be) without breaking them. I have not tried this yet, and hope for now I will not need to. Knock-knock...
I was not sure yet that it had been verified. It seems to be a touchy subject for some members over at TekIO when asked, as can be seen on some past messages. In a situation where a scope lost the calibration constants, some of them will tell you to rather invest the time in getting the scope properly calibrated than to thinker trying to rebuild the cal data with exer02 values, as it might not work, or at best be no longer accurate and on the dot anyhow. I get their point, but then again, my scope is intended for hobby use only, not on a bench at NASA. Also, I can understand the interest in using Exer02 data in a situation where someone lost the cal data, and has no intentions to send the scope out for calibration, or does not have the means to calibrate it himself. 10x better, maybe even 100x better to have your own Exer02 data to play with than having to use a third party bin file from another scope just to bring yours back to life.I agree with you.
My Tek 2445B developed an interesting belly dance at first power up when cold. I think it is the capacitors on the main board. What do you masters think? It stabilises after 2 - 3 minutes and it is stable after that.After the already mentioned power supply checks,
...
My Tek 2445B developed an interesting belly dance at first power up when cold. I think it is the capacitors on the main board. What do you masters think? It stabilises after 2 - 3 minutes and it is stable after that.After the already mentioned power supply checks, maybe try reseating the horizontal output hybrid U800. You could also try some freeze spray on components in that area to try to find something sensitive to warm-up.
...
If it's affecting the whole screen, including the readout as you say, I would highly suspect something around U800 since it's in common to the readout and the traces. At least it's the place to start.
Oops - tggzzz is absolutely right. I was thinking of one of the plug-in hybrids. Don't mess with U800 but you can certainly start your probing in that area.My Tek 2445B developed an interesting belly dance at first power up when cold. I think it is the capacitors on the main board. What do you masters think? It stabilises after 2 - 3 minutes and it is stable after that.After the already mentioned power supply checks, maybe try reseating the horizontal output hybrid U800. You could also try some freeze spray on components in that area to try to find something sensitive to warm-up.
...
If it's affecting the whole screen, including the readout as you say, I would highly suspect something around U800 since it's in common to the readout and the traces. At least it's the place to start.
Be very cautious with U800. There are credible accounts that its mounting bracket can easily be overtightened, destroying that excessively expensive ic.
Personally I'd rule out all other options and positively identify U800 as being the problem before fiddling with it.
Oops - tggzzz is absolutely right. I was thinking of one of the plug-in hybrids. Don't mess with U800 but you can certainly start your probing in that area.My Tek 2445B developed an interesting belly dance at first power up when cold. I think it is the capacitors on the main board. What do you masters think? It stabilises after 2 - 3 minutes and it is stable after that.After the already mentioned power supply checks, maybe try reseating the horizontal output hybrid U800. You could also try some freeze spray on components in that area to try to find something sensitive to warm-up.
...
If it's affecting the whole screen, including the readout as you say, I would highly suspect something around U800 since it's in common to the readout and the traces. At least it's the place to start.
Be very cautious with U800. There are credible accounts that its mounting bracket can easily be overtightened, destroying that excessively expensive ic.
Personally I'd rule out all other options and positively identify U800 as being the problem before fiddling with it.
Previous post updated.
...And U800 is especially fun since it has +87V coming into it (pin 7), which is not shown on the A1 schematic. It's worth looking at the power distribution schematic to know where this and other power pins lie in wait.
In other areas it is worth being careful not to slip and short out IC pins.
I absolutely refuse to discuss why I mention that :(
And U800 is especially fun since it has +87V coming into it (pin 7), which is not shown on the A1 schematic. It's worth looking at the power distribution schematic to know where this and other power pins lie in wait.
I agree with you.
I'm willing to bet the vast majority of these scopes (that are still working) are now in the hands of hobbyists who don't care or need up-to-date calibration. Having a way to backup and restore the existing cal data is all that's needed. And the backup part is easy by just taking a video of flipping through EXER 02.
Why calibration backup and restore is not implemented and openly documented for every piece of test equipment, both old and new, continues to mystify me.
On these scopes, I find it strange that Tek would provide a way to display the cal data, but not have some easier way to put it back. The data itself is meaningless to even a service tech, so why bother displaying it in the first place?. I continue to be suspicious that there's a hidden way to do it from the screen, but I haven't had time to dig through the code to look for it.
...Yes, it's possible to do the dump and restore via GPIB. The commands are here (but there's no GUI or wrapper program for it that I'm aware), and it works on all of them in the series:
Although I think that someone verified (maybe it was you) that one can get the NVRam data dump via the GPIB? And even restore it (not so sure about this last part) the same way? But obviously this is not so easy and straight forward unless you know how to set it up and the proper commands, and not all scopes have this bus build in. My scope has GPIB but I would not even know where to start. (Read the book!, read the book!). :-X
In other areas it is worth being careful not to slip and short out IC pins.
I absolutely refuse to discuss why I mention that :(
...And U800 is especially fun since it has +87V coming into it (pin 7), which is not shown on the A1 schematic. It's worth looking at the power distribution schematic to know where this and other power pins lie in wait.
In other areas it is worth being careful not to slip and short out IC pins.
I absolutely refuse to discuss why I mention that :(
It's also good place to use one of those plastic probe tip covers so it can only contact one pin at a time.
I measured the voltage on pin 7, it is 86.18V sharp on DMM and scope on AC 500mV, straight line, no move whatsoever. I'll do more tests in the weekend when I can find some time. It looks like U800 has been replaced or at least resoldered judging by the amount of solder and flux around the pins. It is a Tek chip, not Maxim and after 5 - 6 minutes it is barely warm, I don't think it needs a heatsink.
I measured the voltage on pin 7, it is 86.18V sharp on DMM and scope on AC 500mV, straight line, no move whatsoever. I'll do more tests in the weekend when I can find some time. It looks like U800 has been replaced or at least resoldered judging by the amount of solder and flux around the pins. It is a Tek chip, not Maxim and after 5 - 6 minutes it is barely warm, I don't think it needs a heatsink.
I might be wrong, and please do correct me if I am, but I think I read somewhere that the temperature of U800 will vary depending on the "load" it is put through. On an idle scope it might remain cool to the touch, but might get hotter while trying to handle more complex or fast signals. Correct?
Are you sure that counter is resettable? It is the ON counter and probably it is stored in the same infamous NVRAM that I replaced this summer.
Just out of curiosity I searched on ebay for a "USB-to-GPIB converter", and only two results came up, both from the UK. One priced at around $1200, and the other for a little over $1000. Both units look exactly the same. Is this really what an interface of this type costs, or did I miss something?
Just out of curiosity I searched on ebay for a "USB-to-GPIB converter", and only two results came up, both from the UK. One priced at around $1200, and the other for a little over $1000. Both units look exactly the same. Is this really what an interface of this type costs, or did I miss something?On ebay, you can easily find Agilent 82357b USB/GPIB adapters for well under $100. Beware that most are clones/counterfeit, not Agilent-made, especially those sold as New. Fortunately, the clones are straight copies with the same 75161 and 75160 proper GPIB bus driver ICs, the same CPLD and USB interface ICs, and copied PCB layout. They use the Agilent I/O suite drivers. The inside of the clones' plastic case is usually not plated for RFI shielding, probably not a big deal. Mine is a clone but works perfectly for me. Some people complain about issues especially with many instruments on the bus... GPIB can be finicky and not all instruments play nice, e.g. I have one older instrument which always "listens" so the drivers think there are 30 devices connected, since something always handshakes for any listen address. Since GPIB-to-GPIB cables (for daisy-chaining devices) cost nearly as much as these adapters, don't bother, just get one per instrument that you must have connected at the same time, and/or swap the adapter(s) between instruments as needed. Having one device per bus also greatly simplifies scripts you write since you can hog the bus instead of trying to write fully asynchronous scripts.
Next step then is to monitor the supply voltages at J119 on the main board and see if one of them is bouncing around. And with that many hours have the Inverter and Regulator boards ever been recapped? If not I highly recommend it be done.
I recapped the power supply few years ago with good Nichicon PW series caps.
OK, but I would still monitor the PSU voltages at initial power up and see if something is amiss. Rule that out first before digging into it further.
Next step then is to monitor the supply voltages at J119 on the main board and see if one of them is bouncing around. And with that many hours have the Inverter and Regulator boards ever been recapped? If not I highly recommend it be done.
I recapped the power supply few years ago with good Nichicon PW series caps.
OK, but I would still monitor the PSU voltages at initial power up and see if something is amiss. Rule that out first before digging into it further.
Ok, I think I found the reason for the jitter. It is +15V that bounces around for a minute or so and then stabilizes. The question now is if the LM317 - U1260 is defective or the problem comes from the input. The difficulty with this defect is that it goes away after about 1 minute and I need to wait for hours before it shows up again for a minute or less.
One thing that I've noticed is that the unregulated voltages are a bit low. For example +15V Unreg should be 19.2V according to the schematic but I measure only +18.4V, +5VD should be +5.1V but in my case it is +5.00V.
Maybe I'm on the edge of the minimum VIO for LM317.
Ok, I think I found the reason for the jitter. It is +15V that bounces around for a minute or so and then stabilizes. The question now is if the LM317 - U1260 is defective or the problem comes from the input. The difficulty with this defect is that it goes away after about 1 minute and I need to wait for hours before it shows up again for a minute or less.
One thing that I've noticed is that the unregulated voltages are a bit low. For example +15V Unreg should be 19.2V according to the schematic but I measure only +18.4V, +5VD should be +5.1V but in my case it is +5.00V.
Maybe I'm on the edge of the minimum VIO for LM317.
On ebay, you can easily find Agilent 82357b USB/GPIB adapters for well under $100. Beware that most are clones/counterfeit, not Agilent-made, especially those sold as New. Fortunately, the clones are straight copies with the same 75161 and 75160 proper GPIB bus driver ICs, the same CPLD and USB interface ICs, and copied PCB layout. They use the Agilent I/O suite drivers.
Ok, I think I found the reason for the jitter. It is +15V that bounces around for a minute or so and then stabilizes. The question now is if the LM317 - U1260 is defective or the problem comes from the input. The difficulty with this defect is that it goes away after about 1 minute and I need to wait for hours before it shows up again for a minute or less.
One thing that I've noticed is that the unregulated voltages are a bit low. For example +15V Unreg should be 19.2V according to the schematic but I measure only +18.4V, +5VD should be +5.1V but in my case it is +5.00V.
Maybe I'm on the edge of the minimum VIO for LM317.
I am assuming that any of the unregulated voltages may vary 10% from what is stated in the manual, in accordance to the mains voltage variation at your location. Also in general, maybe not directly related to your problem but good to keep in mind is that all regulated voltages of the power supply are referenced to the +10 supply, and any deviation there will reflect on all others. This power supply should measure between +9.99 and +10.01V. Anything outside is considered out of spec. Problem is, if you attempt to readjust it, you might affect a whole bunch of other internal scope calibrations as well, so best to leave as is, unless its seriously out of spec, or you intend to perform a full scope calibration.
I would try to measure the input voltage to the LM317, if you also see variations there you know the problem is originating before the regulator. Also check the reference input of the regulator. I would think that an input of +18.4v as opposed to the expected +19.2v should make no difference whatsoever to get a stable 15V output as it is more than 3v above which I would think is still very much ok.
Maybe solder a couple of temporary flying wires at the points of interest that you can easily access to quickly make the measurement as soon as you turn on the scope without having to move things around too much.
The reference voltage is stable at 10.004V right after power up and goes down slowly to 10.0005V few minutes after that. Flat line on the scope and rock stable on the multimeter so it is out of the suspects list. The input voltage doesn't drop much below 8.4V so I think the min 3V I/O requirement for LM317 is met.
What's left is LM317 itself, U1371 that drives it, or a fluctuating load (a dying capacitor or hybrid IC) on the +15V line. This drives me nuts...
At one point I wanted to sell the bastard as is and be done with it but now I really want to fix it even if it is only to humiliate it...... It can't win :rant:
The reference voltage is stable at 10.004V right after power up and goes down slowly to 10.0005V few minutes after that. Flat line on the scope and rock stable on the multimeter so it is out of the suspects list. The input voltage doesn't drop much below 8.4V so I think the min 3V I/O requirement for LM317 is met.
What's left is LM317 itself, U1371 that drives it, or a fluctuating load (a dying capacitor or hybrid IC) on the +15V line. This drives me nuts...
At one point I wanted to sell the bastard as is and be done with it but now I really want to fix it even if it is only to humiliate it...... It can't win :rant:
Here's a thought to help narrow it down. Isolate the +15V from the LM317 and connect power supply to the load and watch the current as it powers up. If it never exceeds 1.5 amps I'd say the LM317 is weak and the source of the variation. If it does exceed 1.5 amps then your problem is on the load side.
The reference voltage is stable at 10.004V right after power up and goes down slowly to 10.0005V few minutes after that. Flat line on the scope and rock stable on the multimeter so it is out of the suspects list. The input voltage doesn't drop much below 8.4V so I think the min 3V I/O requirement for LM317 is met.
What's left is LM317 itself, U1371 that drives it, or a fluctuating load (a dying capacitor or hybrid IC) on the +15V line. This drives me nuts...
At one point I wanted to sell the bastard as is and be done with it but now I really want to fix it even if it is only to humiliate it...... It can't win :rant:
Here's a thought to help narrow it down. Isolate the +15V from the LM317 and connect power supply to the load and watch the current as it powers up. If it never exceeds 1.5 amps I'd say the LM317 is weak and the source of the variation. If it does exceed 1.5 amps then your problem is on the load side.
If you look at the schematic, there's a power up sequence that goes +87V > +42V > +15V .... It would be pretty hard to do that with an external power on +15V and the result may be less than happy. I think is better to replace the LM317 and see the result. It costs only a buck or two, the hard part is to get to it. :palm:
...It would be indicating frequency if it was a normal, repeating signal. But the signal is essentially random noise, and in addition it's low amplitude, so who knows what points it's picking to compute the frequency.
Or am I looking at the wrong area of the screen shot? Never used one of those Rigol digital scopes but the CH1 label inside the rectangle on the top right side with the square wave seems to be indicating the measured frequency of the (AC) input signal.
Hey Mark,Great - let us all know how it goes! The Aries adapters are good quality.
Last week ordered a GQ-4x4 programmer, and already have the new D1225 waiting in the drawer. Only need to get the low profile machined socket, which I thought I had ordered the correct one, but received a narrow 28 pin DIP instead, its like two 14-pin sockets end to end. Never trust pictures, they are for "reference only", although the description seemed right. Oh well. But this time I've got the right one in the cart.
Also have my eye on a FM16W08, but can't seem to get the SOIC to DIP adapter board until they are back in stock at Mouser early December. Rather buy one that has the pins installed and ready to go then those plain chinese boards on ebay.
Great - let us all know how it goes! The Aries adapters are good quality.
It may be a little ugly, but you could always cut the socket in half lengthwise if it's just ribs holding the two rows together. Who's going to see it under the chip? Or file down the cuts to make it look like two nice SIP headers.
Yes I could do that if no other option, but the contacts on this socket are not machined, but rather of the one leaf swipe type, not the ideal socket for the DS1225 round pins. But it could work.Ah, I was imagining it was a machined socket.
BTW, one thing I want to definitely try first is to write the template file with all the values I added from the exer 02 data. I presume it would be safe to just write the DS1225 with this data, then test the scope, and if all works out, erase the chip, and then write it again but this time with the data I hopefully was able to read to a file from the original NVRAM. Doable?Yes, to both. When you bring up the scope with just the template EXER 02 data, however, the settings will be random since the settings are not stored in the EXER 02 data. When you boot with the original NVRAM data it should be indistinguishable from when you powered it off.
EDIT: I was thinking a good way to check the data integrity of the first programming with the exer02 values, would be to run the exer02 again with the new chip in the scope, and if all the data matches it should be good to go. Or am I missing something?That would be a good check, but the scope will do it for you. Stored in the EXER 02 data is a checksum at location 00, so if you got something wrong it's is going to complain about it at boot time with a FAIL 04.
Miti: Sounds like you found your culprit! Did you freeze the other suspect components with little to no effect? The problem seems to be so sensitive and subtle that the cold could have wicked along the board and traces to affect more than just U1371.
It might also be good to put a little pressure on U1371 and the other suspects to make sure it's not something mechanical like a bad solder joint or cracked trace.
In general I would agree that C1261, a ceramic, would be an unlikely candidate, but I've been surprised on a several occasions. Suspect *everything* in these old scopes!
I froze the area first then only U1371 using a frozen Q tip. It is the culprit apparently but I will do more experiments tonight.Great idea on the Q tip... sounds like you've really got it pin-pointed.
CHASING THE ILLUSIVE MILLIVOLT & NANOSECOND – PART II
....
Letting the scope automatically measure the 462 MHz frequency via. the red HELP button, indicated 474.7 MHz, which is 2.3% high.
...
Great - let us all know how it goes! The Aries adapters are good quality.
I froze the area first then only U1371 using a frozen Q tip. It is the culprit apparently but I will do more experiments tonight.Great idea on the Q tip... sounds like you've really got it pin-pointed.
I froze the area first then only U1371 using a frozen Q tip. It is the culprit apparently but I will do more experiments tonight.Great idea on the Q tip... sounds like you've really got it pin-pointed.
Son of a gun, I replaced U1371, now it doesn't react to the cold anymore but it stays at 14.78V instead of 15V. Before, it would drop to about 14.8 when cold but would stabilise to 14.98V after awhile. Now it is worse. The IC is from Digikey so I don't expect it to be defective. The interesting thing is that the inverting and non inverting inputs are at different levels. The positive input (pin5) is at 10.00V sharp and the negative one (pin 6) is at 9.84V. Shouldn't they be at the same level?
I would think they should be the same. But the big question is.....did it fix your start up jitter?
Son of a gun, I replaced U1371, now it doesn't react to the cold anymore but it stays at 14.78V instead of 15V. Before, it would drop to about 14.8 when cold but would stabilise to 14.98V after awhile. Now it is worse. The IC is from Digikey so I don't expect it to be defective. The interesting thing is that the inverting and non inverting inputs are at different levels. The positive input (pin5) is at 10.00V sharp and the negative one (pin 6) is at 9.84V. Shouldn't they be at the same level?
Son of a gun, I replaced U1371, now it doesn't react to the cold anymore but it stays at 14.78V instead of 15V. Before, it would drop to about 14.8 when cold but would stabilise to 14.98V after awhile. Now it is worse. The IC is from Digikey so I don't expect it to be defective. The interesting thing is that the inverting and non inverting inputs are at different levels. The positive input (pin5) is at 10.00V sharp and the negative one (pin 6) is at 9.84V. Shouldn't they be at the same level?
If your +15V PS buss is now at 14.78V it is a tiny bit out of spec, it should be between 14.775 and 15.225V with no more than 15mV ripple (check at J119 pin 6). Strange for a 317 not to output something closer to the expected 15V, with the associated circuitry unless something is still amiss. What is the voltage at the 317 reference input?
Done:
- 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.
Done:
- 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.
This is very interesting. Some time ago I bought a Ramtrom FM16W08 from Ebay and it didn't work in my 2445B. Now I bought a Cypress FM16W08 thinking that the one from Ebay was defective but this one doesn't work either. First time after it is programmed in the programmer, it starts normally but after the first power cycle, I get Test 04 Error 10.
I have a Xeltek 5000 at work.
From what I learned so far, there is one crucial difference between programming a D1225 and the FRAM, in that one of the control lines needs to be toggled during each individual write instead of staying in a specific state all the way throughout the whole write process of the chip. Not sure that makes sense as it is only what I remember reading, and again I am new to programmers and will use one for the first time once I have all the remaining bits here to save my 2465B cal data.
Son of a gun, I replaced U1371, now it doesn't react to the cold anymore but it stays at 14.78V instead of 15V. Before, it would drop to about 14.8 when cold but would stabilise to 14.98V after awhile. Now it is worse. The IC is from Digikey so I don't expect it to be defective. The interesting thing is that the inverting and non inverting inputs are at different levels. The positive input (pin5) is at 10.00V sharp and the negative one (pin 6) is at 9.84V. Shouldn't they be at the same level?
If your +15V PS buss is now at 14.78V it is a tiny bit out of spec, it should be between 14.775 and 15.225V with no more than 15mV ripple (check at J119 pin 6). Strange for a 317 not to output something closer to the expected 15V, with the associated circuitry unless something is still amiss. What is the voltage at the 317 reference input?
It is 1.23V below the output and it is where it should be. I don't suspect 317.
I think I had something similar, it turned out that a specific version OpAmp had a +and- 15V range power supply, and others had a +and- 18V power supply range, so only the version with the higher specs on power supply voltage would work.
It had something todo with the version letters after the 324...
I have to look into my notes for more details.
The LM324 V+ on the other side of R1400 is 15V. Not enough for safe operation.
Regarding the FRAM, if it does that...crazy thing...at boot, that explains a lot. For some reason my TL866II Plus can "almost" program this FRAM even though it is not in the device list. I select DS1225 as the device and it can program successfully 0x00 and 0xFF but when I try to program the real content of my scope's NVRAM, it fails to program few locations.....the same locations that get altered after the first power cycle.If it's consistently the same locations, maybe it's a bad FRAM? Are there counterfeit FRAMs floating around?
What I mean is, if I program properly the FRAM using the Xeltek programmer (that fully supports it), the first power up is ok, it runs well or at least I didn't see any issues in the short time that I ran it. But once I power cycle, two locations in the calibration constants area, the same locations that can't be programmed with TL866II Plus, are modified. Probably once it does the 0x55 then 0xAA, it cannot put back the original content. But why does it work for some people, that beats me.
...Wow - thanks for the detailed write up! It's nice when things work as expected.
What do you guys think?
...It's a Fluke 79 III. The range for measuring the 5V is 10Mohm (40V range) with 10mV resolution. So we're talking about the least significant digit here.
Edit: Actually I think I have the answer regarding 5VD in the level at Pin 9 U1371. Not sure what meter you used but if it has a 10M input, 5VD should be around 5.03-5.04V.
Is your concern that the 5VD is noted as 5.1V in the schematic?
Thanks AMR Labs!
Now I'm really pissed off.... Is it possible that both my FRAMS are defective? I can understand the one from Ebay for $6 but from Digikey?
How can I test it? What can be wrong with my scope considering that it works perfect with the old and two new DS1225?
Edit: I just had a live chat with Digikey's customer service. They will send a replacement, no questions asked. Impressed!
...So, you're saying the corruption shows up on the second boot. It's possible the FRAM is getting corrupted during the scope's power-down sequence. That would also explain why it passes the 0x55/0xAA test; the corruption has already happened.
What I mean is, if I program properly the FRAM using the Xeltek programmer (that fully supports it), the first power up is ok, it runs well or at least I didn't see any issues in the short time that I ran it. But once I power cycle, two locations in the calibration constants area, the same locations that can't be programmed with TL866II Plus, are modified. Probably once it does the 0x55 then 0xAA, it cannot put back the original content. But why does it work for some people, that beats me.
EDIT: One more thought before starting down this path... With good data in the FRAM, you could do one power cycle, remove the FRAM, and read it to see if corruption occurred.
That's a good question. According to the two service manuals I have, the 2445B and 2465B have the same EPROM part numbers 160-5370 and 160-5371 for U2160 and U2260. The 2445B lists versions -04, -08, and -09, and the 2465B lists versions -04, -05, -08, -09.EDIT: One more thought before starting down this path... With good data in the FRAM, you could do one power cycle, remove the FRAM, and read it to see if corruption occurred.
If it is of any help, yesterday I went manually through the Exer 02 procedure with the FRAM in place, and all cal data values where still spot on to what I programmed into it, nothing changed. As of today scope still booting up fine.
Is it possible there might be some kind of a Firmware difference in the 2445B that might be causing his corruption problem? I wonder if there are any documented 2445B scopes running FRAMs. As far as I can remember, all the writeups out there seem to refer to '65B scopes.
Did your FRAM from Digikey arrive in a controlled humidity package like mine did? Maybe yours got a bit wet along the way! ;) ;D
...So, you're saying the corruption shows up on the second boot. It's possible the FRAM is getting corrupted during the scope's power-down sequence. That would also explain why it passes the 0x55/0xAA test; the corruption has already happened.
What I mean is, if I program properly the FRAM using the Xeltek programmer (that fully supports it), the first power up is ok, it runs well or at least I didn't see any issues in the short time that I ran it. But once I power cycle, two locations in the calibration constants area, the same locations that can't be programmed with TL866II Plus, are modified. Probably once it does the 0x55 then 0xAA, it cannot put back the original content. But why does it work for some people, that beats me.
You could use the PWR DN signal as a trigger and start looking at the behavior of the control signals into the FRAM, including the +5V power, during power down. Maybe there's something marginal that the DS1225 tolerates.
If you have an MSO or a logic analyzer with enough inputs, you might also try setting up a trigger to capture when the corrupted address in the FRAM is accessed or written. But keep in mind this could be an analog signal issue and a logic analyzer might not catch it.
EDIT: One more thought before starting down this path... With good data in the FRAM, you could do one power cycle, remove the FRAM, and read it to see if corruption occurred.
...After the 0x55/0xAA test, which is considered part of the TEST 00 kernel test, it gets to TEST 04, which is a checksum procedure across all the constants (but not the entire 0x1E00 - 0x1FFF block). It's a read-only test.
The question is how does it test the integrity of the calibration constants? If it does a CRC, that mean the constants are correct at the first power up. What I will do first is an Exerciser 02 right after the first power up so if the self test corrupts the data, I will catch it.
I don't have a logic analyzer but I do have a Rigol DSO with 4 channels.
I'm trying to raise the unregulated +15V by few hundred mV. For that I want to replace the four diodes in the bridge CR1103 - CR1106 with Schottky diodes. The original diodes are 400V 1A but I don't see the need for 400V. I bought two type of diodes from Digikey and I would like to ask your opinion.I think either would be ok for substitution. If it were me I'd probably use the 100V one. The difference in the Vf @ 1A is only 0.06V.
1. STPS1L60RL 60V 1A
2. SB1H100-E3/73 100V 1A
The first one has the lowest forward voltage drop of about 500mV at about 800mA.
I think 60V VRRM should be good enough, what do you think?
...My primary suspicion is still that it's happening during power down. I think something is happening with the FRAM control inputs while the +5 is fading. They're not being controlled carefully enough for the FRAM while it's transitioning to power off, and it's trashing that location most of the time.
The only location that gets corrupted is 0x1F00, location 80 in EXER 02, validated through EXER 02 and with the programmer.
I ran TEST 04 multiple times after the first power up and passed with flying colours. Once it even passed the second power up but usually, after the second power up, location 80 changes from 0x11 to 0x20.
My primary suspicion is still that it's happening during power down. I think something is happening with the FRAM control inputs while the +5 is fading. They're not being controlled carefully enough for the FRAM while it's transitioning to power off, and it's trashing that location most of the time.
Something similar could be happening on power up, but you said it always works perfectly on the first power up after externally reprogramming the FRAM.
What matters is what's happening on the nCE and nWE pins to the FRAM. Follow the +5 all the way down to 2.7V while watching those pins.
My primary suspicion is still that it's happening during power down. I think something is happening with the FRAM control inputs while the +5 is fading. They're not being controlled carefully enough for the FRAM while it's transitioning to power off, and it's trashing that location most of the time.
Something similar could be happening on power up, but you said it always works perfectly on the first power up after externally reprogramming the FRAM.
That was my suspicion as well but take a look at the power down sequence. The power down sequence happens between PWR_UP going down and RESET going down. +5V Digital is still stable at least 7ms after that. With the scope probes attached, it passed 3 power ups. What a .....
Here you go. There are some glitches on nCE but nothing on nWE.Interesting. Did this cause a corruption event? And tried it several times since it doesn't happen consistently?
Edit: I guess the question is why does it works for everybody but me?I don't why it would be inconsistent. Maybe everyone else is getting away with it. Or there's something wierd about the FRAM.
Interesting. Did this cause a corruption event? And tried it several times since it doesn't happen consistently?
Does your scope have a PEAK acquisition mode (just to make sure there's not a short pulse lurking in nWE)?
I'm not happy with the glitch on nCE, especially right when chip is transitioning to power down, but as long as nWE remains high I think it should be ok according to the datasheet.
Maybe it's also worth looking at the power-up cycle to make sure there's nothing odd with nWE or nCE there.
I don't why it would be inconsistent. Maybe everyone else is getting away with it. Or there's something wierd about the FRAM.
Have you tried your new FRAM from Digikey yet? Your likely to get one from the same batch - check the date code.
You said your TL866II had an issue with a location. Was it also 0x1F00? Maybe don't let the new FRAM near the TL866II; just use the Xeltek.
Internally, a F-RAM operates with a read and restore mechanism. Therefore, each read and write cycle involves a change of state. The memory architecture is based on an array of rows and columns. Each read or write access causes an endurance cycle for an entire row. In the FM16W08, a row is 64 bits wide. Every 8-byte boundary marks the beginning of a new row. Endurance can be optimized by ensuring frequently accessed data is located in different rows. Regardless, F-RAM offers substantially higher write endurance than other nonvolatile memories. The rated endurance limit of 10^14 cycles will allow 150,000 accesses per second to the same row for over 20 years.
Maybe, or not a reliable drop-in in a 2445B, right?I don't think so. The basic problem is putting a FM16W08 in a circuit where the control inputs (nCE, nWE) are undefined during a power down because, in both scopes, the chips driving those inputs are way out of their operating range while the FM16W08 is still listening.
Are the 2445B/2465B similar in the relevant hardware and code (paths) that this goes for both?I haven't looked at the NMI power down code. But by the traces Miti obtained, the problem happens while nRESET is being asserted, so there's no code running at that time anyway.
Perhaps one or more 2465B owners should take some measurements to determine the behavior upon power down and compare. I have a working 2465B with FRAM but no time for it at the moment. I haven't seen this problem mentioned before so it's worth investigating.I agree, it may be interesting to know exactly how bad it is. I nominate AMR Labs if the lid is still off the 2465B.
Some time ago I built this Avalanche Picosecond Pulse Generator:
https://entangledwaves.wordpress.com/2013/07/15/avalanche-pulse-generator/ (https://entangledwaves.wordpress.com/2013/07/15/avalanche-pulse-generator/)
BTW the specified now obsolete 2N2369 transistor is still available at Mouser in TO-18 metal case for about $2, although a usable alternative seems to be a common 2N3904, but the former has a more desirable breakdown characteristic. I did not need to build the DC-DC converter part for the 90V avalanche bias supply, but instead used my Heathkit IG-4505 Scope Calibrator as a power source with the DC output set to the 100V position.
There is also another very well known website on the same subject:
http://www.kerrywong.com/2013/05/18/avalanche-pulse-generator-build-using-2n3904/ (http://www.kerrywong.com/2013/05/18/avalanche-pulse-generator-build-using-2n3904/)
Wanted to share pictures of the pulse as shown on both my 2465B and the 2247A, and possibly hear opinions. Cursor time measurement are located between the 10% and 90% points of the rising edge. Thanks.
Hello
What is the model for your earom burner?
As an EBay search came up blank.
73's
Mike G4WYZ
OK then, I'll do the following:I would recommend not doing anything with the A1 board until you have the PS in spec.
- Finish recapping the A5/PS and put it to spec (the PS, I have no idea how to debug the A5 if it's not a power problem).
- Remove the A1 mainboard (looks a bit like a pain), recap it and remove U800 and replace it with a nice Augat socket.
Always good to see a successful repair. Congrats! :-+ :-+
U800: Leave it alone. It WILL get warm when you have the scope outside the case and you have an active sweep. Once back in the case as long as the fan is in good shape the airflow will keep it within acceptable temperatures.
Always good to see a successful repair. Congrats! :-+ :-+
U800: Leave it alone. It WILL get warm when you have the scope outside the case and you have an active sweep. Once back in the case as long as the fan is in good shape the airflow will keep it within acceptable temperatures.
What about the recapping and calibration ?!?!?
Also the U800 DO gets hot, should I put for peace of mind some radiator on it ? Please advise, or the lucky X-mas scope will be closed and it will take a place on the bench together with the AGILENT and Rigol.
Just a headsup for those thinking about a recap.
The 330uf/250V replacements for C1021 and C1022 are pretty scarce at the moment and I couldn't find anyone with current stock for Nichicon UPW caps. Mouser has them on order with 2 delivery dates and, as of today, there were 10 uncommitted for the mid-January delivery. Once those are gone the next scheduled delivery is in May.
Yep, the design is clearly flawed, badly.
(Thought experiment: when was the last time you operated
your 2465 at 50C?)
What I do not understand is why they did not put a thermally conductive spacer under U800 before soldering it down. Was it too much trouble on an otherwise automated manufacturing processed?
What I do not understand is why they did not put a thermally conductive spacer under U800 before soldering it down. Was it too much trouble on an otherwise automated manufacturing processed?
What I do not understand is why they did not put a thermally conductive spacer under U800 before soldering it down. Was it too much trouble on an otherwise automated manufacturing processed?
Back at those era, did non metallic thermal pad was still not very good ? :-//
Also the gap is quite large.
(Thought experiment: when was the last time you operated
your 2465 at 50C?)
Other than us Australian's without aircon. :P
But he underestimated the strain placed on the package by the mounting solution he ended up using.
Related to the U800 discussion. I conducted some experiments with the 24XX cooling system with these results and observations...
https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg1215559/#msg1215559 (https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg1215559/#msg1215559)
And....ALL 24XX scopes should have the black heatsink bonded to the front bottom of the case. If it's missing you could have issues.
But he underestimated the strain placed on the package by the mounting solution he ended up using.
+1 , thats the main problem that I see.
Even the two nuts were mildly fastened enough, there is no guarantee those two star washers will be the exact height to fill the gap underneath the chip, without stressing the embedded metal tab inside the chip, which is also will create the another strain vs the soldered pins.
Wonder if the stressed metal tab will affect the attached silicon die inside the chip, as the whole chip body + washers + nuts + soldered pins went thru so many thermal cycles and thermal expansion and contraction physically. :-//
Wonder if the stressed metal tab will affect the attached silicon die inside the chip, as the whole chip body + washers + nuts + soldered pins went thru so many thermal cycles and thermal expansion and contraction physically. :-//
Also definitively a valid but again with all due respect <secondary> point unless one plans to mess with the mounting studs/nuts of U800. I thought we where mainly discussing the temperature issue of a <undisturbed> U800, which is what user DC1MC was initially inquiring about.
Wonder if the stressed metal tab will affect the attached silicon die inside the chip, as the whole chip body + washers + nuts + soldered pins went thru so many thermal cycles and thermal expansion and contraction physically. :-//
Strain in the lead frame absolutely affects reliability of the die attachment and it gets worse at higher temperatures and with more temperature cycles. This is why the correct mounting of power packages is so important. Motorola has a great application note (https://www.nxp.com/files/rf_if/doc/app_note/AN1040.pdf) discussing the issue.
Wonder if the stressed metal tab will affect the attached silicon die inside the chip, as the whole chip body + washers + nuts + soldered pins went thru so many thermal cycles and thermal expansion and contraction physically. :-//
Strain in the metal tab absolutely affects reliability of the die attachment and it gets worse at higher temperatures and with more temperature cycles. This is why the correct mounting of power packages is so important.
Also definitively a valid but again with all due respect <secondary> point unless one plans to mess with the mounting studs/nuts of U800. I thought we where mainly discussing the temperature issue of a <undisturbed> U800, which is what user DC1MC was initially inquiring about.
Ok, fair enough, thanks for reminding, its just this issue pop out again in my head when every time this U800 discussion surfaced.
Also the two nuts of mine are gone, not used anymore when I realized while ago, the U800's of course. :P
Related to the U800 discussion. I conducted some experiments with the 24XX cooling system with these results and observations...
https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg1215559/#msg1215559 (https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg1215559/#msg1215559)
And....ALL 24XX scopes should have the black heatsink bonded to the front bottom of the case. If it's missing you could have issues.
Hi med,
Do you by any chance have pics of that heatsink you mention? Did not see any pics of it on your post, not 100% sure where to exactly look for so as usual always would be nice to have one or two pics if you happen to have them. Thanks!
Hi David, but just to be clear do you imply that there might be some mechanical strain already in place from the initial install/mounting of the U800 chip at the factory?
Wonder this is related with the service of fixing the U800 chip provided years ago by 3rd party, which they sent the chip to a special shop in Japan to be re-heated if I'm not mistaken, and they claimed this fixed the common problem that was affecting this particular chip.
I propose that the piece is there to insure airflow to the vents just behind it when the scope is down on it's feet. That's where U800 is located. That's the only thing that makes sense to me.
Wonder this is related with the service of fixing the U800 chip provided years ago by 3rd party, which they sent the chip to a special shop in Japan to be re-heated if I'm not mistaken, and they claimed this fixed the common problem that was affecting this particular chip.
Reheating melted the die attachment material reattaching the chip to the lead frame.
FWIW, none of the 3 2465s I own have that ribbed plastic/rubber/vinyl what-the-fuggever-it-is on the bottom front, though the suggestion that it serves to prevent occlusion of that most important vent over the U800 certainly sounds plausible. Possibly some vendor-added spacer for a 2465 that was assembled into/made part of a larger, special-purpose test gear?
mnem
*tzzt*
If there was a TSB for U800 and it's mounting it apparently wasn't known outside Tektronix. And as a side light how come no one, other than that one individual, produced one with that mod?
One of my 2465's was owned by IBM. IBM was very diligent about insuring their test equipment was up to snuff and had it's own instrument labs who's sole responsibility was repair/calibration. Only "tuff nuts" or unable to fix equipment was sent back to Tek which didn't happen very often. The U800 in this 2465 is untouched and the scope would have been back to the instrument lab on a yearly basis for a minimum a calibration. So I'm questioning the validity of this "TSB". IBM has bought literally thousands of instruments from Tek over the past 60 years so my thought in the interest of customer support this "TSB" would have been published and available.
And as another side light the last IBM internal instrument lab was disbanded about 2006 or so and all instrument repairs/calibrations are now contracted to outside cal labs.
I have a question about the coding rings on the Tek 24xx series. If you don't use probes with coding pin, your scale factor is wrong. How do you mitigate that?
Mental arithmetic and knowing what I'm probing :)
Hello all: I am struggling with both models to do a CAL.
Result form normal 2465/7B A5 board problem:
Failed NVRAM Dallas Semi battery, replace with new part, program with default parameters, place new NVRAM on low profile socket.
And removed and replaced all SMD lytics that leaked on the boards, repaired damages.
NEW Issue on 2465B CTT : CT TEST 81 Fail 03
Using TEK cal procedure with 1V pk sw wave at 1.00 MHz, to CH 1,
I consistently get FREQ OUT OF LIMITS message.
I verified the input signal is fine.
Is there an internal clock CAL step? I am just doing this part of the CAL not the entire procedure.
I have the CAL/NO CAL jumper on A5 board in CAL position.
Any assistance is appreciated!
Many thanks
Jon PAUL
I have a question about the coding rings on the Tek 24xx series. If you don't use probes with coding pin, your scale factor is wrong. How do you mitigate that? Do you just ignore it? I use a small interposer ring with a 10K 0402 resistor on the edge and a springy ring on top, but it is not always reliable.
Also: I can not locate the SERV manual or Adjustment for 2465B CTT opt 06, only for 2465B, and 2465 CTT.
Does it exist? Any differences in the adj procedure? May have to do a full CAL anyway, but hope a partial on just CTT will get it running without the failure errors.
MANY THANKS AGAIN!
Jon Paul
I have a question about the coding rings on the Tek 24xx series. If you don't use probes with coding pin, your scale factor is wrong. How do you mitigate that? Do you just ignore it? I use a small interposer ring with a 10K 0402 resistor on the edge and a springy ring on top, but it is not always reliable.
Not ideal, but when in need to use a non-readout pin 10x probe just making a mental note to multiply the readout by a factor of 10 works for me. So basically 100mV/DIV really is 1V/DIV, and so on. After all its not like this is going to affect the calibration of the scope or anything similar. Just the On-screen V/DIV -scale readout- will be wrong. Problem is in the middle of a procedure while my brain is concentrating on something more important, or I get distracted, sometimes I do forget.
Not suggesting you did not know this already, but your question seems to point a bit in the direction that the scope always needs to be told when using a 10x probe in order to stay accurate, or perhaps I just misunderstood your question.
b/ old issue: This 2465B CTT op 06 (SN 066xxx) is losing the panel settings at next turn on and default to 50 mv/DIV AC coupling etc regardless of previous settings. I believe that this symptom existed before the old NV RAM failed and was replaced. Besides CAL data does the NVRAM also get FP settings written at shutdown? Since NV RAM is new and works and the scope seems to initialize and shutdown normally, what can cause this symptom?Take a look at EXER 06 in the diagnostic menu. This allows you to select either SETUP 1 or the power-down configuration when powering on. COUPLING UP selects between the two. Sounds like it's set to SETUP 1.
c/ Misc cleanup:Offhand I wouldn't go cutting off any connectors.
A5 board options connector J4241 mates to the option ribbon cable with 2 connectors on the A5 end and 2 more with greater separation on options end. That links A5 to CTT options board. At A5, The second connector and thick cable loop interferes with the NVRAM as the machine pin socket raises it a bit. Any reason not to just cutoff the unused connectors?
Dear MarkL!You're welcome!
WOW perfect, indeed EXER 06 was on SETUP 1. Changed to initialize to last settings. MANY THANKS!
Last issues (I hope).......
1/ Fan is noisy, replacement is the NIDEC Beta SL?
Many such NIDEC models exist, I have 12V 0.12 and 12V 0.16 A spares. Any tips on best replacement part?
2/ Usual dead graticule lamps, any pitfalls in replacing? Suggest the original incandescent lamps or LEDs?
With Kind Regards,
Jon
...The cal data still sits at those locations.
Has anybody looked into how the 6264 RAM could be reprogrammed with cal data if the worst happened and it was corrupted or cleared accidentally? I guess you could solder wires directly to the chip with a CR2032 and diode, and transfer it between a programmer and the A5 board after reloading the cal data. Does the cal data sit at the same address in RAM (0x1E00 to 0x1FFF) as on the DS1225?
Could the 6264 RAM be replaced with a DS1225 - pinout is the same apart from pin 26 which is CE2 on the RAM and NC on the DS1225?I don't have the 2445B schematics to know for sure, but after looking at the 2445A schematics which use a keeper battery, and the 2465B schematics which use the DS1225, it looks like it would work. CE2 is only used as an enable once the +5V is stable and nRESET is high. The DS1225 has an internal enable controlled by the Vcc voltage so it doesn't really need the protection function that CE2 provides.
New upcoming "home-work" ::), a dead fail to power on, 2465 with Option 10 & 11, missing 2 front feet, 4 front knobs and also top cover thin plastic that covers the opening for accessing the filter screen, looks like previous owner replaced the blue with clear acrylic, and forgot to install it back.
Anyone got spare knobs ? :P
Hello all: RE U800, tempsSee replies #6 and 12. Read carefully. All you need to know is there. ;)
Scared to overheat U800 during full CAL.
From Chuck Harris at https://groups.io/g/TekScopes/
...At 25C ambient, U800 runs 49C with the scope... 46C with case installed.... U800 would..handle 30C + 46C = 76C max specified ambient.
1/ working on 2465/7B, with original TEK U800s. U800 runs cool.
Continuous op at highest H sweep would be a worst case temp of U800? Any temp measurements running on the 5ns/div sweep?
2/ Doing a full (or even partial) CAL requires cover off and preliminary 20 min warmup. Procedures can take hours and U800 and other hybrids on A1 could overheat.
3/ Placing an external fan on A1 mainboard could cool the A1 board below normal op temp in the case.
So there seems to be contradictions in cooling when doing long CAL.
I appreciate any recommendations and observations from the 2465B veterans re cover/external fan/cooling during a CAL 01/02 or full cal for cover, warmup and external fan.
Many thanks again!
Jon
"See replies #6 and 12. Read carefully. All you need to know is there. ;)"On page 1.
Unsure you mean PAGE 6, 12 of the 58 pages or how to locate, by date?
Links to those replies appreciated!
MANY THANKS
Jon
"See replies #6 and 12. Read carefully. All you need to know is there. ;)"On page 1.
Unsure you mean PAGE 6, 12 of the 58 pages or how to locate, by date?
Links to those replies appreciated!
MANY THANKS
Jon
Suggestion, just unscrew the two nuts that are holding the U800 chip, it is not going to fall down or separated from the board anyway, as the chip's pins all are soldered firmly on the pcb.
Thermal expansions and contractions actually stress out the whole U800 chip body with that 2 nuts attached, imo.
Hello Med6753, old but great thread. Please see my previous posts today for full story.
This is preventive maintaince especially for the 1989 battery backup NVRAM.
Eventual battery failure was my motivation to open the scope up!
Agree to leave U800 asis.
If it ain't broke don't fix it!
With 2 other 2465/7B with the failed NVRAM and complete reCAL, I have learned the hard way.
Enjoy,
Jon
To BravO re A1/U800:
I wonder if the screws provide any heatsinking or better thermal contact to PCB?
Perhaps replacement of the lockwasher with a constant tension spring or Belleville washer?
Suggestion, just unscrew the two nuts that are holding the U800 chip, it is not going to fall down or separated from the board anyway, as the chip's pins all are soldered firmly on the pcb.
Thermal expansions and contractions actually stress out the whole U800 chip body with that 2 nuts attached, imo.
Please tell me you're not serious. :o Just kidding, right? :-// It's been in there 30 years and worked fine and now you want to monkey with it? Do so at your own risk.
Anecdotal evidence: This thread is 8 years old. Has ANYONE come in here and said that U800 took a dump? Not that I recall.
This is my conclusion, I could be wrong, but this what I believe, the two nuts basically serve no purpose, and if over tightened, will actually do more harm than good.
So, its up to you. :-//
Hey folks, I'm really struggling with a 2467B with a "CT TEST 86 FAIL 02."I don't have the 2467B options service manual, but the options from model to model in the 24xx family are very similar.
...
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.
Geez... what happened Dave ? :o
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.
I just discovered the exact same fault. Measured C1115 ESR in circuit and it looked sussed, so sucked out only to find a 10uF 160V cap. Traced and the circuit a bit and figured it was swapped on the overlay diagram |O
Uh oh. Possible one of those fakes "built" by that EBay scammer? :-// :scared:
Uh oh. Possible one of those fakes "built" by that EBay scammer? :-// :scared:
Very suspicious indeed, example the well known eBay seller called "2465b" , the shop is also selling the handle decal for 2465B, example ebay item -> 123714403213
They're printed in single color, as example mine it was printed with dual colours, check the very 1st post of this thread.
Oh gawd... this schizz has infected ANOTHER thread. :palm:
These are JUNKED OSCILLOSCOPES. You can't assume anything about them.
mnem
:popcorn:
Show me anything that in any way ties this guy we all already know about to a busted, scrapped out scope on a trash heap halfway around the world.
THAT is what's wrong with this. It's effing mob mentality, pure & simple. Dave has been notified; that could have been done via PM. All the rest of this is needless sensationalism that makes this place smell more like an episode of COPS than anything resembling reasonable discourse. ::)
There's a whole thread already DEDICATED TO STIRRING UP THE SENSATIONALISM... can we PLEASE just leave it there until we actually KNOW something?
mnem
|O
Repost here as reference.Looking at the part numbers in the service manual, the case is part 437-0286-03 for 2465 serial B021870 and up, and also for 2465B serial B050000 to B050740. So, for some period of time it was the same case for both scopes. Looking back at the video, it's a little hard to read, but it looks like Dave's 2465B is B050574.
A fellow forum member, mnementh was requesting for a confirmation (HERE (https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg2380248/#msg2380248)), whether 2465B vs 2465 blue outer cases are identical, as he has part mules that planning to donate it related to Dave's at his EEVblog #1203 - 2465B repair video.
While for the back cover, the B version has thicker part at the internal axial fan location, compared to non B that uses a squirrel cage fan instead, I guess its not suitable for replacement, not very sure though. :-//
...
Repost here as reference.Looking at the part numbers in the service manual, the case is part 437-0286-03 for 2465 serial B021870 and up, and also for 2465B serial B050000 to B050740. So, for some period of time it was the same case for both scopes. Looking back at the video, it's a little hard to read, but it looks like Dave's 2465B is B050574.
A fellow forum member, mnementh was requesting for a confirmation (HERE (https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg2380248/#msg2380248)), whether 2465B vs 2465 blue outer cases are identical, as he has part mules that planning to donate it related to Dave's at his EEVblog #1203 - 2465B repair video.
While for the back cover, the B version has thicker part at the internal axial fan location, compared to non B that uses a squirrel cage fan instead, I guess its not suitable for replacement, not very sure though. :-//
...
The rear cover for the 2465 has two part numbers, 200-2685-00 for the squirrel cage fan and 200-2685-01 for the updated axial fan. The 2465B is 200-3200-01. So, Dave will presumably need the rear cover specifically for the 2465B.
(I'll just post here since mnementh reads this thread too.)
Can you inspect the other side of the board? Since your battery is showing as-new voltage, I suspect somebody may have replaced the Keeper pack either after the cal data was already lost, or without providing proper backup power while doing the swap.
mnem
*Back into the abyss*
Yep, some gorilla has been in there. Now I can't help you with the availability of parts but I can tell you how to get that front panel assembly out.
Remove the Intensity, Focus, Readout, and Scale knobs. Be careful and use heat or else they will crack.
Running along the top edge of the scope is a plastic strip. Carefully pry it up.
There will be screws in there. Remove them. There will also be screws on the bottom. Remove them too. Edit....and on both sides too.
The front bezel will pull off. Once off you can pull the front panel assembly.
Can you inspect the other side of the board? Since your battery is showing as-new voltage, I suspect somebody may have replaced the Keeper pack either after the cal data was already lost, or without providing proper backup power while doing the swap.
mnem
*Back into the abyss*
That appears to be the answer (see photo) as the battery solder connections look different and less precise than the rest of the board.
From my notes, very likely from this thread somewhere...
/e-pirate quote snipped/
I am hoping for a more general writeup outlining the equipment I will need and any pitfalls for new players, I don't have any experience working with chips like this.
Is there any "permanent" solution for this? or is plugging in "less old" parts the best we can do?
Thank you Cooler, I will get one of those programmers and see what I can do.
Is there any "permanent" solution for this? or is plugging in "less old" parts the best we can do?
What part did you use David?
...I would not opt for the FRAM solution. There was a discussion from user Miti having corruption problems starting here-ish:
I have also heard reports of parallel FRAM memories working as direct replacements as I mentioned in an earlier post. This have special timing requirements for their -CS pin because they require a precharge operation before every read but these Tektronix oscilloscopes apparently meet this requirement which is not unusual.
What is it?
DMI 500-2044
It is in the tek tronix power supply
How i can check it?
Anu data sheet?
(http://)
...I would not opt for the FRAM solution. There was a discussion from user Miti having corruption problems starting here-ish:
I have also heard reports of parallel FRAM memories working as direct replacements as I mentioned in an earlier post. This have special timing requirements for their -CS pin because they require a precharge operation before every read but these Tektronix oscilloscopes apparently meet this requirement which is not unusual.
https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg2003207/?topicseen#msg2003207 (https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg2003207/?topicseen#msg2003207)
The short version of the related posts is that the power-down behavior of the 24xx does not meet the FRAM (in Miti's case, FM16W08) datasheet requirements for safe power down. It seems to work for most people, but from a design perspective it's still risking the data without additional support circuitry to safely control the chip select.
The Simtek/Cypress part, now CY14E256LA, looks like a great suggestion.
My scope works well with FRAM after I installed the pull-up resistor. If you have a copy of the calibration constants, I think it's worth a try. Even though, replacing DS1225 with a new DS1225 would push scope's life beyond its reasonable life expectancy. I don't expect many Tek 2445, 2465 in use in another 20 years.
Actually I didn't run the scope for long when I received it. Just turned it on to make sure it worked, then shut it down. I didn't want to risk any explosions.
Removing the PSU boards is very easy, just need to remove the screws from the mains connector and move it out of the way to get access to the Voltage Selector wires. Also de-solder the fan power wire(make sure to re-connect during install - just saying).
After separating the boards, the recap took about an hour. I removed all the caps and cleaned the board then replaced with the new using the board overlay from the manual as a guide. This is where I hadn't done enough research about the error on the overlay.
After re-assembly and replacing the PSU, I discovered it was ticking on what I assumed to be over current. While checking the unregulated rails on the A3, I discovered the overlay error which I quickly fixed. Replaced the PSU and all was well.
Miti, if you don't mind, what value pull-up resistor did you use, and at what pin did you connect it to?
OK, I had the video of Exerciser 02 for safety's sake. The video quality was so bad that it's a miracle that I was still able to write all the data to the hex editor ... <snip>
But the device did not start now, Trigger'D flickered happily, the device complained about corrupt calibration values.....<snip>
... looking at the solder joints of the NVRAM under the microscope and discovered that I had severed a trace directly at the solder pad while soldering out ...<snip>
<snip>... everything work again.
Of course, as soon as I got the assembly free and out into the light, I had to wince. Yeah, something caught fire and went boom there. I knew the box caps in the rectifier were problematic, but damn. They took out at least one resistor and possibly other components with them, as well. But fortunately nothing else in the rectifier section *looks* immediately damaged. Looks be damned, I'll be verifying the spec of every other component in this section and immediately downstream of the rectifier section. If only a minimum of components in the rest of the power supply assembly are damaged, then I'm tempted to turn that fried resistor into memorial, honoring its self-sacrifice to protect the rest of the PSU.
I presume you've seen 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)
I've had that Rifa take out that resistor and some of the prepreg :( It was fine after cleaning and replacement.
However, I wanted to take the time to understand the circuit at little better, and get a feel for what the components in that list (or elsewhere on the board, if needed) are supposed to do in that circuit. I figure if I can understand a component's role, then why Tek selected the parts they did during the original design should become apparent, and therefore inform what currently-available parts would best serve as replacements in that role. For all I know, that list is still current. But, I'd like to understand why, as opposed to just blindly throwing a bunch of parts on a board.Wise approach. :-+
Today there are better components available than the designers had available however as always the cost of the BOM always guided component choice.
But there are some traps where existing component characteristics must be carefully considered before any substitution can be made.
In the case of these Tek 24xx series power supplies, are you aware of gotchas in component substitution? Anything that if substituted with a part with supposedly better specs would actually work against the goal of a stable, clean, supply voltage with sufficient amp capacity?Not 24xx in particular but study these posts where a member battled with FET Millar capacitance after selecting a replacement.
...
Another thing I note is that I don't have the famous Dallas battery-backed SRAM, as seen on the later, SMD-style A5 boards. This thing looks like a plain battery, not a RAM-chip or ROM chip of any kind, especially given it's only 4 pins on the board. Apologies for the blurry photo there, but it looks like there's some dried flux residue on those solder joints. I don't know if that's normally there, or if that means that this board has been worked on before, and the battery has already been replaced once. It's hard to tell, given the lack of date codes on the label. I'll have to compare the A5 boards in my other pre-B5xxxx scopes.
I'm not sure what this board is, or what it does. I do believe it is a standard board, as when I opened up B0120xx for comparison, it also had this board in it. Whatever it is/does, it fits in the central cavity of the scope, between the option boards and metal wall, and has a ribbon cable that goes through the floor of the central cavity and connects to the A1 board. I was going to leave it in place, initially, but I found it easier to get at the power supply assembly with both hands with it out of the cavity.That's the A4 readout board, responsible for the on-screen text and cursor display generation. The labeled chip in the middle is the character ROM (actually an EPROM). There's a giant section (10 pages) in the theory part of the service manual on how this board works, if you're curious.
(Attachment Link) (Attachment Link)
That's the A4 readout board, responsible for the on-screen text and cursor display generation. The labeled chip in the middle is the character ROM (actually an EPROM). There's a giant section (10 pages) in the theory part of the service manual on how this board works, if you're curious.
If you follow the procedure as posted here and use the parts listed you will have no issues when re-capping the PSU:
https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg1658102/#msg1658102 (https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg1658102/#msg1658102)
In the case of these Tek 24xx series power supplies, are you aware of gotchas in component substitution? Anything that if substituted with a part with supposedly better specs would actually work against the goal of a stable, clean, supply voltage with sufficient amp capacity?Not 24xx in particular but study these posts where a member battled with FET Millar capacitance after selecting a replacement.
Start here:
https://www.eevblog.com/forum/repair/tektronix-2215-scope-repair/msg1647551/#msg1647551 (https://www.eevblog.com/forum/repair/tektronix-2215-scope-repair/msg1647551/#msg1647551)
Then jump to here:
https://www.eevblog.com/forum/repair/tektronix-2215-scope-repair/msg1824401/#msg1824401 (https://www.eevblog.com/forum/repair/tektronix-2215-scope-repair/msg1824401/#msg1824401)
Then read a few more posts.
I found it quite interesting and it just proves there are hidden traps for the unwary especially when just dropping a substituted component in and not understanding or modifying the design to account for it.
There is a pair of 15Ohm, 1/2W carbon film resistors parallel with the NTCs (R1010 & R1019) as part of the inrush protection mechanism. In the work I've read on this so far, I've seen people up-rating them and replacing them with 3W resistors or the like. Clearly, these are subject to some degree of thermal stress, being inline with with the mains before it enters the first rectifier. Is this necessary, or is it a bit of an insurance policy to make sure they don't fail and thus cause a cascade of failure in more expensive parts? Or is upgrading these resistors risking the failure of more expensive parts by causing what was intended as a sacrificial component to not fail when it should?Yes, preventive replacement.
Additionally, I note that in both of the Pre-B05xxxx supplies I've seen so far, one or both of resistors R1016 and R1018, have been burnt by failures of C1015 and C1018. I find myself wondering if perhaps it wouldn't be a good idea to increase those from 1/2 watt thermal ratings to something higher. My understanding from reading about X and Y ratings for caps is that an X-rated capacitor is supposed to fail shorted, with the idea being that in doing so it would cause a breaker to trip for a fuse to short. By my reading, resistors typically fail open. So of C1015 or C1018 fails, and draws the full mains current across R1016 or R1018, forcing them to release their magic smoke and become open in short order. Do we want to preserve that short so fuses start blowing? Or are these resistors intended as sacrificial components, and thus supposed to self destruct in the presence C1015 or C1018 shorting? In which case, would it be a good idea to go for a lower thermal rating so the resistor blows even sooner? Or is 1/2W the smallest thermal rating that could fit in that role?Sacrificial resistors IMHO.
Looking at this parts list, I find myself questioning the the changes in voltage or capacitance.While I've not analyzed the design there are more important consideration for SMPS cap selection than primarily capacitance or for that matter even voltage headroom.
For example let's take the filtering capacitors hanging off the output of the inverter transformer, C1110, C1111, C1113, C1114, C1115, and C1116. The originals are a blend of 180 and 250 uF. 330 seems like a bit of a jump, moving the poles of the LC filters the form from 2.2 kHz and 1.9kHz to 1.6kHz. That, I'm less worried about, since I don't see knocking an extra few dB off the ~41Khz switching noise as a particularly bad thing, and I don't think the increase in charging current from the increase in capacitance would load down the inverter too much more. However, is there not a consideration on undercharging electrolytic capacitors shortening their life? Per the voltages in the diagram, the stock 180uF caps on the +/- 15V lines, at 19.2V at this point in the circuit are being charge up to about 48% of their max voltage, and the 250uF caps on the unregulated +/- 5V lines (at 7.1V) are being charged up to about 35%. However, with the 50V rating on the proposed parts list, those unregulated lines are only being charged up to 14% of their rating. Is this too low of a charge for a healthy cap life?
I'm not saying these are unreasonable choices, given the choice of the Panasonic EB series. Looking on the datasheet, 330uF was the smallest value that wasn't lower than the original value 250uF caps. However, 220 uF is available to replace the 180 uF 40V, and a 220uF 50V is cheaper than 330uf 50V. Was this part selection driven somewhat by a desire to keep the parts list small and simple?
The A4 EPROM is just character data. If you're after the actual 6800 code, you'll want to look at the EPROMs on the A5 board on the side, or just grab one of the many images that others have already read out.That's the A4 readout board, responsible for the on-screen text and cursor display generation. The labeled chip in the middle is the character ROM (actually an EPROM). There's a giant section (10 pages) in the theory part of the service manual on how this board works, if you're curious.
Interesting. I remember seeing an easter egg of Tetris, or maybe it was Centipede hidden on an HP scope, so perhaps I shall have to dump the ROM and see what secrets lurk therein. At a later date, though.
...
Hello all, fine notes. But the recent posts refer only to 2465 and 2465A power supply recap. The 2465B PSU must be different.
At the moment, I have a very late SN 2465B opt 06,09 that needs recapping.
Is there a recent BOM for the 2565/7B PSU recap, the old boms have many broken links/ stock numbers from DK, Mouser.
Many thanks
Bon Soirée
Jon
I have a 2465B that I've come to (lovingly?) address as a red headed child. All voltages present at the test point and in spec, ripple is in spec, Nothing wrong with it except that it has no cal data (new chip) and won't boot. Anybody have any ideas here?What's the history with this unit? Did it work and now it doesn't or did you receive it broken?
I have a 2465B that I've come to (lovingly?) address as a red headed child. All voltages present at the test point and in spec, ripple is in spec, Nothing wrong with it except that it has no cal data (new chip) and won't boot. Anybody have any ideas here?What's the history with this unit? Did it work and now it doesn't or did you receive it broken?
Are there any LEDs lit on the front panel? Does it go through part of the boot sequence and get stuck? Are any relays clicking as it boots? Any flashes of anything on the CRT? Or does it just sit there like a lump? Need more info.
One thing you could do is try working through the troubleshooting flowcharts in the back of the service manual (immediately after the schematics). They don't cover every possibility, but can at least lead you to the right area to start digging.
...What "restoring" things did you do? Maybe posting decent resolution photos of those areas you worked on would allow someone to spot something.
Worked when I got it, then i tried restoring it.
Right now, what it does when powered on is exactly this;
Brief flash on the CRT, fan comes on, seemingly all front panel LEDS light, then it just sits there like a lump. Doing nothing except running the fan and staring at me with a brightly lit front panel.
Completely unresponsive beyond this and it will sit there for half an hour at least without change, does this every single time I try turning it on.
What "restoring" things did you do? Maybe posting decent resolution photos of those areas you worked on would allow someone to spot something.New capacitors, a new fan and a new chip. I tried to transfer the cal data to the new chip but, like an idiot, botched it.
One of the first things the CPU does is take control of the front panel LEDs. So, it's not even getting off the ground. Very few components need to be working for this initial phase. Not even the SRAM is needed.
I would focus on the CPU and EPROM functions. Make sure nRESET is going high and that the CPU has a working clock and supply. Make sure J503 NORM/DIAG jumper is in the NORM position.
Have you tried the troubleshooting flowchart? It will take you through all these checks, plus if the NOP diagnostic loop on the CPU should be run.
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+
...
Maybe some one can answer this for me and others, maybe it has already been done.
Can we use the:
DS1225AD-70+ chip here? is 70ns vs 200ns.
Looking at this parts list, I find myself questioning the the changes in voltage or capacitance.
For example let's take the filtering capacitors hanging off the output of the inverter transformer, C1110, C1111, C1113, C1114, C1115, and C1116. The originals are a blend of 180 and 250 uF. 330 seems like a bit of a jump, moving the poles of the LC filters the form from 2.2 kHz and 1.9kHz to 1.6kHz. That, I'm less worried about, since I don't see knocking an extra few dB off the ~41Khz switching noise as a particularly bad thing, and I don't think the increase in charging current from the increase in capacitance would load down the inverter too much more. However, is there not a consideration on undercharging electrolytic capacitors shortening their life? Per the voltages in the diagram, the stock 180uF caps on the +/- 15V lines, at 19.2V at this point in the circuit are being charge up to about 48% of their max voltage, and the 250uF caps on the unregulated +/- 5V lines (at 7.1V) are being charged up to about 35%. However, with the 50V rating on the proposed parts list, those unregulated lines are only being charged up to 14% of their rating. Is this too low of a charge for a healthy cap life?
I'm not saying these are unreasonable choices, given the choice of the Panasonic EB series. Looking on the datasheet, 330uF was the smallest value that wasn't lower than the original value 250uF caps. However, 220 uF is available to replace the 180 uF 40V, and a 220uF 50V is cheaper than 330uf 50V. Was this part selection driven somewhat by a desire to keep the parts list small and simple?
This is my first post and am a newbie.
I am waiting for my 2465B to show up. Everything is like new, the only thing is the scale illumination is not working. Is it worth replacing? I looked in the service manual and there are not pics to help me replace it.
Should I replace the board or just leave it?
If I should replace it and pics or video that show how to do it? I searched YouTube and everywhere and can't find anything
Thanks in advance for the help!
Bill
This is my first post and am a newbie.
I am waiting for my 2465B to show up. Everything is like new, the only thing is the scale illumination is not working. Is it worth replacing? I looked in the service manual and there are not pics to help me replace it.
Should I replace the board or just leave it?
If I should replace it and pics or video that show how to do it? I searched YouTube and everywhere and can't find anything
Thanks in advance for the help!
Bill
And finally! Onto the power supply! :D
....
Moving onto the rest of the CPU, we can see the usual components of a switching power supply. Fortunately, none of the regular electrolytic capacitors look swollen or otherwise damaged, but they're going to be checked anyway, given their age, and especially given the current surge the PSU was subject to. I do see more of those problematic box caps. Those are getting replaced, period, given their history. I'm not waiting for them to fail.
There must be a RIFA flu going around, saw a recent post here a couple of pages back saying the same thing. Was using my 2465B (serial +50K) today and all of the sudden POP and a lot of smoke. RIFA cap exploded and burned up 30 ohm resistor in series, even tough this scope has been on 120V line all its life, as far as I know. Saw the RIFAs where pretty crazed when I did the NVRAM/A5 caps about a year ago but figured I'll get to it eventually. Well, it got to me instead.
No other evident damage was found anywhere inside. So decided it would be a good time to finally use all those caps that I ordered months ago to do the full recap. Pulled out the power supply board sandwich and installed new caps all around (one at a time to avoid mistakes) including the main filter caps, the 4.7uF Tantalum, and the 3x 1uF NP. The only film caps I forgot to order back when where the two 2200pf 250V, one 0.01uF 250V, and one 0.056uF 250V so I'll do those next time. Also replaced both 15 ohm resistors with bigger units, and the 270K resistor.
Upon first plugin test the fan runs and all front panel lights flash once in unison and then only the green Sweep/Trig led stays on and nothing else happens. The 3 GPIB indicator are also staying lit. Not sure the Sweep/Trig Led might mean something (error code) although I looked it up in the SM and all I found is the list of indicators the scope goes through in sequence on boot, and if it stops on one that can be looked up in this list. But mine is not even going through this sequence, so not even booting. Nothing visible on screen, no trace no nothing.
Measured voltages at J119 as follows:
-15 -> -11.7v
+5D -> +4.3V
+10 -> +7.3
-5 -> -3.5V
+15 -> +10.4V
+87 -> +59.6V
+42.4 -> +28.8V
-8 -> -5.3V
+5A -> +3.3V
Needless to say all rails are low and way out of spec. Also checked voltage on the (new) main caps and got about 150V on each and around 300V total, so the primary rectifier is working and juice is getting into the supply. No sounds, no clicking, nothing heard.
Just now after pulling out the power supply again double and tipple checked that all caps are in the correct position, correct value/voltage, and correct polarity before installing the boards. All are correct. And yes, I am aware of the cap layout error in the service manual. Actually I did one cap at a time, just to be extra sure not to mix anything up.
All connectors are positively in place. There is the one going to A5 which is impossible to screw up, one with the multicolor wires under the fuse, and the all-white wires next to it, and no misaligned/missed pins. Other than that, the only other plug is a 3-wire that sends power to the GPIB board. Oh, and also checked continuity of all the pins of the stab (long pin) connectors between the two boards, as they sometimes can go intermittent if pushed the wrong way.
Anybody have any ideas/suggestions? I was reading the troubleshooting charts in the SM but wanted to first ask here in case these symptoms ring a bell and have happened before to someone else after a recap. I know there are plenty of people here that have gone through this procedure, some even more then once. Besides in order to for those charts to make sense would first need to order a couple of 20/25-watt resistors to construct a load as shown in the manual in able to run the supply outside the scope to be able to poke into it without blowing it up after shorting out something. BTW has anybody build one of those test loads? The SM only shows Tek PN for a diode and a 3.3uF cap (v?) needed.
Oh man, I was so hoping this recap would go without a hitch. I found that all the 180uF and 250uF where just staring to leak a tiny bit, so that would probably mean that now with better filtering in place I would get those sharper traces etc that many people have reported. O well... And yes what little was leaking from those caps was cleaned up, no harm at all to any traces or the board. Just a funny smell when desoldering those blue caps. All other caps looked fine but where replaced anyhow. Why not have all the fun at one time. Right, I'm having fun now.
Thanks for any input.
Alex
They key is your +10V reference. It's at +7.3V. It originates from the unregulated +15V on the A2 board.
Here's a thought....are you sure you connected the jumpers from the AC line filter to the A2 board correctly? If you scrambled them the A2 board may think it's connected for 120V which would explain the low voltage.
Ya gotta thank the designers for putting 30 ohm current limiting resistors in there. :clap:
Resistors might be toast but at least you have the traces left. :phew:
I now once again have the PS outside of the scope and on the bench.
BTW did you ever need to build that test load they describe in the service manual to troubleshoot any of your your power supplies? It allows to run the PS without T1060 the primary output transformer or the switching transistors being part of the circuit by just opening a jumper (W1060) next to the transformer. But first I need to have the proper load and I don't have the specified resistors on hand.
UPDATE: I found a problem and now the power supply is working again. But I am being greeted now by a 04 11 error message which indicates a faulty cal constant checksum. Maybe the FRAM did not like the lower power supply voltages or spikes etc. When I swapped out the old NVRAM I also programmed a fresh one and put it away just in case the FRAM would not work out, plus I also have the original 1990 NVRAM which should be still ok. Guess I could just swap in that new programmed NVRAM to confirm if the error goes away, and then try to reprogram the data back into the FRAM.
So the problematic one is the new FRAM which was normal before ?
If the voltage rails were the culprit, this is important reference.
Anyone else had problems trying to get the 1uF Bipolar capacitors (UEP1H010MDD RS part #5232678) from the list, the UK site says they are unavailable, yet other global RS sites say they are available? :wtf:
(Attachment Link)
David
Anyone else had problems trying to get the 1uF Bipolar capacitors (UEP1H010MDD RS part #5232678) from the list, the UK site says they are unavailable, yet other global RS sites say they are available? :wtf:
David
Well I asked RS and they claim the part number doesn't exist, even though you can add it to the quick order box here https://uk.rs-online.com/web/ (https://uk.rs-online.com/web/) which gives the error pictured (also provides the details they can't find).
Neither RS or Farnell in the UK can supply a 1uF non-polar capacitor (CPC only have no-name brand), so I'm left with the choice of trying to buy the Nichicon part from RS Germany or from reseller on ePay, or to use a film capacitor which I have some of.
.....
A couple of notes on a 2467b repair - graticule bulbs and SRAM.
1) To replace the graticule bulbs:
- remove the four knobs under the CRT. They just pull off. Be careful.
........
Ok David understood and thank you for the clarification. But if what you are saying is that to bring in about $5 worth of capacitors you have to pay around $20 shipping, I think it is still manageable. A as long as it is small amounts like these I for one in the same circumstances would still go for it just to solve the situation, specially as you say if you could add in some more parts to make it worth the cost. But if the shipping numbers get out of control then I'm definitively with you. Oh and then I assume that even if you place your order through Mouser EU the parts are still shipped from the US?
I have an 2467B that has that slight flickering of the intensity as well...
Recap already done, all voltages rock steady, but still.
Must be something with these MCP intensity amplifier CRT's.
Also going to have a look at the IEC filter at the weekend, forgot to photo it. :blah:
...
However, it appears that the 2445 (no A or B) use an ER1400 EAROM instead. There is a thread from 2013 here (https://www.eevblog.com/forum/testgear/tektronix-2445-teardown-pictures/) that suggests a replacement part as M5G1400P, they can be had, but I don't know if it is even safe to desolder this thing?
Any ideas guys?
However, it appears that the 2445 (no A or B) uses an ER1400 EAROM instead. There is a thread from 2013 here (https://www.eevblog.com/forum/testgear/tektronix-2445-teardown-pictures/) that suggests a replacement part as M5G1400P, they can be had, but I don't know if it is even safe to desolder this thing?
Any ideas guys?
It's basically broken down as follows:
2445/2465 (No suffix): Pin thru hole A5 board. The EAROM does not have, nor does it require, a battery backup.
snip
It's basically broken down as follows:
2445/2465 (No suffix): Pin thru hole A5 board. The EAROM does not have, nor does it require, a battery backup.
2445A/2465A: Pin thru hold A5 board. Don't recall chip type but it does have an external battery soldered to the A5 board.
2445B/2465B: SMT A5 board. Has the Dallas chip with internal battery.
Now supposedly some 2445A/2465A also have the SMT A5 board but not sure.
I do have a 2465B with the THT A5 board and the Li/SOCl2 cell soldered on it.
It's basically broken down as follows:
2445/2465 (No suffix): Pin thru hole A5 board. The EAROM does not have, nor does it require, a battery backup.
2445A/2465A: Pin thru hold A5 board. Don't recall chip type but it does have an external battery soldered to the A5 board.
2445B/2465B: SMT A5 board. Has the Dallas chip with internal battery.
Now supposedly some 2445A/2465A also have the SMT A5 board but not sure.
My 2445B has a through-hole board. The memory IC is an NEC D4364C-15LL
well this is stupid
I can't seem to find suitable axial caps anywhere to replace the 290uF 200V units in the fan motor plastic on A3.
You would think that 330uF 250V would be the modern one...Digikey lists 2, both non stock with minimums in the tens...
Mouser has none
RFParts is showing 470uF 200V axials in stock...but that seems like a lot of extra cap...do I just buy radials and fold the lead over and extend it?? seems...inelegant.
well this is stupidPlenty to choose from here:
I can't seem to find suitable axial caps anywhere to replace the 290uF 200V units in the fan motor plastic on A3.
Plenty to choose from here:
https://www.tedss.com/Capacitors/Browse/aluminum-electrolytic-axial (https://www.tedss.com/Capacitors/Browse/aluminum-electrolytic-axial)
Try this one:well this is stupidPlenty to choose from here:
I can't seem to find suitable axial caps anywhere to replace the 290uF 200V units in the fan motor plastic on A3.
https://www.tedss.com/Capacitors/Browse/aluminum-electrolytic-axial (https://www.tedss.com/Capacitors/Browse/aluminum-electrolytic-axial)
That is a neat site that I was not aware of, but the only 330uF 250V axial I'm seeing is 3" long :(
My 2445B has a through-hole board. The memory IC is an NEC D4364C-15LL
Your "Keeper" battery seems to have a 1990 date code, perhaps its time to replace it.
My 2445B has a through-hole board. The memory IC is an NEC D4364C-15LL
Your "Keeper" battery seems to have a 1990 date code, perhaps its time to replace it.
Well spotted! This photo was taken before I exchanged the battery - it was replaced shortly after. :)
Anthony
so guys
I am just about to reassembly on my vanilla 2445 after a full recap and I wanted to show off my custom U800 heatsink solution. I'm pretty proud of it.
It seems pretty clear to me that Tektronix, at some point in the design process, contemplated a heatsink here given the mounting screws they included. So I tried to make something close to what I imagined they had in mind.
(https://i.imgur.com/RcKAwjZ.jpg)
(https://i.imgur.com/Bcwkhk1.jpg)
was
(https://i.imgur.com/Pb2VPqd.jpg)
As I understand one of the U800 threaded studs is at +5V potential and the other is at ground, so joining both with a piece of aluminum will in essence create a short circuit. Again, I am up for being corrected if this is not correct, but I think I am not wrong.
Edit: And in my general opinion messing at all with the U800 setup as it came from the factory might create serious problems were there where none, specially if undoing and reinstalling those two nuts onto the studs. Be very careful about the torque and evenness of both nuts or the delicate IC substrate will be damaged during the process, of possibly even further down the line due to thermal stresses added to improperly torqued down nuts.
Cautions about torque are well taken, but I believe I will go ahead with my heatsink with moderate torque applied.
Scored a 2465B, while try to replace the NVRAM with STK16C68-W45 found the board with 2 feed through capacitor from the factory instead of the SMD leaking one :-+
For the power supply, I just replaced 2 68nF RIFA cap.
At least no visible crack on the casing
(Attachment Link)
(Attachment Link)
(Attachment Link)
At least no visible crack on the casing
At least no visible crack on the casing
Did you ever power it when the RIFAs were installed ? Consider your self lucky.
I saw your photos for just a quick glance using my phone at the 1st time, and didn't catch the details, and when I visited this thread again and used desktop big monitor, was curious and tried to zoom in :o , well, picture speaks thousand words, attached of the zoomed & tweaked photo of your RIFA below. :scared:
Scored a 2465B, while try to replace the NVRAM with STK16C68-W45 found the board with 2 feed through capacitor from the factory instead of the SMD leaking one :-+
(Attachment Link)
(Attachment Link)
If anyone with a plain 2465 or the A version is in need of the original Siemens fan motor, over at the Tekscopes-IO group someone found a seller on ebay that seems to have a big inventory of what seems to be brand new exact replacement motors. As far as I know the B series scopes never used this motor but rather a more common muffin fan type. But I might be wrong on that, and even some early B SN also use this fan. Since this motor is not easy to source, let alone in new condition, and a pain to repair, I thought I pass along this information. Even if yours is still working fine, perhaps a good idea to keep a spare on hand just in case for future needs.The price is going up. I bought one for a 2445A a few days ago at $9.99. Yesterday they were $14.99. Now $19.99.
Edit: this fan will also fit the plain 2445 scopes, and as pointed out by the seller, it will also fit some 46x and 47x series as well. Do your own homework, and probably a good idea to check the Tekscopes thread to be sure as I have no experience with those older scopes.
I am in no way connected to the sale.
https://www.ebay.com/itm/274013390896 (https://www.ebay.com/itm/274013390896)
Here is the original thread at Tekscopes group:
https://groups.io/g/TekScopes/topic/71491839 (https://groups.io/g/TekScopes/topic/71491839)
The price is going up. I bought one for a 2445A a few days ago at $9.99. Yesterday they were $14.99. Now $19.99.
The buying history says someone bought 20 of them, maybe to cash in when they're unobtanium again.
Unable to find it in Hong Kong except those Israel made AA lithium battery :-DD
Hi guys!
I bought a 2465A with a bad channel 1 input module. The problem was a burned resistor in the 50ohm input path.
I soldered two thru hole resistors and the unit got back to normal operation! I got very impressed because with a fast pulse generator I'm not seeing any difference between this channel and the original channel 2. Pretty interesting !
(https://i.ibb.co/YbRzhMX/image.png) (https://imgbb.com/)
Since it is not mentioned, the question would of course be what was the highest frequency (or fastest pulse width) used as comparison between ch1 and ch2 performance. I bet it was not anywhere near to about 100MHz where you would expect the leads of the resistors to start playing a part by adding inductance.
The original resistor was not 50 ohm. It was very close do 34 ohm. The amplitude response is right on the mV level and the rise time is near 800ps
(https://i.ibb.co/k2cn5Jk/image.png) (https://imgbb.com/)
:)
I can't see why the avalanche pulse is not useful for bandwidth estimation.
Obviously that the trace will be the convoluted response of the pulse and the scope front-end....
I can't see why the avalanche pulse is not useful for bandwidth estimation.
Obviously that the trace will be the convoluted response of the pulse and the scope front-end, but the rise-time needs to be preserved in the perspective of a first-order bandwidth estimation. If the test avalanche impulse is fast enough, the dominant pole will be from the scope itself.
Unfortunately this is the fastest rising edge I can generate here in the lab and it's rise time is not far from the 2465B bandwidth :-\
I measured it with a 1Ghz scope and it still measures ~800ps
(https://i.ibb.co/wBscjKD/image.png) (https://ibb.co/wBscjKD)
But what I really think that matters is that the 2465B fixed channel 1 and original channel 2 still show exactly the same waveform, so it seems that the parasitics of the modification are not so important in for the bandwidth of this Tek...
Well.. I'm happy with the results and the purpose of my latest posts was to show that a burned Tek 24XX input module is not the end of the world hehehe
You can not measure rise time with an impulse. It can only be done with a step. The impulse can only show you the slew rate. The reason is simple: you never see the true "top" of the impulse before it begins decreasing in amplitude causing the scope response to follow. Therefore you can't set the 90% to anything meaningful. This is where the step is used; the top of the step eventually becomes clearly visible, so you can set the 90% mark against this 100% reference. Put another way, knowing that the trace is increasing is meaningless unless you know what point it is increasing toward.
My 2465A (350MHz) had a rise time to a very fast step (<50 ps rise time) of dead on 1.0 ns, and I had also measured the actual -3 dB point at about 375 MHz (using a leveled sine generator). It follows that a 400 MHz 2465B should be about 8.7 ns or so. The apparently significantly shorter response to your impulse generator is misleading and not accurate.
With that said, you can fairly easily convert an avalanche impulse generator to a step generator by substituting the capacitor for a short piece of 50 ohm coax, acting as a charge line. It needs only store a few ns of charge, so with 1 ns per 20 cm, you don't need much at all. (don't go too long, nor pulse too frequently as it stresses the transistor). A follow up Jim Williams app note builds upon his avalanche pulse (impulse) generator to make a step generator using coax as a charge line (AN94).
Does anyone know offhand how many layers there are on the mainboard of these scopes? I have an otherwise nice 2465 that was 'drilled' and I'm considering whether to attempt a bodge repair or part it out. I actually have two of these boards that have been drilled in two slightly different spots. Apparently some corporation out there decided to drill all of their test equipment before selling it to the surplus (scrap) market.Wow, that's a shame.
so guys
I am just about to reassembly on my vanilla 2445 after a full recap and I wanted to show off my custom U800 heatsink solution. I'm pretty proud of it.
It seems pretty clear to me that Tektronix, at some point in the design process, contemplated a heatsink here given the mounting screws they included. So I tried to make something close to what I imagined they had in mind.
Tektronix had initially designed the board in order to accommodate a heatsink thinking it would be necessary but then after initial testing was done they noticed that the chip temperature was keeping well within the limits without it, so the heatsink idea was abandoned.
This IC is also very sensitive to over tightening and can easily be damaged by decontamination of the actual die from the substrate, something that will certainly ruin your day.
or even if one side is slightly torqued down tighter than the other could cause enough unbalance to create internal stress to break something.
4. Leave U800 alone.- unacceptable 8)
Tektronix SUCKS!!!!!
Tektronix is trying to manipulate the oscilloscope market. Today I learned from
my local dealership that they are required by contract to destroy every scope
which is traded in for a new Tektronix scope, regardless of age or condition. So
if you decide to trade in that old scope for a Tektronix, know ahead of time
that it is NOT going to end up in the hands of a ham, or of some kid learning
and experimenting in electronics on a tight budget like I was thir... er, twenty
years ago. No, Tektronix needs to raise their profits by destroying every used
scope they can get their greedy little hands on, regardless of who feels the
pinch!
https://groups.google.com/g/rec.radio.amateur.homebrew/c/FfNSJ6Ho50k?pli=1 (https://groups.google.com/g/rec.radio.amateur.homebrew/c/FfNSJ6Ho50k?pli=1)
::)
p.s.
why they do not tell us how to, or build, make new U800.... i believe on market we heave 1000 units still operate... because of this IC all unit become trash permanently......
I am indignant because of that .. and then I wonder what ecology and consciousness is ...
The “inventor” never proceeded with his design.Check the video in this thread:
Hi nice observation but you do not take cost-effectiveness, investment, programmed obsolescence, etc. if the factory meant absolute quality, then it would not install or produce a maxim IC chip that is structural unstable, etc. very bad also RIFA madness :) @ all! and a complete minimum investment / performance calculation for maximum profit.
the goal is to stop the temperature oscillation in order to make us lucky. we should achieve absolutely better cooling, with higher air flow, I found a great replacement.
p.s.
why they do not tell us how to, or build, make new U800.... i believe on market we heave 1000 units still operate... because of this IC all unit become trash permanently......
I am indignant because of that .. and then I wonder what ecology and consciousness is ...
PMD1208PKB1-A 90m3/h
fan dimesion 80x80x20mmQuoteTektronix SUCKS!!!!!
Tektronix is trying to manipulate the oscilloscope market. Today I learned from
----[snip]-----
"dirt" on the AC mains. Perhaps rating it at a bit higher voltage margin then 275VAC (I think it is the cap rating) might have helped a bit stave off some degradation to coming close to short out when the scope is operated on 240V mains, but back then Tek figured it would be enough. And again 275V cap on a 240V line still sounds quite ok (its definitively far from blowing up) even today with a new off the shelve good quality AC rated capacitor.
+1, and at that video, without the cover, the owner should use a fan blowing the board, as the hybrid ICs are heating up that way as no air flow at all.Maybe he didn't read post #6 from a wise old tech that has worked on these for decades.
Ok, maybe its fine for 1 or 2 minutes for the purpose of shooting that video, but say when trouble shooting this scope with that position for hours without cover, the poor hybrids will be overheated.
Hi. One a modest idea. placement of tvs diode in power supply. Extra Surge protection is possible?
Thank you in advance?
"Is there a similar thread to this one for the 2245a?" ---->Thanks. I'm aware of that thread... assumed it was not the preferred way to go as he seemed to be making adjustments for some different type of caps. Also, I can print ABS. Haven't done exploratory surgery on the 2245a, but does that power supply not have any paper RIFA capacitors?
https://www.rc-cam.com/forum/index.php?/topic/4165-tektronix-2245a-oscilloscope-smps-repair-re-cap/ (https://www.rc-cam.com/forum/index.php?/topic/4165-tektronix-2245a-oscilloscope-smps-repair-re-cap/)
I just scored a 2465 (no suffix) with a service manual at a local charity.
And it's functional except an issue with "beam find" button is flaky but I see it has the original caps.
I found parts list of replacement caps for the power supply posted by med6753.
Are there any other caps that need to be replaced such as on other boards?
I don't see a battery for the RAM... is that a newer thing (only needed for 2465a and b) and no battery replacement needed for the 2465.
I also got a fully operational 2245a that clearly needs a battery (and recap). Is there a similar thread to this one for the 2245a?
Appreciate any help.
This forum has done such an awesome job in helping me better understand my 2445B oscilloscope that I wanted to post here that with the help of the many comments and the 2465B bill of materials I was able to recap the A3 and A2A1 boards and eventually fixed a faulty diode that was causing the constantly resetting at power-up (aka 'tick mode') issue.
For those interested I have documented my repairs in this video:
.. <snip> ..
Hopefully this scope will last another 30 years!
Hi,
WD40 is better than the alcohol to remove acid action from the electrolytics! WD40 don't cause any problem in the board with fiberglass epoxy clad. The A5 board don't suffer this problem wits "HF", don't have enough to capacitance to act in low frequebcy pulses.
The microprocessor clock is 20MHz, and working very well after all!
Hi,
WD40 is better than the alcohol to remove acid action from the electrolytics! WD40 don't cause any problem in the board with fiberglass epoxy clad. The A5 board don't suffer this problem wits "HF", don't have enough to capacitance to act in low frequebcy pulses.
The microprocessor clock is 20MHz, and working very well after all!
Hi,
Has anybody come across this issue - readout display is shifted too far to the right, see photo. The problem is that if you look at the display not directly but from an angle, some characters covered by CRT frame and not visible.
Service manual offers no adjustment to shift readout display horizontally. But must be something in readout schematic to tweak it?
Mark
I wouldn't use Water Displacement 40 on a digital PCB. The nearest I use is Craig DeOxit, and I'm careful to use that only on contacts.
I wouldn't use Water Displacement 40 on a digital PCB. The nearest I use is Craig DeOxit, and I'm careful to use that only on contacts.
There is a WD40 branded contact cleaner which is probably much the same as any other contact cleaner, Servisol etc. That may be the source of confusion here. As for classic WD40, used for cars and lawnmowers etc, it's absolutely the wrong thing thing to use on electronics.
Yes it does. Section 5-13 of the 2465B Service Manual. Read the entire section carefully. It adjusts the horizontal centering which should fix the readout offset.
Yes it does. Section 5-13 of the 2465B Service Manual. Read the entire section carefully. It adjusts the horizontal centering which should fix the readout offset.
That's it! This is what I was needed. Thank you. It's a R801 if somebody will be looking for it.
The battery read 3.2V, but just touching the DMM with the fingers dropped to 2.7V, so go figure if only the capacitive kick when touching the + terminal with the earthed iron (Battery not earthed though) was enough to kill the data.
...At a minimum, the last operating configuration at power down (knob positions, etc.) and user presets are in there.
About the DS1225Y NVRAM, do we know what else is stored there?
I know cal data is @ 0x1FE00 - 0x1FFFF, but the scope displays a lot of interrogation signs when not programmed properly.
From now I'll use the EXER 02 procedure to manually extract the cal data on still working scopes, before touching anything, hand-copying 512bytes will take 10 minutes, but way less than running a full calibration!You can also just take a video of flipping through the locations and transcribe it later when, or if, you need it (this also avoids transcribing errors). If you have a GPIB interface, you can dump the NVRAM data directly to a computer (and reload it too).
But some 2465B have extra boards on them (I.E. GPIB, TV(?) modules), I have no idea if they're recognized automatically or they need to me added manually in the diagnostic menu?They are recognized automatically.
If you have a GPIB interface, you can dump the NVRAM data directly to a computer (and reload it too).Can you give a pointer to the procedure?
...I've never seen it documented. J504 allows the -1.25V reference to be provided by an imprecise resistor divider. The -1.25V reference is usually provided by the DAC. The jumper allows allows easier troubleshooting of the DAC and associated circuitry by removing dependency on proper operation of the DAC.
Does anybody know what is the jumper J504 on A5 board 2465B & 2467B? (SN B050000 & above) How it can help in troubleshooting? No word in forums/service manual about it.
I've never seen it documented. J504 allows the -1.25V reference to be provided by an imprecise resistor divider. The -1.25V reference is usually provided by the DAC. The jumper allows allows easier troubleshooting of the DAC and associated circuitry by removing dependency on proper operation of the DAC.
If you search for "J504" on TekScopes on groups.io, you can read how people have employed it to help in their troubleshooting.
Curious how easy it'd be to add the counter timer option to a unit that doesn't already have one? IIRC those modules are automatically recognized when present. Is it just a matter pulling the PCB and hooking it up?
Curious how easy it'd be to add the counter timer option to a unit that doesn't already have one? IIRC those modules are automatically recognized when present. Is it just a matter pulling the PCB and hooking it up?
I was able to do just that to my 2465B thanks to a member of Tekscopes that sold me the whole kit and caboodle and had done it himself more than once on other 2465B's, so he knew very well all there was to know about this option add-on.
Basically you will need the CTT card, and several ribbon and coax cables with specific connectors on their ends, plus also the rear Ext Ref and Word Recognizer jacks with their cables. The scope power supply needs to temporarily be removed, and some jumpers need to be taken off a connector where one of the new ribbon cables will plug into.
...snip...
...
Seems like the ideal combo is to have a 2247A for general purpose and a 2465 for high bandwidth stuff, as the former has a better feature set for general bench stuff.
Great video on the 2247A. I have both the 2247A and the 2465BDV. I have to admit, I somewhat like the 2247A a bit better as a bench scope.
So I have a general question.... which is the last and best digital or digital storage scope Tek made in this family before the TDS and TAS scopes?
Anyone? Was the 2440 the last?
2467BHD
So I have a general question.... which is the last and best digital or digital storage scope Tek made in this family before the TDS and TAS scopes?
Anyone? Was the 2440 the last?
...You're right about the clock speed. Perhaps your processor is a different manufacturer? Does it have the Motorola logo on it?
By fact on A5 board I've got MC6802P CPU installed and its datasheet says that max input freq for MC6802P is 4.0MHz. Crystal on board is 10MHz as it should be so a CPU freq input is 5.0MHz. How it could be? Where is a flaw?
You're right about the clock speed. Perhaps your processor is a different manufacturer? Does it have the Motorola logo on it?
It could the simplest answer that someone who wasn't paying attention to clock speed put the wrong processor in there.
All my 2445x/2465x boards have an A or B processor on them.
By fact on A5 board I've got MC6802P CPU installed and its datasheet says that max input freq for MC6802P is 4.0MHz. Crystal on board is 10MHz as it should be so a CPU freq input is 5.0MHz. How it could be? Where is a flaw?
Yes it does have Motorola logo, see the snapshot. I double checked a soldering and it looks like factory installation. No freaking idea how it could be :) So the CPU is overclocked and works fine. Mistery.Interesting. It does look very factory.
...
Interesting. It does look very factory.
Well, it's not going to stop working at 4.01 MHz, but it may not work properly at some of the operating extremes, such as temperature and supply voltage.
You could double check that pin 39 (EXTAL) is 5MHz, but I can't imagine it would be anything else.
Maybe it's from a mis-labeled batch and Tektronix was told by Motorola? Or maybe Tektronix qualified them in-house themselves for 5MHz knowing the scope's operating constraints?
Hello
Need advise from experienced users.
Tek 2465B along with readout information started to output some artefacts to the display. Can't upload the video right now, but they are clearly seen at photos, attached. They are on signals area and are flickering 3-5 times per sec. When I turn readout intensity knob to the middle position they go away with readout info. Channel independent, even with grounded. Temperature also independent, coming up with cold device and go away with turning off readout only.
Now close to the point. I have another A5 board taken from a scope. When replaced - all is working fine, no problem, no artefacts. So the issue is in A5.
In original A5 board there was well known electrolytic caps leakage. All were replaced, potential damaged areas were inspected, cleaned. Proximate smd resistors, ceramic caps, traces are checked. Tantalum caps checked. Wima caps also checked.
Another point is that when I touch by finger test point TP32 (on readout schematic <7>) artefacts stop flickering and look like exactly at the photo. This is dot cycle generator section in readout schematic.
So this is the situation. What do you recommend to do?
Check resistor R2890 on <7> ( on output of gate U2890B) If that one is drifted or open it would explain the 'finger trick' The diagram says 1k for the value.
Perhaps the electrolyte has affected the value
Edit : updated the resistor value to 1k
Update on 2465B readout problem:Just as a quick test you can try to readjust the CRT GRID bias a bit and see if you can turn away the ghosting...
Ghost images start to appear only at the fast sweeps - 1us and less.
Also I've found that on slow sweeps signal trace and readout are alternated, see the shot attached.
No description of these symptoms in SM & charts but may be somebody faced such problem before?
The electrolytic caps in the PSU sometimes leak conductive electrolyte over the boards, as well as eating the traces, this can cause expensive failures all over the scope when the PSU malfunctions. YMMV
tl;dr ;-)
What an informative thread. Thank you Bravo and all the others who contributed here. Im the happy owner a 2465A CT and I wanted to follow the advice of many here and recap the PS. Especially get those RIFAs out before they pop. Not sure if I should replace any other caps besides those. All my J119 DC voltages are within spec. I also have no error messages and scope appears to be working pretty good. My calibration waveform seems a bit noisy at certain timebases since the trace is not a thin line but a thick fuzzy line. Maybe that’s normal.There are plenty of varying opinions on this, but mine is "if it ain't broke, don't fix it". If your voltages and ripple are in spec, then leave well enough alone. You can find plenty of posts from people looking for help after "recapping" because they've destroyed their equipment. The only exception in these scopes is the RIFA caps, as they are a well-known and frequent point of failure.
Also wanted to replace the Keeper II battery. Its reading 3.3v but dont want to risk losing my data. What’s the best method for attaching a backup battery while doing the replacement? I found these two online:Of those two, I like the Jestine approach since he is replacing the dead battery and not stacking a new one on a dead one. Leaving a dead battery in there is asking for leaks, and there's no guarantee it wouldn't reduce the life of the new battery.
https://jestineyong.com/tektronix-2465a-dv-oscilloscope-memory-backup-battery-replacement/
https://cdn.hackaday.io/files/1638907011869760/Piggyback%20batt.JPG
Also I would be using my grounded soldering iron. Could that be a problem if the A5 board is out of the scope? Would it be possible that the iron would ground the battery and the EAROM would lose its data?The EAROM is used on 2445 and 2465. On later A and B scopes, it was replaced with battery backed SRAM , either combined in a single package or as two separate devices. As long as the board is isolated, soldering should be ok. Just don't short any pins by accident.
Lastly as a backup plan I was thinking of backing up my data with the a GBIP adapter which was mentioned in this thread. Maybe using the NI USB model. Has it been confirmed that it can be used to backup and fully restore the EAROM data in case I accidentally delete it during the battery replacement?Yes. I can attest the data can be saved and successfully restored with this method. I have done it about a half dozen times.
I come from the same camp. I haven't tested for ripple yet. but my DC voltages are fine.
There are plenty of varying opinions on this, but mine is "if it ain't broke, don't fix it". If your voltages and ripple are in spec, then leave well enough alone. You can find plenty of posts from people looking for help after "recapping" because they've destroyed their equipment. The only exception in these scopes is the RIFA caps, as they are a well-known and frequent point of failure.
Also wanted to replace the Keeper II battery. Its reading 3.3v but dont want to risk losing my data. What’s the best method for attaching a backup battery while doing the replacement? I found these two online:I agree I don't want to leave an old dead battery in there. I was more asking for suggestions on which points to use to attach the temporary battery. Also @factory added a third option for connection points: https://www.eevblog.com/forum/testgear/tektronix-2455b-ram-battery-replacement-advice-needed/msg5277409/#msg5277409 (https://www.eevblog.com/forum/testgear/tektronix-2455b-ram-battery-replacement-advice-needed/msg5277409/#msg5277409)
https://jestineyong.com/tektronix-2465a-dv-oscilloscope-memory-backup-battery-replacement/ (https://jestineyong.com/tektronix-2465a-dv-oscilloscope-memory-backup-battery-replacement/)
https://cdn.hackaday.io/files/1638907011869760/Piggyback%20batt.JPG (https://cdn.hackaday.io/files/1638907011869760/Piggyback%20batt.JPG)QuoteOf those two, I like the Jestine approach since he is replacing the dead battery and not stacking a new one on a dead one. Leaving a dead battery in there is asking for leaks, and there's no guarantee it wouldn't reduce the life of the new battery.
The EAROM is used on 2445 and 2465. On later A and B scopes, it was replaced with battery backed SRAM , either combined in a single package or as two separate devices. As long as the board is isolated, soldering should be ok. Just don't short any pins by accident.
Yes. I can attest the data can be saved and successfully restored with this method. I have done it about a half dozen times.Excellent thanks. I will follow your advice. What software do I use to send commands to the scope?
Before trying anything with either GPIB or the battery, I would suggest you take a video of flipping through the NVRAM using EXER 02 and record all the values. While the methods to get that data back in the NVRAM in case of failure will vary depending on what equipment you have at your disposal, at least you have the data.
I will probably leave these alone if they are unlikely to fail. But great advice. Also great advice on how to proceed with changing the caps one by one and which ones to change. Thanks. Any preferred shopping list?QuoteBeen there done that on my 2465B. If I remember correctly the usual leaking caps where the two (blue) 180uF 40V, and the (also blue) 250uF 20V ones, all to be replaced with 330uF 50V. Thing is sometimes you won't see the leakage pooled up under the cap until the cap itself has been pulled, but if the case make sure to clean well before installing the replacement. The green caps are usually still good, but while you are in there...
Also keep in mind the orientation error for one of the caps on the PCB silkscreen, which is reversed. Best to replace only one cap at a time without using the silkscreen as a guide, and making sure to take notes of each cap's orientation before pulling it so as to install it exactly the same way the original was. Also when taking notes don't confuse the 10uF 100V with 100uF 10V (I think it was) as both will look almost identical in size. I did that mistake when I followed my own bad notes and ended up getting a loud POP which was the only thing that finally revealed the mistake, as I was still checking everything against my notes and could not figure out what was wrong. Not sure the silk screen error applies in your case with an earlier 2465ACT, but certainly it does in the 2465B. You can find plenty more information on this error here on this thread, plus recommended capacitor shopping lists, etc.tl;dr ;-)
Those two 290uF 200V high quality SPRAGE brand caps are usually almost always still in perfect condition, but you could also replace them if desired with 330uF 250V. But it will be hard to find those in axial type, so usually a bit of conversion needs to be done to more conventional radial types by extending and insulating one of the leads and bending it upwards over the body of the cap towards the other end to create a quasi-axial cap.
The worst offenders were the larger radial Sprague caps with the resin bung, these were often found cracked and/or peeing electrolyte. I would give a list of what I used, but most of the caps I used are now discontinued.Thanks David. Found a list by CondorAudio in the Tek group. Unfortunately some caps are not available. Any recommendations for substitutes?
(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=2065427;image)
Also if you don't have much experience replacing parts on double sided boards, I would suggest practising on something of no value first.
And as your scope has options, take note or pictures of where all the extra connectors are fitted, before removal.
David
The worst offenders were the larger radial Sprague caps with the resin bung, these were often found cracked and/or peeing electrolyte. I would give a list of what I used, but most of the caps I used are now discontinued.Thanks David. Found a list by CondorAudio in the Tek group. Unfortunately some caps are not available. Any recommendations for substitutes?
(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=2065427;image)
Also if you don't have much experience replacing parts on double sided boards, I would suggest practising on something of no value first.
And as your scope has options, take note or pictures of where all the extra connectors are fitted, before removal.
David
Part# Value Watts Mouser Part#
C1021 290 µF 200 ELCTLT 647-UPW2E331MRD
C1022 290 µF 200 ELCTLT 647-UPW2E331MRD
C1066 4.7 µF 35 ELCTLT 647-UPW1H4R7MDD
C1112 4.7 µF 35 ELCTLT 647-UPW1H4R7MDD
C1120 10 µF 100 ELCTLT 647-UPW2A100MED
C1130 10 µF 100 ELCTLT 647-UPW2A100MED
C1220 10 µF 100 ELCTLT 647-UPW2A100MED
C1240 10 µF 100 ELCTLT 647-UPW2A100MED
C1400 47 µF 25 ELCTLT 647-UHE1E470MDD
C1402 47 µF 25 ELCTLT 647-UHE1E470MDD
RT1010 7.0 ohm NTC Thermistor 995-SG210
On Linux, you can use the ibtest utility that comes with the linux-gpib package. It's somewhat low-level and not the most convenient, but it gets the job done without having to load or make anything extra.Yes. I can attest the data can be saved and successfully restored with this method. I have done it about a half dozen times.Excellent thanks. I will follow your advice. What software do I use to send commands to the scope?
Before trying anything with either GPIB or the battery, I would suggest you take a video of flipping through the NVRAM using EXER 02 and record all the values. While the methods to get that data back in the NVRAM in case of failure will vary depending on what equipment you have at your disposal, at least you have the data.
$ ibtest
Do you wish to open a (d)evice or an interface (b)oard?
(you probably want to open a device): d
enter primary gpib address for device you wish to open [0-30]: 8
trying to open pad = 8 on /dev/gpib0 ...
You can:
w(a)it for an event
write (c)ommand bytes to bus (system controller only)
send (d)evice clear (device only)
change remote (e)nable line (system controller only)
(g)o to standby (release ATN line, system controller only)
send (i)nterface clear (system controller only)
ta(k)e control (assert ATN line, system controller only)
get bus (l)ine status (board only)
go to local (m)ode
change end (o)f transmission configuration
(q)uit
(r)ead string
perform (s)erial poll (device only)
change (t)imeout on io operations
request ser(v)ice (board only)
(w)rite data string
send group e(x)ecute trigger (device only)
: w
enter a string to send to your device: id?
sending string: id?
gpib status is:
ibsta = 0x2100 < END CMPL >
iberr= 0
ibcntl = 4
You can:
w(a)it for an event
write (c)ommand bytes to bus (system controller only)
send (d)evice clear (device only)
change remote (e)nable line (system controller only)
(g)o to standby (release ATN line, system controller only)
send (i)nterface clear (system controller only)
ta(k)e control (assert ATN line, system controller only)
get bus (l)ine status (board only)
go to local (m)ode
change end (o)f transmission configuration
(q)uit
(r)ead string
perform (s)erial poll (device only)
change (t)imeout on io operations
request ser(v)ice (board only)
(w)rite data string
send group e(x)ecute trigger (device only)
: r
enter maximum number of bytes to read [1024]:
trying to read 1024 bytes from device...
received string: 'ID TEK/2445A,V81.1,SYS:FV08,BB:FV02,CTT:FV05,DMM:FV01,GPIB:FV02;'
Number of bytes read: 64
gpib status is:
ibsta = 0x2100 < END CMPL >
iberr= 0
ibcntl = 64
You can:
w(a)it for an event
write (c)ommand bytes to bus (system controller only)
send (d)evice clear (device only)
change remote (e)nable line (system controller only)
(g)o to standby (release ATN line, system controller only)
send (i)nterface clear (system controller only)
ta(k)e control (assert ATN line, system controller only)
get bus (l)ine status (board only)
go to local (m)ode
change end (o)f transmission configuration
(q)uit
(r)ead string
perform (s)erial poll (device only)
change (t)imeout on io operations
request ser(v)ice (board only)
(w)rite data string
send group e(x)ecute trigger (device only)
: w
enter a string to send to your device: key 0
sending string: key 0
gpib status is:
ibsta = 0x2100 < END CMPL >
iberr= 0
ibcntl = 6
You can:
w(a)it for an event
write (c)ommand bytes to bus (system controller only)
send (d)evice clear (device only)
change remote (e)nable line (system controller only)
(g)o to standby (release ATN line, system controller only)
send (i)nterface clear (system controller only)
ta(k)e control (assert ATN line, system controller only)
get bus (l)ine status (board only)
go to local (m)ode
change end (o)f transmission configuration
(q)uit
(r)ead string
perform (s)erial poll (device only)
change (t)imeout on io operations
request ser(v)ice (board only)
(w)rite data string
send group e(x)ecute trigger (device only)
: w
enter a string to send to your device: earom? f
sending string: earom? f
gpib status is:
ibsta = 0x2100 < END CMPL >
iberr= 0
ibcntl = 9
You can:
w(a)it for an event
write (c)ommand bytes to bus (system controller only)
send (d)evice clear (device only)
change remote (e)nable line (system controller only)
(g)o to standby (release ATN line, system controller only)
send (i)nterface clear (system controller only)
ta(k)e control (assert ATN line, system controller only)
get bus (l)ine status (board only)
go to local (m)ode
change end (o)f transmission configuration
(q)uit
(r)ead string
perform (s)erial poll (device only)
change (t)imeout on io operations
request ser(v)ice (board only)
(w)rite data string
send group e(x)ecute trigger (device only)
: r
enter maximum number of bytes to read [1024]: 2048
trying to read 2048 bytes from device...
received string: 'EAR 0:215,1908,1921,1921,1927,10204,10088,1917,10118,1970,10304,506,522,8715,8712,548,8647,8671,481,8668,508,8318,32,32,8221,28,15534,16052,7414,15560,16299,8099,16299,16292,16309,566,566,8756,8756,7450,7934,7699,4096,16304,16295,8105,16280,8105,743,744,740,740,10078,10334,2140,2133,10304,10340,2120,104,2133,10319,10322,2108,10321,2102,8297,835,820,817,1646,9814,9842,1630,722,752,14501,3762,3781,1840,1878,560,569,8545,314,1377,10238,1015,8970,1'
Number of bytes read: 448
gpib status is:
ibsta = 0xc100 < ERR TIMO CMPL >
iberr= 6
EABO 6: Operation aborted
ibcntl = 448
You can:
w(a)it for an event
write (c)ommand bytes to bus (system controller only)
send (d)evice clear (device only)
change remote (e)nable line (system controller only)
(g)o to standby (release ATN line, system controller only)
send (i)nterface clear (system controller only)
ta(k)e control (assert ATN line, system controller only)
get bus (l)ine status (board only)
go to local (m)ode
change end (o)f transmission configuration
(q)uit
(r)ead string
perform (s)erial poll (device only)
change (t)imeout on io operations
request ser(v)ice (board only)
(w)rite data string
send group e(x)ecute trigger (device only)
: r
enter maximum number of bytes to read [1024]:
trying to read 1024 bytes from device...
received string: '261,1948,9614,1975,1586,1349,1832,9242,9710,9014,710,9000,1362,9158,1187,1029,9109,1015,8928,8387,203,8361,20735,57054,57054,57054,57054,199,252,254,4,58,57054,57054,5543,5290,5366,5323,532,5500,5460,5517,5470,5386,8279,8286,8323,8292,8205,8,6359,6382,6484,7034,7110,6649,6612,6741,7291,7354,5525,5537,5509,5181,5535,5570,5575,5549,5221,5608,8292,65246,280,57054,57054,15764,37288,56338,24767,57054,57054,9480,57054,38308,9781,35954,25263,57054,5705'
Number of bytes read: 449
gpib status is:
ibsta = 0xc100 < ERR TIMO CMPL >
iberr= 6
EABO 6: Operation aborted
ibcntl = 449
You can:
w(a)it for an event
write (c)ommand bytes to bus (system controller only)
send (d)evice clear (device only)
change remote (e)nable line (system controller only)
(g)o to standby (release ATN line, system controller only)
send (i)nterface clear (system controller only)
ta(k)e control (assert ATN line, system controller only)
get bus (l)ine status (board only)
go to local (m)ode
change end (o)f transmission configuration
(q)uit
(r)ead string
perform (s)erial poll (device only)
change (t)imeout on io operations
request ser(v)ice (board only)
(w)rite data string
send group e(x)ecute trigger (device only)
: r
enter maximum number of bytes to read [1024]:
trying to read 1024 bytes from device...
received string: '4,57054,57054,12168,13935,20320,30175,57054,57054,57054,57054,30465,23778,44986,9647,57054,57054,57054,57054,48387,47423,41792,57871,57054,57054,57054,57054,64452,24830,31824,27670,57054,57054,57054,57054,41740,12751,16266,5113,57054,57054,57054,57054,50098,2404,34593,63623,57054,57054,57054,57054,63304,2170,65206,18463,57054,57054,57054,57054,54824,8886,63400,47442,57054,57054,57054,57054,38880,2266,60688,13813,57054,57054,57054,57054,48872,16499,14;'
Number of bytes read: 455
gpib status is:
ibsta = 0x2100 < END CMPL >
iberr= 0
ibcntl = 455
You can:
w(a)it for an event
write (c)ommand bytes to bus (system controller only)
send (d)evice clear (device only)
change remote (e)nable line (system controller only)
(g)o to standby (release ATN line, system controller only)
send (i)nterface clear (system controller only)
ta(k)e control (assert ATN line, system controller only)
get bus (l)ine status (board only)
go to local (m)ode
change end (o)f transmission configuration
(q)uit
(r)ead string
perform (s)erial poll (device only)
change (t)imeout on io operations
request ser(v)ice (board only)
(w)rite data string
send group e(x)ecute trigger (device only)
: r
enter maximum number of bytes to read [1024]:
trying to read 1024 bytes from device...
received binary data (hex): ffffffff
Number of bytes read: 1
gpib status is:
ibsta = 0x2100 < END CMPL >
iberr= 0
ibcntl = 1
You can:
w(a)it for an event
write (c)ommand bytes to bus (system controller only)
send (d)evice clear (device only)
change remote (e)nable line (system controller only)
(g)o to standby (release ATN line, system controller only)
send (i)nterface clear (system controller only)
ta(k)e control (assert ATN line, system controller only)
get bus (l)ine status (board only)
go to local (m)ode
change end (o)f transmission configuration
(q)uit
(r)ead string
perform (s)erial poll (device only)
change (t)imeout on io operations
request ser(v)ice (board only)
(w)rite data string
send group e(x)ecute trigger (device only)
:
$ ibtest
Do you wish to open a (d)evice or an interface (b)oard?
(you probably want to open a device): d
enter primary gpib address for device you wish to open [0-30]: 8
trying to open pad = 8 on /dev/gpib0 ...
You can:
w(a)it for an event
write (c)ommand bytes to bus (system controller only)
send (d)evice clear (device only)
change remote (e)nable line (system controller only)
(g)o to standby (release ATN line, system controller only)
send (i)nterface clear (system controller only)
ta(k)e control (assert ATN line, system controller only)
get bus (l)ine status (board only)
go to local (m)ode
change end (o)f transmission configuration
(q)uit
(r)ead string
perform (s)erial poll (device only)
change (t)imeout on io operations
request ser(v)ice (board only)
(w)rite data string
send group e(x)ecute trigger (device only)
: t
enter the desired timeout:
(0) none
(1) 10 microsec
(2) 30 microsec
(3) 100 microsec
(4) 300 microsec
(5) 1 millisec
(6) 3 millisec
(7) 10 millisec
(8) 30 millisec
(9) 100 millisec
(10) 300 millisec
(11) 1 sec
(12) 3 sec
(13) 10 sec
(14) 30 sec
(15) 100 sec
(16) 300 sec
(17) 1000 sec
13
gpib status is:
ibsta = 0x100 < CMPL >
iberr= 0
ibcntl = 0
You can:
w(a)it for an event
write (c)ommand bytes to bus (system controller only)
send (d)evice clear (device only)
change remote (e)nable line (system controller only)
(g)o to standby (release ATN line, system controller only)
send (i)nterface clear (system controller only)
ta(k)e control (assert ATN line, system controller only)
get bus (l)ine status (board only)
go to local (m)ode
change end (o)f transmission configuration
(q)uit
(r)ead string
perform (s)erial poll (device only)
change (t)imeout on io operations
request ser(v)ice (board only)
(w)rite data string
send group e(x)ecute trigger (device only)
: w
enter a string to send to your device: id?
sending string: id?
gpib status is:
ibsta = 0x2100 < END CMPL >
iberr= 0
ibcntl = 4
You can:
w(a)it for an event
write (c)ommand bytes to bus (system controller only)
send (d)evice clear (device only)
change remote (e)nable line (system controller only)
(g)o to standby (release ATN line, system controller only)
send (i)nterface clear (system controller only)
ta(k)e control (assert ATN line, system controller only)
get bus (l)ine status (board only)
go to local (m)ode
change end (o)f transmission configuration
(q)uit
(r)ead string
perform (s)erial poll (device only)
change (t)imeout on io operations
request ser(v)ice (board only)
(w)rite data string
send group e(x)ecute trigger (device only)
: r
enter maximum number of bytes to read [1024]:
trying to read 1024 bytes from device...
received string: 'ID TEK/2445A,V81.1,SYS:FV08,BB:FV02,CTT:FV05,DMM:FV01,GPIB:FV02;'
Number of bytes read: 64
gpib status is:
ibsta = 0x2100 < END CMPL >
iberr= 0
ibcntl = 64
You can:
w(a)it for an event
write (c)ommand bytes to bus (system controller only)
send (d)evice clear (device only)
change remote (e)nable line (system controller only)
(g)o to standby (release ATN line, system controller only)
send (i)nterface clear (system controller only)
ta(k)e control (assert ATN line, system controller only)
get bus (l)ine status (board only)
go to local (m)ode
change end (o)f transmission configuration
(q)uit
(r)ead string
perform (s)erial poll (device only)
change (t)imeout on io operations
request ser(v)ice (board only)
(w)rite data string
send group e(x)ecute trigger (device only)
: w
enter a string to send to your device: key 0
sending string: key 0
gpib status is:
ibsta = 0x2100 < END CMPL >
iberr= 0
ibcntl = 6
You can:
w(a)it for an event
write (c)ommand bytes to bus (system controller only)
send (d)evice clear (device only)
change remote (e)nable line (system controller only)
(g)o to standby (release ATN line, system controller only)
send (i)nterface clear (system controller only)
ta(k)e control (assert ATN line, system controller only)
get bus (l)ine status (board only)
go to local (m)ode
change end (o)f transmission configuration
(q)uit
(r)ead string
perform (s)erial poll (device only)
change (t)imeout on io operations
request ser(v)ice (board only)
(w)rite data string
send group e(x)ecute trigger (device only)
: w
enter a string to send to your device: earom? f
sending string: earom? f
gpib status is:
ibsta = 0x2100 < END CMPL >
iberr= 0
ibcntl = 9
You can:
w(a)it for an event
write (c)ommand bytes to bus (system controller only)
send (d)evice clear (device only)
change remote (e)nable line (system controller only)
(g)o to standby (release ATN line, system controller only)
send (i)nterface clear (system controller only)
ta(k)e control (assert ATN line, system controller only)
get bus (l)ine status (board only)
go to local (m)ode
change end (o)f transmission configuration
(q)uit
(r)ead string
perform (s)erial poll (device only)
change (t)imeout on io operations
request ser(v)ice (board only)
(w)rite data string
send group e(x)ecute trigger (device only)
: r
enter maximum number of bytes to read [1024]: 2048
trying to read 2048 bytes from device...
received string: 'EAR 0:215,1908,1921,1921,1927,10204,10088,1917,10118,1970,10304,506,522,8715,8712,548,8647,8671,481,8668,508,8318,32,32,8221,28,15534,16052,7414,15560,16299,8099,16299,16292,16309,566,566,8756,8756,7450,7934,7699,4096,16304,16295,8105,16280,8105,743,744,740,740,10078,10334,2140,2133,10304,10340,2120,104,2133,10319,10322,2108,10321,2102,8297,835,820,817,1646,9814,9842,1630,722,752,14501,3762,3781,1840,1878,560,569,8545,314,1377,10238,1015,8970,1261,1948,9614,1975,1586,1349,1832,9242,9710,9014,710,9000,1362,9158,1187,1029,9109,1015,8928,8387,203,8361,20735,57054,57054,57054,57054,199,252,254,4,58,57054,57054,5543,5290,5366,5323,532,5500,5460,5517,5470,5386,8279,8286,8323,8292,8205,8,6359,6382,6484,7034,7110,6649,6612,6741,7291,7354,5525,5537,5509,5181,5535,5570,5575,5549,5221,5608,8292,65246,280,57054,57054,15764,37288,56338,24767,57054,57054,9480,57054,38308,9781,35954,25263,57054,57054,57054,57054,12168,13935,20320,30175,57054,57054,57054,57054,30465,23778,44986,9647,57054,57054,57054,57054,48387,47423,41792,57871,57054,57054,57054,57054,64452,24830,31824,27670,57054,57054,57054,57054,41740,12751,16266,5113,57054,57054,57054,57054,50098,2404,34593,63623,57054,57054,57054,57054,63304,2170,65206,18463,57054,57054,57054,57054,54824,8886,63400,47442,57054,57054,57054,57054,38880,2266,60688,13813,57054,57054,57054,57054,48872,16499,14;'
Number of bytes read: 1352
gpib status is:
ibsta = 0x2100 < END CMPL >
iberr= 0
ibcntl = 1352
You can:
w(a)it for an event
write (c)ommand bytes to bus (system controller only)
send (d)evice clear (device only)
change remote (e)nable line (system controller only)
(g)o to standby (release ATN line, system controller only)
send (i)nterface clear (system controller only)
ta(k)e control (assert ATN line, system controller only)
get bus (l)ine status (board only)
go to local (m)ode
change end (o)f transmission configuration
(q)uit
(r)ead string
perform (s)erial poll (device only)
change (t)imeout on io operations
request ser(v)ice (board only)
(w)rite data string
send group e(x)ecute trigger (device only)
:
Thanks for helping with substitutes. I'm confused on the importance of brand (i.e Nichicon) and ripple. (Nichicon UPW vs UCA). Do these factors matter? I'm reading some mixed information.The worst offenders were the larger radial Sprague caps with the resin bung, these were often found cracked and/or peeing electrolyte. I would give a list of what I used, but most of the caps I used are now discontinued.Thanks David. Found a list by CondorAudio in the Tek group. Unfortunately some caps are not available. Any recommendations for substitutes?
(https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=2065427;image)
Also if you don't have much experience replacing parts on double sided boards, I would suggest practising on something of no value first.
And as your scope has options, take note or pictures of where all the extra connectors are fitted, before removal.
David
Part# Value Watts Mouser Part#
C1021 290 µF 200 ELCTLT 647-UPW2E331MRD
C1022 290 µF 200 ELCTLT 647-UPW2E331MRD
C1066 4.7 µF 35 ELCTLT 647-UPW1H4R7MDD
C1112 4.7 µF 35 ELCTLT 647-UPW1H4R7MDD
C1120 10 µF 100 ELCTLT 647-UPW2A100MED
C1130 10 µF 100 ELCTLT 647-UPW2A100MED
C1220 10 µF 100 ELCTLT 647-UPW2A100MED
C1240 10 µF 100 ELCTLT 647-UPW2A100MED
C1400 47 µF 25 ELCTLT 647-UHE1E470MDD
C1402 47 µF 25 ELCTLT 647-UHE1E470MDD
RT1010 7.0 ohm NTC Thermistor 995-SG210
For the 647-UPW2A100MED, I used 647-UCA2C100MPD for all of them, it's obsolete, but there are still a few thousand in stock.
For the 647-UHE1E470MDD, my choice of UPW1V470MED is no longer available, alternates I would choose from are; 667-EEU-FC1V470, 661-ELE-350ELL470MF1, or 232-35YXM47MEFR63X11, these are all 35V, but you could go with 25V as per the originals, I stocked up on the 35V version for various projects.
For the 647-UPW1H4R7MDD, there are some still available under numbers 647-UPW1H4R7MDD1TD (straight leads) and 647-UPW1H4R7MDD1TA (formed leads to 5mm pitch), all are obsolete.
The other parts I didn't replace.
David
Here's a better example of using ibtest to capture the NVRAM data. Previously I didn't notice that the reason multiple reads were needed was because ibtest does not use the default timeout from the GPIB configuration file (gpib.conf). Each read got some of the data but then timed out because the scope is so slow.
Here it is again, explicitly setting the timeout to 10 seconds in ibtest so the response is read in one shot. Also note the larger buffer of 2048 bytes specified for the "r" (read command).
Sorry for the re-do. I don't usually use ibtest.Code: [Select]$ ibtest
Do you wish to open a (d)evice or an interface (b)oard?
(you probably want to open a device): d
enter primary gpib address for device you wish to open [0-30]: 8
trying to open pad = 8 on /dev/gpib0 ...
You can:
w(a)it for an event
write (c)ommand bytes to bus (system controller only)
send (d)evice clear (device only)
change remote (e)nable line (system controller only)
(g)o to standby (release ATN line, system controller only)
send (i)nterface clear (system controller only)
ta(k)e control (assert ATN line, system controller only)
get bus (l)ine status (board only)
go to local (m)ode
change end (o)f transmission configuration
(q)uit
(r)ead string
perform (s)erial poll (device only)
change (t)imeout on io operations
request ser(v)ice (board only)
(w)rite data string
send group e(x)ecute trigger (device only)
: t
enter the desired timeout:
(0) none
(1) 10 microsec
(2) 30 microsec
(3) 100 microsec
(4) 300 microsec
(5) 1 millisec
(6) 3 millisec
(7) 10 millisec
(8) 30 millisec
(9) 100 millisec
(10) 300 millisec
(11) 1 sec
(12) 3 sec
(13) 10 sec
(14) 30 sec
(15) 100 sec
(16) 300 sec
(17) 1000 sec
13
gpib status is:
ibsta = 0x100 < CMPL >
iberr= 0
ibcntl = 0
You can:
w(a)it for an event
write (c)ommand bytes to bus (system controller only)
send (d)evice clear (device only)
change remote (e)nable line (system controller only)
(g)o to standby (release ATN line, system controller only)
send (i)nterface clear (system controller only)
ta(k)e control (assert ATN line, system controller only)
get bus (l)ine status (board only)
go to local (m)ode
change end (o)f transmission configuration
(q)uit
(r)ead string
perform (s)erial poll (device only)
change (t)imeout on io operations
request ser(v)ice (board only)
(w)rite data string
send group e(x)ecute trigger (device only)
: w
enter a string to send to your device: id?
sending string: id?
gpib status is:
ibsta = 0x2100 < END CMPL >
iberr= 0
ibcntl = 4
You can:
w(a)it for an event
write (c)ommand bytes to bus (system controller only)
send (d)evice clear (device only)
change remote (e)nable line (system controller only)
(g)o to standby (release ATN line, system controller only)
send (i)nterface clear (system controller only)
ta(k)e control (assert ATN line, system controller only)
get bus (l)ine status (board only)
go to local (m)ode
change end (o)f transmission configuration
(q)uit
(r)ead string
perform (s)erial poll (device only)
change (t)imeout on io operations
request ser(v)ice (board only)
(w)rite data string
send group e(x)ecute trigger (device only)
: r
enter maximum number of bytes to read [1024]:
trying to read 1024 bytes from device...
received string: 'ID TEK/2445A,V81.1,SYS:FV08,BB:FV02,CTT:FV05,DMM:FV01,GPIB:FV02;'
Number of bytes read: 64
gpib status is:
ibsta = 0x2100 < END CMPL >
iberr= 0
ibcntl = 64
You can:
w(a)it for an event
write (c)ommand bytes to bus (system controller only)
send (d)evice clear (device only)
change remote (e)nable line (system controller only)
(g)o to standby (release ATN line, system controller only)
send (i)nterface clear (system controller only)
ta(k)e control (assert ATN line, system controller only)
get bus (l)ine status (board only)
go to local (m)ode
change end (o)f transmission configuration
(q)uit
(r)ead string
perform (s)erial poll (device only)
change (t)imeout on io operations
request ser(v)ice (board only)
(w)rite data string
send group e(x)ecute trigger (device only)
: w
enter a string to send to your device: key 0
sending string: key 0
gpib status is:
ibsta = 0x2100 < END CMPL >
iberr= 0
ibcntl = 6
You can:
w(a)it for an event
write (c)ommand bytes to bus (system controller only)
send (d)evice clear (device only)
change remote (e)nable line (system controller only)
(g)o to standby (release ATN line, system controller only)
send (i)nterface clear (system controller only)
ta(k)e control (assert ATN line, system controller only)
get bus (l)ine status (board only)
go to local (m)ode
change end (o)f transmission configuration
(q)uit
(r)ead string
perform (s)erial poll (device only)
change (t)imeout on io operations
request ser(v)ice (board only)
(w)rite data string
send group e(x)ecute trigger (device only)
: w
enter a string to send to your device: earom? f
sending string: earom? f
gpib status is:
ibsta = 0x2100 < END CMPL >
iberr= 0
ibcntl = 9
You can:
w(a)it for an event
write (c)ommand bytes to bus (system controller only)
send (d)evice clear (device only)
change remote (e)nable line (system controller only)
(g)o to standby (release ATN line, system controller only)
send (i)nterface clear (system controller only)
ta(k)e control (assert ATN line, system controller only)
get bus (l)ine status (board only)
go to local (m)ode
change end (o)f transmission configuration
(q)uit
(r)ead string
perform (s)erial poll (device only)
change (t)imeout on io operations
request ser(v)ice (board only)
(w)rite data string
send group e(x)ecute trigger (device only)
: r
enter maximum number of bytes to read [1024]: 2048
trying to read 2048 bytes from device...
received string: 'EAR 0:215,1908,1921,1921,1927,10204,10088,1917,10118,1970,10304,506,522,8715,8712,548,8647,8671,481,8668,508,8318,32,32,8221,28,15534,16052,7414,15560,16299,8099,16299,16292,16309,566,566,8756,8756,7450,7934,7699,4096,16304,16295,8105,16280,8105,743,744,740,740,10078,10334,2140,2133,10304,10340,2120,104,2133,10319,10322,2108,10321,2102,8297,835,820,817,1646,9814,9842,1630,722,752,14501,3762,3781,1840,1878,560,569,8545,314,1377,10238,1015,8970,1261,1948,9614,1975,1586,1349,1832,9242,9710,9014,710,9000,1362,9158,1187,1029,9109,1015,8928,8387,203,8361,20735,57054,57054,57054,57054,199,252,254,4,58,57054,57054,5543,5290,5366,5323,532,5500,5460,5517,5470,5386,8279,8286,8323,8292,8205,8,6359,6382,6484,7034,7110,6649,6612,6741,7291,7354,5525,5537,5509,5181,5535,5570,5575,5549,5221,5608,8292,65246,280,57054,57054,15764,37288,56338,24767,57054,57054,9480,57054,38308,9781,35954,25263,57054,57054,57054,57054,12168,13935,20320,30175,57054,57054,57054,57054,30465,23778,44986,9647,57054,57054,57054,57054,48387,47423,41792,57871,57054,57054,57054,57054,64452,24830,31824,27670,57054,57054,57054,57054,41740,12751,16266,5113,57054,57054,57054,57054,50098,2404,34593,63623,57054,57054,57054,57054,63304,2170,65206,18463,57054,57054,57054,57054,54824,8886,63400,47442,57054,57054,57054,57054,38880,2266,60688,13813,57054,57054,57054,57054,48872,16499,14;'
Number of bytes read: 1352
gpib status is:
ibsta = 0x2100 < END CMPL >
iberr= 0
ibcntl = 1352
You can:
w(a)it for an event
write (c)ommand bytes to bus (system controller only)
send (d)evice clear (device only)
change remote (e)nable line (system controller only)
(g)o to standby (release ATN line, system controller only)
send (i)nterface clear (system controller only)
ta(k)e control (assert ATN line, system controller only)
get bus (l)ine status (board only)
go to local (m)ode
change end (o)f transmission configuration
(q)uit
(r)ead string
perform (s)erial poll (device only)
change (t)imeout on io operations
request ser(v)ice (board only)
(w)rite data string
send group e(x)ecute trigger (device only)
:
Thanks for helping with substitutes. I'm confused on the importance of brand (i.e Nichicon) and ripple. (Nichicon UPW vs UCA). Do these factors matter? I'm reading some mixed information.
Thanks for helping with substitutes. I'm confused on the importance of brand (i.e Nichicon) and ripple. (Nichicon UPW vs UCA). Do these factors matter? I'm reading some mixed information.
hi all. I was trying to understand how to measure the ripple for chart 5-1 in the service manual. Can someone please explain the difference between total p-p ripple and 2x the line frequency p-p ripple and how each is measured. I have a 20MHz analog scope I was going to use with a 1x probe grounded to the chassis set to the settings in the manual below Table 5-1. Also I'm a bit worried about the Tek scope overheating, especially U800. I've read warnings against running the scope with the cover off for extended periods, but this check requires that you let the scope warm up for 20mins plus the time needed to perform the checks.Total p-p ripple is letting the measuring scope trigger on whatever it finds and you can measure the p-p on the resulting waveform. To measure twice the line frequency, you need to synchronize the scope triggering to the incoming AC line by selecting LINE trigger. Basically you're looking for variation of two peaks spaced 120Hz apart to make sure there's no major imbalance between the positive and negative peak of the incoming AC after it's been rectified.
For a temporary battery attachment point, any ground on the card will do for the battery negative, and the battery positive should go to any point connected to the SRAM Vcc. The link you posted before from Jestine shows two possible points that would work.
I was thinking power would not be applied again until this operation was complete, since you don't want to be soldering these wires with the board un-isolated. But if you did, and the scope was powered on, you're right that the +5V would flow into the temporary battery. The lithium battery already has a diode which would keep its contribution below the 3V of the temporary battery, so that should be ok.For a temporary battery attachment point, any ground on the card will do for the battery negative, and the battery positive should go to any point connected to the SRAM Vcc. The link you posted before from Jestine shows two possible points that would work.
Don't forget to put a small 1N4148 diode in series with the temporary battery, just in case to avoid any current going into that battery while the main lithium battery is still connected, or the power of the instrument is still turned on.
Thanks Mark. I tried CH1 trigger and LINE trigger and the waveform is exactly the same. Also there are tiny spikes in the waveform, do I measure those or just the center band of the waveform?hi all. I was trying to understand how to measure the ripple for chart 5-1 in the service manual. Can someone please explain the difference between total p-p ripple and 2x the line frequency p-p ripple and how each is measured. I have a 20MHz analog scope I was going to use with a 1x probe grounded to the chassis set to the settings in the manual below Table 5-1. Also I'm a bit worried about the Tek scope overheating, especially U800. I've read warnings against running the scope with the cover off for extended periods, but this check requires that you let the scope warm up for 20mins plus the time needed to perform the checks.Total p-p ripple is letting the measuring scope trigger on whatever it finds and you can measure the p-p on the resulting waveform. To measure twice the line frequency, you need to synchronize the scope triggering to the incoming AC line by selecting LINE trigger. Basically you're looking for variation of two peaks spaced 120Hz apart to make sure there's no major imbalance between the positive and negative peak of the incoming AC after it's been rectified.
About keeper battery replacement.Thanks for your advice but if you look at the data sheet you will see that the Keeper II batteries die abruptly. Also lithium batteries can leak acid and destroy the board. Therefore I’d rather not take a chance and remove the old one and replace it with the same brand and model.
I was worrying about this 37 year old battery (dated 1987). So have bought new chinese one, manufactured 2023.
But when measured the voltage, both old and new battery measured 3,5V (within few of 1/1000 tolerance).
Who knows which battery will fail first or maybe last for the next 30 years?
This chemistry lasts 100 years in theory, but manufacture culture makes difference in practice.
So, the solution:
Attached new battery without detaching the old one. Each battery is connected via own diode and resistor, so these are isolated from each other.
No need to take the board off and de-solder, no risk of loosing calibration. Double reliability.
...On your photo of pin 2, it looks like about 30mV p-p total ripple and maybe 10mV 2x line ripple. On pin 4, about 7mV total and I can't see any 2x ripple.
Thanks Mark. I tried CH1 trigger and LINE trigger and the waveform is exactly the same. Also there are tiny spikes in the waveform, do I measure those or just the center band of the waveform?
Attached are some example waveforms and my results below:
J119 Pin Vdc p-p ripple (with spikes, without spikes)
1 -14.95 8mw, 4mv
2 4.98 35mv, 20mv
4 9.96 8mv, 4mv
5 -4.96 10mv, 7mv
6 14.92 8mw, 5mv
8 86 10mv, 8mv
9 41.7 8mv, 6mv
11 -7.99 8mv, 4mv
12 4.96 15mv, 5mv
...A clarification on this... The DMM on AC will remove the DC and show you a measurement of the remaining AC signal which would be the total ripple and noise, but it will be displaying the RMS of that AC signal (assuming a true RMS DMM), and not the p-p value that you would get off the scope screen. The p-p value would be 2.8 * DMM reading for an ideal sine, which admittedly this is not, but it would at least provide a ballpark estimate to compare with the table and tell you if something was radically wrong filter-wise.
Another approach is to use a DMM set on AC volts. This will measure the total p-p ripple up to the frequency limit of the DMM. As long as that's 20kHz or higher, it will catch any poorly performing filter caps that are need of replacement.
...On your photo of pin 2, it looks like about 30mV p-p total ripple and maybe 10mV 2x line ripple. On pin 4, about 7mV total and I can't see any 2x ripple.
Thanks Mark. I tried CH1 trigger and LINE trigger and the waveform is exactly the same. Also there are tiny spikes in the waveform, do I measure those or just the center band of the waveform?
Attached are some example waveforms and my results below:
J119 Pin Vdc p-p ripple (with spikes, without spikes)
1 -14.95 8mw, 4mv
2 4.98 35mv, 20mv
4 9.96 8mv, 4mv
5 -4.96 10mv, 7mv
6 14.92 8mw, 5mv
8 86 10mv, 8mv
9 41.7 8mv, 6mv
11 -7.99 8mv, 4mv
12 4.96 15mv, 5mv
The total p-p ripple would have components from the AC line and also the switching power supply which runs at approx. 20kHz. The tiny spikes in your pin 4 photo don't correspond to that, or 2x the line frequency. But even if you count them, you are still well under the total p-p ripple.
It's a somewhat subjective series of tests, as you are trying to visually average the trace on the screen. A digital scope could do it for you now-a-days, but I don't think that's what the authors had in mind.
Another approach is to use a DMM set on AC volts. This will measure the total p-p ripple up to the frequency limit of the DMM. As long as that's 20kHz or higher, it will catch any poorly performing filter caps that are need of replacement.
The tiny spikes might be common mode noise. You can check by probing pin 7 or 14 on J119. This is GND and if you still see the same noise, it's going to be visible in all your measurements.
Thank you all so much. I have my order ready. It's definitely more than I was hoping to spend. I checked the hours with EXER 05 and the scope has 5000. Is there a particular point when a full recap is truly necessary? Or can I get away with just changing the SRAM battery and the RIFA caps? Is checking the ripple important to make this decision? I also took a video of EXER 02 as recommended by many here. Also any help on the proper/best points to attach a temp battery to the SRAM will be greatly appreciated.
....I get a dreaded error message: CT TEST 84 FAIL 0C. I didn't even touch or disconnect any components. All I did was remove the case, probe J119, and put the case back on.
Hope this isn’t too much of a newbie request but Im having a hard time finding any good instructions online with videos or pictures on how to check p-p ripple and 2x line frequency ripple using an analog scope. I think the p-p ripple is just the measurement of the max top and min bottom of the waveform across the screen. See my zoomed in picture of pin 2 with annotations. But I can’t seem to figure out the 2x line frequency number which is a very small number for most pins in table 5-1. I also did check the ground pins 7 and 14 for noise and here is the result. Seems like minimal noise of less than 1mv.I think it's a good question.
Use line triggering to make the ripple measurement.Thanks and yes all my tests were done with the LINE trigger per the service manual.
Wow thank you so much for the explanation. I'm almost there. Would my attached picture be a proper yet subjective interpretation of your 2x frequency ripple? I added two black lines comparing the two peaks at 120hz apart. They are about <1mv apart.Hope this isn’t too much of a newbie request but Im having a hard time finding any good instructions online with videos or pictures on how to check p-p ripple and 2x line frequency ripple using an analog scope. I think the p-p ripple is just the measurement of the max top and min bottom of the waveform across the screen. See my zoomed in picture of pin 2 with annotations. But I can’t seem to figure out the 2x line frequency number which is a very small number for most pins in table 5-1. I also did check the ground pins 7 and 14 for noise and here is the result. Seems like minimal noise of less than 1mv....I've also included some shots of the same pin on an analog scope (actually the same 2465 measuring itself). It's a subjective call where to place the p-p cursors and I'm not including the extreme outliers. For the 2x line ripple, it may help to set up the cursors as shown for 120 Hz, so you know what periodicity you're looking for in the envelope.
...You're welcome! Sorry I didn't get a chance to post back sooner.
Wow thank you so much for the explanation. I'm almost there. Would my attached picture be a proper yet subjective interpretation of your 2x frequency ripple? I added two black lines comparing the two peaks at 120hz apart. They are about <1mv apart.
I got it!!! You are a great teacher Mark!You're welcome! Sorry I didn't get a chance to post back sooner.
I too have been thinking about this test and what the Tek engineers really wanted. I want to propose another interpretation. Could they have wanted us to measure the p-p ripple at 2 points 120hz apart and subtract the two voltages? See the pic attached. Point A has a p-p of 24mv. Point B (120hz later) has a p-p of 23mv. So the p-p ripple at 2x the line frequency would be 24-23=1mv.
...Again the measurement on the analog scope is very subjective, but in the photo it's in the right ballpark and maybe the upper cursor should be a little higher. If the ripple was near the limit, in this case 30mV, you would clearly see the deviation in the envelope. With some of the other rails on J119, it's just going to be impossible to see their limits of a mV or two.
It would have been nice if Tek provided more than a half a sentence or an example of what they intended.
I think the end result of that measurement would be the variation in the high frequency amplitude.I too have been thinking about this test and what the Tek engineers really wanted. I want to propose another interpretation. Could they have wanted us to measure the p-p ripple at 2 points 120hz apart and subtract the two voltages? See the pic attached. Point A has a p-p of 24mv. Point B (120hz later) has a p-p of 23mv. So the p-p ripple at 2x the line frequency would be 24-23=1mv.
...Again the measurement on the analog scope is very subjective, but in the photo it's in the right ballpark and maybe the upper cursor should be a little higher. If the ripple was near the limit, in this case 30mV, you would clearly see the deviation in the envelope. With some of the other rails on J119, it's just going to be impossible to see their limits of a mV or two.
It would have been nice if Tek provided more than a half a sentence or an example of what they intended.
...Have you checked the other vertical ranges for accuracy? Are they ok or off by the same percentage? Do the cursor readings match the graticule?
Ive come across 3 new issues with my scope that I wanted to share with everyone:
1. The voltage readings appear a bit off from my other scope and a tektronix signal generator I have. If I set the generator for a sine or square wave with 20v amplitude (the max for the generator) my other scope reads them as 20v but the 2465A reads 21.5V. Unfortunately the 2465A doesn’t have the cool measurement function that the 2465B has to double check the voltage reading. Btw any way of adding that feature to a 2465A?
2. The trace comes and goes as the unit warms up. Sometimes it disappears completely. This seems to fix itself after it warms up. Still testing to make sure. Adjusting the readout knob doesn’t help.Is it fading out and then back in, or does it suddenly disappear and reappear?
3. My focus knob is set to 3 oclock in order to be in focus. I would think a properly functioning scope would be closer to 12 oclock.I have a 2465 and a 2445A and neither of my focus knobs sit at 12:00. They're both around 2:00.
I have not heard of any way to upgrade an A to a B. The A1 board in the B has some additional hardware dedicated to the parametric measurements.
Yeah, he's still selling on ebay, and even more is that the "conversion" is not 100%, as unhappy buyers found out way after the purchase. Have a read:I have not heard of any way to upgrade an A to a B. The A1 board in the B has some additional hardware dedicated to the parametric measurements.
There's a fleabay seller that allegedly converts 2445b into 2465b. Allegedly comes complete with "do not tamper" stickers, so that if you spot his perfidy he can refuse to refund money.
The generator is a Tek CFG250. It was a switch for either (i) up to 2V or (i) up to 20v amplitudes, so I tried both and maxed the anplitude setting in hopes it would read exactly 2V and 20V. Both voltages have the same problem by the same percentage and even across different vertical ranges of the scope. If it wasn't for my other scope reading the generator as accurate at 2v and 20v, I would probably assumed it was the generator that was off. The cursor readings match the graticle. To make matters more confusing the calibration point on the scope does read accurately at .4v.
Have you checked the other vertical ranges for accuracy? Are they ok or off by the same percentage? Do the cursor readings match the graticule?
Is it fading out and then back in, or does it suddenly disappear and reappear?The trace dims in and out many times in no discernable pattern. Sometimes the dimming is light, sometimes it is accompanied by a slow flicker while dimming and then other times it continues until it's disappeared. Mostly happens during warming up but I have also noticed it after the 20min warm up cycle.
The readout knob? Does the readout fade, or did you mean the trace intensity knob? Or do you mean everything disappears?
Maybe it's heat related? Perhaps a session with a can of freeze spray (or inverted canned air) might provide some clues.
I have a 2465 and a 2445A and neither of my focus knobs sit at 12:00. They're both around 2:00.If your scopes are also in this position then I will just let it be. Thanks.
There are additional adjustments you can try, and all in combination with each other because they interact. The front panel ASTIG for one, and on the HV board there is HIGH DRIVE FOCUS, and depending on your serial number, there might be an EDGE FOCUS. This is covered in the adjustment procedure.
It takes some patience to iterate for the best focus. I've found it difficult to get everything on the screen in perfect focus and it usually ends up being a compromise.
I'd recommend marking the current pot positions with a fine Sharpie before tweaking.
I meant that when adjusting the readout intensity knob it didn't affect it. The trace intensity knob does correct it temporarily, but it then corrects itself. Meaning if the trace starts dimming and/or disappears
if I immediately set the trace intensity knob to compensate for the dimming it will brighten up, but then in a few seconds it corrects itself and become super bright. Maybe the pot for this knob needs to be cleaned?
The generator is a Tek CFG250. It was a switch for either (i) up to 2V or (i) up to 20v amplitudes, so I tried both and maxed the anplitude setting in hopes it would read exactly 2V and 20V. Both voltages have the same problem by the same percentage and even across different vertical ranges of the scope. If it wasn't for my other scope reading the generator as accurate at 2v and 20v, I would probably assumed it was the generator that was off. The cursor readings match the graticle. To make matters more confusing the calibration point on the scope does read accurately at .4v.
Have you checked the other vertical ranges for accuracy? Are they ok or off by the same percentage? Do the cursor readings match the graticule?
Mark your suggestion was genius. My DMM is only accurate at 60hz so I set the generator to that frequency and immediately noticed that with the amplitude maxed out it was over 7.07v. So I lowered it to give me that value and the waveform was spot on 20v on the scope! Im thrilled that my scope is well calibrated but Im mindblown that my generator and other scope were both uncalibrated in voltage by the exact amount.
Thanks AMR for the tip in Vdc amplitude testing. I think that’s how I checked my other scope when I got it.Sometimes it's ok to use the same scope to measure itself, but given the issues with dimming which may blank the display just when you need it, I would use a separate scope to observe #2. #3 is the DAC brightness output and would normally be a static DC voltage when the INTENSITY knob is not being moved, so you could either watch it on a DMM or on a second channel on the other scope.
Mark sorry for the delay in testing but for some strange reason the scope wasn’t dimming. Today it finally started acting up again and I tried your first test. It passed. The EXER 01 values for pot 17 never changed. Unfortunately I couldnt tell if the trace was dimming since the trace disappears once you enter diagnostics. But I tried to go into your test once I noticed the trace acting up and dimming or disappearing.
Sorry if this question is a dumb one but for test 2 do I use a second scope or the same scope to see the waveforms?
Test #3 passed with flying colors.On test #3, meaning the dimming issue occurred but no changes in the intensity DAC output? I guess you didn't get a chance to probe VZ at the same time.
test #2 created the 2 expected waveforms but the trace never dimmed so test was inconclusive. I adjusted the intensity and noticed the amplitude changing accordingly. Even opened the window right next to scope to let in some cooler air. Not sure what could be the cause yet but will try again tomorrow.
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)
Sent from my Tablet
This utility will also work for SN50K+ 2465B scopes? (with surface mount A5 board and NVRAM). I was loosely following a thread on Tekscopes2 which I think is about the same utility, and was under the impression that only B version scopes with SN under 10K (thru-hole A5 board) would be the only ones that can be recovered with this utility. Can you please clarify?
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I will look to buy an A5 SMD board when I can find one for cheap, or if anyone has a working spare to loan me in the US for a few weeks, I promise to return it unscathed.
Thank you for pointing that out. I can only say it works with thru-hole A5 boards that use a 27512 EPROM in U2160. I did not take into account the different memory model used in the SN50K+ B scopes (SMD A5). The D27011 paged EPROM (U2360) operates quite differently, and the memory control PLD U2250 is also different.