Author Topic: Tektronix 2465B oscilloscope teardown  (Read 395824 times)

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Online BravoV

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Re: Tektronix 2465B oscilloscope teardown
« Reply #25 on: December 21, 2011, 07:33:49 am »
Scott, thanks for that links and bookmarked, definitely a precious resources if my old scope hoarding nerves get excited again.  ;D

Offline slburris

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Re: Tektronix 2465B oscilloscope teardown
« Reply #26 on: December 21, 2011, 04:54:21 pm »
Oh, I forgot this other site for firmware (and manuals):

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

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

Scott
 

Online BravoV

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Re: Tektronix 2465B oscilloscope teardown
« Reply #27 on: December 24, 2011, 06:57:47 pm »
Oh, I forgot this other site for firmware (and manuals):

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

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

Scott

Yeah, I have that bookmarked already, good site it is,  thanks, personally I'm very grateful for these old resources maintained by these people all this time.

Offline m1gry

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Re: Tektronix 2465B oscilloscope teardown
« Reply #28 on: January 27, 2012, 12:31:42 am »
I've just bought a 2465A from Ebay  ;D. I've had my eye on this model scope for a while as I'm interested in the high bandwidth. It came with 2 off P6139A 500MHz Tek scope probes. I've never used this particular scope before, so I was interested to test it out. Everything appears to work OK, diagnostics pass, and it shows 4000+hrs and 800+ on/off cycles. Serial is B0106XX. I have no idea how old it is.

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

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

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

--Gary
 

Online BravoV

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Re: Tektronix 2465B oscilloscope teardown
« Reply #29 on: January 27, 2012, 06:29:21 am »
Gary, 1st of all, welcome to the forum ! ;)

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

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

Looking at your problems, I guess its time for another 24xx teardown thread of yours ? Especially on cleaning and fixing the mechanical switch, it should be interesting to observe.  :D
« Last Edit: January 27, 2012, 08:40:40 am by BravoV »
 

Offline butmach

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Re: Tektronix 2465B oscilloscope teardown
« Reply #30 on: March 31, 2013, 06:54:32 pm »
Hello everyone, this is my first post to EEVBLOG  :-BROKE

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

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

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

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

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

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

Pawel
 

Offline hepcat

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




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

Regards,


Jason
 

Offline grenert

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Re: Tektronix 2465B oscilloscope teardown
« Reply #32 on: March 31, 2013, 09:37:17 pm »
QService in Greece sells these NVRAM chips pre-loaded with standard calibration data:
http://www.qservice.tv/vpasp/shopexd.asp?id=1252&bc=no

Perhaps they can sell/give you the data for your scope.
 

Online BravoV

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Re: Tektronix 2465B oscilloscope teardown
« Reply #33 on: April 02, 2013, 01:33:59 am »
@Pawel (butmach),

Welcome to the forum on your 1st post.

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

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

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

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


@Jason (hepcat)

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

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

Offline hepcat

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Re: Tektronix 2465B oscilloscope teardown
« Reply #34 on: April 02, 2013, 02:02:08 am »
<snip>
@Jason (hepcat)

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

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



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

Regards,


Jason
 

Online BravoV

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Re: Tektronix 2465B oscilloscope teardown
« Reply #35 on: April 02, 2013, 11:10:34 am »
Jason, interesting mod, as my thought and described at my earlier posts when I saw the nuts and bolts, its simply a design flaw, thanks a lot for sharing that photo.  :-+

Online BravoV

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Re: Tektronix 2465B oscilloscope teardown
« Reply #36 on: April 05, 2013, 09:54:24 am »
Sad news, a failed to attempt to find the better replacement for the pesky Dallas DS1225Y BBSRAM, cause the F-RAM Ramtron FM1608-120 is not compatible. It was an impulse purchase thru a friend visiting abroad without checking the detail 1st, and also I was mis-leaded by info gathered from the Tektronix's Yahoo mailing list.  |O

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

What a waste, another addition into the components bin labeled "It will be useful .. someday".  :palm:

Offline butmach

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Re: Tektronix 2465B oscilloscope teardown
« Reply #37 on: April 05, 2013, 07:22:45 pm »
In my 2467B all functionality is restored  :-DMM, as before the disaster, thanx very much, my old humble scope is reincarnated.
Next NVRAM loss will never happen again ... now I have a backup :)
I have also tested NVRAM dump from a 2445B, (provided by an attentive and helpful ham radio operator), it is also working perfect.
I have tested the calibration to 50MHz, the error of measurement is from 1 ... 3% on readouts (dT, d1/T, dV), im very lucky.
Now I'm waiting for a TG501 to test the scope in full range and if it will be necessary I will perform a calibration.

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

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

Regards,
Pawel
« Last Edit: April 05, 2013, 07:34:20 pm by butmach »
 

Online BravoV

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Re: Tektronix 2465B oscilloscope teardown
« Reply #38 on: April 06, 2013, 09:07:36 am »
Pawel, congratulation on reviving back your 2467B  :-+, so you did use 2465B SRAM image or others ?

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

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

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

Cause the best heat dissipation path is through the metal body part straight under the chip's die. Shot of U800's bottom view, pardon the texts, made this pic while ago to someone else on precautions when handling this damn chip.  >:(
« Last Edit: April 06, 2013, 09:35:40 am by BravoV »
 

Offline butmach

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Re: Tektronix 2465B oscilloscope teardown
« Reply #39 on: April 06, 2013, 08:52:14 pm »
I'm using the 2445B image, because the measuring errors are satisfactory for me without calibration. Your images also operate normally, but the calibration data does not  match to my hardware - error of measurement is 15...20% in my scope.

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

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

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

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

Regards,
Pawel
« Last Edit: April 06, 2013, 09:15:28 pm by butmach »
 
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Online BravoV

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Re: Tektronix 2465B oscilloscope teardown
« Reply #40 on: April 07, 2013, 01:42:50 pm »
I'm using the 2445B image, because the measuring errors are satisfactory for me without calibration. Your images also operate normally, but the calibration data does not  match to my hardware - error of measurement is 15...20% in my scope.

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


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

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

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

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


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

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

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

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

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

Btw, thanks for the U800 heat sinking photos.  :-+

Offline grumpydoc

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Re: Tektronix 2465B oscilloscope teardown
« Reply #41 on: April 07, 2013, 01:52:43 pm »
Quote
Looks like all analog Tek 24xxB scope's SRAM image are compatible each other, never expected that, great finding.

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

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

Needless to say the mailing list's opinion of the seller was rather low!
 

Online BravoV

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Re: Tektronix 2465B oscilloscope teardown
« Reply #42 on: July 25, 2013, 06:29:58 am »
Got few PMs lately asking how I copied this scope's cal data from the battery backed up SRAM Dallas DS1225Y, all read from old chip & write to fresh chip was using the cheap MiniPro TL866 Universal Programmer as reviewed by Dave.

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

Edit : Quote from above link on supported Dallas chips :

[ DALLAS ]     19 PCS

DS1220 (RW)                DS1220 (TEST)            DS1225 (RW)            DS1225 (TEST)               
DS1230AB (RW)            DS1230AB (TEST)        DS1230W (RW)           DS1230W (TEST)             
DS1230Y (RW)              DS1230Y (TEST)          DS1245AB                   DS1245W                     
DS1245Y                      DS1249AB                    DS1249W                    DS1249Y                     
DS1250AB                    DS1250W                     DS1250Y       
« Last Edit: July 25, 2013, 06:37:02 am by BravoV »
 

Offline Stonent

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Re: Tektronix 2465B oscilloscope teardown
« Reply #43 on: July 25, 2013, 06:55:51 am »
I'd be reasonably sure that 1996 fan was a replacement.  They wouldn't be using Dallas chips with a 1989 date code in a 1996 scope.  A lot of old Sun workstations use similar Dallas chips to hold the MAC address and configuration data and it is fairly common for those to have died with an FF:FF:FF:FF:FF:FF MAC address.
The larger the government, the smaller the citizen.
 

Online BravoV

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Re: Tektronix 2465B oscilloscope teardown
« Reply #44 on: July 25, 2013, 10:34:27 am »
I'd be reasonably sure that 1996 fan was a replacement.  They wouldn't be using Dallas chips with a 1989 date code in a 1996 scope.  A lot of old Sun workstations use similar Dallas chips to hold the MAC address and configuration data and it is fairly common for those to have died with an FF:FF:FF:FF:FF:FF MAC address.

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

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

Picture of that DS1225Y replacement with the cal data already copied into it DS1225AD, purchased from Digikey few months ago.

Offline PM33AUD

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Re: Tektronix 2465B oscilloscope teardown
« Reply #45 on: December 15, 2013, 05:06:05 am »
Hello!

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

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

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

Thanks!
Phil
 

Offline linux-works

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Re: Tektronix 2465B oscilloscope teardown
« Reply #46 on: March 05, 2014, 01:49:04 am »
80x80x20, on mouser:

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

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

(clue: I was looking on ebay for a fan for the 2400(a/b) series and someone had this very fan pictured as an 'exact replacement'.  I searched on that model # and lo and behold, mouser had it!  if mouser carries it, its probably not a cheap POS fan).
 

Offline linux-works

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Re: Tektronix 2465B oscilloscope teardown
« Reply #47 on: March 06, 2014, 07:28:08 am »
got my mouser order today.  I can confirm that that fan is an exact size replacement.  I have not turn it on or compared it to the old one, but size wise, its 100% exact.

fyi
 

Online BravoV

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Re: Tektronix 2465B oscilloscope teardown
« Reply #48 on: March 06, 2014, 07:35:25 am »
Even though chances of getting it wrong is quite low just for the simple DC fan replacement, suggesting to measure the working voltage & current of the old fan before installing the new one, and then re-measure again at the new one once installed, just an extra precaution on this little piece of good scope.

Great  :-+ , looking forward to see the process of your 2465B getting "the rejuvenation".   8)
« Last Edit: March 06, 2014, 07:59:37 am by BravoV »
 

Offline linux-works

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Re: Tektronix 2465B oscilloscope teardown
« Reply #49 on: March 06, 2014, 07:42:40 am »
good point about the voltage.  I just assumed 12v.  fortunately, I guessed right and both fans are marked as 12v.

fitting it to the scope was fine.

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

the new fan is rated a slightly higher current draw but not by much.  the old fan has more blades, but I'm not going to worry about that.  I'm sure that its not going to be that critical.  certainly better than the dusty old one that was in there.
 


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