Tektronix 2465B oscilloscope teardown

[m1kta]

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

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

Dom

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

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

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

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

Dom

[KJDS]

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.   

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

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

I just prefer living in an analog world. There's no more logical reason to it than my choice of cars.

[SL4P]

Gotta say - even though it's a long time ago - these photos remind me why the 2465 series are still my favourite old school scope.  No question. Before I used a 2465, it was easy to lug around a 465B - and it was lighter!

[chksum3]

Progress report on repairing my 2465B with A5 board leak-damage from 2 of the 4 notorious electrolyic caps.  The 4 offending caps were removed with both a fine-tipped solder station and using a soldering tweezers.  Also, 3 of the small 0.1uf caps in the vicinity of the leaking electrolytics were also removed.  The electrolytics were replaced with tantalum types and the 0.1s with ceramics. 

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

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

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

Parts list for the repair:

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

[GreyWoolfe]

Congratulations on the repair job.  Enjoy the scope!

[m1kta]

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

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

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

72
Dom
M1KTA

[BravoV]

@Gary, congratulations !  Looks really neat after the re-cap  , I can see the traces are not too corroded. Great, at least you don't need to worry about loosing the calibration and since yours also made in 90s, hopefully it will last many years to come.

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

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




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



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



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

Btw, your A5 board doesn't use the bbsram and not infected by those leaky smd electrolytic caps.

[chksum3]

Many thanks!  After a little breather, I'll open the cabinet again and begin work on the LV and HV sections. Although all is well, I gather it is best to be proactive and swap out all those older electrolytics before disaster strikes.  I'll be sure to look for those highly problematic caps in the HV area first - just in case they were still being used.  Best to all.   

[m1kta]

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.




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



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

No problem.

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

72

Dom
M1KTA

[m1kta]

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

BTW everyone do not assume just because the serial number (front panel to the right under the 2nd channel input) is >50000 these capacitors are not used.... my serial is B050949, visually check them, mine had a HV black cover over the area so you have to take that off first.

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

Dom

[MarkL]

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

Dom

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

I have a 2465 with these options, but not bought as a CTS.  Before you go through the trouble of getting GPIB connectivity, be aware that the GPIB functionality is very limited (read the option 10 manual).  You can set and query things as you would from the front panel, but you can't do automatic measurements (e.g., Volts pk-pk) since the 2465 can't do them natively.  The only exception to this is that you have full control over the counter/timer unit so you can do those measurements remotely.

[m1kta]

Tnx 72 Dom M1KTA

[fpliuzzi]

Here's the link to the "24X5A/2467 Options Service Manual". It contains service info for the following options.

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

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

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

Regards

[MarkL]

Here's the link to the "24X5A/2467 Options Service Manual". It contains service info for the following options.
[...]

These are for the "A" version.  From the old catalog info I have, the CTS version is based on the plain 2465 (no A or B).

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

I have a printed copy of the "2445/2465 Option 06 and Option 09 Counter/Timer/Trigger and Word Recognizer Service Manual", pub #070-4632-00, so I can say the service manual is not the same.

[fpliuzzi]

Thanks for the clarification.

[guido]

I just need to find two small replacement knobs for the intensity and focus controls.

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

I'm currently fighting the edge focus circuit. Found a 10nF cap that measured 25 ohms. Low enough to kill the pot when turned to 42V. Put in a new pot and swapped the cap. Now the opamp is not behaving.... Work in progress 

[mwilson]

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?

[chksum3]

Please wait for others to comment on this, as my experience is very limited.  I had success with first removing the offending components, then repeatedly cleaning with 99% isopropyl alcohol and Q-tips.  I next removed every trace of old solder I could on the pads with gentle use of solder wick, and then again alcohol re-cleaned everything in sight until, under magnification, all gunk was gone and no residue was seen on the just used Q-tip.

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

If it's not too difficult, please consider uploading a close-up photo of the board damage for all to see.
 
Have fun, and congratulations on your new 2467B!
 

[guido]

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

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

Thanks.

[BravoV]

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

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

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

Please, share some close up photos like before and after re-work, especially the affected area as it will be a good reference for others in the future.

[mwilson]

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

BTW everyone do not assume just because the serial number (front panel to the right under the 2nd channel input) is >50000 these capacitors are not used....

Confirmed. My scope is from late 1991, serial number B051767, and it has those transparent caps, not the red ones. Looks like getting that board out to replace the high voltage caps is more of an ordeal than getting the A5 board out for the other repairs. The transparent caps haven't burst yet but I should probably take care of those now before it does eventually happen. I'll grab pics for everyone as I go....

[BravoV]

I've read it somewhere that film cap with transparent case especially the old one, is plagued by that outer transparent plastic material it self, that it will dry out and crack once its aged enough.

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

While the one like the opaque red case doesn't have this problem since it uses much better plastic material.

[iloveelectronics]

I just joined the Tek 2465B club and got this unit from China last week. It seems to be functioning alright but BravoV told me to take a few inside pictures as mine looks like a Japanese made unit with a Sony/Tektronix badge on the back and a serial number that starts with "J3". I took it apart quickly and snapped a few pictures with my phone today, just before I had to leave the shop. I see some worrying images

Yes, I turned it on, before taking it apart:


There's a small blip near the second horizontal division with no signal (only on a couple of timebases):


Back side of the scope. You can see "Sony/Tektronix Corp. TOKYO, JAPAN":


Main board on the bottom. Apart from being a bit dusty, all seems to look good:


On the side:


On the top, the CRT. Now this really doesn't look right That thing looks like a big piece of charcoal! Can anybody tell me what that thing is and what could have been going on here?


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


Right side of the A5 board:


Left side of the A5 board. Again, I didn't read this thread so didn't know about the leaky caps area. I only reviewed the photo after I've taken it and I was shocked to see the corrosion and the completely missing electrolytic caps!!


Here's an enlarged view:


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

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

[linux-works]

missing caps!  wow ;(

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

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

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

647-PCF1C330MCL1GS
647-PCX1V100MCL1GS

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

check me on those part numbers, but I think those are correct.

[grumpydoc]

That thing looks like a big piece of charcoal! Can anybody tell me what that thing is and what could have been going on here?

It's the coupling for the final anode connector - so that you don't have to disconnect the cup if changing a CRT.

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

Probably worth cleaning all that soot off with some IPA (take care, the anode potential is 14kV so not one to do with the 'scope powered up and if you pull it apart bear in mind that a CRT anode connector can bite even with the power off).