Author Topic: Tektronix 2465B oscilloscope teardown  (Read 459240 times)

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Offline Old-E

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Re: Tektronix 2465B oscilloscope teardown
« Reply #625 on: February 11, 2016, 07:34:26 am »
Guess I still don't have the picture part working yet.   This is frustrating!   There must be detailed instructions some place on how to add pictures to a message.

Frustrated
 

Offline miguelvp

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Re: Tektronix 2465B oscilloscope teardown
« Reply #626 on: February 11, 2016, 07:46:42 am »
Service manual:

http://bama.edebris.com/manuals/tek/2465service/

Other manuals here:
http://bama.edebris.com/manuals/tek/

Look for:
2465b
2465b-mil
2465bfull
2465dmm
2465service (linked above)

As for posting pictures, click on the choose file and make sure it's one of the allowed fie types and the image is less than 1000KB as this screenshot depicts:


Once posted click on the picture to make it bigger, right click on the image and select "Copy Image Address" (at least that's what it is in Chrome)

Then edit your message and add

Code: [Select]
[img]https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=200673;image[/img]
where the link between the begin img and end img is the link you just copied.

The example above is my image that I attached to my post and added later to my post.
« Last Edit: February 11, 2016, 07:55:54 am by miguelvp »
 

Online tautech

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Re: Tektronix 2465B oscilloscope teardown
« Reply #627 on: February 11, 2016, 08:34:23 am »
Thanks tautech for the instructions on posting photos.   But I need more information!   I have the forum compatible photos ready to go.   Then - if I understand correctly -

1.  Place the curser where the photo is to be located on the text page and left click.   This pegs the location for the photo.
2.  Click on the "Insert Image" icon (located above on the far left side).   This displays the "IMG's" where the photo is to be located.
3.  Click on "Attachments and other options" (below).   This displays the "Attach:" path.
4.  Click on "Browse."   This displays the "Choose file to up load" page.
5.  Locate intended photo on the up load page, then click on the "Open" button (lower right).   This displays the photo file info in the "Attach:" path.

If this is correct so far, I got that.   But now what?   Clicking on "Preview" displays the message text, but no indication of a photo.   It appears that something is missing.   And if I click on "(Clear Attachments)," nothing happens.   I would like to get it right before posting on the blog, but there does not seem to be a way to do that!

Frustrated.
You've nearly got it.....

You can upload numerous files/pics in posts up to the limit allowed per post.
They'll be either a thumbnail or a file available for download by members.
So use "Attachments" and (more attachments) for more than one upload.

If you want to attach a large image do it like this:
Copy the thumbnail URL.
Edit your post and Paste the image/s URL within in the IMG brackets.



Note this is a much larger file than is needed and to be fair to Dave's server you should reduce the size of images to les than 100Kb whenever possible.
Quote this post to see the syntax used.  ;)
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Offline Old-E

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Re: Tektronix 2465B oscilloscope teardown
« Reply #628 on: February 11, 2016, 08:53:28 am »
Thanks miguelvp - Yes, I have the photos in the acceptable jpg format and reduced to < the pixel count limit.

Do I understand correctly that none of the icon buttons at the top are used to post a picture as I have been trying to do?

After clicking on "Attachments and other options" the "attach:" path is displayed.   But it's blank.   There is no "Choose file" or "No file chosen" as shown in your example.   The only other option I have is to click on "Browse" (or any place on the "Attach: path)."   This brings up my pictures displayed on the "Choose File to Upload" page.   From there I can select a photo, click on the "Open" button which displays the photo address back in the Attach path.   But then how to I get that attached to the message?

Maybe another problem I'm having is trying to locate photos between text lines.   Maybe photos can only be added at the end of the message.   Is this true?   I hate to clutter up the blog with test entries.   I've looked everyplace on this site for instructions.   The process seems much more complicated than necessary.
 

Offline miguelvp

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Re: Tektronix 2465B oscilloscope teardown
« Reply #629 on: February 11, 2016, 09:51:11 am »
Attach one picture then and look what that does on the post.

As for the buttons, if you look on the 2nd row, the first column that is the icon that will allow you to get the format for inserting a picture, but you can type it too.
Code: [Select]
[img]url link to picture on the web or attachement[/img]

For now just use the attachment to post the picture. At least that way, members can click on the thumbnail and it will expand to full size.
Even if it doesn't look like my screen capture, use the browse to select the image to attach and say ok and then post.

 

Offline FireDragon

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Re: Tektronix 2465B oscilloscope teardown
« Reply #630 on: February 11, 2016, 10:02:59 am »
After investigation - the fan on my 2465BCT was NOT running!

However, the fan is ok and the control voltage is ok. It turns out that the feed through capacitor 281-0697-00 is shorted. I bypassed the capacitor and the fan works normally. So, I need to replace that. I don't have a really good definition of the part, but I think that 2425-018-X7W0-502PLF at Mouser is possibly a fit. It appears to match all of the available specifications. It has 8-32 threads which are close to the measured threads on the removed part. I can take it to Lowes to see if the existing part has 8-32 threads.

I did put the fan in so that it fit into the detents on the case. However, there is only one way to do so, so that the wires reach and the fan cover does not rest directly on the fan hub, preventing it from turning. In particular the logo of the fan faces outwards. So I had that correct and the only problem is the capacitor.

The above part is $7.84. I may replace the fan as well to reduce noise and / or improve air flow.

 

Offline Old-E

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Re: Tektronix 2465B oscilloscope teardown
« Reply #631 on: February 13, 2016, 07:47:20 pm »
Back to refurbishing my 2465B scope with the cooling issues/solutions previously reported and laid to rest.

When first receiving it, it had an intermittent problem with the signal trace lines jittery.   While looking for the problem they continued getting worse to almost full time jumping around vertically.   But it always passed the initial self test and never displayed an error message.   Photo of display below is using a short time exposure.

But before any work could be done on the scope, it needed a fixture to stand it in for removing the case.   I'm told that tech's usually use the plastic face cover to stand it up in, but that was missing from scope.   And I understand that front controls are sometimes broken from owners trying to remove the case without any protection.   So first step was to make a stand-up fixture.   Photo below shows the one I made out of wood which works very well.

 

Offline Old-E

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Re: Tektronix 2465B oscilloscope teardown
« Reply #632 on: February 13, 2016, 07:53:11 pm »
Still having picture problems.   Whenever I load one, it erases the previous one.   I've posted countless pictures on various media and blogs and never had this much trouble.

Anyway this is a photo of the jittery trace that was supposed to be with the last entry.

 

Offline Old-E

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Re: Tektronix 2465B oscilloscope teardown
« Reply #633 on: February 13, 2016, 08:34:33 pm »
Once the case was off, a neighbor friend and I started looking for the cause of the jittery trace.

Fist step was a visual of everything inside looking for anything that did not look right, but nothing caught our attention.

Power supply voltages at J119 were all perfect.

When starting to probe through the digital logic on the A5 board we found the 3 leaking caps, C2011, C2331, C2113, which we had not previously read about.   But since, have found numerous entries here and other places about this time bomb.

We also found the 2 reference voltages (~ .142 mv) on pin 14 & 15 of the DAC, U2101, were moving around a few millivolts as measured with a digital voltmeter.   The resistor divider network feeding pins 14 & 15 are near the 3 leaking caps.

The photo below shows the original 3 aluminum electrolytic caps and the corrosive damage to the adjacent components.
 

Offline Bryan

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Re: Tektronix 2465B oscilloscope teardown
« Reply #634 on: February 13, 2016, 08:44:19 pm »
Unfortunately pretty typical issue. Make sure to replace the caps and I believe there is a fourth on the far right side of the board. I would also replace the SMD components near the corrosion and absolutely make sure you clean the board thoroughly around the corrosion. Hopefully there has been no damage to the traces.
-=Bryan=-
 

Offline Old-E

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Re: Tektronix 2465B oscilloscope teardown
« Reply #635 on: February 13, 2016, 08:55:13 pm »
Regarding the jittery trace; looking more closely we found the 4th cap, C2965 on the A5 board also leaking.   The adjacent screw was also corroded.   It appears like much of the leaking material might be in a gas form, because of the way it collects on anything metallic in the area.   Photo shows the 4th aluminum cap with the adjacent damage.
 

Offline Old-E

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Re: Tektronix 2465B oscilloscope teardown
« Reply #636 on: February 13, 2016, 09:28:27 pm »
After finding the leaky caps - and numerous other entries looking just like this, the old caps were removed, board was cleaned with alcohol and new caps installed.   The old caps were measured after removal and found to have <1% of the original capacity.   The caps were replaced with 10 uf, 35 v & 33 uf, 10 v tantalums from Digikey for a few dollars each.   The corrosion had not eaten through any of the traces, so the mess was cleaned up and all the other parts were left, even though the solder had been clearly attacked too.

The result was no more trace jitter!   And the wandering reference voltages on pin 14 & 15 of U 2101 are now rock solid.   At this point the scope was working perfectly, so we started stepping through the functional tests when the readout digits started going crazy.   The individual pixels, making up each digit, were modulating in the z axis/intensity.   With time they got so bad they would temporarily disappear and they began to affect the trace line.

Photo below shows 3 of the 4 new tantalum caps (yellow) in place.   
 

Offline Bryan

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Re: Tektronix 2465B oscilloscope teardown
« Reply #637 on: February 13, 2016, 09:50:35 pm »
At this point the scope was working perfectly, so we started stepping through the functional tests when the readout digits started going crazy.   The individual pixels, making up each digit, were modulating in the z axis/intensity.   With time they got so bad they would temporarily disappear and they began to affect the trace line.

Photo below shows 3 of the 4 new tantalum caps (yellow) in place.   

That could be a adjustment may be needed on the Grid Bias. Have a look at 2465B CRT adjustments -Grid Bias in the service manual.
-=Bryan=-
 

Offline Old-E

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Re: Tektronix 2465B oscilloscope teardown
« Reply #638 on: February 14, 2016, 10:07:54 pm »
Thanks Bryan for the much appreciated suggestions.   Are you saying the grid bias pot may have become intermittent/noisy?   This scope is all a learning experience in process.

Continuing on (several weeks ago) in search for the cause of the jittery readouts, we started looking at various digital signals and voltage levels on the A5 bd.   In the mean time the condition was getting worse to where the readout digits started displaying rows of 1's and dashes across the screen and diagonally.

On the board, the first problem encountered was that some voltages were not showing up where they should be.   This led to ohming out signal lines which led to the realization that there are numerous errors on the schematic.   This is a surface mount bd with s/n > 50000 in a 2465B scope.   And the documentation in the Service Manual correctly reflects those numbers.   It appears that somewhere in the design phase, the last design iteration did not get updated on the schematic.   The thought of reverse engineering the bd by buzzing out every connection, to every other connection, seem impractically daunting.   The changes/errors found so far are in the vicinity of the gates across the lower part of the schematic, and add up to 13!   Some changes were also confirmed visually by following the traces on the bd.   In some cases where they disappeared under an IC, they could be found in close up photos taken by others of the bd after certain IC's had been removed.   

The next issues were found around resistor R 2590, listed as 1k on the "Readout" schematic.   A closer look found that the 1k resistor was really stamped as 332 ohms!   And the parts list showed it as 332 ohms.   But there was also a voltage drop across that resistor that did not compute.   Tracing signals to find what else was connected to that line, we found it fed inputs to 3 other gates which should all be high impedance and should not pull that line down to ~ 2 volts.   The digital lines running off the +5v supply should always be very near 0 or 5v, except when transitioning.   Something was abnormally loading it.   As much as I hated too, started lifting the input pins from the gates on that line.   The line remained loaded until the last one was lifted, pin 2 of U2890 A.   Soldering the pin back down again did not recreate the load, so maybe some thermally sensitive part inside fixed itself.

So U 2890 (74HCT00) was replaced.   Finally - clean and stable readouts!   But - there was sometimes a hiccup on power up when going through its self test.   It would stop midway and show something like TEST 03 PASSED.   Never indicated anything failed.   Pressing A/B TRIG returned the scope to normal operation where it worked perfectly.   Following a couple of days of occasionally fiddling with it, that problem went away and now it can not be recreated.   The scope was even set to continually loop through all the self tests - and it did that for hours without a hiccup.   Checked all the PS voltages at J 119 and they are all golden, but I did not follow them through the turn on cycle.   So something is still amiss and is highly likely to eventually return.

The Service Manual I'm using is -
Tektronix
2465B & 2467B
070-6863-01
 

Offline BravoV

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Re: Tektronix 2465B oscilloscope teardown
« Reply #639 on: February 15, 2016, 04:45:02 am »
Still having picture problems.   Whenever I load one, it erases the previous one.   I've posted countless pictures on various media and blogs and never had this much trouble.

Old-E, pay attention at the attachment dialog box, to have more than one attachment, you have to click the "(more attachments)" at below example provided by miguelvp.

Watch closely below picture as its easy to miss  :P (its hiding between the two red highlighted box) , once clicked, it will pop up another "Choose File" dialog box for you to select another attachment for uploading, just keep doing that if you have more, and up to ten attachments are allowed in single post.

« Last Edit: February 15, 2016, 05:29:20 am by BravoV »
 

Offline Bryan

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Re: Tektronix 2465B oscilloscope teardown
« Reply #640 on: February 15, 2016, 08:41:12 am »
Thanks Bryan for the much appreciated suggestions.   Are you saying the grid bias pot may have become intermittent/noisy?   This scope is all a learning experience in process.

No, what I meant is you may need to perform the Grid bias adjustment procedure. This adjustment will help the flickering of traces and readouts, although from what you describe your issue may be something much more.
-=Bryan=-
 

Offline MSO

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Re: Tektronix 2465B oscilloscope teardown
« Reply #641 on: February 15, 2016, 04:15:10 pm »
OLD-E,

Probably a typo, but maybe wrong schematic. I was unable to locate resistor R2590 anywhere in the service manual.  I did find R2830 (322ohms) on the 10MHz line feeding one of the clock inputs on U2830.  U2890 drives one of the master resets on U2830, so I though that might be the one you were looking at.
 

Offline Old-E

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Re: Tektronix 2465B oscilloscope teardown
« Reply #642 on: February 17, 2016, 04:42:38 am »
MSO

That would really be nice to find it was as simple as the wrong schematic!   But looking again (on my paper work) - it is R2890 and it is next to U2890 B which is located on the schematic at position 6L which is confirmed by the parts list on the same page, as 6L.   The schematic I'm looking at is listed as Figure 10-10 in the Manual under LIST OF ILLUSTRATIONS on page iii.   But this schematic page is actually located between Fig. 10-10 & 10-11 and has no figure number on it.

As you probably know, when the manual pages are displayed, one can press F4 on the key board to bring up a column of thumbnail pictures down the left side of the monitor screen.   You'll have to reduce the size of the schematic page some to acquire the blank space down the left side.   These thumbnail page numbers are much easier to navigate through the Manual.   In that straight sequential order, this is page 433.

This page is listed for S/N > 50000,   The schematic for S/N < 50000 does not have a resistor on the output of U2890.   Also, R2885, located on the far lower right corner of the schematic is shown as 1k, but the parts list says it is 332 ohms.   And, likewise, R2885 does not seem to exist in the earlier S/N model.

Brian -

Replacing U2890 appears to have fixed the jittery readouts.   I've heard of the Grid Bias adjustments, but am not familiar with it, but will keep that in mind if the readouts act up again.

Regarding pictures;   Oh - THAT "More Attachments!"   Who would have ever thunk it?   Hmmm - well that one passed right through me.   Next time I'll have something new to try.   thanks!   
 

Offline Bryan

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Re: Tektronix 2465B oscilloscope teardown
« Reply #643 on: February 17, 2016, 06:20:54 am »
Quote
Brian -

Replacing U2890 appears to have fixed the jittery readouts.   I've heard of the Grid Bias adjustments, but am not familiar with it, but will keep that in mind if the readouts act up again.


The Grid Bias Adjustment is one of the procedures outlined in the calibration procedure that you will no doubt be following shortly once your scope is all fixed and operating properly.
-=Bryan=-
 

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Re: Tektronix 2465B oscilloscope teardown
« Reply #644 on: February 17, 2016, 07:04:13 am »
Regarding pictures;   Oh - THAT "More Attachments!"   Who would have ever thunk it?   Hmmm - well that one passed right through me.   Next time I'll have something new to try.   thanks!
LOL
Now you're got it.  :clap:
 :phew:
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Offline Old-E

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Re: Tektronix 2465B oscilloscope teardown
« Reply #645 on: February 17, 2016, 07:30:17 am »
I'm turning the scope on every day and so far it refuses to hiccup on the initial self test and everything is working perfectly including the calibration.   You might say I should not brag about that or it will speed the arrival of a problem.   But finding that illusive bug from a couple of weeks ago is exactly what I want.   It has to appear first in order to fix it.

In the mean time, need to move on to other issues.   And the next issue on the priority list is the Dallas DS1225Y with the embedded battery.   First order of business is to determine the date of manufacture, which is printed on it as date code 9134d3.   If I read that right in the Dallas spec sheet, it was manufactured in the year 91 (1991) & in the 34th week.   If that is correct, this battery is still running after nearly 25 years!   It's guaranteed for 10 years!   So that needs to be replace ASAP.

Reading Dr. H. Holden's great report "Tektronix 2465B oscilloscope - - - ," dated June 2015, I decided to follow his lead and replace the DS1225Y with the ferroelectric FM16W08 which does not need a battery.   But there is one issue with the timing of the /CE enable line.   According to Holden, the scope is wired to assert the /CE enable at each address location, which is what the FM16W08 requires.   While the DS1225 does not need that asserted for each address location, it will obviously work when it is.   Therefore as luck would have it, the FM16W08 should be a drop in replacement, except that it's only available in surface mount.   The existing DS1225Y is a DIP version soldered through the board.

The physicals of the surface mount issue can be easily fixed by ordering -
Adapter board # 28-650000-10 from Digi-key for $18.54
28 pin socket, to plug the adapter board into, # 828-AG11D-ESL-LF from Digi-Key for $2.34
FM16W08 from Mouser, to solder to the adapter board, for $10.29

The next challenge is to find a programmer to read the DS1225Y and then write to the FM16W08.   Again, I followed Holden's lead and bought a GQ-4X Universal IC programmer along with the other items above.   But I wanted to make sure this all works before removing the DS1225Y from the scope.   The GQ-4X supports the DS1225Y, but does not support the FM16W08.   So we set the programmer up for the DS1225Y with an FM16W08 in the socket.   With the help of a neighbor friend who is more up on programmers, we were able to read & write to the FM16W08 using another set of cal data found on line that was copied out of a another 2465B.   But it will only read the first address location which means it apparently does not assert the /CE for the additional addresses which, of course, is not required for the DS1225Y.

So- don't know how Holden got it to work.   We went on line and found an older version of software for the GQ-4X thinking Holden might have used that one which may have toggled for each address, but that software would not run on my newer version of the Programmer.   I had previously stepped the scope through the Hex codes in the internal test routines out of EXER 02 and hand copied them thinking that in the worst case I could manually enter the data into the GQ-4x to program the FM16W08 (it's a long list of codes, but not impossible).   But that won't work if the programmer won't write to the IC.   We also tried some trickery to no avail.

Next step was to contact the manufacturer of the GQ-4X.   They confirmed all what we had surmised and said that if we had their latest hardware version (GQ-4X4), it has more flexibility and the FM16W08 can be easily added.   The indications are that I have the latest version, not to mention that I just bought it.   So, I'm going to contact them again tomorrow to confirm my version and see what's needed to get them to add the FM16W08 to their programmer.

In the interim, incase this will take too long, I may just replace the existing DS1225Y with another new one that I can program.   Then switch it out (I'll be adding a socket) for the FM16W08 later.

So this is where the scope is now.   It's certainly a much bigger project than I ever imagined when I bought it.   But, it is an education.   And reading all the entries on the internet about the pitfalls and should dos, has been a great help.     
 
« Last Edit: February 17, 2016, 06:26:25 pm by Old-E »
 

Offline MSO

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Re: Tektronix 2465B oscilloscope teardown
« Reply #646 on: February 17, 2016, 07:42:16 am »
That would really be nice to find it was as simple as the wrong schematic!   But looking again (on my paper work) - it is R2890 and it is next to U2890 B which is located on the schematic at position 6L which is confirmed by the parts list on the same page, as 6L.   The schematic I'm looking at is listed as Figure 10-10 in the Manual under LIST OF ILLUSTRATIONS on page iii.   But this schematic page is actually located between Fig. 10-10 & 10-11 and has no figure number on it.

As you probably know, when the manual pages are displayed, one can press F4 on the key board to bring up a column of thumbnail pictures down the left side of the monitor screen.   You'll have to reduce the size of the schematic page some to acquire the blank space down the left side.   These thumbnail page numbers are much easier to navigate through the Manual.   In that straight sequential order, this is page 433.
 

Got it OLD_E, on my schematic it's listed as <7> Readout (hi-serial) on page 10-31; sequential page 433. I usually have the schematics and part layouts magnified up around 200% so rather than scrolling up or down to find where I'm at, I'll just go up to the File->Print... menu and then select current page in the left-center of the dialog. That will show the chapter/page numbers and then in under the lower left of the preview box it lists the sequential page number.

Anyway, R2890 is marked as 1K on my schematic as well with the parts list showing it to be 332 ohms also.  I was looking to see if perhaps my schematics may have been corrected.  No luck there.

I got my TL866A programmer today so I pulled the DS1225Y off the A5 board, put a socket on the board, plugged the NVRAM into the TL866 and got a good copy of the data.  After programming a new DS1225Y, I installed it into the new socket, installed that new fan you found, buttoned up the 2467B and everything is good to go.  With the socket in place and the 21 years the original DS1225Y lasted, I decided to pass on the FM1608 family of replacements. 15 years from now, I'll just pop the NVRAM out and replace it again. Of course, I'll be over ninety by then and will probably have replaced the 2467B with the new AgilTronics 6667A 50 THz quad channel self-calibrating storage scope and spectrum analyzer.

I decided that if any of the electrolytics on the main board leak, the drippings will fall harmlessly on to the bottom of the cabinet instead of on to the PCB, so I'll wait until I have a failure before recapping the main board. Discretion is the better part of valor or some such came to mind.

Good luck with your 'scope and thanks for the info on the fan.
 

Offline Old-E

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Re: Tektronix 2465B oscilloscope teardown
« Reply #647 on: February 18, 2016, 03:04:22 am »
MSO -
Thanks for double checking the schematic.   Unfortunately, there are many errors on that schematic of the A5 bd.

Good work with the DS1225Y!   Were there any particular challenges in removing that IC?      I'm looking forward to replacing mine, hopefully soon.  Looks like the board should be an easy removal.

When you removed the Dallas IC, did you use a solder sucker, or - - ?   Also, is there a problem if the pins on the IC are momentarily shorted during removal?   If that maters, keeping the solder sucker or iron from getting between them could be challenging.

Given that I'm apparently about the same age as you, going the extra mile to get more than 15 years of future life out of the IC replacement probably makes little sense.   But it's hard to shake the habit of believing that me and the stuff I work on will last forever.   And I'm thinking that the special scope on your wish list (and now mine) may be waiting for me at my next destination.   So there's no point in spending your cash on it in 15 years, when you can't can't take it with you anyway.   At least that's what they say.

My next task after the Dallas IC is the PS Bd caps which are still working fine for now.   Then I'll take a good look at the main bd including reports from others.   leaving it may be a good choice.   Thanks.
 

Offline MSO

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Re: Tektronix 2465B oscilloscope teardown
« Reply #648 on: February 18, 2016, 05:14:08 am »
OLD_E,

I've had many runarounds with manuals from the web; pages missing, out of order, illegible and some, without taking the time to prove it, with pages mixed from different versions of the manual in question. Particularly with those oversized pages such as schematics and part locators.  So I generally double check my work.

The DS1225Y came out with no trouble; I did cheat though, I used my Hakko 808 desoldering gun.  About eight years ago, I built an Elecraft K2 with all available options, four Elecraft transceivers and just about every kit they offered. I was new to kit building then, so the Hakko 808 saved my bacon when I lost focus on the task at hand. It was a real life saver then and it handled that DS1255Y with aplomb.

I don't think you need to worry about shorting pins while removing the hybrid.  The positive terminal on the hybrid's battery is only connected to pin 7 of the embedded DS1218 and pin 7 is connected to nothing else. Short of slicing into the hybrid and shorting pin seven to ground, the power supply should remain intact.

I thought about the 'best' solution to the SRAM backup problem, but with more than 20 years of use already on the original DS1225Y (25 years on yours) I looked on the datasheet for the FM1608 and saw that it had a data retention life of 10 years at 85 C and just thought I'd have to replace it as well somewhere down the road, so better the horse I know than buying a pig in a poke.  Besides, while I doubt very much that Tektronix is going to offer an upgrade to the ROM chip that changes the behavior of the CE line, I can't know for sure that that the scope always drops the CE line for every write.  When the choice is between something I know will always work and something else that appears to work to most of time, my OCD kicks in to high gear.

As you delve into the power supply boards, beware that caps C1274, C1291 & C1292 on the A2A1 board are bipolar. I almost missed that, but when looking for the polarization orientation on the caps, I found that there weren't any.   I replaced those with the Nichicon 1uf 50V cap UVP1H010MDD1TD with good results.

Here is the list of caps I found and those that I replaced them with:

Board A2A1:
C1016   0.068uf 250v      -  0.1uf 630v 110c   KEMET F862BK104K310ALR0L
C1018   0.068uf 250v       -  0.1uf 630v 110c   KEMET F862BK104K310ALR0L
C1220   10uf   100V 105c         -  10uf  160V 105c      Nichicon UPW2C100MPD
C1240   10uf   100V 105c           -  10uf  160V 105c      Nichicon UPW2C100MPD
C1260   100uf   50V 105c   -  100uf 50V  105c      Panasonic EEU-EB1H101S
C1274   1uf   50V  85c           -  1uf   50V   85c      Nichicon  UVP1H010MDD1TD
C1280   100uf   50V 105c   -  100uf 50V  105c      Panasonic EEU-EB1H101S
C1291   1uf   50V  85c           -  1uf   50V   85c      Nichicon  UVP1H010MDD1TD
C1292   1uf   50V  85c           -  1uf   50V   85c      Nichicon  UVP1H010MDD1TD
C1300   100uf   50V 105c   -  100uf 50V  105c      Panasonic EEU-EB1H101S
C1330   100uf   50V 105c   -  100uf 50V  105c      Panasonic EEU-EB1H101S
C1350   100uf   50V 105c   -  100uf 50V  105c      Panasonic EEU-EB1H101S
C1400   47uf   25V  85c           -  47uf  35V  105c      Nichicon UPW1V470MED1TD
C1402   47uf   25V  85c           -  47uf  35V  105c      Nichicon UPW1V470MED1TD

A3:                        
C1020   2200pf  250V      - 2200pf 1.25KVDC   KEMET PHE850EA4220MA01R17
C1021   290uf  200V   85c   -
C1022   290uf  200V   85c   -
C1025   100uf  50V   105c   - 100uf 50V  105c      Panasonic EEU-EB1H101S
C1051   2200pf 250V      - 2200pf 1.25KVDC   KEMET PHE850EA4220MA01R17
C1052   10000pf 250V      - 10000pf 1.25KVDC   KEMET PHE850EB5100MB04R17
C1066   4.7uf   35V      - 4.7uf   50V           Nichicon UPS1H4R7MDD1TD
C1072   3.3uf   350V   85c          - 3.3uf   350V         Nichicon UVZ2V3R3MPD1TD
C1101   100uf  50V   105c   - 100uf 50V  105c      Panasonic EEU-EB1H101S
C1102   100uf 50V   105c   - 100uf 50V  105c      Panasonic EEU-EB1H101S
C1110   250uf 20V   105c   - 330uf 50v  105c      Panasonic EEU-EB1H331
C1111   250uf 20V   105c   - 330uf 50v  105c      Panasonic EEU-EB1H331
C1112   4.7f   35V    85c           - 4.7uf   50V           Nichicon UPS1H4R7MDD1TD
C1113   180uf   40V   105c   - 330uf  50V  Panasonic EEU-EB1H331
C1114   250uf   20V   105c   - 330uf 50v  105c      Panasonic EEU-EB1H331
C1115   10uf   160V   85c           - 10uf 16V  105c       Nichicon UPW2C100MPD
C1116   180uf   40V   105c   - 330uf  50V  Panasonic EEU-EB1H331
C1120   10uf   100V  105c   - 10uf  160V 105c      Nichicon UPW2C100MPD
C1130   10uf   100V  105c   - 10uf  160V 105c      Nichicon UPW2C100MPD
C1132   250uf   20V   105c   - 330uf 50v  105c      Panasonic EEU-EB1H331

Good luck with your adventures.
 

Offline Old-E

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Re: Tektronix 2465B oscilloscope teardown
« Reply #649 on: February 19, 2016, 07:41:17 am »
Good news DSO!   I'm apparently a day behind you and it all works!!!

As written before, I was wanting to replace the DS1225Y on the A5 bd before it's nearly 25 year old embedded battery expired, loosing the cal data.   To do that I had bought a GQ-4X4 programmer on line for $99 from MCUmall.   It's software included the DS1225Y, but not the FM16W08 that I wanted to replace the DS with.   Tried making it work by calling the FM a DS, but there was one difference in the way it enabled the address line and so it would not read data off the FM.

Two days ago , the 16th, I contacted support at the GQ manufacture and they modified their existing program to include the FM IC, and e-mailed it to me last night!!!   I was unable to get to it before noon today, but the deal was, I was supposed to do the testing since they didn't have that FM IC in hand.

With the help of a programmer, neighbor, friend, we tested as much as we could with cal data copied off the internet from someone else's scope - and it worked!!!   So we removed A5 bd, then desoldered the DS IC from the bd using a recently purchased Aoyue, INT 474++ desoldering system.   This was my first real use with a vacuum solder remover.   It worked great on all but about a half dozen of the 28 pins, which took more coxing with some solder wick.   But eventually the DS was free with no damage to anything.   In the GQ programmer, it was able to read the data on the DS IC, and successfully write it back into the FM IC.

Back at the scope, a 28 pin socket was soldered in place where the original DS IC had been.   Then the surface mount FM16W08, which was soldered to a 28 pin dip adapter board, was plugged into the socket.   Results were; today, the 18th, the scope turned on with its function and calibration as if nothing had been done to it - it all worked perfectly.   More later.
     
« Last Edit: February 19, 2016, 07:43:45 am by Old-E »
 


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