Author Topic: Tektronix 2465B oscilloscope teardown  (Read 459468 times)

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Offline Kartman

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Re: Tektronix 2465B oscilloscope teardown
« Reply #400 on: March 06, 2015, 07:09:24 am »
Thanks for the responses. Stupid me didn't realise tektronix have the part numbers in the service manuals!
 

Offline mskobier

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Re: Tektronix 2465B oscilloscope teardown
« Reply #401 on: March 08, 2015, 09:10:27 pm »
Well, I went and did it now!  While waiting on components to arrive for the 2445B I found in the salvage yard a few weekends ago, I attended the Puyallup, WA hamfest/electronics swap yesterday. While I was there, I stumbled upon a guy that had two non working 2465's. One is a plain 2465, and the other is a 2456CTS. I was able to acquire them both for a very small sum of money. I purchased them mostly for parts, but I may end up repairing at least one of them. I plugged them in and ran a few tests. the first one has no trace, not even with the beam find button pressed. The second one does not have a trace either, but it does display a trace when I press the beam find. Various panel lights light up on both machines. The previous owner had removed the cases and lost the screws, but all the major parts are there. I figure I can find some 4-40 screws to put them back together again. Looks like a power supply recap on at least one of them, and we will see where the other leads me. Not that I need two more scopes, but I just could not pass them up.

The information I have found and things I have learned will be very useful for getting them back on line. So a big hearty thanks to everyone.

Mitch

 

Offline mskobier

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Re: Tektronix 2465B oscilloscope teardown
« Reply #402 on: March 12, 2015, 03:05:51 am »
All,
  The repairs on my 2445B is progressing. The parts to repair the broken plastic nobs on the front arrived today. Got that all squared away, now just waiting on some electronic parts to make sure the A5 board doesn't take a dump on me while sorting out the channel 1 trace issue. Stillwaiting on the caps and a few other components to arrive.

I should have read more posts before ordering the replacement NVRAM chips. I had already ordered a couple of DS1225AD-200's and Ramtron FM1608 chips from a couple of sellers on -bay. Yes they were located in China before I read the post earlier in this thread about China sourced chips being counterfeit and not working, After I read the post, I ordered a DS1225AD-20o from Mouser. The china chips and the one from Mouser have arrived and been tested. I have access to two different programmers, a Sivava Willen and a TL866. None of the chips from china will program. The chip from Mouser works just fine with no problems at all. The DS1225 chips from china are dated 1317. So they should have been relatively fresh stock. Apparently not. The FM1608's would not program either. I have a couple of them coming from Mouser now too. In an effort not to kill my original programming, I have ordered the same programmer that sparkybg used. I had not planned on ordering the programmer, but a friend of mine has a 2465B that still has the original chip in it too. When I swap mine over, we are going to do his too. Hopefully the better programmer will work without any problems.

If anyone needs any front panel parts, knobs, shafts, indicators, etc, drop me a line. I'll see what I can do.

Later
Mitch
 

Offline monz

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Re: Tektronix 2465B oscilloscope teardown
« Reply #403 on: March 13, 2015, 12:36:32 am »
This pdf contains info on power supply rebuild and gives specific replacement part numbers for the input filter caps. Mine were cracked like this too. He used Vishay type KP339, digikey has them in stock part number BC2586-ND

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

Offline mskobier

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Re: Tektronix 2465B oscilloscope teardown
« Reply #404 on: March 13, 2015, 12:51:57 am »
Monz,
    Thanks for the reply. I had already found that article. It definitely is a good tutorial on repairing the power supply.


All, Im going to move my posting over to the Repair section under a different thread so I am not hijacking this one.

Thanks
Mitch
 

Online BravoV

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Re: Tektronix 2465B oscilloscope teardown
« Reply #405 on: March 13, 2015, 01:13:35 am »
All, Im going to move my posting over to the Repair section under a different thread so I am not hijacking this one.

Mitch, I was going to ask you to share all the repair photos here, and I don't have any problem at all if you post them all here rather to have these 24xxB related infos scatter around.

Offline mskobier

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Re: Tektronix 2465B oscilloscope teardown
« Reply #406 on: March 14, 2015, 04:25:30 pm »
With BravoV's gracious request, I will post the pictures in this thread. Unlike BravoV's teardown, mine should be fairly simple. However, there were a few mechanical repairs I had to make before I attack the electronic ones. Here are some pictures showing the main panel damage after I cleaned it up. Then the teardown showing the sub assembly damage, and finally how it looks now.

The case had a number of dents too. I was able to mostly straighten them out, but the two 2465's I picked up last weekend provided me a very nice case.

I replaced the entire potentiometer sub assembly. It was easier to just replace it than to unsolder and remove the potentiometers from the ribbon strip it was attached to. Less risk of damaging the ribbon

The last picture shows the three extension shafts. The one on the right is broken and should be about 1in (25mm) longer. The parts board I picked up provided the replacement shaft and missing knobs.

I also attached some pictures of the A5 board. Looks like either I have a little bit of leakage, or the ceramic capacitor next to the caps has already been replace and I'm seeing flux residue. Either way, I'll remove the cap, clean around it and replace. This will also be the time when I remove the Dallas chip, and hopefully be able to copy the calibration data file. I've also been having some fun finding the replacement tantalum caps to replace the electrolytic. The caps on my A5 board show 10uf 35v and 33uf at 35v. The manual specs them out as 15uf 25v and 45uf 25v. I'll probably go with what the latest manual calls for, 15uf and 45uf. However, finding the 45uf in a C size form factor has been interesting. Kemet doesn't seem to make one. Will have to try a different manufacturer.

Enjoy
Mitch

« Last Edit: March 14, 2015, 05:01:33 pm by mskobier »
 

Offline SeanB

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Re: Tektronix 2465B oscilloscope teardown
« Reply #407 on: March 14, 2015, 04:49:49 pm »
47uF is as close as you can get to 45uF, and will work. Nice job on the repair, I wish I could find one locally that is not either close to new price or just a stop short of the crusher.
 

Offline mskobier

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Re: Tektronix 2465B oscilloscope teardown
« Reply #408 on: March 14, 2015, 04:59:14 pm »
SeanB,
      Actually, it is a 47, the 45 was a typo. I can find them in D size all day, but C size to fit the board is more difficult. I literally found this scope in the crush pile at the local metal salvage yard. Along with a HP 45601A that works great and two frequency counters, a Fluke 7220A and a BK Precision 1856C. Both of the frequency counters work too, they just need a good calibration.

Also, here is a picture of the potentiometer board ribbon connector. I chose not to unsolder the broken pot, and just replace the entire sub assembly.

Mitch
« Last Edit: March 14, 2015, 05:19:55 pm by mskobier »
 

Offline mskobier

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Re: Tektronix 2465B oscilloscope teardown
« Reply #409 on: March 14, 2015, 10:45:56 pm »
SUCCESS!!!!
Today, I was able to remove the Dallas chip from my A5 board and read the calibration data to a file! Then I promptly wrote it to the new Dallas chip and everything worked fine. What a relief! The original chip in my 2445B has a date code of 9026. That is a 25 year old battery That was still working. Anyway, as soon as the caps and IC socket arrive, I'll put it all back together and start the channel 1 diagnostics. I was hesitant to spend a lot of time of fixing that issue until I was sure I would not loos the calibration info in the Dallas since I lack the necessary equipment to perform a recalibration.

On a side note, I was able to read the chip with both the MiniPro TL866 and the EasyPro 90B. One strange thing about using the 90B. I was doing some experiments when I first got it and the new Dallas chip. I would program one of the bin files I have downloaded, and it would say everything was programmed correctly. When I would run a verification of the data on the chip, it would have two errors. Always in location 000000 and 000040. So I read my original chip in both programmers, and the data came out exactly the same. I could program the chip with the TL866, and it would program perfectly. I could read the chip in the 90B, and it would be correct. Strange to say the least. Anyway, I have a couple of copies of the data on two different computers and burned to a CD, as well as programmed on the new Dallas chip. I will be programming it to one of the FM1608 chips for safe keeping too. I know it is probably overkill for a scope that is 25 years old, but I don't want to take any chances. Of course, if I had lost the cal data, I would have been forced to pick up even more test gear. Hummm.......

Mitch

Here is the calibration file from my 2445B if anyone wants it.
 

Offline malch

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Re: Tektronix 2465B oscilloscope teardown
« Reply #410 on: March 14, 2015, 11:06:28 pm »
When I removed the Dallas chip I read and stored it.
Then I cut out the little battery and wired in a large battery. I read and stored that too.
I then compared the info between the first and second read with Beyond Compare.
In handling the chip so much to gain access to the battery some info was lost- about 10 lines.
After everything was done I burnt it to the first reading and it was successful.
 

Offline cutemonster

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Re: Tektronix 2465B oscilloscope teardown
« Reply #411 on: March 15, 2015, 09:10:03 am »
I'm trying to replace Channel 1 BNC because it's loose and not usable.  Can you provide guide on how to replace it?
I have a 2465A.  Is the part easy to buy online?

thanks!
 

Offline mskobier

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Re: Tektronix 2465B oscilloscope teardown
« Reply #412 on: March 15, 2015, 01:16:05 pm »
cutemonster,
      I'm fairly new to tek scope repair myself. Been learning a lot. I think the BNC is part of the attenuator module. I also think you have to remove the module to get to the BNC. I have a module on order, it should be here in a few days. When it gets here, Ill take a look to see what it takes. I do not know if you have to remove the A1 board to get the module out. Maybe BravoV can weigh in and give you better guidance.

Mitch
 

Offline malch

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Re: Tektronix 2465B oscilloscope teardown
« Reply #413 on: March 15, 2015, 03:02:15 pm »
cutemonster try https://www.eevblog.com/forum/repair/tektronix-2445-repair/

Two thirds of the way down this thread is a 2445A teardown showing the BNC connectors.
A 2445A should be close to a 2465A
 

Offline cutemonster

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Re: Tektronix 2465B oscilloscope teardown
« Reply #414 on: March 15, 2015, 05:56:17 pm »
thanks mskobier and malch.
I will try to open up and check.
 

Offline mskobier

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Re: Tektronix 2465B oscilloscope teardown
« Reply #415 on: March 19, 2015, 01:41:45 am »
Time for another update.

I have been working with the different versions of the replacement NVRAM chips as discussed in this thread. Here is what I have learned. When programming the DS1225AD chip with the EasyPro90B (same one sparkybg used) I had a similar issue with not writing the 000000 location and the 0000040 location. Don't have an explanation as to why, just that the error was consistent and repeatable. I ended up using The MiniPro TL866 to program it. No issues using that programmer and the DS1225AD

When programming the Ramtron FM1608, I had no problems with the 90B. The TL866 does not have that chip in it device list, and I was unable to program it.

When programming the FM16W08 (SOIC) on the adapter board, I got the same error as described by sparkybg in his post from Jan 12 2015. I kept getting the error at location 000000. All the other locations programmed fine. When I would run the verify routine, everything except 00000 took the programming correctly. I finally selected the 18L08 from the device list, I could get it to program, but when I ran the verify routine, it showed that I had errors in all locations starting at 00002000, all the way to 000017FF. Then it dawned on me that those memory addresses were outside the addresses that the FM16W08 chip has. I told the programmer to only program from 000000 to 00001FF, and ran the programming routine again. Everything worked fine then and the error at location 00000 was corrected. I tried a couple of different bin files. Everything was correct, and repeatable.

Many thanks to sparkybg for his many contributions to this thread.

Here is a picture of the ram chips I have programmed so far. Remember, when I get mine finished a friend has a 2465A that need to have the NVRAM replaced before it looses its calibration. We'll probably start on that in a couple of weeks. I also have the two 2465's. They take a different set of chips, but what I am learning will hopefully help me repair those.

I'm still waiting for the Tantalum smd capacitors to arrive so I can replace the electrolytics. Hopefully they will be here in a couple of days.

Here's the chip picture.

Mitch

 

Offline flynwill

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Re: Tektronix 2465B oscilloscope teardown
« Reply #416 on: March 20, 2015, 04:05:01 pm »
Thanks for the responses. Stupid me didn't realise tektronix have the part numbers in the service manuals!
Did you manage to find a suitable replacement for your power switch?  The switch in my 2465B is failing as well (arcing, sticking and sometimes giving of that fine odor of burning phenolic).  There are still manufactures making that form-factor of switch, but I haven't had a chance to tear the unit down, and do the necessary measurement to find a replacement.
 

Offline mskobier

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Re: Tektronix 2465B oscilloscope teardown
« Reply #417 on: March 20, 2015, 05:42:20 pm »
Got another question that maybe someone else has encountered. In the process of removing the leaky A5 board capacitors, I discovered that the component values on my board are significantly different than what the latest version of the service manual states they should be. On my board, I have in the C2011 position, a 33uf @10v. The manual shows a 15uf @25v. In the C2113 and C2331 position, I have 10uf @35v and the manual calls for 47uf @25v. So, has someone replaced the caps with improper values, or is there a later rev to the service manual that has different values? The manuals I have are from 1989. My scope was manufactured sometime in 1990. I recall seeing some where a picture of a board with the same values I have. So I guess the question is, which values should I use? I am strongly leaning towards using the same values that are currently installed.

I removed all of the suspect items from my board today, cleaned it up and found one pad/trace had failed. It is location R2016. I was able to install a replacement resistor using the one good pad to anchor then solder bridge to the existing trace. Other than that, everything looks great, and is ready for parts as soon as the capacitor question is resolved. I'll post before and after pictures later.
 

Offline mtdoc

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Re: Tektronix 2465B oscilloscope teardown
« Reply #418 on: March 20, 2015, 05:59:38 pm »
 I have seen mentions on the Yahoo Classic Tek scopes group of errors in the service manual re caps.  I don't recall exactly which ones but I'm sure if you pose the question to that group you'll get a quick response. It is a very active group.
 

Offline mskobier

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Re: Tektronix 2465B oscilloscope teardown
« Reply #419 on: March 20, 2015, 06:43:31 pm »
Thanks for the reply. I am a member over on the Yahoo Tek group. I should have posted my question over there too.

Mitch
 

Offline malch

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Re: Tektronix 2465B oscilloscope teardown
« Reply #420 on: March 20, 2015, 07:12:19 pm »
I changed the caps with the free 2465B service manual like so many others.
 I haven't run that scope very much, so It's not much of a test.
There must be lots of recapped scopes out there.
Have you measured the voltage across C2011?
 

Offline mskobier

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Re: Tektronix 2465B oscilloscope teardown
« Reply #421 on: March 20, 2015, 08:40:59 pm »
malch,
    No, I have not measured the voltage. Currently the board is on the bench. I planned on using at least the same voltage rating as is already there. It was the capacitance rating I was concerned about.

 

Offline mskobier

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Re: Tektronix 2465B oscilloscope teardown
« Reply #422 on: March 22, 2015, 06:12:17 pm »
Well, I've been a bit busy this morning. The caps I have been waiting for finally arrived yesterday afternoon. This morning I installed the replacement tantalums as well as a few .1uf ceramics. Everything went well. Here are a couple of pictures showing the replaced components. I did take before pictures of the bare pads, but they did not turn out well, so they don't get posted.

I also reinstalled the A5 board, and tested all four of the replacement chips. The first one was the replacement Dallas 1225AD , the second was a DIP FM1608 and the last two were FM16W08 on SOIC to DIP adapter boards. All four chips work just fine. The scope went through its startup routine and seemed to operate normally. So at this point, I am declaring the A5 board electrolytic replacement as well as the NVRAM replacement/upgrade to be a success.

I also pulled the power supply cover and saw that I have the problematic HV capacitors. Looks like I have a power supply cap replacement coming in the near future. I had hoped that mine was late enough that it had different caps. I visually inspected the HV caps, and they do not look bad at all. No indication from what I could see of near term failure. 

I also manually ran all of the self diagnostics. Its interesting in that the scope passed all test when I run the auto routine. I noticed that it cycles through each input channel. On all but channel 1, I get a bunch of little dots on the screen while the test of that particular channel is running. However, there are no dots on the screen when channel 1 routine runs. The display says it passed though.

Anyway, here are the pictures.

Mitch
 

Offline SoundTech-LG

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Re: Tektronix 2465B oscilloscope teardown
« Reply #423 on: March 23, 2015, 09:11:01 pm »
Nice JOB!!!  :-+

Mine is not nearly as neat, and professional looking.
 

Offline Howardlong

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Re: Tektronix 2465B oscilloscope teardown
« Reply #424 on: March 23, 2015, 09:59:59 pm »
My 2467B is starting to show a few "signs", the CTT frequency counter for example is unreliable sometimes.

It serial number <50000, being lazy I am wondering if someone has an electrolytic cap BOM they'd care to share that they've used for one of these, or indeed a 2465B for serial <50000?

Many thanks!
 


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