Author Topic: Tektronix 2465B oscilloscope teardown  (Read 475222 times)

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Offline Kartika

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1700 on: December 07, 2020, 05:26:53 pm »
U800 ic for tektronics 2465b 2467b

Ramkumar Ramaswamy . 14 hours ago Update - Finally got the initial batch of assembled boards this week . Everything has slowed down thanks to that willy virus . I will begin testing and tuning each of them this week , and then list them on eBay .
 
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Offline Kartika

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1701 on: December 15, 2020, 07:43:13 pm »
 :-+  great news U800 replacment

https://youtu.be/nfc_z2FNeb8
The RU800 - A Drop - In Replacement for the Tektronix U800 Hybrid Ramkumar Ramaswamy . 7 views - 14 Dec 2020 This video shows the working of the RU800 - a drop - in replacement for the Tektronix 155-0241 - XX , also called the U800 in Tek schematics , used in the 2400 series oscilloscopes . These chips suffered from field failures , and now being unobtanium , command premium prices on online auction sites . As of Dec 14 , 2020 , an initial batch of ten RU800s has been assembled and is undergoing testing . They will shortly be listed for sale on eBay .


 
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Offline AMR Labs

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1702 on: December 15, 2020, 08:15:45 pm »
A worthy cause it seems, and please don't think I am trying to discourage anyone.

But I wonder, when was it the last time anyone here needed to actually replace the U800 chip in their scopes that died of "natural" causes?
Just wondering if there is really still a big demand for these, or a substitute replacement. Not too long ago I remember to sometimes see a listing for an original working Tek chip on ebay, at around BIN $125-150, but no takers for weeks or months. I was once close to buying one just as a future rainy day spare, but given the high price and apparent reliability of these chips, never did. If it has been in place for 30+ years and is still working fine, seems unlikely it might suddenly fail out of the blue. Unless of course the scope suffers a fan failure or airflow intake block. Or people insisting on messing around with the chip and damaging it by trying to attach an unneeded heatsink on them. But otherwise these chips appear to me to be pretty stable.

But if anyone has indeed a damaged U800 story, I would certainly like to hear about it.
 
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Offline Kartika

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1703 on: December 18, 2020, 10:15:41 pm »
Temperature stability and oscillation is most important for prevention future thermal stress that can causes separation...


https://groups.io/g/TekScopes/topic/28139676?p=Created,,,20,2,0,0::recentpostdate%2Fsticky,,,20,2,940,28139676
https://www.eevblog.com/forum/repair/tektronix-2467b-display-issues/
 

Offline 0culus

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1704 on: December 20, 2020, 06:31:10 am »
FWIW, all the damaged hybrid IC stories I have heard about in these scopes stem from disrupted airflow under the case. The vent holes in the bottom are there for a reason. DO NOT block them!!
 
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Offline BravoV

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1705 on: December 20, 2020, 07:03:01 am »
+1, and at that video, without the cover, the owner should use a fan blowing the board, as the hybrid ICs are heating up that way as no air flow at all.

Ok, maybe its fine for 1 or 2 minutes for the purpose of shooting that video, but say when trouble shooting this scope with that position for hours without cover, the poor hybrids will be overheated.

Offline tautech

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1706 on: December 20, 2020, 07:18:47 am »
+1, and at that video, without the cover, the owner should use a fan blowing the board, as the hybrid ICs are heating up that way as no air flow at all.

Ok, maybe its fine for 1 or 2 minutes for the purpose of shooting that video, but say when trouble shooting this scope with that position for hours without cover, the poor hybrids will be overheated.
Maybe he didn't read post #6 from a wise old tech that has worked on these for decades.

Yes it's a poor show and not at all setting a good example to others that might watch that vid.  ::)
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Offline mawyatt

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1707 on: December 20, 2020, 06:23:02 pm »
I've repaired two of these Tek 2465 scopes in the past year or so. Good advise to keep an airflow over the hybrids with the scope cover removed, there's considerable difference in the effective thermal impedance of these hybrid heatsinks without any airflow.

Wonderful instruments from back in the heyday of Tektronix and HP :)

Best,
Research is like a treasure hunt, you don't know where to look or what you'll find!
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Offline Kartika

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1708 on: December 23, 2020, 11:05:57 am »
Hi. One a modest idea.  placement of tvs diode in power supply. Extra Surge protection is possible?
Thank you in advance?
 

Offline med6753

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1709 on: December 23, 2020, 12:00:34 pm »
Hi. One a modest idea.  placement of tvs diode in power supply. Extra Surge protection is possible?
Thank you in advance?

Not necessary. The PSU in the 2465 is not prone to surge issues.
An old gray beard with an attitude.
 

Offline Miti

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1710 on: December 27, 2020, 06:42:39 am »
I just downloaded the latest SW for TL866II Plus from Autoelectric and I was pleasantly surprised to see that now it has support for the FM16W08 FRAM, that can be used to replace the battery backed RAM. I hope this is not old news.
That big spark at power up was by design!
 
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Offline troth530

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1711 on: February 09, 2021, 05:24:10 am »
I just scored a 2465 (no suffix) with a service manual at a local charity. 
And it's functional except an issue with "beam find" button is flaky but I see it has the original caps. 
I found parts list of replacement caps for the power supply posted by med6753.
Are there any other caps that need to be replaced such as on other boards?
I don't see a battery for the RAM... is that a newer thing (only needed for 2465a and b) and no battery replacement needed for the 2465.

I also got a fully operational 2245a that clearly needs a battery (and recap).  Is there a similar thread to this one for the 2245a?

Appreciate any help.
 

Offline philwong5176

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1712 on: February 09, 2021, 05:35:46 am »
 
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Offline troth530

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1713 on: February 09, 2021, 05:56:49 am »
"Is there a similar thread to this one for the 2245a?" ---->

https://www.rc-cam.com/forum/index.php?/topic/4165-tektronix-2245a-oscilloscope-smps-repair-re-cap/
Thanks.  I'm aware of that thread... assumed it was not the preferred way to go as he seemed to be making adjustments for some different type of caps.  Also, I can print ABS.  Haven't done exploratory surgery on the 2245a, but does that power supply not have any paper RIFA capacitors?
 

Offline philwong5176

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1714 on: February 09, 2021, 06:29:56 am »
Look here:A

https://bradthx.blogspot.com/2015/05/tektronix-2246-repair.html

The 2246 has the same SMPS as the 2245A.
 
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Offline med6753

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1715 on: February 09, 2021, 08:12:59 am »
I just scored a 2465 (no suffix) with a service manual at a local charity. 
And it's functional except an issue with "beam find" button is flaky but I see it has the original caps. 
I found parts list of replacement caps for the power supply posted by med6753.
Are there any other caps that need to be replaced such as on other boards?
I don't see a battery for the RAM... is that a newer thing (only needed for 2465a and b) and no battery replacement needed for the 2465.

I also got a fully operational 2245a that clearly needs a battery (and recap).  Is there a similar thread to this one for the 2245a?

Appreciate any help.

There are a few small electrolytics scattered throughout the instrument but for the most part they can be left alone.

The 2465 uses non-volatile EAROM to store calibration data and does not require a battery backup.
An old gray beard with an attitude.
 
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Offline slburris

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1716 on: Yesterday at 04:23:38 pm »
Now my own “B” adventure begins.  I also have two 2465’s and I’ve recapped one of them.  I’ve just come into possession of a 2465BDM with intact Tektronix stickers sealing the case.  Oh dear this case hasn’t been opened in a very long time.

First up, the A5 board.  The capacitors leaked of course.  I’ve removed the damaged components and started to clean the mess.  Some of the pads were either eaten away or flaked off as I swabbed them, so this is going to take some work to repair.  And the precision 10K resistor got clobbered as well.  I may measure my stock of 1206 resistors and see if I can find one in tolerance, otherwise I’ll have to order a replacement. 

I didn’t anticipate how hard it was to get the corroded solder to heat up.  I had to do a combo of precleaning and adding new solder to desolder some of the components. 

Then I’ll have to tackle the NVRAM issue and figure out how to get to the power supply.  It doesn’t look as simple as the 2465.
 

Offline med6753

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1717 on: Yesterday at 04:32:23 pm »
I'm assuming that a 2465BDM has the DMM option and probably the Counter/Trigger option, correct? If yes the teardown to get to the PSU will be essentially the same as an older 2465DMS. Procedure here:

https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg1861713/#msg1861713
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Offline slburris

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1718 on: Yesterday at 04:43:02 pm »
Yeah it’s like the CT with the DMM option included.  I have capacitors on order, but I had to split the order between Mouser and Digi-Key, and both seem to be struggling a bit with fulfillment.
 

Offline med6753

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1719 on: Yesterday at 06:40:37 pm »
Ever since the ice storm in Texas a few weeks ago Mouser has been struggling with order fulfillment. Not sure about Digi-Key.
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