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 .
great news U800 replacment
https://youtu.be/nfc_z2FNeb8The 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 .
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.
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!!
+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.
+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.
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,
Hi. One a modest idea. placement of tvs diode in power supply. Extra Surge protection is possible?
Thank you in advance?
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.
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.
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.
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.
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.
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.
Ever since the ice storm in Texas a few weeks ago Mouser has been struggling with order fulfillment. Not sure about Digi-Key.
Well bummer, I replaced the caps and collateral damage on the A5 board and now instead of powering up normally, it hangs with the add light on partway through self test. Did a quick check of the voltages at J119 on the main board, and buzzed out continuity of the repairs, but nothing obvious comes up. Voltages around the DAC resistor repair area look reasonable.
I’m assuming the repair is either incomplete or cleaning it caused another problem. Off to the archives to study what this particular hang means.
So one of the precision 10K resistors has magically gone open after I cleaned this. I unsoldered the resistor and measured it out of circuit to confirm. Bits of it seem to be flaking off as well. So I guess the electrolyte plague made it farther than I thought.
I have no 0.1% resistors with a low tempco, so I’ll have to throw some on the next Digi-Key order and regroup.
Indeed, replacing that resistor with an ordinary 10K 1206 brought the scope back to life. Obviously this isn’t the correct repair long term, but it allowed me to run the EXER 02 routine to dump my calibration data. Looks like the NVRAM is dated 1990, so next step is to unsolder and see if I can extract that data.
This forum has done such an awesome job in helping me better understand my 2445B oscilloscope that I wanted to post here that with the help of the many comments and the 2465B bill of materials I was able to recap the A3 and A2A1 boards and eventually fixed a faulty diode that was causing the constantly resetting at power-up (aka 'tick mode') issue.
For those interested I have documented my repairs in this video:
Hopefully this scope will last another 30 years!