Tektronix TDS 744A teardown and repair 2

I continue working on the 1990s Tektronix TDS744A digital 4-channel 500 MHz oscilloscope. My plan was to fix the colors, but I ended up taking a closer look at the switching power supply board, testing and replacing a lot of high ESR electrolytic capacitors, fixing a board damage from electrolyte leakage and relubricating the fan. I did some experiments with the sequential color system. The color shutter has no voltage going into it. There's definitely a problem in its driver, but the shutter itself might be deteriorated too. For now, I decided to remove the color shutter. This gives me a bright monochrome picture. The oscilloscope is perfectly usable this way. I might try to put the shutter back in and fix its driver, but I'm not sure I want to spend my time on it, risking an accidental damage, as this oscilloscope is perfectly usable as it is now. This old Tektronix oscilloscope uses a CRT-LCD hybrid display technology - a monochrome CRT tube with a solid state sequential color filter (liquid crystal color shutter / LCCS / LCS / NuColor).

The 1st episode:

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[amydamon]

I always learn a lot from your videos. Thank you for making them "bloody long". Two nice things about your videos are that you don't repeat yourself half a dozen times and don't teach us the same basic things in every video. That saves your videos from being "excessively, redundantly bloody long". Kudos for that. Keep up the good work!

[Fluxkompressor]

Watching you solder with that sledgehammer of a soldering gun expecting total incineration I must say: Best solder job I have seen with the tools given
Imagine what you could accomplish with a proper soldering station!

[LawpickingLocksmith]

Still a good score. 500MHz is not cheap even technology changed a bit. I am still fixing my 100MHz Hitachi analog.

[SINHRO-FAZA]

Даа, 500МГц, да ещё и 2GS/s на каждый из 4х каналов осциллографа. Представляю каких денег он стоил в своё время, хотя и щас, даже такой старинный дедушка, будет не дёшев. Хорошо что смогли отремонтировать.. 👍🏼

[tigerelectronics]

Bloody long videos are the best! What a sweet scope! I learned a few things here, these more in depth videos are awesome. I didn’t know the timers contained internal batteries, definitely something I gotta check out on my own equipment!

[pcfred]

It is amazing that scope was working with that big skid mark burn in the board it had.

[jeroenjeroen]

I like the more extensive videos; if people don't want to watch it, let them be. I'm sure more people like to watch videos in depth!

[a.lisnenko]

The oscilloscope is interesting.
Please continue!

[eskisful]

I want to see you replacing those timers with rotting batteries inside.

[AllLoudNation]

"Changing these crapacitors..." lol

[daniloxyz]

Don't run the thing for too long without a case on, or the airflow from the fan won't reach the ceramic hybrids, they will overheat, expand, contract, and the solder joints of the relays will crack. Ask me how I know... Btw, try to run the Signal Path Calibration. If it succeeds, it will compensate and calibrate all channels (e.g., weird offsets, tiny differences in amplitude, etc.) and confirm the scope signal path is 100% working. If SPC fails, there may be some lingering problem in the hybrids (or somewhere else on the bottom board) and a reflow of the solder joints goes a long way. Also, there are scripts that you can put on a floppy to hack it with all options, but it seems you already have most of them. Nice donation though, particularly because the most expensive part is the 4 probes...

[Sloxx]

This era of Tek scopes from the 90s are notorious for having bad caps everywhere, I've rebuilt a TDS 420A and a TDS 540 and it was the same issue and some were leaking. I ended up just replacing all capacitors throughout the scope, probably around a hundred of them. Not a difficult repair, but time consuming and expensive.

These scopes are not bad for what you get, if you can get used to the clunky, lagging menu/interface design.

[German_byte]

Thanks. Btw I love your Soviet era soldering gun.
Nice.

[madscientist]

Nice vid. Maybe you could try to solder some thin wires to the connector of the color filter and route them to the outside of the case. This way, you can reassemble the oscilloscope and still have access to the signals.

Also @ 3:42, fully agree with you, I feel the same way.

[pulsar]

Maybe a cheap LCD display running from the VGA output would look OK.

[tj]

Post apocalyptic. I love it, keep up the good work Danny ! And your cat has wise comments.

[SuperHaptics]

I am the guy who is screaming about your soviet era nuclear plant soldering iron😂 . I like your videos mr wild diode, also your crazy soldering iron. Say hi to your lovely cat....

[williampowell]

Nice scope. You might consider a piece of leaded glass in front of the CRT. I suspect it was part of the LCD color overlay. There are a couple of guys selling replacements on ebay for the battery backed RAM. Additionally, there is another guy selling an LCD conversion to delete the CRT.

I have a tds520 myself, and after seeing this, I am actually happy to not have the colorized display.

[tajtrlik]

Ďakujem za ďalší diel z tejto zaujímavej série, kľudne v nej môžeš pokračovať a rád sa pozriem aj na ďalšie diely, ak ich natočíš. Ale pekne si ten osciloskop dal dohromady, teraz ti môže pekne slúžiť a štvorkanálový digitálny osciloskop, to je aj dnes dosť drahá záležitosť a takto si aspoň získal pekný kúsok do dielne.

[CJWarlock]

@9:32 - "crapacitors" (a new word for crappy capacitors) - Ha! Ingenious! :D Congrats on the funny wordplay. :)