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Inspired by the CRT safety related aspect of this recent repair question: Why might my CRT fry any HOT I put in it?

Shouldn't this be more a question for electronics.stackexchange.com? – chthon

After safely discharging all residual voltage from the tube, you should start with a thorough visual inspection of the electronics. What you describe would often result in visible damage surrounding the damaged component. A "smell test" is also helpful, as a lingering odor is also a common result of the damaged component. – Brian H

@chthon Yes it might be more of a question to electronics.se, but "Questions on the repair of consumer electronics, appliances, or other devices must involve specific troubleshooting steps and demonstrate a good understanding of the underlying design of the device being repaired.", so based on that, asking what's wrong with the circuit after it still blows up after randomly swapping components might not be on topic on ee.se. Having said that, having a service manual with schematics and some proper measuring equipment will help - maybe just the transistor snubber circuitry is defect here. – Justme


Repair questions seem to be a borderline use case; if the question is well-researched it can be useful and answerable, but it's not enough to just want to fix the thing. Good repair technique and solid technical background are important. But it's hard to deliver that in a Q&A post format, and it's also (sometimes) hard to determine whether the person asking has the right tools and training to be able to attempt the repair.

CRT (Cathode Ray Tube) displays have a lot of additional hazards, which aren't obvious to the uninitiated:

  • the CRT tube itself is under a great deal of vacuum pressure, and could implode if mishandled
  • the electronics that drives the CRT uses high voltages
  • high voltages may be present on the capacitors for a surprisingly long time after power is disconnected
  • mistakes can cause injury, harm, possibly death

The electronics.stackexchange.com site has some possibly relevant information:

Both electronics.stackexchange.com and retrocomputing have about 70+ questions tagged crt (or ), so it may be on-topic for both sites. At this point in time I think new CRT related questions are more likely to appear on retrocomputing than anywhere else, since most modern equipment has phased out CRT in favor of LCD or other comparable display technologies.

Should there be a "canonical" CRT Repair Safety question on retrocomputing.se?

  • would be a good place to summarize the various safety tips
  • restoring an old CRT in 2021 is different than repairing a TV set in 1970
  • capacitors may have leaked
  • dirt and grime can provide a pathway for unwanted HV corona discharge
  • replacement parts may be no longer available

Related meta:

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In theory, this is a great idea. In reality, discoverability on SE is low. For example, I participated along with the top DIY SE user in creating:

https://diy.stackexchange.com/questions/168564/first-time-changing-switches-and-outlets-receptacles-anything-special-i-shoul

but it turns out to be almost impossible to find when you actually want to refer to it. I worry that if we create a canonical "CRT repair" question that it will be nearly impossible to find unless you bookmark it in your browser.

This is an SE problem - not specific to Retrocomputing. And SE hasn't been great lately at coming up with user-driven enhancements.

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