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So quick update. Tested all the secondary rectifiers, and discovered the clicking stopped when I disconnected D1934 from the circuit, so the fault must lie on that line. Opto isolator checked out fine, and was starting to work on testing each stage when my thermal camera arrived. I don't mind a...
Getting one diode as short circuit for a few seconds, then it stops. Reversing the leads gives the same result. I'll take it out of circuit and test properly. I'm guessing this is a cap charging though?
Frustratingly both test okay out of circuit. Back to the drawing board.
Thanks Nigel. Excellent advice. I'll wait for the new meter to arrive tomorrow and get going on the caps then. I can at least check some readings with the scope today.
Funnily enough, I've got 4 of these monitors, and two are bad, so I'm hoping it's the same thing for both. I've been reading up...
I have, yes. All within tolerance and reactance. My meter is not the best (always been reasonably reliable though), but got a new one arriving Monday
Dug out my oscilloscope today. What should I be checking?
Apologies, I should have mentioned earlier, that cap was fine. The crusty was that it had been replaced before and they hadn't cleaned the board. I also tested the 330uF 450V cap and it's fine. The 2200uF caps are also good.
I'll work my way through the others a well. I'm sort of ignoring the...
sagor1
At C1935 I get 2V (should be 8.6V measured on good monitor) and no output from pin 2 IC1936 as ON/OFF is low (this is controlled from signal board I believe, which is not getting power).
At C1934 I get 7.27V (should be 16V) and no output from pin 2 IC1933 or IC1934 . Again on/off pin 5...
Evening!
I'm trying to diagnose a CRT monitor that appears to have no power. Don't worry, I'm used to working on live voltage systems and all precautions are being taken.
Strap in....this could be a long ride as I learn!
Symptoms - No power light or control on front panel. No HV as HV is...
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