2011 Panasonic Viera TC-P50X3 50" plasma dead - Videokarma.org TV - Video

pac.attack76 · #1 10-08-2025, 06:21 PM

No power at all. Removed back and metered both fuses and beeps on both. Do these have to be removed to test or is there something else I need to be looking at? No bulging caps.

pac.attack76 · #2 10-12-2025, 07:42 AM

I did also notice when plugging into outlet, there's a relay click but no lights or power.

kf4rca · #3 10-12-2025, 10:28 AM

Check the Mosfets in the PS for short.

pac.attack76 · #4 10-12-2025, 10:34 AM

Quote:

Originally Posted by kf4rca

Check the Mosfets in the PS for short.

Ok, thanks!

pac.attack76 · #5 11-03-2025, 08:38 AM

Quote:

Originally Posted by kf4rca

Check the Mosfets in the PS for short.

Only time I've ever had dealing with mosfets was in an xbox 360. Im a bit confused as I tested what I thought were mosfets but the only one that beeped on the multimeter was actually a shottky barrier diode. What should I be looking for on here? I think I'm missing something 😕

Alex KL-1 · #6 11-04-2025, 07:01 AM

Quote:

Originally Posted by pac.attack76

Only time I've ever had dealing with mosfets was in an xbox 360. Im a bit confused as I tested what I thought were mosfets but the only one that beeped on the multimeter was actually a shottky barrier diode. What should I be looking for on here? I think I'm missing something 😕

Probably it will have a permanent resistive load in the PSU (but only older PSU's have it), then the solution for testing is desoldering. Or, is a special MOSFET with a Schottky diode in antiparallel, normally used for syncronous rectifying.

pac.attack76 · #7 11-04-2025, 07:47 AM

Quote:

Originally Posted by Alex KL-1

Probably it will have a permanent resistive load in the PSU (but only older PSU's have it), then the solution for testing is desoldering. Or, is a special MOSFET with a Schottky diode in antiparallel, normally used for syncronous rectifying.

So I should take it off the heat sink and remove from board before testing? It's a YG862C15.

Alex KL-1 · #8 11-05-2025, 06:16 AM

Quote:

Originally Posted by pac.attack76

So I should take it off the heat sink and remove from board before testing? It's a YG862C15.

According with the data, is simply a Schottky diode. But in doubt, desolder some terminal, or remove them. To be sure if is not a subsequent circuit having trouble (like a post buck regulator going do-do).

pac.attack76 · #9 11-05-2025, 06:21 AM

Ok, hopefully today, I can get around to it.

pac.attack76 · #10 11-05-2025, 08:19 AM

Quote:

Originally Posted by Alex KL-1

According with the data, is simply a Schottky diode. But in doubt, desolder some terminal, or remove them. To be sure if is not a subsequent circuit having trouble (like a post buck regulator going do-do).

Would you be able to mark all of the ones I should remove as I'm not sure which ones to check?
https://flic.kr/p/2rDEQSL

Alex KL-1 · #11 11-05-2025, 11:57 AM

Quote:

Originally Posted by pac.attack76

Would you be able to mark all of the ones I should remove as I'm not sure which ones to check?
https://flic.kr/p/2rDEQSL

Outrageously busy now but... you can measure all, note that Schottky will have a typical low value of measurement (in the diode scale of a DMM), like 80-160 (after some seconds for charging the caps), you can need to remove only the ones that measure far from it (eg. if one measures 30, or short - near zero). Ordinary P-N diodes will measure 450-700.

pac.attack76 · #12 11-05-2025, 08:28 PM

Quote:

Originally Posted by Alex KL-1

Outrageously busy now but... you can measure all, note that Schottky will have a typical low value of measurement (in the diode scale of a DMM), like 80-160 (after some seconds for charging the caps), you can need to remove only the ones that measure far from it (eg. if one measures 30, or short - near zero). Ordinary P-N diodes will measure 450-700.

Ok, I'll check in the morning.

pac.attack76 · #13 11-06-2025, 08:34 AM

Quote:

Originally Posted by Alex KL-1

Outrageously busy now but... you can measure all, note that Schottky will have a typical low value of measurement (in the diode scale of a DMM), like 80-160 (after some seconds for charging the caps), you can need to remove only the ones that measure far from it (eg. if one measures 30, or short - near zero). Ordinary P-N diodes will measure 450-700.

Ok, i tested all the "similar in appearance" components mounted to 3 different heat sinks and got the following readings from each:
204 - YG862C15
689 - K3607
2.793 - YG971S8
847 - 06N903
1.180 - K8A50D
961 - K8A50D
1.676 - K20A60U
2.746 - Y0972S6

Not sure if I did this right but I had my meter set to diode testing. Triangle pointing to a line.

Alex KL-1 · #14 11-07-2025, 05:53 AM

At least none indicates shorting. In relay clicks, my fear is taht some another board have trouble. This is way outside my field since I changed the job just when LCD and plasma started to proliferate.

pac.attack76 · #15 11-07-2025, 08:51 AM

Quote:

Originally Posted by Alex KL-1

At least none indicates shorting. In relay clicks, my fear is taht some another board have trouble. This is way outside my field since I changed the job just when LCD and plasma started to proliferate.

Yeah, alot of changes since crt design. Most techs never moved on.