Panasonic TH-42PY80 plasma dead (no standby LED and no 15v)
Good day folks. I fixed this plasma once before, but now the guy came back with it for a different issue: it wouldn't turn on AT ALL. While it had the 10-blink error code the first time which was due to a faulty ceramic cap on MC301, now it doesn't do anything....not even a standby light. The schematic PDF is too large to upload, so feel free to get it here if you want to lend a hand.
D551 gives me the 5v standby alright. I took out the power supply and jump-started it by bridging pins 8 and 10 on P12 (page 33) and then also pins 5 and 6 on P7 (bottom of the same page). This simulates the power button at the front being pressed and the TV being turned on. The relays do close and stay closed, I get 400v on the main input caps, 5v on the appropriate pins of P25, but NOT 15v. This opens up two issues:
1. Why, despite getting 5v stand-by and the supply being "willing" to turn on, I get no standby LED with the 10 blink SOS code ? Could be a dead A-board (logic control board) ? If so, it would make pushing on with the repairs fruitless because even if I fix the supply, it's highly unlikely I'll be able to fix the A-board
2. Why doesn't the 15v rail come on as well ? The thing is C352 DOES have 15v on it, so the SMPS operates, but those 15v don't make it to the connector. Having a look on page 33 shows 15v goes through Q351 which is in turn controlled by MC352, which is further controlled by MC701, so one of these components is faulty.
Any thoughts ? Cheers and thanks.
D551 gives me the 5v standby alright. I took out the power supply and jump-started it by bridging pins 8 and 10 on P12 (page 33) and then also pins 5 and 6 on P7 (bottom of the same page). This simulates the power button at the front being pressed and the TV being turned on. The relays do close and stay closed, I get 400v on the main input caps, 5v on the appropriate pins of P25, but NOT 15v. This opens up two issues:
1. Why, despite getting 5v stand-by and the supply being "willing" to turn on, I get no standby LED with the 10 blink SOS code ? Could be a dead A-board (logic control board) ? If so, it would make pushing on with the repairs fruitless because even if I fix the supply, it's highly unlikely I'll be able to fix the A-board
2. Why doesn't the 15v rail come on as well ? The thing is C352 DOES have 15v on it, so the SMPS operates, but those 15v don't make it to the connector. Having a look on page 33 shows 15v goes through Q351 which is in turn controlled by MC352, which is further controlled by MC701, so one of these components is faulty.
Any thoughts ? Cheers and thanks.
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