Panasonic Viera TH-P42UT30A plasma unresponsive with continuously on green LED

[dscarlett]

Hi everyone,
I've got a Panasonic Viera TH-P42UT30A plasma that has suddenly become unresponsive. When powered on, the display stays blank, and the status LED just remains a constantly on green. (The status is supposed to start red, then turn green when the TV is woken from standby mode, and flash when commands from the remote are received.) It doesn't respond to remote control commands (and I've checked that the remote is sending an IR signal), and doesn't respond to any of the buttons on the TV either. Just a continuously on green LED and no picture. No red LED error codes.

I'm happy to pull it apart, test for bad caps, unexpected shorts, etc, but does anyone have any advice as to where I should start looking?

Thanks!

[tw2005]

Re: Panasonic Viera TH-P42UT30A plasma unresponsive with continuously on green LED

given what series this is I'm thinking shorted SN board is a possibility. When you turn this tv on and the front led is green, have a look on the Sn board and see if there is a tiny smd led lit which will be green. It's bright enough to spot it.

If it is not themn I'd be checking across sn2 connector and see if you have 200-215v dc. If not then shut it down and at the SN2 pins, check resistance and see if shorted.

Alternative would be turn off, disconnect sn2 then power on, if it goes to start then shutsdown giving a red error blink then that also would suggest shorted SN.

I believe the Sn will be TNPA5349 VER AB.It maybe an easy repair of replacing shorted transistors. i know I've been lucky with a U30 ans St30 both just needed these replaced but sometimes some other related parts ,ike diodes or the FET driver Ics need replacing.

could try a search on ebay for the board number and see what repair kits have in them or try and find a good board if it is in fact the sn. Also, the screws they use to mount these are wrong and work loose causing bad earth which may contribute to failure, may see some evidence or arcing between the chassis and the pad on the board.

[tw2005]

Re: Panasonic Viera TH-P42UT30A plasma unresponsive with continuously on green LED

Just had a quick look for you. The kits I see do appear to have the same parts as the U30 I did.
From what i see 4 x 30F131 IGBTs, the 4 gate resistors for those but mine were fine and 2 super fast rectifier diodes which also I found were ok on mine.

So if it is the SN shorted,, locate the 30F131 x 4 check if shorted. then remove these and then check the 2 diodes to see if they're ok, then inspect the 4 resistors for any sign of burning, if ok measure their resistance.

The diodes are possibly RFN10 and RF1501.

For the 30F131 I subbed with FGD4536 which is a smaller package but possible to fit on the same pads. Did this and that TV has been running well for about 7 months now.

Only other issue I see is since this is a Sn board with the buffer boards integrated if the buffer ICs have shorted then you'll have to track down a board.