Panasonic Plasma TH-P42V20A – 13 Blinks

[Dave-2]

Hi Guys,

I'm trying to diagnose a Panasonic 42” plasma TH-P42V20A which is displaying 13 red blinks.

It started to fail some months ago. Initially it would power on fine and after maybe 1-2 hours of watching it would appear to power down (accompanied by sound of the power board relays clicking), and after 1 or 2 seconds then power on again. Over time, and perhaps in different temperature conditions, the random switching off events began occurring sooner after powering on, became more frequent, and the periods of power down became longer. Now it is difficult to get the unit to display a picture at all. When powering on it clicks and displays the usual fast blinking green LED as its starting up, and then the LED is solid green but there's no picture. After a few mins it displays 13 red blinks. I have the service manual for my exact model but its ‘Power LED Blinking Timing Chart' only lists up to 12 blinks. I've read the thread at https://www.badcaps.net/forum/showthread.php?t=22926 which suggests a comms error at IC8001 but my TV has a different model main (A) board and does not have an IC8001. My A board is Part Number: TXN/A1LAUA42, PCB Number: TNPH0845 BA (2)(A). The No Picture fault diagnosis chart in the service manual also suggests that if the OSD is NG yet the LED on both the SC board and SS board are on (which they are in my case) then it's the A board that's faulty.

I've tried heating the power and A boards with a heat gun whilst the TV is operating in an attempt to change the state of dry joints but there's no change. I've now pulled the A board out to inspect for dry solder joints and reflowing as required. However any suggestions on the likely problem area on the board would be much appreciated! Failing reflowing joints fixing the problem, should I just replace the A board, or is there a chance the A board not at fault? The caps on the power supply board look fine, and functionally it seems that the power board is OK?

Thanks in advance…

Cheers,

David.

[tw2005]

Re: Panasonic Plasma TH-P42V20A – 13 Blinks

Going to be A board and at a guess I'm thinking failed solder under a bga chip. Statewide appliance spares show available at $360. Other options is find a broken tv to scrap. There is/ was a 50" in SA ebay maybe see if they will pull the boards and ship.sell what you don't need
Then use the A board but will need to swap some eeproms and flash chips from your dead board to make it a 42" version

[Dave-2]

Re: Panasonic Plasma TH-P42V20A – 13 Blinks

Going to be A board and at a guess I'm thinking failed solder under a bga chip. Statewide appliance spares show available at $360. Other options is find a broken tv to scrap. There is/ was a 50" in SA ebay maybe see if they will pull the boards and ship.sell what you don't need
Then use the A board but will need to swap some eeproms and flash chips from your dead board to make it a 42" version

Thanks TW2005. Yes there is one BGA on the board which I had my suspicions about and of course is harder to inspect/rework. There's no socketed flash/PROM devices on my A board so swapping firmware to a second hand unit looks more difficult. I read in the service manual of the data copy process to/from SD card when changing the A board, but I imagine this is user settings only (not firmware)? Besides, in my case as the screen is not running that process would be difficult to run!

MXM Electronics appear to have one at http://www.mxmee.com.au/index.php?ro...roduct_id=1341 If the part number is exactly the same can I safely assume it's a drop in replacement?

Cheers,

David.

[tw2005]

Re: Panasonic Plasma TH-P42V20A – 13 Blinks

Looks to be right. There's about 4 or 5 chips probably only 2 would need changing just a matter of either desoldering them anyway board is easier .