Panasonic Plasma TV TH-P42XT50D PCB - 7 blinks

[tom66]

Re: Panasonic Plasma TV TH-P42XT50D PCB - 7 blinks

It is surprising the panel lit up - cracks usually lead to loss of gas, which is terminal to the panel. It won't light up, even if you shove 2000V across it!

[Chaks]

Re: Panasonic Plasma TV TH-P42XT50D PCB - 7 blinks

Tw2005 I forgot to remove the ss55a and ss53 panel connectors on the ss board (power + ss board) when I tested earlier ( it was a mistake) .

I did the test again now .... The panel does not lit up when both ( SN -> panel ribbon cable and SS -> panel ribbon ) were removed. The led blinks 7 times and shuts off. The transition from blinking white power led to flashing red 7 times was noticeably faster. It's quick.

I did one more test by removing the p35 connector along with both the ss and SN panel connectors ... It's the same result .... Panel does not lit up and very quick transition of power led from flashing
white to 7 red blinks.

[Chaks]

Re: Panasonic Plasma TV TH-P42XT50D PCB - 7 blinks

The SN board block diagram:
https://drive.google.com/file/d/0Bxc...ew?usp=sharing

[tw2005]

Re: Panasonic Plasma TV TH-P42XT50D PCB - 7 blinks

I think the chances are the SN could be damaged. I know whenever I've purchased boards from a smashed TV that was operating at least on buffer usually sd is shorted, since this is combined it makes it difficult to check. I think you'll have to base your decision based on the expectation other boards may need replacing.

I'm out of ideas.

[Chaks]

Re: Panasonic Plasma TV TH-P42XT50D PCB - 7 blinks

Thanks a lot for your replies tw2005 and others on this forum.

The components on the SN are too small to test and even more difficult without a full schematics of the pcb. I had been on this for a week now and it's time to decide either way ...

1. Dump the whole thing and buy a new led tv. OR
2. Take the tv to panasonic service centre and get it estimated and then decide.

I will update when I get a feedback from panasonic service centre.

[Chaks]

Re: Panasonic Plasma TV TH-P42XT50D PCB - 7 blinks

Yesterday morning I carried my tv to the service centre. It was late afternoon they called me to come as they estimated the repairs.They told me that the panel is working for the moment but cannot guarantee how long as the crack may become larger over time ( ... short time ) and will eventually fail. The SN board was faulty - gone bad from the shock of the impact and it has to be replaced.

The estimate was $150 for the SN board, $30 for labour, and if I want to replace the panel it would be cost me $500. Total repair would cost me $680 with new panel and without any warranty on it ( they said 30 days it's as good as nothing).

At a minimum I have to buy the SN board to take back a working but a broken tv.

They did show me the tv with a working SN board to support their estimate. They were a total of 12 missing lines (5 vertical and 7 horizontal). They sealed the cracked area with a transparent glass-like adhesive sheet.

Do I need to pay $180 for the SN board ? ... To be installed in a broken tv.

I finally paid $25 as estimation charges and brought back the tv.

The service guy was kind enough to explain me why the panel could survive the crack. He told me that there is a vacuum seal just like a flask on the top-right corner of the panel (back side). It is very fragile and can easily break open due to shock from impact. Crack on my tv was on the bottom-left of the screen (facing the panel) and thus the panel was still alive. The shock may not have travelled anywhere near the most venerable point. The momentary fluctuation of scan pattern on impact will kill the driver IC's on the SN board. A senior technician in late forties says he has seen many plasma TV's destroyed that way. A small punch to the left-top corner of the panel (facing the panel) is enough to destroy the pana tv.

So this is the end of the story for my tv. I will keep the tv just for academic interest.

I don't have enough courage right now to buy a new big tv again.

Thanks everybody ... Bye

[tom66]

Re: Panasonic Plasma TV TH-P42XT50D PCB - 7 blinks

The missing lines won't come back, and the panel is damaged and shorted in that area which will kill the new SN board within short order. If the crack was somehow only on the outer surface it might be ok but since there are missing lines the panel itself has been compromised. It might not have leaked gas (somehow...), but it has shorted.

I have seen this before. Some cracked plasmas will operate for some time, especially the more modern ones. The buffers always die though, usually taking the picture with them. In some rare cases the buffer ICs fail open circuit and just that part of the picture dies.

The instantaneous short idea is interesting, but I have heard of boards from shipping damaged TVs which are bad, after customers power the TV on for the first time with the crack. I think the short just kills the boards in many cases. Not always, but often.