LG 50PG20 720p Plasma TV

[bullwinkle]

Need help again. My friend gave me this LG 50PG20 720p Plasma TV.

But here is the problem and what is the cause for this particular problem?

Note: Screen has no cracks.

[bullwinkle]

Re: LG 50PG20 720p Plasma TV

Is this repairable?

[bullwinkle]

Re: LG 50PG20 720p Plasma TV

any suggestions?

[bullwinkle]

Re: LG 50PG20 720p Plasma TV

More info:

Once I press the power button, the display will be shown like the attached pics. But after 5 seconds, it shuts off and the LED indicator turns red from blue. No cables connected. Only AC power cord.

[bullwinkle]

Re: LG 50PG20 720p Plasma TV

Powering up I see: Vs = 193.4V (194V printed on sticker) and Va = 60.1V (60V printed on sticker).

[bullwinkle]

Re: LG 50PG20 720p Plasma TV

Additional info:

-Vy = -195V
Vscan = 135V
Z-Bias = 98V

[tom66]

Re: LG 50PG20 720p Plasma TV

All voltages are OK. Can be panel gas leakage. It doesn't need to be a large crack to cause this. Just a tiny chip can do it. Also check the gas filling pip above the Y-buffer or Z-sustain board. If you have a scope check the Y-sustain & Z-sustain waveform.

[bullwinkle]

Re: LG 50PG20 720p Plasma TV

Many thanks tom66. But unfortunately I dont have a scope to check.

[bullwinkle]

Re: LG 50PG20 720p Plasma TV

can i post a short video clip here? just asking

[tom66]

Re: LG 50PG20 720p Plasma TV

You can use YouTube and give us the link.

[bullwinkle]

Re: LG 50PG20 720p Plasma TV

https://www.youtube.com/watch?v=PogrAJbCaTE

[bullwinkle]

Re: LG 50PG20 720p Plasma TV

Any other inputs that we can look into?

[bullwinkle]

Re: LG 50PG20 720p Plasma TV

Shorted 12V rail? Since it will just turn off less than 5 seconds after power up. My guess

[tom66]

Re: LG 50PG20 720p Plasma TV

Is that a relay clicking off at the end? High white fault image like that could cause the PSU to shut down.

[bullwinkle]

Re: LG 50PG20 720p Plasma TV

yes theres a faint relay clicking at startup but the shutdown relay clicking is more audible during recording

[bullwinkle]

Re: LG 50PG20 720p Plasma TV

@ tom66: any suggestion?

[tom66]

Re: LG 50PG20 720p Plasma TV

I think the panel is bad myself, but I could be wrong.

Try tweaking Vsc and -Vy on the Y-sustain board.
Try tweaking Yrr/Yfr too.

Your panel is in here, PDP50G1, page 79:


Of note, "If V-Set-Dn exceeds 120us the unit will shut down".

[bullwinkle]

Re: LG 50PG20 720p Plasma TV

Got rid of the unit. Its the panel.

Thank you tom66. You are correct.

[martino]

Re: LG 50PG20 720p Plasma TV

hey,your from Edmonton ! I'm by Ponoka.
Could be handy for swapping boards etc....

[bullwinkle]

Re: LG 50PG20 720p Plasma TV

mods pls close thank you