LG 50pa5500 turns on, no picture no sound

[Vlives]

Hi, I've got this LG 50pa5500 TV for free because it is broken. It does turn on, a power supply seems to work fine. I think I narrowed the problem down to Y-buffers.
I tested VSC, VY, VZB voltages which were reading about 40, 4, and 50 volts. Then I disconnected and unplugged the top Y-buffer, and got a faint light on the bottom half of the screen, which was unevenly striped. I tested VSC, VY, VZB voltages which became much higher and stable (didn't write it down, but something around 150, 50 and -140 volts). Tested the top Y-buffer for shorts with a multimeter , and sure enough it had one shorted IC.
I left the TV off for about 30 minutes to look at the cost of replacements, and when I came back the TV no longer showed anything on the bottom half when turned on . Voltages went back to low. I unplugged the bottom Y-buffer and tested it for shorts - and found another shorted IC - which is probably why it showed stripes when it briefly worked?
My theory is that Y-sustain damaged both buffers. And since Z-sustain passes power to Y-sustain, could the Z-sustain also be the culprit?
It seems that I could get both buffers for 40$, so it's OK, but if they will get burned out immediately by Y or Z sustain - then I would like to avoid it.
Can I somehow test if either Y or Z sustain burn stuff?

[freakaftr8]

Re: LG 50pa5500 turns on, no picture no sound

You could replace the buffers and when you do that leave the very top y ribbon cable disconnected from the buffer boards. Lines are most likely from a shorted IC ready to go on the lower buffer anyway. I should know that this model has a history of problems with the very top Y ribbon cable Rubbing the plastic frame around the TV so you might want to inspect that y ribbon very carefully.

[mmartell]

Re: LG 50pa5500 turns on, no picture no sound

Do you have this buffer board ? Look what shopjimmy has to say about it...

[Nick's Tvs]

Re: LG 50pa5500 turns on, no picture no sound

You will indeed want to replace the Y-sustain as well as both buffers. The reason they say that is because on this model, the damage travels to the other boards.
Most definitely replace all boards.

[Vlives]

Re: LG 50pa5500 turns on, no picture no sound

Thank you for your replies!

... you might want to inspect that y ribbon very carefully.

I checked and none of the ribbon cables rub the plastic part, all of them are completely fine.

Do you have this buffer board ? Look what shopjimmy has to say about it...

Mine is very similar - only one digit is different. So I will replace all 3 of them then.

Most definitely replace all boards.

By all boards you mean Y-sustain and Y-buffers, right? Nothing to do with the Z stuff?

[mmartell]

Re: LG 50pa5500 turns on, no picture no sound

Yes that's correct.