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