LG 50PC5D YSUS/ZSUS Issues

[drussell]

Originally Posted by YamahaFreak

After removing the YSUS board from the chassis, a small black chunk fell out. After judicious inspection, I believe this chunk blew out of a similarly-sized hole I can just barely see on the IPM under the smaller, black heat sink on the YSUS board. I believe we have found the problem...

Heh, that could be a sign of trouble, for sure...

I would have expected the IPM to be under the bigger heatsink but perhaps it has modules under both on that model? If it has a hole blown in the side of it, I would definitely desolder it and take a closer look, obviously...

Yes, those two voltages were taken with everything hooked up. I have not checked any other voltages yet. I have verified that the plasma panel has no glow at all; it appears to be completely off. Where would I be checking for VZB on the ZSUS board? I'll try to get photos of both boards for you.

I can't see too well in that photo but in the upper right corner of the photo (so would be the lower right in the TV I assume) there is a <----Vzb---> (Vzb is the Z bias, or panel bias and is really all the Z board does is supply that voltage to an array of elements across the entire panel) so it looks like you're supposed to measure it across that film capacitor, I suspect...

I'm actually somewhat surprised that the panel isn't doing the dull glow but you may have multiple parts/systems failures, of course...

As an aside, I'm not harming anything else by leaving the set running in its current condition, am I?

I wouldn't run it except for measurements when you don't know precisely what is wrong yet... Voltages applied to the wrong electrodes when other voltages are missing can permanently damage the panel!

Best to be safe as this still seems like it is likely a fixable situation to make a working TV.