LG Plasma TV will not turn on - Need Help

[Meiko]

Hello all. I'm in need of some help.

I have a LG Plasma TV 50PC3DH that will not turn on. It died while watching a show when it blinked with a white screen two or three times before turning off. Now when I try to turn on the TV, it clicks like its trying but then, after about 3 seconds, it turns back off. No picture or light is shown while it's trying to turn on.

I opened the TV and noticed some bulging capacitors on the power board, so I sent the power board to get repaired. When I reinstalled the power board, the symptoms didn't change.

Next, I checked the resistance between the Vs and ground on the YSUS and the ZSUS boards and found a short on the ZSUS. I replaced the ZSUS board with a refurbished board. Still, the TV will not turn on.

I checked all the voltages on the connectors, and they all seem to be correct. I don't know what to check next or how to find the problem component. If anyone can please give me some advice on how to determine what the problem is, I would greatly appreciate it.

Attached is a visual of the tv circuitry.

[tds-1541]

Re: LG Plasma TV will not turn on - Need Help

This unit appears use the same chassis as a plasma that I was just able to repair: https://www.badcaps.net/forum/showthread.php?t=34861. Long story short, I had to replace a MOSFET on the power supply board as well as an defective Z-sustain board.

The manual entitled " lg_50pc1dr_troubleshooting_manual.pdf" was VERY helpful. I would recommend that you download a copy of that. That PDF outlines resistance values for each board and their major components. You should quickly be able to determine which board/boards are bad by measuring the resistances and comparing them to the values in that PDF. Good luck!

[Meiko]

Re: LG Plasma TV will not turn on - Need Help

Sorry for the slow reply, I had to go out of town.

After going through the trouble shooting guide mentioned above, I checked what I could make sense of, but I did not come up with anything definitive. While checking all the voltages against what is printed on the ysus board again, I measured 5.8 volts on the +5VF pin on the connector from the ysus to the y driver board. All the other pins on the ysus board calling for 5 volts measure 4.9 volts. Does this show a faulty ysus board or is the 5.8 volts an acceptable reading?

Also, how do I check to see if the y driver boards are ok?

I'd really appreciate more help!