Lg 60pa6500-ug - no picture

[jamie21091]

I was given a free LG plasma TV from a friends neighbor.
It is an LG 60PA6500-UG.ACCLLHR
I was told it wouldn't turn on, and was told it worked fine and then one day wouldn't turn on. I do not know the history of this TV.

I powered the TV on and it powered up for a second and shut off immediately on it's own, there was a weird noise coming from the Y-sustain board.

I replaced the Y-sustain board and both buffer boards.
The TV powers on, but there is nothing on the screen at all.

I did some voltage checks, all the voltages were wrong, the Va, Vs, Vsc, Vy, and Vzb. I got the Va, Vs, and Vzb set correctly, but the Vsc and Vy are around 30 volts and turning the adjustment potentiometers on the Y-sustain board does nothing, the only thing that did anything was the set-up potentiometer but it only changed it about 2 to 3 volts different.

Why am I not getting the proper Vsc or Vy voltage, and how do I set the 4 potentiometers on the Y-sus board correctly, one of them is not labelled??

I have no picture on the screen so not sure what to check next.

I've spent days and hours looking on the internet for an answer and can't find an answer that fixes my problem.

[Biruslapio]

Re: Lg 60pa6500-ug - no picture

Thoroughly test the all your 4 buffer boards, they are known to short easily and cause no picture, or unstable behavior like low VScan and sometimes blow Y-SUS IGBTs. You have Z-bias, so maybe Z-SUS is not related to the fault. The other 2 trimpots on Y-SUS are not to be messed with, they control SET_UP and SET_DN pulses to the plasma display and incorrectly setting them can cause more image retention and pixelation on near black colors, among other picture problems.

Testing Y-buffers: Place positive lead of multimeter in the floating ground of Buffer board, negative lead on the pins that output to the screen, in diode mode, 0.6V or more should be read for good pins, 0.0V or close to it for a defective buffer IC, there are many ways to do it, I prefer this one.