LG 60PS11 plasma no picture with sound y board problem

[Sevenqi]

When turn on the power, it only flash the screen for less than a second then goes black, sound is good.
Took off the back cover and measured the VS,VA from power board, they all normal; Checked the fuses on y board (EBR55492901), all good. Vs and VA also good on y board.
When I measured the -Vy and VSC, the voltage dropped from normal to 0v when while power on, these should be the problem and explain why it lite up a second then black.
Tried to disconnect the two buffers and checked the -Vy and vsc, the same result, so I assume the buffer boards are good.
Now the next step is to find out what causes the voltages dropped, no idea so far. The nearest transistors are the two big guys Toshiba K3453 attached the black heatsink, but they don't seem to be shorted or open (I just measured on board).

[tom66]

Re: LG 60PS11 plasma no picture with sound y board problem

Check Vzbias too. If that's dropping out, fair chance control board is shutting it down.

[Sevenqi]

Re: LG 60PS11 plasma no picture with sound y board problem

I checked Vzbias, it also dropped from 105V to 0v but much slower (took a few minutes).
So Tom, the control board you mentioned is the main board ? or the digital board ?

[tom66]

Re: LG 60PS11 plasma no picture with sound y board problem

Control board is the one which connects all the boards. Also connects to main board (which has HDMI, etc.)

It sounds like the control board is shutting down the sustains, for some reason or another.

You can try unhooking the Y-sus logic cable (ribbon cable) and see if that makes it stay on. Ideally, you'd use an oscilloscope to monitor the output of both boards to see if there's any abnormality before it cuts out.

[Sevenqi]

Re: LG 60PS11 plasma no picture with sound y board problem

Tom, I think you refer to the logical board EBR55609201.
I disconnect the ribbon cable from the y-board to the logical board,no light at all, even the power up lite doesn't show up.
I checked the voltages to this logical board, good, there are three regulators and their outputs are also good. (3.3,3.3,2.5). There are two leds, one is steady white, the upper one is blinking (Normal?).

Any other suggestions?

[Sevenqi]

Re: LG 60PS11 plasma no picture with sound y board problem

Update: I replaced the y board, TV works fine now.

[Jeff Pepin]

Re: LG 60PS11 plasma no picture with sound y board problem

i can get a 2nd life to this topic : did someone can help me to found this board schematic ? , look like if dosent exist :/
ebr55492901