LG 50PS70FD Not turning on

[Josh094]

Hi guys,
I've got a LG 50PS70FD here which won't turn on. I first inspected the power supply for bad caps and cold solder joints however all seem to be fine. When the power button is hit the tv clicks begins to power up then a buzz sound comes from the ZSUS board and the it shuts down. I tried unplugging the ZSUS board and the power supply then powers up and stays on. Would this point to a faulty ZSUS board?

Thanks

[Josh094]

Re: LG 50PS70FD Not turning on

Quick follow up, I've checked the VS and VA voltages with the zsus unplugged and the voltages appear normal. VS and VA are around 210 and 67

[tom66]

Re: LG 50PS70FD Not turning on

Are Vs and Va low if the boards are connected?
A Vs of 210V on an LG panel of this generation is very unusual...they were using low gas pressure at the time and Vs of around 185-195V was more common...are you sure about that reading?

[RCA2000]

Re: LG 50PS70FD Not turning on

CHeck the power devices on the Z-sUS board (either MOSFETS or IGBT"S) for shorts or leakage. Likely you WILL find at least one bad one. If NOT ...then there is likely a driver or other IC bad on the board.

[Josh094]

Re: LG 50PS70FD Not turning on

My mistake Tom, the vs reading was incorrect. It's in fact 201 which is a little high considering the sticker on the back of panel says 195 for the Vs voltage. Could this be an issue?
I've got the Zsus board out now and will begin to look it over, at first glance nothing appears to be visibly faulty