LG 50PS70FD Not turning on

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  • Josh094
    Member
    • Jul 2013
    • 17
    • Australia
    #1

    LG 50PS70FD Not turning on

    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
    Tags: None
    • Josh094
      Member
      • Jul 2013
      • 17
      • Australia
      #2
      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

        Comment

        • tom66
          EVs Rule
          • Apr 2011
          • 32560
          • UK
          #3
          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?
          Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
          For service manual, schematic, boardview (board view), datasheet, cad - use our search.

            Comment

            • RCA2000
              Senior Member
              • Sep 2014
              • 111
              • USA
              #4
              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.

                Comment

                • Josh094
                  Member
                  • Jul 2013
                  • 17
                  • Australia
                  #5
                  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

                    Comment

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