LG42PW450T blows zsus

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  • blib
    Senior Member
    • Feb 2012
    • 56
    • UK
    #1

    LG42PW450T blows zsus

    Originally this TV would power up for about a couple of seconds then shut down.
    The wiring to the ysus goes via the zsus. I disconnected the ysus board result the same.I then disconnected the zsus board and the power supply runs with correct vsus and va voltages.I then found some short circuit diodes on the zsus.Fitted a new zsus and the screen flashed on for 2 seconds then off with power supply still running.I then checked voltages to the ysus with set running all correct but the heatsinks were cold as though not drawing any current.When I turned the set off and on again after a short while I heard a pop and the new zsus failed.Should I go for a replacement Ysus and Zsus and Is there anything else that can cause this.Thanks.
    Last edited by blib; 11-21-2013, 10:37 AM.
    Tags: None
    • blib
      Senior Member
      • Feb 2012
      • 56
      • UK
      #2
      Re: LG42PW450T blows zsus

      Just hoping it does not blow again and I waste my money.

        Comment

        • Ltank
          Badcaps Veteran
          • Jun 2013
          • 776
          • USA
          #3
          Re: LG42PW450T blows zsus

          Most of the time the Zsus power is supplied by the P.S. or Ysus. I have never seen it go to the Zsus first then to the Ysus. If both the Ysus and Zsus are disconnected from the
          P.S. do the voltages come up? Use your mutimeter across the inputs to the Ysus and Zsus and check for shorts. there should not be a low reisistance across them. Shouold be several K OHMS. The one with the low resistance should be the culprit. Connect the good one to the P.S. and check the voltages. Do you have a bad buffer board? with the Zsus buffers disconnected will the voltages be good and not shut down?

            Comment

            • blib
              Senior Member
              • Feb 2012
              • 56
              • UK
              #4
              Re: LG42PW450T blows zsus

              Thanks for the reply Ltank.I have posted a picture of the inside of the TV which I think shows the ysus being connected from the zsus.
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