Please help in diagnosising a bad transistor.

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  • Heaths
    Heaths
    • Jul 2011
    • 3
    • United States
    #1

    Please help in diagnosising a bad transistor.

    Hey guys I just got this plasma tv for free so I figure its worth fixing. Its a DP50749. I got to the Y sustain board before I found a transistor that might be bad. But this is my first tv that went bad that wasn't a bad cap, so im not sure. I posted a video for you guys to please check out. If the transistors are good then i'm not sure what is wrong with it. Let me know what you guys think and then ill give a full description of the issues with pics. Thanks guys

    http://www.youtube.com/watch?v=s2iUzs7xvIw
    Tags: None
    • Alastair E
      Chief Womble
      • Mar 2013
      • 1963
      • U.K.
      #2
      Re: Please help in diagnosising a bad transistor.

      Fourth one you test--is suspect.
      --IF in fact, its a Transistor. There are also double-diodes fitted to these things, plus other items in circuit that may give odd readings when tested in circuit.

      Pull it out and re-test
      TELEFIX

      How PLASMA SCREENS WORK, X-SUS and Y-SUS what they do--
      http://www.irf.com/technical-info/appnotes/an-1088.pdf
      PLEASE DO NOT EMAIL ME PRIVATELY FOR REPAIR ADVICE. QUESTIONS BELONG ON THE FORUM!

        Comment

        • tw2005
          Badcaps Legend
          • Oct 2011
          • 6458
          • Australia
          #3
          Re: Please help in diagnosising a bad transistor.

          Originally posted by Alastair E
          Fourth one you test--is suspect.
          --IF in fact, its a Transistor. There are also double-diodes fitted to these things, plus other items in circuit that may give odd readings when tested in circuit.

          Pull it out and re-test
          Yep, I'm thinking the same. Last item i'd say was a double diode with identical readings on 2 pins. I did not see anything showing short which is usually how the IGBTs fail so good chance all those videoed are ok.

          Transistors are marked Q, diodes D and will have pins A & K where the IGBTs have pins G,C,E and FETs will have pins G,D,S.

          The fast recovery diodes and transistors on those heatsinks have the same packaging so appearance wise they'll look similar.

          Looks like a panasonic based panel and drive boards so you may be able to research for common boards that fail based on the SC, SD, SU and SS board numbers assuming it's one of those that is the issue.

            Comment

            • Heaths
              Heaths
              • Jul 2011
              • 3
              • United States
              #4
              Re: Please help in diagnosising a bad transistor.

              Man, thats why I love you guys.

                Comment

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