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Samsung HP-R4252 42" Plasma No Picture

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    Samsung HP-R4252 42" Plasma No Picture

    No picture symptom on this plasma TV suggested a problem with Y-sustain board and Y-buffers. It features problematic LJ92-01203A / LJ41-02761A and LJ92-01202A / LJ41-02760A with 6 ICs. I checked out Coppell Repair Blogs and some threads here, that helped me to identify shorted buffer and a shorted power FET.

    I replaced a shorted lower buffer and one bad IXTA36N30P power fet under the heat sink on the Y-sustain board.

    The TV still powers up and stays on with NO picture. I even tried connecting one buffer at a time - no half picture. Checked the voltages, Vscan is present and stable with Y-sustain connected or disconnected. Nothing is getting hot, both Y-sus and Z-sus are making a normal "hum". Ve for Z-sustain present and stable.

    I checked the Y-sustain board's main IC - no shorts. The fuse was also fine.
    Output voltages to Y-buffers are around -71V.

    Looks like something else might go bad on Y-sustain board. Any ideas?

    All suggestions very appreciated!
    Thanks,
    Rob

    #2
    Re: Samsung HP-R4252 42" Plasma No Picture

    Forget about it. That -71 volts indicates there is another problem. As indicated, these are problematic. By the time you replace all buffer ICs and the Y-sustain you have spent the major part of the cost of a new 42" plasma TV.

    PlainBill
    For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

    Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

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      #3
      Re: Samsung HP-R4252 42" Plasma No Picture

      Well, I was lucky to get a replacement lower Y-buffer board from E-bay for $ 36.00, shipping included. The upper buffer tests okay.

      So the only problem seems to somewhere on Y-sustain board. I replaced the shorted FET and the main IC tested okay. What else does usually go bad on this board? How can I test the board to make sure, the problem is not somewhere else? Too bad I don't have a similar, working TV to test the boards.... :-(

      Thanks,
      Rob

      Comment


        #4
        Re: Samsung HP-R4252 42" Plasma No Picture

        This is, how I tested the main Y-sus IC:

        http://blog.coppelltvrepair.com/2011...s-ipm-for.html

        My IC passed all tests okay.

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