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Samsung PL51D550 Clicking Noise + No Video/Sound/etc (Brazilian model of PN51D550)

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    Samsung PL51D550 Clicking Noise + No Video/Sound/etc (Brazilian model of PN51D550)

    Hello ppl.

    I've a Sasmsung PDP PL51D550 that I've bought on 2012. Two days ago my mother was watching the television and suddenly it lost it's image while keeping the sound on. After shutting down the television and trying to power on again, it simply fails.

    Reading through this forum I've already started some debugging but I'm in a point where I can't define which board is damaged and what should be replaced.

    I've done multiple tests and definitely theres a problem on one or more of those components:

    X-Main
    Y-Main
    Y-Buffer
    Power Supply Board (BN44-00444A)

    During my debugging I've done the following pattern:

    1. With everything connected If I try to turn on the TV I got some clicking noises, and the LED on the Logic Board blinks erractly. It appears to be entering in a reset state, five times in a row, and them it stops.

    2. Unplugged the Y-Main board power cable and the TV only clicks one time. The Logic Board blinks as it's missing Y-Main and/or X-Main boards. Which appears to be correct.

    3. Plugged back the Y-Main board but removed the power cable to the X-Main board on the Y-Main board, since the power connector appears to be daisy chained to the board. Got the same results on the item 2.

    After this test I've came to conclusion that X-Main should be bad. But I've found a strange thing:

    -> I can't get any of the "vital signs". Vs, Va, Vsc and obviously Ve can't be measured with a voltimeter. All stays at zero or near zero. I even had doubts if Vs and Va should be AC or DC, due to this behavior.

    Now I don't know if the Power Supply board is bad, or if the X-Main and the Power Supply board are both bad.

    How can I debug this? I've done some ohmmeter tests on the MOSFETs on the X-Main and on the Power Supply board, and on some of them I got near 0Ohm between the Drain and Source, which appears to be shorted, but I've done this directly on the boards, and not with the components removed, and I'm not even sure if this was right, since on the Power Supply board the FET's near the Vs and Va probes appears to be used as rectifiers for AC/DC conversion.

    Thanks,
    V.
    Last edited by ferrao; 04-23-2017, 12:42 PM.

    #2
    Re: Samsung PL51D550 Clicking Noise + No Video/Sound/etc (Brazilian model of PN51D550

    I believe that if you have shorted mosfets then the set powers down immediately. You need to check all the mosfets for short circuit (even while on the board) and remove them in turn. You can then check them out of circuit to be sure that they are faulty.
    That will just be the start to repairing the set.

    Photo's of your boards would go a long way towards help being provided.
    Willing to help but I'm no expert.

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