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Samsung PS42E7HD will not display problem

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    Samsung PS42E7HD will not display problem

    My neighbour was throwing out a Samsung 42" plasma TV so I said I'll take it. A nice project to work on I thought as I have fixed a few TV's by changing capacitors, nothing really that technical.
    I got the TV home, the screen looked ok and so I plugged it in. I smelt smoke so shut it off. Opened it up and noticed some capacitors blown on the power board. I swapped them and then I got clicking with 4 red blinks from the button on the front. I checked the Vs etc points and they all read good. I checked the y-main LJ92-01346A and there was a capacitor and two resistors not working. I replaced those. Tried TV and still nothing.
    I then checked the X-main and found a few odd readings so instead of fixing it I purchased a working board off eBay as it wasn't that expensive. Plugged it in and the screen flashed patches and then the resistors on the y-main went bang! They were the ones I replaced. Originals were Brown, Black, Gold and Gold. They were large and a dark grey colour. I bought the same band colours and dimensions but the resistors were blue. Would that be a problem?
    After that I thought just buy another Y-main. So I did and it came today and I plugged it in. The screen had a few flashes then I heard a pop. I checked and a capacitor had blown on the y-main. I also noticed a resistor getting very hot very quickly. I've replaced the capacitor but haven't turned it on again. The y-main is connected via two ribbon cables. One from the smaller power board. The readings are good from that board supplying power. Then there is a smaller ribbon cable connected to the logic board LJ92-01432A. Now I'm thinking could this be the faulty board? I can't see any points to check voltages, so how do I check? I could spend more money but then if that doesn't work I'm just throwing money away.
    It has been good as I am learning a lot but now I'm stuck. Any help would very much appreciated. Thank you.
    Last edited by gizmouk; 06-12-2015, 06:35 PM.

    #2
    Re: Samsung PS42E7HD will not display problem

    This morning I plugged everything in except the cable from the logic board to the y-main. The TV clicks and then nothing, no hot resistor or anything going pop! So I decided to measure some voltages.
    Main Board:
    Vs - 198v, Va - 65v, Vg - 14v, Vt - 32v, D5.3 - 4v, A6.5 - 5v, 18v Amp - 17v, 12v - 11v, STD5 - 4v.
    Mini board - LJ44-00105A
    Va - 65v, Vset - 195v, Vscan - -188v, Ve - 104v.
    X-main
    XS1 - 0v, XS2 - 76v, XG1 - 4v, XG2 - 4v, XE1 - 0v, XF1 - 89v, XR1 - 84v.
    Y-main (Logic board not connected)
    Vsc_h - (-188v), Yrr1 - 35v, Ysc2 - (-188v), Ysc1 - (-188v), Yfr1 - (-188v), Yf1 - 99v, Yr1 - 19v, Ys1 - 34v, Ys2 - 34v, Ypn2 - 0v, Ypn1 - 0v, Ypn3 - 0v, Yg1 - 0v, Yg2 - 0v.

    If I plugged in the logic board to the y-main I'm sure it would go pop like before. Should I simply replace the logic board.?

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      #3
      Re: Samsung PS42E7HD will not display problem

      Also found out today that the sound works. The cable from the logic board to the y-main is still disconnected.
      Any help would be very appreciated please. Thank you.

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        #4
        Re: Samsung PS42E7HD will not display problem

        I bought a replacement logic board and turned the tv on. The screen kept flashing 3/4 white and the other with green pixels. It clicked everytime it flashed too. Then smoke appeared from the back. It was a chip on the Y-buffer board. I think it's time to give up on this tv.

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