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Samsung PN50C540G3FXZA 50" Plasma, power cycling, Y-Main problem, Canada

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    Samsung PN50C540G3FXZA 50" Plasma, power cycling, Y-Main problem, Canada

    Just starting to crack into this one and wanted to get the ball rolling.

    At power on (plug in), power light on, relays click, repeat (sometimes)

    After disconnecting Y-Main from SMPS power stays on and boot up jingle is heard from speakers

    Removed Y-Main for inspection and testing

    This pic from:
    PN50C540G3FXZA Fast Track Troubleshooting Manual - Rev 1/10/12
    Click image for larger version

Name:	Samsung PN50C PCB layout.jpg
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    #2
    Y-Main board

    Model No: 50U(F)2P X-MAIN(1LAYER)
    PCB No: LJ41-08457A
    Rev No: R1.2(09/11/18)

    Comment


      #3
      Test everything you can on y-main, be sure to check the transistors for shorts, a short will show continuity between any of the 3 pins of the transistor, so if you measure in ohm mode and have close to 000 ohms thats a short.

      Comment


        #4
        Components I'll be testing shortly from the Y-Main board.

        Results are DCV from DMM diode test.

        SMALL HEATSINK
        Q6000 - SMK1360 MOSFET
        /OL/OL/0.525//OL/OL/0.1+/

        Q5402 - GT30F123 IGBT TOSHIBA
        /0/0/0//0/0/0/ - (shorted)

        Q5401 - GT30F123 IGBT TOSHIBA
        /OL/OL/OL//OL/OL/OL/ - (open)

        D5406 - RF1501 Diode 300V 12A
        /0//0/ - (shorted)



        LARGE HEATSINK
        Q5102 - RJP63F3
        /.017/.017/0// same / - (shorted)

        D5101 - STTH12R06FP Diode 600V 12A
        /0.371//OL/

        Q5403 - GT30F123 IGBT TOSHIBA
        /.017/.017/0// same / - (shorted)

        Q5408 - GT30F123 IGBT TOSHIBA
        /.027/.027/0// same / - (shorted)

        D5402 - STTH1004FP
        /0.422//OL/

        Q5303 - 1K31AJ
        /OL/OL/0.503//OL/OL/1.835/

        Q5304 - RJP30E2
        /.011/.011/0// same / - (shorted)



        D5401 - RD2006 Diode 600V 20A
        - 0.389/OL
        Last edited by bcstedt; 12-19-2023, 08:45 AM.

        Comment


          #5
          Y-Main

          Small Heatsink
          Click image for larger version

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          Large Heatsink
          Click image for larger version

Name:	IMG_20231218_112713_DRO~2.jpg
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ID:	3164671

          Comment


            #6
            With the Y-Main board disconnected, the SMPS test points read:

            Vs = 212VDC (211 on label)
            Va = 54.8VDC (55)

            Not sure where to check Vsc & Ve yet.
            (I need the Y-Main functioning to get these)


            Click image for larger version  Name:	IMG_20231214_184503_DRO~2.jpg Views:	15 Size:	964.4 KB ID:	3164733
            Last edited by bcstedt; 12-20-2023, 03:49 PM.

            Comment


              #7
              Yep it's a mess, many just try to get a good replacement board from somewhere because of how hard parts are to find and all the counterfeit components that are being sold.

              Comment


                #8
                Originally posted by nomoresonys View Post
                Yep it's a mess, many just try to get a good replacement board from somewhere because of how hard parts are to find and all the counterfeit components that are being sold.
                Thanks, I'm beginning to see that. I've got a few other things to check before I order a board but I don't even know if the PDP is functional.

                Comment


                  #9
                  Not a fan of plasmas, cons seem to outweigh the pros, too heavy, too hard to repair because of hard to find parts etc, use 3 times as much energy, 1080 max resolution, just to name a few.

                  Comment


                    #10
                    I finished testing the Y-Buffer, X-Main and SMPS boards. All diodes and transistors check out but there is some soldering rework needed.

                    I've ordered an X-Main board and hope I'll find an acceptable result soon. Updates to follow.

                    Comment


                      #11
                      Did some solder rework on the SMPS and X-Main boards. Inspect & test the "new" Y-Main board, looks good and significantly less heat damage.

                      Installed & test. Was getting some hissing noises from the Y-Buffer and the screen looks like this:

                      Click image for larger versionName:	IMG_20231227_153549_DRO~2.jpgViews:	0Size:	4.63 MBID:	3169007

                      Click image for larger versionName:	IMG_20231227_153603_DRO~2.jpgViews:	0Size:	4.35 MBID:	3169008
                      Last edited by bcstedt; 12-27-2023, 05:07 PM.

                      Comment


                        #12
                        Make sure y-buffer to y-main connections are as they should be. For testing unhook y-buffer from y-main, because a faulty buffer can kill a y-main and vice versa, maybe test the little mlc caps on y-buffer at least for shorts and retest y-buffer IC's , testing there if needed: https://www.youtube.com/watch?v=5hVi5gd0aec

                        Comment

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