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INSIGNIA NS-50D40SNA14 half screen has image, half is white.Suspecting panel

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    #1

    INSIGNIA NS-50D40SNA14 half screen has image, half is white.Suspecting panel

    INSIGNIA NS-50D40SNA14
    Tcon 5550T12C10
    panel AU model 96.50S12.002


    At first TV would turn on with just grey screen no image at all. Sound,back light, ports and remote all work fine.
    Disconnecting right flat panel cable from Tcon , and cycling the power would produce perfectly fine image on left connected side, and whole white left disconnected side. Took the bezel and metal covers off the panel to expose the board with bonding tabs and drivers, measured all ceramic capacitors-none is shorted.Measured transistors, diodes -no luck.
    Could anyone teach me and hopefully many others how to troubleshoot Tcon or panel short situation ? Don't want to buy another Tcon just to find out that it's the panel.
    Thanks in advance.
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    #2
    Re: INSIGNIA NS-50D40SNA14 half screen has image, half is white.Suspecting panel

    It would be useful if you could follow the guidelines which would prove helpful.

    https://www.badcaps.net/forum/showthread.php?t=39740
    Willing to help but I'm no expert.

    Comment

      #3
      Re: INSIGNIA NS-50D40SNA14 half screen has image, half is white.Suspecting panel

      Agreed the guidelines will prove helpful. I must add my note here though. When a panel produces no image or a bad image but when you disconnect one side from the t-con and get a perfect image on one side only this is not a t-con failure as it is working now. A bad driver on a carrier package is most likely shorted on the opposite side.
      Did I leave the soldering iron on?

      Comment

        #4
        Re: INSIGNIA NS-50D40SNA14 half screen has image, half is white.Suspecting panel

        Have you checked out putting t con voltages with both sides connected. Do you have VADD listed on the t con board? This voltage I will believe to be significantly dropped when the short is appearing
        Did I leave the soldering iron on?

        Comment

          #5
          Re: INSIGNIA NS-50D40SNA14 half screen has image, half is white.Suspecting panel

          sorry for not posting pictures. It was too late in the night.
          This particular panel does not have row drivers, they must be incorporated with column drivers , and 2 sides of panel have different connector pinouts, so swapping cables from tcon is not an option.
          Upon closer inspection I discovered one spot in the corner of non-working side of panel that has burn mark on outside plastic film, and it glows white when bad panel is connected to tcon (see picture).
          another test I did was to apply outside 13V from power supply to bad half of the panel with both panel flat cables disconnected (to see if one of the analog IC's drivers is shorting ), and voltage does not sink. Next I will try to do the same to remaining panel voltages (Von, Voff, logic supply and Vcom reference) once I find where they are on the panel.
          Tcon provides proper voltages as long as bad panel is not connected. I tried connecting bad side when tv was on, and Tcon makes buzzing short circuit noise and everything disappears.
          For now I am convinced that problem is in the panel, but more tests to come.
          Thanks everyone for reply and help, it is really appreciated.
          No matter how knowledgeable and experienced one is, good advice from fellow repairmen is very helpful and appreciated
          Attached Files

          Comment

            #6
            Re: INSIGNIA NS-50D40SNA14 half screen has image, half is white.Suspecting panel

            Bad smd caps on panel strips have caused issues on various tv drawing voltage down.
            I assume no responsibility for any stupid suggestions I might post.

            Comment

              #7
              Re: INSIGNIA NS-50D40SNA14 half screen has image, half is white.Suspecting panel

              I had 2 Samsungs before with crappy no name panels that had shorted SMD capacitors, but that was easy-no fuse on Tcon, so power supply was in protection-very easy find, just disconnect 1 module/cable at a time until power comes on.
              But this one is not that short. maybe they fail under 14-15V or higher, because meter only applies less than 3volts.
              Saga continues, will keep you guys posted.
              Thanks

              Comment

                #8
                Re: INSIGNIA NS-50D40SNA14 half screen has image, half is white.Suspecting panel

                I would imagine that spot on the panel is the problem.
                I assume no responsibility for any stupid suggestions I might post.

                Comment

                  #9
                  Re: INSIGNIA NS-50D40SNA14 half screen has image, half is white.Suspecting panel

                  will look if it is possible to cut off few voltages feeding driver for that particular area

                  Comment

                    #10
                    Re: INSIGNIA NS-50D40SNA14 half screen has image, half is white.Suspecting panel

                    so it turned out to be the shorted panel. After ripping off one bond tab at the time, tv turned on when last one was removed. I tested voltages on PCB, and they all seemed OK, so tcon was OK.
                    Case closed.
                    thanks everyone.

                    Comment

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