Panasonic TX-50A400B No picture Backlights on

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  • london-freddie
    Badcaps Veteran
    • May 2015
    • 472
    • UK

    #1

    Panasonic TX-50A400B No picture Backlights on

    Hi got another one for you guys that has me stumped now
    Not my tv looking at it for a mate from work
    TV powers on backlights come on but no picture, he tells me it has sound but I have not heard any sound
    My first thought was a mainboard problem, replaced the mainboard with a used board but still no picture
    Moved on to Tcon board and replaced that, still no picture,
    I do have 12v at the white tcon board fuse
    Now I am stumped any ideas out there please where to look next
    Just before posting this I removed one ribbon at a time from the tcon to panel
    first ribbon off right hand side as looking down on the board gave me Half a picture
    second ribbon removed made no difference no picture on other half
    Attached Files
  • diif
    Badcaps Legend
    • Feb 2014
    • 6978
    • England

    #2
    Re: Panasonic TX-50A400B No picture Backlights on

    Only half a picture suggests either a COF has failed or if you are lucky a capacitor is short. You should be able to get to it by removing the metal guard that covers it if the design is like the 50" Panasonic I did last night.

    Comment

    • london-freddie
      Badcaps Veteran
      • May 2015
      • 472
      • UK

      #3
      Re: Panasonic TX-50A400B No picture Backlights on

      just refitted original mainboard so now has replacement tcon and same backights on no picture, removing ribbons gives same results one ribbon removed {right} gives half picture, left ribbon removed no change no picture at all but backlights still on
      maybe a faulty panel
      He tells me this tv is just out of warranty ?

      Comment

      • london-freddie
        Badcaps Veteran
        • May 2015
        • 472
        • UK

        #4
        Re: Panasonic TX-50A400B No picture Backlights on

        will try and check the panel boards later, being honest, with it not being my tv I maybe do not want to put the same effort into it that I would if it were my tv

        Comment

        • diif
          Badcaps Legend
          • Feb 2014
          • 6978
          • England

          #5
          Re: Panasonic TX-50A400B No picture Backlights on

          Shouldn't need the panel stripping down, just 5 or 6 screws hold each cover on.

          Comment

          • london-freddie
            Badcaps Veteran
            • May 2015
            • 472
            • UK

            #6
            Re: Panasonic TX-50A400B No picture Backlights on

            just got the covers off these panel driver boards, can not see anything obvious wrong

            Comment

            • diif
              Badcaps Legend
              • Feb 2014
              • 6978
              • England

              #7
              Re: Panasonic TX-50A400B No picture Backlights on

              What about testing the caps for shorts. It's rare to see caps that small burnt. It's the side that has no picture you need to test.

              Comment

              • london-freddie
                Badcaps Veteran
                • May 2015
                • 472
                • UK

                #8
                Re: Panasonic TX-50A400B No picture Backlights on

                thanks for that diif do you know easy way of testing the caps on the board for short without removing them

                Comment

                • diif
                  Badcaps Legend
                  • Feb 2014
                  • 6978
                  • England

                  #9
                  Re: Panasonic TX-50A400B No picture Backlights on

                  The way I test for shorts is put my multimeter into diode mode. Then the red lead on ground then probe with the black. A short is about 0v non short .5v

                  Comment

                  • london-freddie
                    Badcaps Veteran
                    • May 2015
                    • 472
                    • UK

                    #10
                    Re: Panasonic TX-50A400B No picture Backlights on

                    ok just spent some time checking caps on the driver board everything seems ok

                    Comment

                    • diif
                      Badcaps Legend
                      • Feb 2014
                      • 6978
                      • England

                      #11
                      Re: Panasonic TX-50A400B No picture Backlights on

                      That suggests a faulty COF then, unless there's anything else on that board that could be faulty.

                      Comment

                      • london-freddie
                        Badcaps Veteran
                        • May 2015
                        • 472
                        • UK

                        #12
                        Re: Panasonic TX-50A400B No picture Backlights on

                        faulty board maybe ??
                        Attached Files

                        Comment

                        • comptek
                          Badcaps Veteran
                          • Aug 2013
                          • 606
                          • uk

                          #13
                          Re: Panasonic TX-50A400B No picture Backlights on

                          Check flex cables tcon- screen had 2 shorting tracks out before it was on a Samsung but still worth a try looked at it with an eye loop and I could see one track was out of line straightened it up and all was fine

                          Comment

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