LG 55LN5750 -- Bad backlight board or strips? So confused.

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  • FadedSpark
    New Member
    • Oct 2017
    • 3
    • Canada
    #1

    LG 55LN5750 -- Bad backlight board or strips? So confused.

    Hey all.

    Pulled this thing out of the trash room in my apartment building the other day, and it's no backlight, so that was pretty straightforward.

    Went to ripping it down today to see how many strips I would need to buy/how many LEDs were bad etc, and turns out, none of them. Suddenly, as if by pure magic, they all turned on and stayed lit long enough to take a picture, SUCCESS! Right?

    By the time I got it back together, turned it back on, still working, but as soon as I hooked it up to a source to play on it (SNES Classic ) the backlight promptly died again.

    It still fully flashes every time I toggle power, no surprise there.

    What do you guys think?

    Leaky near failing LEDs causing power cut off, or bad board that's failing under load?

    Can't for the life of me nail it down.

    Thanks!
    Tags: None
    • budm
      Badcaps Legend
      • Feb 2010
      • 40746
      • USA
      #2
      Re: LG 55LN5750 -- Bad backlight board or strips? So confused.

      We need good clear straight shot pictures of all the boards and pictures that show how all the boards are connected together, that will a start.
      Did you take pictures of LED strips showing how all the LED strips are connected together?
      Never stop learning
      Basic LCD TV and Monitor troubleshooting guides.
      http://www.badcaps.net/forum/showthr...956#post305956

      Voltage Regulator (LDO) testing:
      http://www.badcaps.net/forum/showthr...999#post300999

      Inverter testing using old CFL:
      http://www.badcaps.net/forum/showthr...er+testing+cfl

      Tear down pictures : Hit the ">" Show Albums and stories" on the left side
      http://s807.photobucket.com/user/budm/library/

      TV Factory reset codes listing:
      http://www.badcaps.net/forum/showthread.php?t=24809

        Comment

        • FadedSpark
          New Member
          • Oct 2017
          • 3
          • Canada
          #3
          Re: LG 55LN5750 -- Bad backlight board or strips? So confused.

          I did, thankfully hahah

          Don't have a picture of the back of my exact same model TV, but this one shares a panel, just has a different IO board, same TCON set up etc.

          https://youtu.be/gvnbaEkpnQo?t=48

          The Red linked bars are one circuit, the blue is the second, and the interconnects are shown as well.
          Attached Files

            Comment

            • dick_barton
              Badcaps Legend
              • Aug 2015
              • 6643
              • Wales
              #4
              Re: LG 55LN5750 -- Bad backlight board or strips? So confused.

              Quite often it's better to solder wires across all the connectors to bridge any possible poor connection.
              Willing to help but I'm no expert.

                Comment

                • tw2005
                  Badcaps Legend
                  • Oct 2011
                  • 6458
                  • Australia
                  #5
                  Re: LG 55LN5750 -- Bad backlight board or strips? So confused.

                  I'd lean towards bad LEDs only because that series / panel in all sizes seem to burn them out, in fact they get so hot the glues that holds the lenses gets toasted and then the lenses fall off too. Just picked up another LB series 2014 model which has the same strips, flashing backlight, it'll be a bad LED but normally it's total darkness not flashing so must be only one or two

                    Comment

                    • vinceroger69
                      Badcaps Legend
                      • Mar 2012
                      • 6714
                      • uk
                      #6
                      Re: LG 55LN5750 -- Bad backlight board or strips? So confused.

                      i wonder if its worth carrying out the led current mods like in this video would it make the leds last a lot longer and get less hot etc
                      https://www.youtube.com/watch?v=dPu_BeKVONI

                        Comment

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