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LG 55UH615A Half Screen Dark, Replaced LED's & Power Board, Completely Stumped

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    #1

    LG 55UH615A Half Screen Dark, Replaced LED's & Power Board, Completely Stumped

    I have this LG 55UH615A with half screen is Dark. This is an edge lit TV with 2 small LED strips that run along the bottom of the TV. When I got it, only one half of it was lit. Also, there was a buzzing noise coming from the power board. I ordered new LED strips and also a replacement power board. Installed both and I'm still getting the same problem. When I test the wires going to both LED strips, Im getting solid, non fluctuating voltages from the power board and also at the connectors plugged into the LED strips. I tried to rule out if possibly the new LED strip on the dark side was bad. I took the old strip that was still good and plugged it into the side that lights up, and it lit up the strip, but when I plugged it into the other side... nothing.

    Any one with suggestions or ideas of what else I can try, I would really appreciate the help. I'm completely stumped on this.
    Tags: None
    #2
    Re: LG 55UH615A Half Screen Dark, Replaced LED's & Power Board, Completely Stumped

    This is a fact of connectors, this is for exclusion, obviosly there aren't any other things. How does it come to your mind to get led trip together with powerboard? The first culprit cndidate was the strip...

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      #3
      Re: LG 55UH615A Half Screen Dark, Replaced LED's & Power Board, Completely Stumped

      The power board was buzzing before I replace it, so I thought the old LED's were causing the buzzing on the board. So I replace the LED's first, but board was still buzzing after and the LED's were dimly lit. Still only on 1 side though. So then I thought to replace the power board. Once the new board arrived, there was no more buzzing and the LED strip was at full brightness, but still only just one side. When I test the side that doesn't light up, I get steady 261.6v out of the red wire and a steady 201.1v from the black wire, but the LED strip still doesn't turn on.

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        #4
        Re: LG 55UH615A Half Screen Dark, Replaced LED's & Power Board, Completely Stumped

        Show us good clear pictures of the whole backside of the TV showing all the boards, then good clear straight shots of the whole power supply board so we can see what we are dealing with.
        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

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          #5
          Re: LG 55UH615A Half Screen Dark, Replaced LED's & Power Board, Completely Stumped

          i don't understand, you have only two cables output but referring to the ground you have 260v on red and 200v on black? i think between red black must be higher until 260 when full brightness.. anyway check those cabling..

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            #6
            Re: LG 55UH615A Half Screen Dark, Replaced LED's & Power Board, Completely Stumped

            I have attached photos of my multimeter readings of all the wires coming out from the power board and also going into the LED Strips. I also have a photo where I plugged in the old strip on the side that works showing that it lights up, but when I plug the same strip into the bad side, it doesn't light up. I just don't know what else could be the fault causing this problem. If anyone knows, please advise.
            Attached Files

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              #7
              Re: LG 55UH615A Half Screen Dark, Replaced LED's & Power Board, Completely Stumped

              Originally posted by TvtechNue-b View Post
              I have attached photos of my multimeter readings of all the wires coming out from the power board and also going into the LED Strips. I also have a photo where I plugged in the old strip on the side that works showing that it lights up, but when I plug the same strip into the bad side, it doesn't light up. I just don't know what else could be the fault causing this problem. If anyone knows, please advise.
              from the photo of the strip socket i can tell yours replacement strips are for right side not the left... you need to flip wires of - + to let it work... but then how you will fit it ?

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                #8
                Re: LG 55UH615A Half Screen Dark, Replaced LED's & Power Board, Completely Stumped

                Hi! Ok now is very clear, forget my diagnisis of cabling, by your photo you have 2 led driver output channels, one working at 75v , and one not working at 60v. Time to search for a schematic of power board. If you can't find it at least post two extraclear pictures of top and bottom.

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                  #9
                  Re: LG 55UH615A Half Screen Dark, Replaced LED's & Power Board, Completely Stumped

                  Originally posted by budm View Post
                  Show us good clear pictures of the whole backside of the TV showing all the boards, then good clear straight shots of the whole power supply board so we can see what we are dealing with.
                  Can you post photo's as Budm suggested, It could help.
                  Willing to help but I'm no expert.

                  Comment

                    #10
                    Re: LG 55UH615A Half Screen Dark, Replaced LED's & Power Board, Completely Stumped

                    Have you checked Q801, Q802 and what is the part number of IC801
                    Attached Files
                    Last edited by dick_barton; 12-10-2020, 01:20 PM.
                    Willing to help but I'm no expert.

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