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LG 50LA6205 Bad Backlight and Bad Panel

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    LG 50LA6205 Bad Backlight and Bad Panel

    This TV had a logo flash on plug in which is symptoms of a bad LED backlights. Replaced 4 shorted LEDs and now getting horizontal lines. Tcon ribbons connected one at a time show both vertical and horizontal lines with one side. Confirm this is a bad panel before I scrap this tv?
    Attached Files
    Last edited by neilc6; 09-16-2018, 11:26 AM.

    #2
    Re: LG 50LA6205 Bad Backlight and Bad Panel

    Yes...I see a bad panel.

    Comment


      #3
      Re: LG 50LA6205 Bad Backlight and Bad Panel

      With some work it may be salvaged.. many methods on the field to try.. the easiest one to remove the side tab where the problem starts... also masking with tape on tcon can be tried..

      Comment


        #4
        Re: LG 50LA6205 Bad Backlight and Bad Panel

        No side tabs. Pushed down the tab bonds on the bad side with no change. Scrapped the TV already. Thanks for the input.

        Comment


          #5
          Re: LG 50LA6205 Bad Backlight and Bad Panel

          Bad panel

          Comment


            #6
            Re: LG 50LA6205 Bad Backlight and Bad Panel

            Thanks Davi.p! Was ready to take the TV to recycling and decided one last attempt with the tape method on the tcon ribbon after reassembling the TV. Luckily none of the parts sold yet on ebay. On the side that showed lines (right), I blocked off around 20 pins on the leftmost side and it worked!!
            Attached Files

            Comment


              #7
              Re: LG 50LA6205 Bad Backlight and Bad Panel

              Good works! Lets see how long it will last, at least it is working for now.
              Can I get good clear pictures of the T-CON board so may be I can see what those pins are for.
              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


                #8
                Re: LG 50LA6205 Bad Backlight and Bad Panel

                Sorry, not the best focussed since it was for the ebay listing. Don't want to take the tv apart again since it has been reassembled about 5 times and I've already busted some plastic tabs.
                Attached Files

                Comment


                  #9
                  Re: LG 50LA6205 Bad Backlight and Bad Panel

                  Thanks for the pictures, at least I can read the PCB and PCBA numbers so now I can go to shopjimmy to get good clear pictures.
                  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


                    #10
                    Re: LG 50LA6205 Bad Backlight and Bad Panel

                    OK, where do you have found instructions on how to block signals? I have tried with my 50 inch Hisense w/AUO panel but the result is not perfect, the line still persist due to some gate drv outputs maybe shorted that keep the opposite output low or high, the bigger part of defect is disappeared.. the outer part of the flat is usually reserved for clock signals to the gate drivers.. In mine i have blocked only one signal that disables all the faulty side gate drv, but i will try block others.. maybe it's necessary also to block VGON/VGOFF
                    Last edited by Davi.p; 09-20-2018, 01:56 PM.

                    Comment


                      #11
                      Re: LG 50LA6205 Bad Backlight and Bad Panel

                      Saw two youtube videos before about putting tape on the tcon ribbons. One wasn't really clear what he was doing. Tape is actually used to block the pins and not to apply more pressure to the contacts. Another one I recall was to vary the pins blocked and location. Mainly trial and error with the location and width of the tape. I'll see if I can find them since it was awhile ago.

                      I fixed a Samsung before blocking just a few pins.

                      https://www.badcaps.net/forum/showthread.php?t=50646
                      Last edited by neilc6; 09-20-2018, 02:08 PM.

                      Comment


                        #12
                        Re: LG 50LA6205 Bad Backlight and Bad Panel

                        Yes i saw a shopjimmy picture, them are all the gate driver related signals,except Vcom, Vcomr_FB that maybe better to leave connected, i will check..

                        Comment


                          #13
                          Re: LG 50LA6205 Bad Backlight and Bad Panel

                          Here is one video

                          https://youtu.be/j7vl7-vZEL8

                          Comment


                            #14
                            Re: LG 50LA6205 Bad Backlight and Bad Panel

                            yeah i knew that video..

                            Comment


                              #15
                              Re: LG 50LA6205 Bad Backlight and Bad Panel

                              2 lines intermittently came back along with a pattern across the whole screen. I replaced the scotch tap with electrical tape and will run for a few days to see if it comes back.

                              Comment


                                #16
                                Re: LG 50LA6205 Bad Backlight and Bad Panel

                                Is your tv still working today?
                                You live and you learn right?

                                Comment


                                  #17
                                  Re: LG 50LA6205 Bad Backlight and Bad Panel

                                  Tv came back recently. Another backlight failed even though all inputs were set at 60/100. Repaired and back up and no lines. I would exoect it to last as long as the side tab removal fix.

                                  Comment


                                    #18
                                    Re: LG 50LA6205 Bad Backlight and Bad Panel

                                    What? Another re-badged Sharp panel?
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                                    "did I see a chair fly? I think I did! Time for popcorn!" -ratdude747

                                    Comment


                                      #19
                                      Re: LG 50LA6205 Bad Backlight and Bad Panel

                                      Hi neil, i suspect your customer has mains power line disturbances, next time i suggest you to protect all the screen (backlight and tcon/panel matrix) with TVS diodes or varistors and check the backlight driver's power semicon for cracks in solders and esr of the output el.caps. The suppressors must blow a fuse so your work will be easy and cheap in replacing it.. Bye.
                                      Last edited by Davi.p; 12-31-2018, 01:34 AM.

                                      Comment


                                        #20
                                        Re: LG 50LA6205 Bad Backlight and Bad Panel

                                        What is theory on this type of repair ? I mean, how are these parts of the panel still displaying an image when the signal containing the image information is being blocked with tape ?

                                        Comment

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