LG 65UH5500 Flashes on then off

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  • pinstripebob
    New Member
    • Nov 2020
    • 4
    • USA
    #1

    LG 65UH5500 Flashes on then off

    Hi all,

    I have an LG 65UH5500 built in 2016 that won't turn on and stay on. When you turn it on, the screen comes on like normal and shows the LG logo, but turns off in less than a second (or very quickly). I took off the back panel, read through a couple threads here, ran through Bud's TV troubleshooting PDF, and have come to a stopping point.

    On the power supply board, there is a connector with 80V and 13.2V connections. With power plugged in and the TV off, these measure 63.6V and 9.7V, respectively. The TV won't stay on, so getting voltages with the TV on is a bit tricky.

    I looked at all the capacitors and did not find any evidence of failure. Fuses appear to be intact as well.

    Are there any troubleshooting tips I can use to help diagnose the issue with this TV?

    Thanks!
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    • RJARRRPCGP
      Badcaps Legend
      • Jul 2004
      • 6301
      • USA
      #2
      Re: LG 65UH5500 Flashes on then off

      Originally posted by pinstripebob
      Hi all,

      I have an LG 65UH5500 built in 2016 that won't turn on and stay on.
      This looks like a close predecessor of the UH6100 series, IIRC, which was also built in 2016. I got it in 2017 and gave it to my sister in later-2018. Now it looks like possibly failing LEDs on it. Looks purplish and looks like possibly some dead LEDs on the bottom. We have a 49UH6100.
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      "¡Me encanta "Me Encanta o Enlistarlo con Hilary Farr!" -Mí mismo

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      "Today's lesson in pissivity comes in the form of a ziplock baggie full of GPU extension brackets & hardware that for the last ~3 years have been on my bench, always in my way, getting moved around constantly....and yesterday I found myself in need of them....and the bastards are now nowhere to be found! Motherfracker!!" -Topcat

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        Comment

        • 280zx
          Member
          • May 2020
          • 43
          • US
          #3
          Re: LG 65UH5500 Flashes on then off

          I had a similar problem on a LG 65" and it turned out to be one row of back lights went bad.
          Last edited by 280zx; 11-30-2020, 10:16 AM.

            Comment

            • dick_barton
              Badcaps Legend
              • Aug 2015
              • 6642
              • Wales
              #4
              Re: LG 65UH5500 Flashes on then off

              Originally posted by pinstripebob
              Hi all,

              I have an LG 65UH5500 built in 2016 that won't turn on and stay on. When you turn it on, the screen comes on like normal and shows the LG logo, but turns off in less than a second (or very quickly). I took off the back panel, read through a couple threads here, ran through Bud's TV troubleshooting PDF, and have come to a stopping point.

              On the power supply board, there is a connector with 80V and 13.2V connections. With power plugged in and the TV off, these measure 63.6V and 9.7V, respectively. The TV won't stay on, so getting voltages with the TV on is a bit tricky.

              I looked at all the capacitors and did not find any evidence of failure. Fuses appear to be intact as well.

              Are there any troubleshooting tips I can use to help diagnose the issue with this TV?

              Thanks!
              The connector CN2 has Fail and STB. What are the voltages on those two pins in standby and when you you switch on?
              Willing to help but I'm no expert.

                Comment

                • neilc6
                  Badcaps Legend
                  • Nov 2015
                  • 1550
                  • Canada
                  #5
                  Re: LG 65UH5500 Flashes on then off

                  Should search your model number to see if there are other posts.

                  https://www.badcaps.net/forum/showthread.php?t=84673

                    Comment

                    • pinstripebob
                      New Member
                      • Nov 2020
                      • 4
                      • USA
                      #6
                      Re: LG 65UH5500 Flashes on then off

                      Originally posted by dick_barton
                      The connector CN2 has Fail and STB. What are the voltages on those two pins in standby and when you you switch on?
                      If I have the TV unplugged then plug it in, it seems to turn itself on. Voltages measure 0V on these two pins at this time.

                      If I then press the power button, I believe that puts it into standby. STB measures 3.5V and Fail measures 0V.

                      It's a bit tough to tell if the TV is on or not since the display does not stay on.

                        Comment

                        • pinstripebob
                          New Member
                          • Nov 2020
                          • 4
                          • USA
                          #7
                          Re: LG 65UH5500 Flashes on then off

                          Originally posted by neilc6
                          Should search your model number to see if there are other posts.

                          https://www.badcaps.net/forum/showthread.php?t=84673
                          Good find on that thread, this YouTube video seems to have solved that person's issue which is described the same as mine: https://www.youtube.com/watch?v=5ir7...ature=youtu.be

                          I might buy one of the backlight testers to see if I have an issue with a backlight strip.

                            Comment

                            • abduln21
                              New Member
                              • Nov 2020
                              • 3
                              • USA
                              #8
                              Re: LG 65UH5500 Flashes on then off

                              Im almost 100% sure its your backlight. LG tvs are known for this issue

                                Comment

                                • RJARRRPCGP
                                  Badcaps Legend
                                  • Jul 2004
                                  • 6301
                                  • USA
                                  #9
                                  Re: LG 65UH5500 Flashes on then off

                                  Originally posted by abduln21
                                  Im almost 100% sure its your backlight. LG tvs are known for this issue
                                  Looks likely that I have evidence of LED problems! The 49UH6100 TV that I gave to my sister, looks oddly bluish, a purplish-blue and possibly some dead LEDs!
                                  ASRock B550 PG Velocita

                                  Ryzen 9 "Vermeer" 5900X

                                  32 GB G.Skill RipJaws V F4-3200C16D-32GVR

                                  Arc A770 16 GB

                                  eVGA Supernova G3 750W

                                  Western Digital Black SN850 1TB NVMe SSD

                                  Alienware AW3423DWF OLED




                                  "¡Me encanta "Me Encanta o Enlistarlo con Hilary Farr!" -Mí mismo

                                  "There's nothing more unattractive than a chick smoking a cigarette" -Topcat

                                  "Today's lesson in pissivity comes in the form of a ziplock baggie full of GPU extension brackets & hardware that for the last ~3 years have been on my bench, always in my way, getting moved around constantly....and yesterday I found myself in need of them....and the bastards are now nowhere to be found! Motherfracker!!" -Topcat

                                  "did I see a chair fly? I think I did! Time for popcorn!" -ratdude747

                                    Comment

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