LG55UH615T pulsating Redstanby LED

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  • wushumike
    Member
    • Jun 2016
    • 41
    • singapore

    #21
    Re: LG55UH615T pulsating Redstanby LED

    Originally posted by lotas
    Throw the wires on the cable, and you will find out where the problem is in the power supply or in the LED bar.

    Already did that...confirm is not LED strip because the light switch side....
    Attached Files

    Comment

    • wushumike
      Member
      • Jun 2016
      • 41
      • singapore

      #22
      Re: LG55UH615T pulsating Redstanby LED

      Originally posted by lotas
      Throw the wires on the cable, and you will find out where the problem is in the power supply or in the LED bar.

      I did that already...Confirm not LED strip.
      Last edited by wushumike; 02-24-2023, 06:02 PM.

      Comment

      • lotas
        Badcaps Legend
        • Jan 2016
        • 4474
        • Russia

        #23
        Re: LG55UH615T pulsating Redstanby LED

        So the problem is in the power supply (led driver), the LED strips are in order.

        Comment

        • wushumike
          Member
          • Jun 2016
          • 41
          • singapore

          #24
          Re: LG55UH615T pulsating Redstanby LED

          Originally posted by lotas
          Throw the wires on the cable, and you will find out where the problem is in the power supply or in the LED bar.
          I'll try Dav.P method to check the MOSFET and IC (I did purchase this IC 801 from Ebay but yet to arrive)

          Nothing can get worse, any suggestion to nail the problem are welcome....Only last resort yo get another PS board.

          Comment

          • lotas
            Badcaps Legend
            • Jan 2016
            • 4474
            • Russia

            #25
            Re: LG55UH615T pulsating Redstanby LED

            Well, it's better not to use the TV now until you fix the problem in the led driver.
            Do you know the IC801 number?
            Last edited by lotas; 02-24-2023, 06:39 PM.

            Comment

            • wushumike
              Member
              • Jun 2016
              • 41
              • singapore

              #26
              Re: LG55UH615T pulsating Redstanby LED

              IC 801 = MAP3516

              I try searching for Datasheet... not available.
              I can only assume this is a 2CH LED Backlight controller chip.

              Comment

              • Davi.p
                Hobbist Tech
                • Sep 2009
                • 4277
                • Italy - Milan

                #27
                Re: LG55UH615T pulsating Redstanby LED

                when you buy new ic801 buy n.2 because i think is bad also in your original board

                Comment

                • wushumike
                  Member
                  • Jun 2016
                  • 41
                  • singapore

                  #28
                  Re: LG55UH615T pulsating Redstanby LED

                  Originally posted by Davi.p
                  when you buy new ic801 buy n.2 because i think is bad also in your original board
                  Thanks Davi.p

                  You have nailed the problem.

                  Ironically, I repaired the original board instead of the one I purchased. I use the purchased (faulty board) and did some comparison.

                  So the problem of my original board is as follows:
                  1. IC 801 faulty ...... internal circuit issue and it also affects the reading of R806 (10K)
                  2. R822 4R7 value increased
                  3. While trying to unsolder the MOSFET Q802 5N40, one of the lead drop off , so I cant say if this MOSFET is good or bad....Anyway I don't have this part but replace it with 9N40 which is better spec then the one used.

                  Replace IC, 2 resistor , 1 MOSFET .... Power Up standalone and no smoke before connecting back to the TV..

                  All back to normal!!!!

                  Anyway I didn't bother to repair the CN board.... probably is the same problem as you mentioned.... IC801

                  Closing this thread.... For those who have same problem, can use this as a troubleshooting reference.

                  Thanks All who have chipped in for this troubleshooting.
                  Attached Files

                  Comment

                  • Davi.p
                    Hobbist Tech
                    • Sep 2009
                    • 4277
                    • Italy - Milan

                    #29
                    Re: LG55UH615T pulsating Redstanby LED

                    Ok happy to hear it.. bye!

                    Comment

                    • estrumpf
                      New Member
                      • Jan 2017
                      • 1
                      • Portugal

                      #30
                      Re: LG55UH615T pulsating Redstanby LED

                      Originally posted by wushumike
                      Thanks Davi.p

                      You have nailed the problem.

                      Ironically, I repaired the original board instead of the one I purchased. I use the purchased (faulty board) and did some comparison.

                      So the problem of my original board is as follows:
                      1. IC 801 faulty ...... internal circuit issue and it also affects the reading of R806 (10K)
                      2. R822 4R7 value increased
                      3. While trying to unsolder the MOSFET Q802 5N40, one of the lead drop off , so I cant say if this MOSFET is good or bad....Anyway I don't have this part but replace it with 9N40 which is better spec then the one used.

                      Replace IC, 2 resistor , 1 MOSFET .... Power Up standalone and no smoke before connecting back to the TV..

                      All back to normal!!!!

                      Anyway I didn't bother to repair the CN board.... probably is the same problem as you mentioned.... IC801

                      Closing this thread.... For those who have same problem, can use this as a troubleshooting reference.

                      Thanks All who have chipped in for this troubleshooting.
                      Hello

                      Plese do you confirme that the resistor next to the 4r7 the 010 is 1 ohm resistor I get 100k value. ????

                      Comment

                      • lotas
                        Badcaps Legend
                        • Jan 2016
                        • 4474
                        • Russia

                        #31
                        Re: LG55UH615T pulsating Redstanby LED

                        Originally posted by estrumpf
                        Hello

                        Plese do you confirme that the resistor next to the 4r7 the 010 is 1 ohm resistor I get 100k value. ????
                        01D - 100 kOm
                        Attached Files

                        Comment

                        • alltvrepairs
                          Badcaps Veteran
                          • Jan 2014
                          • 211
                          • Malta

                          #32
                          Originally posted by Storyteller12
                          Re: LG55UH615T pulsating Redstanby LED

                          These TVs have a lot of bad backlight issues. Sad part is only 1 led has to go bad for the whole tv to shut down.
                          Replacing backlights and turning the backlight setting down usually solves the issue. You can also modify the board to lower the amps to the backlights.
                          There is a thread that describes the process
                          Hi, bumped into this as have same issue. Have replaced all components mentioned here but 1 channel on pcb defective as TV restarts occassionally. Can you share the link for the modification mentioned please?

                          Comment

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