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LG 55UB8500 no picture.

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    LG 55UB8500 no picture.

    Hi, I have problem with this LG model 55UB8500, it have no picture,I check voltage in Power Supply , all the voltages 24 volts 12 volts, 3.5 volts are there, when I push power ON, it have Red led on main board it stays red no blinking, on the power supply board when I put Power ON on connector P 802 LED + it have 48 volts on connector P 802 Led+ 48 volts, could you tell me what I have to check now?

    #2
    Re: LG 55UB8500 no picture.

    Are backlights coming on, flashing? If not, is there a picture on screen using a flashlight?
    I assume no responsibility for any stupid suggestions I might post.

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      #3
      Re: LG 55UB8500 no picture.

      No picture with flashlight, no picture flashing

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        #4
        Re: LG 55UB8500 no picture.

        Someone?

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          #5
          Re: LG 55UB8500 no picture.

          check fuse on tcon board, check for 12 volts on each side, neg. probe on metal chassis.

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            #6
            Re: LG 55UB8500 no picture.

            I check it and no voltage on this fuse, I think Main Board is the problem

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              #7
              Re: LG 55UB8500 no picture.

              fuse has continuity, not blown?

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                #8
                Re: LG 55UB8500 no picture.

                Yes continuity no voltage on it

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                  #9
                  Re: LG 55UB8500 no picture.

                  need a good clear picture of the legend/map of the expected voltages of the connector on powerboard, can try stand alone test.

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                    #10
                    Re: LG 55UB8500 no picture.

                    here's a quick test, very carefully check the voltage of the big 460 volt caps on powerboard with tv powered on, careful to only touch it with the probes, 400 VOLTS is a lot of volts and can be deadly.

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                      #11
                      Re: LG 55UB8500 no picture.

                      I check and they have 400 volts, on my first post I told I have voltages on the plug who's goes on Main Board

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                        #12
                        Re: LG 55UB8500 no picture.

                        Check transistor that switches on voltage to t-con.
                        I assume no responsibility for any stupid suggestions I might post.

                        Comment


                          #13
                          Re: LG 55UB8500 no picture.

                          Do you have location number?

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                            #14
                            Re: LG 55UB8500 no picture.

                            Tv turning on with backlight but no picture, tcon board is first suspect. Connect one side at a time between tcon and panel to see if you get half an image. If you do, there is a panel short on the bad side and you can try the tape cutoff method. If no side displays an image, it is worth trying to replace the tcon.

                            OK, just noticed no voltage on fuse. Should have 12V with TV on. 12V is typically switched with a FET on the main board when you turn the TV on and passes through several pins of the LVDS connector.
                            Last edited by neilc6; 07-29-2022, 11:14 AM.

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                              #15
                              Re: LG 55UB8500 no picture.

                              it have no backlight at first

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                                #16
                                Re: LG 55UB8500 no picture.

                                Originally posted by Fripacks View Post
                                Do you have location number?
                                How could I have location? You provide no pictures or schematic. Trace the 12v from t-con terminals back to trans. that controls the power to t-con.
                                I assume no responsibility for any stupid suggestions I might post.

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                                  #17
                                  Re: LG 55UB8500 no picture.

                                  one of those, hey guys look into your magic 8 ball and tell me what's wrong with my tv. This is tv troubleshooting, tests need to be done promptly, as instructed and pictures can speed it up IMMENSELY, if I get a fighter I lose interest very quickly.

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                                    #18
                                    Re: LG 55UB8500 no picture.

                                    That's photo of TCON , I don't have schematic of the tv
                                    Attached Files

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                                      #19
                                      Re: LG 55UB8500 no picture.

                                      Originally posted by Fripacks View Post
                                      I check and they have 400 volts, on my first post I told I have voltages on the plug who's goes on Main Board
                                      every test has a purpose and I very seldom do not comprehend what I read, so I already know you got what is printed on the legend, you seem to be bothered by people trying to help you and you can't follow simple instructions, DONE.
                                      Last edited by nomoresonys; 07-29-2022, 12:12 PM.

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                                        #20
                                        Re: LG 55UB8500 no picture.

                                        Why are you giving picture of t-con? You said you have no voltage going to t-con. Thus you need to look on main board and find where you are losing the 12v.
                                        I assume no responsibility for any stupid suggestions I might post.

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