Samsung UE55MU6120K Boot loop with backlight no video

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  • Davi.p
    Hobbist
    • Sep 2009
    • 4264
    • Italy - Milan

    #81
    Re: Samsung UE55MU6120K Boot loop with backlight no video

    yes, it seem the correct T-RDY3 point is the one marked by Lotas, not so easy to understand..
    Don't expect it will work for long time.. something wrong may exist too..
    Let us to know how it goes, i'm much curious..
    Last edited by Davi.p; 02-24-2023, 12:20 PM.

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    • fanaticgames
      Senior Member
      • May 2017
      • 138
      • italy

      #82
      Re: Samsung UE55MU6120K Boot loop with backlight no video

      Originally posted by lotas
      You didn't seem to put a jumper there.
      according to your photo then I made the bridge between pwm4 and rdy1, how can it be that it works now? it's still on without the jumper

      Update

      take some current photos with the TV on, the temperatures seem perfect both on the motherboard and on the flats of the right and left panel cards which are usually always hot
      Attached Files
      Last edited by fanaticgames; 02-24-2023, 12:21 PM.

      Comment

      • fanaticgames
        Senior Member
        • May 2017
        • 138
        • italy

        #83
        Re: Samsung UE55MU6120K Boot loop with backlight no video

        Originally posted by Davi.p
        yes, it seem the correct T-RDY3 point is the one marked by Lotas, not so easy to understand..
        Don't expect it will work for long time.. something wrong may exist too..
        Let us to know how it goes, i'm much curious..
        it certainly won't last for now it's been on for 30 minutes, maybe I'm talking bullshit could it be that some component "discharged" during these days of inactivity? the esd diodes??
        Last edited by fanaticgames; 02-24-2023, 12:34 PM.

        Comment

        • Davi.p
          Hobbist
          • Sep 2009
          • 4264
          • Italy - Milan

          #84
          Re: Samsung UE55MU6120K Boot loop with backlight no video

          no, nothing discharged, pwm4 might be the signal that goes to the power board and is for brightness level setting, T-RDY1 might be a fixed 3v i guess, putting pwm4 set to steady 3v could have set brightness of part of the backlights bars to full brightness.. nothing to do with lcd panel i think.. those 2 mosfets are probably final switching transistors for the pwm signals
          Last edited by Davi.p; 02-24-2023, 12:40 PM.

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          • fanaticgames
            Senior Member
            • May 2017
            • 138
            • italy

            #85
            Re: Samsung UE55MU6120K Boot loop with backlight no video

            Originally posted by Davi.p
            no, nothing discharged, pwm4 might be the signal that goes to the power board and is for brightness level setting, T-RDY1 might be a fixed 3v i guess, putting pwm4 set to steady 3v could have set brightness of part of the backlights bars to full brightness.. nothing to do with lcd panel i think.. those 2 mosfets are probably final switching transistors for the pwm signals
            but the jumper was held for 4/5 minutes with the TV on, now there is no jumper, I also turned it off for 5 minutes and turned it on again and it works regularly

            I also redid this wrong jumper last time
            Last edited by fanaticgames; 02-24-2023, 12:52 PM.

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            • Davi.p
              Hobbist
              • Sep 2009
              • 4264
              • Italy - Milan

              #86
              Re: Samsung UE55MU6120K Boot loop with backlight no video

              As obvious i don't know what happened, no schematics, no answers, i have a doubt but i let it stay in silence.. we will see

              Comment

              • fanaticgames
                Senior Member
                • May 2017
                • 138
                • italy

                #87
                Re: Samsung UE55MU6120K Boot loop with backlight no video

                Originally posted by Davi.p
                As obvious i don't know what happened, no schematics, no answers, i have a doubt but i let it stay in silence.. we will see
                out of curiosity I disconnected all the flats and reconnected (just to rule out a false contact) and I mounted the cover behind, it still works. Now I'm going to leave a movie playing, let's see...
                Last edited by fanaticgames; 02-24-2023, 01:19 PM.

                Comment

                • fanaticgames
                  Senior Member
                  • May 2017
                  • 138
                  • italy

                  #88
                  Re: Samsung UE55MU6120K Boot loop with backlight no video

                  has been on more than 10 hours without problems, I don't know what to say but it works

                  Comment

                  • Davi.p
                    Hobbist
                    • Sep 2009
                    • 4264
                    • Italy - Milan

                    #89
                    Re: Samsung UE55MU6120K Boot loop with backlight no video

                    i am developing from also other threads an idea that the main board stores in an eprom something like an error flag, the forcing of the tcon outputs can restore a visualization and reset that flag, maybe in certain cases the error flag is set due to a temporary malfunction, i'm following another interesting thread, if i have some news i'll let you inform..

                    Comment

                    • fanaticgames
                      Senior Member
                      • May 2017
                      • 138
                      • italy

                      #90
                      Re: Samsung UE55MU6120K Boot loop with backlight no video

                      Originally posted by Davi.p
                      i am developing from also other threads an idea that the main board stores in an eprom something like an error flag, the forcing of the tcon outputs can restore a visualization and reset that flag, maybe in certain cases the error flag is set due to a temporary malfunction, i'm following another interesting thread, if i have some news i'll let you inform..
                      which of the two eeprom? because I made a backup before doing other tests (I wanted to understand if it had a damaged firmware), I could do a new dump and compare if there are differences

                      Comment

                      • lotas
                        Badcaps Legend
                        • Jan 2016
                        • 4458
                        • Russia

                        #91
                        Re: Samsung UE55MU6120K Boot loop with backlight no video

                        25Q80 is responsible for T-Con.

                        Comment

                        • Davi.p
                          Hobbist
                          • Sep 2009
                          • 4264
                          • Italy - Milan

                          #92
                          Re: Samsung UE55MU6120K Boot loop with backlight no video

                          No, i think the more possible responsible is the main settings eprom, that is the 24c series eprom

                          Comment

                          • fanaticgames
                            Senior Member
                            • May 2017
                            • 138
                            • italy

                            #93
                            Re: Samsung UE55MU6120K Boot loop with backlight no video

                            Originally posted by Davi.p
                            No, i think the more possible responsible is the main settings eprom, that is the 24c series eprom
                            I have a backup of this before making the attempts I've made

                            Comment

                            • Davi.p
                              Hobbist
                              • Sep 2009
                              • 4264
                              • Italy - Milan

                              #94
                              Re: Samsung UE55MU6120K Boot loop with backlight no video

                              and the comparation what says?

                              Comment

                              • fanaticgames
                                Senior Member
                                • May 2017
                                • 138
                                • italy

                                #95
                                Re: Samsung UE55MU6120K Boot loop with backlight no video

                                Originally posted by Davi.p
                                and the comparation what says?
                                identical dumps, no difference

                                Comment

                                • Davi.p
                                  Hobbist
                                  • Sep 2009
                                  • 4264
                                  • Italy - Milan

                                  #96
                                  Re: Samsung UE55MU6120K Boot loop with backlight no video

                                  comparison not comparation sorry..

                                  Comment

                                  • fanaticgames
                                    Senior Member
                                    • May 2017
                                    • 138
                                    • italy

                                    #97
                                    Re: Samsung UE55MU6120K Boot loop with backlight no video

                                    bad news, the tv was installed on the wall in its old place with only the power cable and tv antenna connected, the first time it was turned on the error again ... it has been turned on 4:5 days lately without problems

                                    Comment

                                    • nomoresonys
                                      Badcaps Legend
                                      • Jan 2013
                                      • 12081
                                      • U.S.

                                      #98
                                      Re: Samsung UE55MU6120K Boot loop with backlight no video

                                      almost seems like something on the mainboard is just getting too hot once you get the back on and it back on the wall.

                                      Comment

                                      • nomoresonys
                                        Badcaps Legend
                                        • Jan 2013
                                        • 12081
                                        • U.S.

                                        #99
                                        Re: Samsung UE55MU6120K Boot loop with backlight no video

                                        my buddy tampatec fixed one by putting some good heatsinks on every chip that got pretty warm on the mainboard, might not do the trick but something pretty easy to try.
                                        Last edited by nomoresonys; 03-01-2023, 11:34 AM.

                                        Comment

                                        • fanaticgames
                                          Senior Member
                                          • May 2017
                                          • 138
                                          • italy

                                          #100
                                          Re: Samsung UE55MU6120K Boot loop with backlight no video

                                          Originally posted by nomoresonys
                                          almost seems like something on the mainboard is just getting too hot once you get the back on and it back on the wall.
                                          impossible has worked with the backcover for over 30 total hours

                                          Comment

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