LG 50UH5530 Turns Off And Wont Turn On: diagnoses included

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  • jason123
    Badcaps Legend
    • Oct 2015
    • 1069
    • USA

    #21
    Re: LG 50UH5530 Turns Off And Wont Turn On: diagnoses included

    Originally posted by R_J
    What voltage do you have across C5? is it also fluctuating in standby mode?
    What is the main filter (C2/C3) voltage? does the pfc turn off in standby and back on when powered on?
    Yes C5 fluctuates between 14 and 20V
    C2/C3 have some ripple 392 to 406v, but PFC is on. I dont think it turns off on the model

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    • nomoresonys
      Badcaps Legend
      • Jan 2013
      • 12206
      • U.S.

      #22
      Re: LG 50UH5530 Turns Off And Wont Turn On: diagnoses included

      ok, forgot you had one working, that makes it easier, check each pin on those ic's in question with the good board, take note, then check them with original board, also check the transistors on the heatsinks and the diodes and resistors, check your voltages on the transformers too.
      Quit because THIS SITE LETS A ROGUE MEMBER TYPE ANY GARBAGE HE PLEASES AND THE POWERS THAT BE NEVER DO ANYTHING ABOUT IT SO HE NEVER QUITS. THEN YOU GET A PENALTY FOR RESPONDING TO HIS ATTACKS. BEEN GOING ON FOR WAY TOO LONG. DONE SUPPORTING A SITE THAT ALLOWS THIS BS.

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      • nomoresonys
        Badcaps Legend
        • Jan 2013
        • 12206
        • U.S.

        #23
        Re: LG 50UH5530 Turns Off And Wont Turn On: diagnoses included

        if all that checks out, what's left? down to caps or optos?
        Quit because THIS SITE LETS A ROGUE MEMBER TYPE ANY GARBAGE HE PLEASES AND THE POWERS THAT BE NEVER DO ANYTHING ABOUT IT SO HE NEVER QUITS. THEN YOU GET A PENALTY FOR RESPONDING TO HIS ATTACKS. BEEN GOING ON FOR WAY TOO LONG. DONE SUPPORTING A SITE THAT ALLOWS THIS BS.

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        • nomoresonys
          Badcaps Legend
          • Jan 2013
          • 12206
          • U.S.

          #24
          Re: LG 50UH5530 Turns Off And Wont Turn On: diagnoses included

          maybe check Q8, Q10, Q407, compare to good board.
          Quit because THIS SITE LETS A ROGUE MEMBER TYPE ANY GARBAGE HE PLEASES AND THE POWERS THAT BE NEVER DO ANYTHING ABOUT IT SO HE NEVER QUITS. THEN YOU GET A PENALTY FOR RESPONDING TO HIS ATTACKS. BEEN GOING ON FOR WAY TOO LONG. DONE SUPPORTING A SITE THAT ALLOWS THIS BS.

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          • nomoresonys
            Badcaps Legend
            • Jan 2013
            • 12206
            • U.S.

            #25
            Re: LG 50UH5530 Turns Off And Wont Turn On: diagnoses included

            and those 2 transistors by c57 and d24, d25.
            Quit because THIS SITE LETS A ROGUE MEMBER TYPE ANY GARBAGE HE PLEASES AND THE POWERS THAT BE NEVER DO ANYTHING ABOUT IT SO HE NEVER QUITS. THEN YOU GET A PENALTY FOR RESPONDING TO HIS ATTACKS. BEEN GOING ON FOR WAY TOO LONG. DONE SUPPORTING A SITE THAT ALLOWS THIS BS.

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            • nomoresonys
              Badcaps Legend
              • Jan 2013
              • 12206
              • U.S.

              #26
              Re: LG 50UH5530 Turns Off And Wont Turn On: diagnoses included

              look out for bad solder joints.
              Quit because THIS SITE LETS A ROGUE MEMBER TYPE ANY GARBAGE HE PLEASES AND THE POWERS THAT BE NEVER DO ANYTHING ABOUT IT SO HE NEVER QUITS. THEN YOU GET A PENALTY FOR RESPONDING TO HIS ATTACKS. BEEN GOING ON FOR WAY TOO LONG. DONE SUPPORTING A SITE THAT ALLOWS THIS BS.

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              • nomoresonys
                Badcaps Legend
                • Jan 2013
                • 12206
                • U.S.

                #27
                Re: LG 50UH5530 Turns Off And Wont Turn On: diagnoses included

                Q5. Q404. Q405. F3.
                Quit because THIS SITE LETS A ROGUE MEMBER TYPE ANY GARBAGE HE PLEASES AND THE POWERS THAT BE NEVER DO ANYTHING ABOUT IT SO HE NEVER QUITS. THEN YOU GET A PENALTY FOR RESPONDING TO HIS ATTACKS. BEEN GOING ON FOR WAY TOO LONG. DONE SUPPORTING A SITE THAT ALLOWS THIS BS.

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                • jason123
                  Badcaps Legend
                  • Oct 2015
                  • 1069
                  • USA

                  #28
                  Re: LG 50UH5530 Turns Off And Wont Turn On: diagnoses included

                  Originally posted by nomoresonys
                  Q5. Q404. Q405. F3.
                  These check out.

                  The only big difference I see between the boards is the orange Capacitor section (LED Drive Circuit) - C403, C404, C405

                  Good board reads 0.6 MOhm across these orange caps
                  Problematic board, reads 4.1 MOhm across these caps

                  Opto (and zener dioded - circled) Hot Side:
                  Good board 23.9 k
                  Bad board 2.4k
                  Attached Files

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                  • nomoresonys
                    Badcaps Legend
                    • Jan 2013
                    • 12206
                    • U.S.

                    #29
                    Re: LG 50UH5530 Turns Off And Wont Turn On: diagnoses included

                    "Opto (and zener dioded - circled) Hot Side:
                    Good board 23.9 k
                    Bad board 2.4k" That looks like a pretty big difference.
                    Quit because THIS SITE LETS A ROGUE MEMBER TYPE ANY GARBAGE HE PLEASES AND THE POWERS THAT BE NEVER DO ANYTHING ABOUT IT SO HE NEVER QUITS. THEN YOU GET A PENALTY FOR RESPONDING TO HIS ATTACKS. BEEN GOING ON FOR WAY TOO LONG. DONE SUPPORTING A SITE THAT ALLOWS THIS BS.

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                    • nomoresonys
                      Badcaps Legend
                      • Jan 2013
                      • 12206
                      • U.S.

                      #30
                      Re: LG 50UH5530 Turns Off And Wont Turn On: diagnoses included

                      I might be tempted to change all 5 if I had them on hand.
                      Quit because THIS SITE LETS A ROGUE MEMBER TYPE ANY GARBAGE HE PLEASES AND THE POWERS THAT BE NEVER DO ANYTHING ABOUT IT SO HE NEVER QUITS. THEN YOU GET A PENALTY FOR RESPONDING TO HIS ATTACKS. BEEN GOING ON FOR WAY TOO LONG. DONE SUPPORTING A SITE THAT ALLOWS THIS BS.

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                      • jason123
                        Badcaps Legend
                        • Oct 2015
                        • 1069
                        • USA

                        #31
                        Re: LG 50UH5530 Turns Off And Wont Turn On: diagnoses included

                        Originally posted by nomoresonys
                        "Opto (and zener dioded - circled) Hot Side:
                        Good board 23.9 k
                        Bad board 2.4k" That looks like a pretty big difference.
                        Yes.. factor of 10
                        Though I find it odd that there seems to be 2 failures.. one on the hot side (somewhat isolated?) and one on the cold side
                        Last edited by jason123; 05-01-2022, 06:54 AM.

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                        • nomoresonys
                          Badcaps Legend
                          • Jan 2013
                          • 12206
                          • U.S.

                          #32
                          Re: LG 50UH5530 Turns Off And Wont Turn On: diagnoses included

                          maybe switch out c404.
                          Quit because THIS SITE LETS A ROGUE MEMBER TYPE ANY GARBAGE HE PLEASES AND THE POWERS THAT BE NEVER DO ANYTHING ABOUT IT SO HE NEVER QUITS. THEN YOU GET A PENALTY FOR RESPONDING TO HIS ATTACKS. BEEN GOING ON FOR WAY TOO LONG. DONE SUPPORTING A SITE THAT ALLOWS THIS BS.

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                          • nomoresonys
                            Badcaps Legend
                            • Jan 2013
                            • 12206
                            • U.S.

                            #33
                            Re: LG 50UH5530 Turns Off And Wont Turn On: diagnoses included

                            do you have about 1 ohm across the opto?
                            Quit because THIS SITE LETS A ROGUE MEMBER TYPE ANY GARBAGE HE PLEASES AND THE POWERS THAT BE NEVER DO ANYTHING ABOUT IT SO HE NEVER QUITS. THEN YOU GET A PENALTY FOR RESPONDING TO HIS ATTACKS. BEEN GOING ON FOR WAY TOO LONG. DONE SUPPORTING A SITE THAT ALLOWS THIS BS.

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                            • jason123
                              Badcaps Legend
                              • Oct 2015
                              • 1069
                              • USA

                              #34
                              Re: LG 50UH5530 Turns Off And Wont Turn On: diagnoses included

                              Originally posted by nomoresonys
                              do you have about 1 ohm across the opto?
                              cold side about 1k on both boards
                              hot side 23k on good board, and 2.3k on the bad board

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                              • nomoresonys
                                Badcaps Legend
                                • Jan 2013
                                • 12206
                                • U.S.

                                #35
                                Re: LG 50UH5530 Turns Off And Wont Turn On: diagnoses included

                                what are you getting on that zener in diode mode?
                                Quit because THIS SITE LETS A ROGUE MEMBER TYPE ANY GARBAGE HE PLEASES AND THE POWERS THAT BE NEVER DO ANYTHING ABOUT IT SO HE NEVER QUITS. THEN YOU GET A PENALTY FOR RESPONDING TO HIS ATTACKS. BEEN GOING ON FOR WAY TOO LONG. DONE SUPPORTING A SITE THAT ALLOWS THIS BS.

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                                • jason123
                                  Badcaps Legend
                                  • Oct 2015
                                  • 1069
                                  • USA

                                  #36
                                  Re: LG 50UH5530 Turns Off And Wont Turn On: diagnoses included

                                  Originally posted by nomoresonys
                                  what are you getting on that zener in diode mode?
                                  0.7 VF... tests as good. Out of circuit (when diode removed) hot side of opto now measures 23k (same as good board)

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                                  • nomoresonys
                                    Badcaps Legend
                                    • Jan 2013
                                    • 12206
                                    • U.S.

                                    #37
                                    Re: LG 50UH5530 Turns Off And Wont Turn On: diagnoses included

                                    hmm, seems ok, wonder if it's those caps to blame?
                                    Quit because THIS SITE LETS A ROGUE MEMBER TYPE ANY GARBAGE HE PLEASES AND THE POWERS THAT BE NEVER DO ANYTHING ABOUT IT SO HE NEVER QUITS. THEN YOU GET A PENALTY FOR RESPONDING TO HIS ATTACKS. BEEN GOING ON FOR WAY TOO LONG. DONE SUPPORTING A SITE THAT ALLOWS THIS BS.

                                    Comment

                                    • jason123
                                      Badcaps Legend
                                      • Oct 2015
                                      • 1069
                                      • USA

                                      #38
                                      Re: LG 50UH5530 Turns Off And Wont Turn On: diagnoses included

                                      So transfered the good zener from good board to bad. Now bad board reads 23k across hot opto side. TV powered up for 3 seconds then off. Something else is a problem.

                                      Disconnected LED Connector (to exclude these caps) and no change. I don't think these caps are to blame. Took them off voard, and did ESR and C measurements. No significant difference

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                                      • nomoresonys
                                        Badcaps Legend
                                        • Jan 2013
                                        • 12206
                                        • U.S.

                                        #39
                                        Re: LG 50UH5530 Turns Off And Wont Turn On: diagnoses included

                                        ok, yeah the ceramics are usually pretty reliable, wonder if it's the opto?
                                        Quit because THIS SITE LETS A ROGUE MEMBER TYPE ANY GARBAGE HE PLEASES AND THE POWERS THAT BE NEVER DO ANYTHING ABOUT IT SO HE NEVER QUITS. THEN YOU GET A PENALTY FOR RESPONDING TO HIS ATTACKS. BEEN GOING ON FOR WAY TOO LONG. DONE SUPPORTING A SITE THAT ALLOWS THIS BS.

                                        Comment

                                        • nomoresonys
                                          Badcaps Legend
                                          • Jan 2013
                                          • 12206
                                          • U.S.

                                          #40
                                          Re: LG 50UH5530 Turns Off And Wont Turn On: diagnoses included

                                          so you tested the pins of those 2 ic's to make sure both boards give the same readings? and tested all the transistors including the little ones standing by themselves?
                                          Quit because THIS SITE LETS A ROGUE MEMBER TYPE ANY GARBAGE HE PLEASES AND THE POWERS THAT BE NEVER DO ANYTHING ABOUT IT SO HE NEVER QUITS. THEN YOU GET A PENALTY FOR RESPONDING TO HIS ATTACKS. BEEN GOING ON FOR WAY TOO LONG. DONE SUPPORTING A SITE THAT ALLOWS THIS BS.

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