Sony KDL-55HX800 no power

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  • digitalscorpion
    Member
    • Mar 2012
    • 37
    • USA
    #1

    Sony KDL-55HX800 no power

    No power. No LEDs.
    Purchased power supply repair kit from SJ.. Same symptoms. No power, no LEDs.
    Standby voltage is present = 3.3v (CN6152, Pin1). No other voltages.
    Jumpered Pins 1 + 3, Standby voltage pulses from 3v => 0V => 3v, repeatedly.
    Transistors and diodes seem to test OK. Not sure how to test MIP2H2(IC6201) or CXA3740M(IC6502), although both of these are new and installed with no issue.
    Power supply board for reference. Thoughts?
    Attached Files
    Tags: None
    • R_J
      Badcaps Legend
      • Jun 2012
      • 9535
      • Canada
      #2
      Re: Sony KDL-55HX800 no power

      The standby voltage should'nt drop, If you can try loading just the 3.3v standby with around a 5Ω resistor to see if the standby voltage drops, If it does I would suspect C6205, C6210 and C6206 are weak.

        Comment

        • digitalscorpion
          Member
          • Mar 2012
          • 37
          • USA
          #3
          Re: Sony KDL-55HX800 no power

          Originally posted by R_J
          The standby voltage should'nt drop, If you can try loading just the 3.3v standby with around a 5Ω resistor to see if the standby voltage drops, If it does I would suspect C6205, C6210 and C6206 are weak.
          Do you mean take that standby pin(pin1) with a 5ohm resistor to ground? This would be different vs pin1 jumped to pin3?

            Comment

            • digitalscorpion
              Member
              • Mar 2012
              • 37
              • USA
              #4
              Re: Sony KDL-55HX800 no power

              Looking for more thoughts on this..

              I've done a resistor from pin 1 to pin 3 as well. No difference. Only voltages shown is the standby, then when forced on its does up/downs from 3v to 0v (cycling).. Can't get this power board to turn on..

                Comment

                • neilc6
                  Badcaps Legend
                  • Nov 2015
                  • 1550
                  • Canada
                  #5
                  Re: Sony KDL-55HX800 no power

                  No front leds but standby power present means main board is suspect. Not the same model but worth a read https://www.badcaps.net/forum/showthread.php?t=81575
                  Last edited by neilc6; 06-30-2020, 09:53 AM.

                    Comment

                    • digitalscorpion
                      Member
                      • Mar 2012
                      • 37
                      • USA
                      #6
                      Re: Sony KDL-55HX800 no power

                      If main board removed from equation, Shouldn't I be able to get full supply voltages on the power board (using jumpered power on method)?
                      With Power board installed, and plugged into main board, fluctuating standby voltage is same scenario (3v-0v-3v).

                        Comment

                        • neilc6
                          Badcaps Legend
                          • Nov 2015
                          • 1550
                          • Canada
                          #7
                          Re: Sony KDL-55HX800 no power

                          Service manual for your model. Looks like your model is LCD. I don't bother with LCD TVs any more because of their weight, age, being obsolete and low resale value.
                          Last edited by neilc6; 06-30-2020, 10:38 AM.

                            Comment

                            • digitalscorpion
                              Member
                              • Mar 2012
                              • 37
                              • USA
                              #8
                              Re: Sony KDL-55HX800 no power

                              Originally posted by neilc6
                              Service manual for your model. Looks like your model is LCD. I don't bother with LCD TVs any more because of their weight, age, being obsolete and low resale value.
                              Thank you for the link.
                              hopefully I can report back with findings and positive results.

                                Comment

                                • R_J
                                  Badcaps Legend
                                  • Jun 2012
                                  • 9535
                                  • Canada
                                  #9
                                  Re: Sony KDL-55HX800 no power

                                  Originally posted by digitalscorpion
                                  Do you mean take that standby pin(pin1) with a 5ohm resistor to ground? This would be different vs pin1 jumped to pin3?
                                  Yes, resistor to ground, this will check if the 3.3 volt standby supply is providing enough current or not. If the 3.3 volts drops with the resistor in place then the standby circuit has a problem, if it stays up, disconnect the main board and try a 1k between 3.3v standby and POWER_ON pin to see if the other voltages come up.
                                  A 5Ω resistor across the 3.3v standby should draw about 660ma
                                  Last edited by R_J; 06-30-2020, 12:36 PM.

                                    Comment

                                    • digitalscorpion
                                      Member
                                      • Mar 2012
                                      • 37
                                      • USA
                                      #10
                                      Re: Sony KDL-55HX800 no power

                                      Update: After triple checking my SJ parts kit, I was then getting a blinking red indicator light. Blinks = 12v issue. Could not troubleshoot any further. Ordered replacement power supply board from china. TV works now. Thanks for assistance.

                                        Comment

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