Hisense 50H5G has sound no backlight

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  • nwcs
    Badcaps Veteran
    • Dec 2015
    • 311
    • usa
    #1

    Hisense 50H5G has sound no backlight

    I just got this one, customer was watching and the picture faded but they could still see the picture. Changed the channel and picture came back. Then later it went black. I can see the picture but no back light. I am suspecting a open led but I do not see the usual flash of back light when I turn it on. Checked the voltages to the led's 220V on red lead and 110V on white. XP805 on the power supply board is gnd, gnd, pwm is 5v, sw is 4v, 12, 12, stb is 4v, gnd then the last two are both 19v but should be 16v. Am I right in thinking it is a open led or should I be looking at something else?
    Attached Files
    Tags: None
    • budm
      Badcaps Legend
      • Feb 2010
      • 40746
      • USA
      #2
      Re: Hisense 50H5G has sound no backlight

      More likely open circuit in the LED strings due to open LED or open connections between LED strips.
      You only has two wires to the LED strips inside the panel so the strips are connected in series to form one long LED string.
      Never stop learning
      Basic LCD TV and Monitor troubleshooting guides.
      http://www.badcaps.net/forum/showthr...956#post305956

      Voltage Regulator (LDO) testing:
      http://www.badcaps.net/forum/showthr...999#post300999

      Inverter testing using old CFL:
      http://www.badcaps.net/forum/showthr...er+testing+cfl

      Tear down pictures : Hit the ">" Show Albums and stories" on the left side
      http://s807.photobucket.com/user/budm/library/

      TV Factory reset codes listing:
      http://www.badcaps.net/forum/showthread.php?t=24809

        Comment

        • nwcs
          Badcaps Veteran
          • Dec 2015
          • 311
          • usa
          #3
          Re: Hisense 50H5G has sound no backlight

          Kind of what I thought. I have been replacing led strips like crazy in LG and toshiba tvs but they always seem to flash the few leds that do light up, and since they usually have more than two that makes sense. I will take the panel apart and take a look. I am not even sure if the led's are available for this TV.

            Comment

            • budm
              Badcaps Legend
              • Feb 2010
              • 40746
              • USA
              #4
              Re: Hisense 50H5G has sound no backlight

              The LED strips/LEDs are connected in series like Christmas lights so one goes open circuit then the whole thing will not light up, but if the LED shorted out then the string will still light up.
              Never stop learning
              Basic LCD TV and Monitor troubleshooting guides.
              http://www.badcaps.net/forum/showthr...956#post305956

              Voltage Regulator (LDO) testing:
              http://www.badcaps.net/forum/showthr...999#post300999

              Inverter testing using old CFL:
              http://www.badcaps.net/forum/showthr...er+testing+cfl

              Tear down pictures : Hit the ">" Show Albums and stories" on the left side
              http://s807.photobucket.com/user/budm/library/

              TV Factory reset codes listing:
              http://www.badcaps.net/forum/showthread.php?t=24809

                Comment

                • nwcs
                  Badcaps Veteran
                  • Dec 2015
                  • 311
                  • usa
                  #5
                  Re: Hisense 50H5G has sound no backlight

                  Removed the lcd panel and tested all of the led strips. Found two bad led's in one strip were open. I want to make sure but has anyone bypassed the led's by shorting around them?
                  Attached Files

                    Comment

                    • budm
                      Badcaps Legend
                      • Feb 2010
                      • 40746
                      • USA
                      #6
                      Re: Hisense 50H5G has sound no backlight

                      Not good idea to bypass, you can use 3.3V 1W Zener connected in reverse bias or use 5 1N4007 connected in series to simulate Vf of one LED.

                      https://www.badcaps.net/forum/showthread.php?t=46403

                      https://www.badcaps.net/forum/showthread.php?t=51251
                      Last edited by budm; 01-29-2016, 04:54 PM.
                      Never stop learning
                      Basic LCD TV and Monitor troubleshooting guides.
                      http://www.badcaps.net/forum/showthr...956#post305956

                      Voltage Regulator (LDO) testing:
                      http://www.badcaps.net/forum/showthr...999#post300999

                      Inverter testing using old CFL:
                      http://www.badcaps.net/forum/showthr...er+testing+cfl

                      Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                      http://s807.photobucket.com/user/budm/library/

                      TV Factory reset codes listing:
                      http://www.badcaps.net/forum/showthread.php?t=24809

                        Comment

                        • nwcs
                          Badcaps Veteran
                          • Dec 2015
                          • 311
                          • usa
                          #7
                          Re: Hisense 50H5G has sound no backlight

                          I will try that. I need to order the diodes first since I do not seem to have any. I just got back into TV repair after being out of it for 10 years. All of the TV repair shops in our county have closed for health or other reasons.

                            Comment

                            • nwcs
                              Badcaps Veteran
                              • Dec 2015
                              • 311
                              • usa
                              #8
                              Re: Hisense 50H5G has sound no backlight

                              Well it turns out I did have some 1n4728 zener's in the store soldered them in and now all of the led's work now. Thanks for all of the help BUDM.

                                Comment

                                • budm
                                  Badcaps Legend
                                  • Feb 2010
                                  • 40746
                                  • USA
                                  #9
                                  Re: Hisense 50H5G has sound no backlight

                                  Thanks for the follow-up, you should also turn down the Backlights level as low as you can to extend the life of the LEDs.
                                  Never stop learning
                                  Basic LCD TV and Monitor troubleshooting guides.
                                  http://www.badcaps.net/forum/showthr...956#post305956

                                  Voltage Regulator (LDO) testing:
                                  http://www.badcaps.net/forum/showthr...999#post300999

                                  Inverter testing using old CFL:
                                  http://www.badcaps.net/forum/showthr...er+testing+cfl

                                  Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                                  http://s807.photobucket.com/user/budm/library/

                                  TV Factory reset codes listing:
                                  http://www.badcaps.net/forum/showthread.php?t=24809

                                    Comment

                                    • nwcs
                                      Badcaps Veteran
                                      • Dec 2015
                                      • 311
                                      • usa
                                      #10
                                      Re: Hisense 50H5G has sound no backlight

                                      I do that on any tv that I replace the led's in. Thanks again for the help.

                                        Comment

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