Sharp LC-50LB371U

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  • ljintexas
    LJinTexas
    • Jan 2015
    • 669
    • USA
    #1

    Sharp LC-50LB371U

    When power is applied, red LED comes on bright, then dim, then flashes slowly.
    If I push the power button, the flashing will stop and LED will remain lit. If I push power again it makes a clunk audio sound and LED is off. DIM pin on smps changes from 2.4v to 3.3 volts. PS ON has continuous 3.3 volts if set is plugged in. Pins 15 and 16 measure 0 volts in all states of operation. All pins marked 12V do have 12 volts and GND pins are grounded. At no time does backlight come on. I did find 3.3 volts and 12 volts on the TCON when set was in what I think is ON state.
    Attached Files
    Last edited by ljintexas; 01-31-2021, 07:11 AM.
    Tags: None
    • ljintexas
      LJinTexas
      • Jan 2015
      • 669
      • USA
      #2
      Re: Sharp LC-50LB371U

      Here is TCon. Sorry I left it out.
      Attached Files

        Comment

        • handsworth
          Senior Member
          • Oct 2015
          • 174
          • United States
          #3
          Re: Sharp LC-50LB371U

          This Sharp series is notorius for bad leds. Do flashlight test or check leds with a tester.

            Comment

            • neilc6
              Badcaps Legend
              • Nov 2015
              • 1550
              • Canada
              #4
              Re: Sharp LC-50LB371U

              TV turning on and off with no backlight is a symptom of bad backlights. Think I have done that model before or similar. My replacement strips were a bit off and caused the reflector sheet to shift a bit and pinch on the edge causing a slight shadow. Didn't want to remove the panel again.

                Comment

                • budm
                  Badcaps Legend
                  • Feb 2010
                  • 40746
                  • USA
                  #5
                  Re: Sharp LC-50LB371U

                  How about Voltage on pin 2 O/F (BL-ON)?
                  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

                    • ljintexas
                      LJinTexas
                      • Jan 2015
                      • 669
                      • USA
                      #6
                      Re: Sharp LC-50LB371U

                      Pin 1 = 2.4V, Pin 2= 3.3V
                      Flashlight test shows getting started screen.
                      V+LED1 = 65V to chassis, V+LED2 = 65V to chassis. V+LED1 = 0V to V-LED1, V+LED2 = 0V to V-LED2.
                      LED1 circuit = OL, LED2 circuit = 2.3Mohms

                      I think the LEDs are shot!

                      Thanks to all for your assistance.

                      LJ
                      Last edited by ljintexas; 02-02-2021, 06:12 AM.

                        Comment

                        • ljintexas
                          LJinTexas
                          • Jan 2015
                          • 669
                          • USA
                          #7
                          Re: Sharp LC-50LB371U

                          Has anyone done LEDs on one of these? I have done a 46 but not a 50. Some of them are a real pain to get apart and back together.

                            Comment

                            • neilc6
                              Badcaps Legend
                              • Nov 2015
                              • 1550
                              • Canada
                              #8
                              Re: Sharp LC-50LB371U

                              I recall it was a pain to do. Double sided tape and lots of screws. Sharps are made by Hisense. One test I do to check the panel is to power the backlight with my tester only and turn on the TV.
                              Last edited by neilc6; 02-02-2021, 09:38 AM.

                                Comment

                                • handsworth
                                  Senior Member
                                  • Oct 2015
                                  • 174
                                  • United States
                                  #9
                                  Re: Sharp LC-50LB371U

                                  Yeah, lots of small screws holding the strips down. Don't replace them with preowned either as you will be back doing it again very shortly. Buy complete set of new ones. Lastly, the screen is probably glued down in a few sections around the edges. See threads on best way to separate it.

                                    Comment

                                    • ljintexas
                                      LJinTexas
                                      • Jan 2015
                                      • 669
                                      • USA
                                      #10
                                      Re: Sharp LC-50LB371U

                                      Did the flashlight test and saw the set up screen.

                                        Comment

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