Sharp LC-50UB30U no backlight

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  • landyboy
    Badcaps Veteran
    • Apr 2013
    • 443
    • USA

    #1

    Sharp LC-50UB30U no backlight

    Have the above TV isolated it to the Led? There is a picture on the panel with sound but no backlights. Looking at the board it appears to have 2 strings of Led's. Testing from ground to Voltout1 and Voltout2 both voltages are 89.1VDC with led strings plugged in or unplugged. Seems low but I haven't worked on many led units yet. What voltage should I be seeing on those pins? Am I reading it correctly?

    Thanks
    Attached Files
  • landyboy
    Badcaps Veteran
    • Apr 2013
    • 443
    • USA

    #2
    Re: Sharp LC-50UB30U no backlight

    After more testing it appears when I first turn the power on with ledss trips unplugged it starts at about 115 vdc then settles to 85vdc. If I do it with leds plugged in its starts at 30vdc and continues to go down. I'm assuming some sort of protect mode.

    Comment

    • budm
      Badcaps Legend
      • Feb 2010
      • 40746
      • USA

      #3
      Re: Sharp LC-50UB30U no backlight

      But how about the Voltage reading on LED1 and LED 2 pins with ref to the chassis GND?
      You need to keep the meter probes in place while turning on the TV so you can see what the Voltage shows each time you turn on the TV, you will be doing that twice.
      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

      • landyboy
        Badcaps Veteran
        • Apr 2013
        • 443
        • USA

        #4
        Re: Sharp LC-50UB30U no backlight

        I decided to take the set apart down to the led strips. Put some 9v batts in series and tested each strip. On the bottom strip all but 4 lit up brightly, 2nd and 3rd strip from the bottom nothing at all and the top strip had about half of the lights come on dim. Pretty sure I have a bunch of bad Led's. No replacement strips available anywhere....
        Attached Files

        Comment

        • budm
          Badcaps Legend
          • Feb 2010
          • 40746
          • USA

          #5
          Re: Sharp LC-50UB30U no backlight

          What is the LCD panel model number, when you get that then you can search for the LED strips that will fit that panel.
          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

          • landyboy
            Badcaps Veteran
            • Apr 2013
            • 443
            • USA

            #6
            Re: Sharp LC-50UB30U no backlight

            T500QVN02.0 really can't find anything out there this panel. I did get a quote for a repair on the strips though.

            Comment

            • budm
              Badcaps Legend
              • Feb 2010
              • 40746
              • USA

              #7
              Re: Sharp LC-50UB30U no backlight

              I just search the web using that model:
              http://www.shopjimmy.com/hisense-rsa...rips-50h7c.htm
              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

              • mmartell
                Badcaps Legend
                • Oct 2013
                • 3189
                • Canada

                #8
                Re: Sharp LC-50UB30U no backlight

                Lol

                Comment

                • Andrew F. Ali
                  Badcaps Legend
                  • Jan 2014
                  • 2450
                  • Trinidad & Tobago

                  #9
                  Re: Sharp LC-50UB30U no backlight

                  Originally posted by budm
                  I just search the web using that model:
                  http://www.shopjimmy.com/hisense-rsa...rips-50h7c.htm
                  Looks like this will work for your TV. If you can get the spacing measurement between LEDs to see if they match yours, go ahead and replace ALL the strips and get your baby up and running again.

                  Comment

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