LG 55LV5500-UA no picture or sound

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  • dick_barton
    Badcaps Legend
    • Aug 2015
    • 6643
    • Wales

    #61
    Re: LG 55LV5500-UA no picture or sound

    Looks like some sort of feedback error signal to the main IC is keeping the backlights off.
    Last edited by dick_barton; 03-31-2017, 08:00 AM.
    Willing to help but I'm no expert.

    Comment

    • budm
      Badcaps Legend
      • Feb 2010
      • 40746
      • USA

      #62
      Re: LG 55LV5500-UA no picture or sound

      Originally posted by Dgtech
      Something just will not let me give up on this TV yet. I followed the jumper instructions on how to get the backlights to turn on. They and thier voltages are correct. They stay on as long as I have the set on.

      Now... I just using that as a starting point. The circuit never fires up the backlights. If the test has me jumper 3.5 volts to the pin 18.... then pin 18 (as shown in this drawing) should have about that 3.5 voltage for a normal running situation. This drawing taken from the training manual shows 3.28 volts should be present there on pin 18.
      My board only shows .034 on pin 18 when hooked up regular ( not jumpered). Please take a look at my notes on the drawing for that circuit. They dont seem right at all but where do I look next? I would assume taht IC602 is putting out the right voltage on that pin 10 (3.5) and then is Q504 isnt doing it's job? One thing that I didnt check is for the emmitter to be properly grounded as shown in the drawing. I dont know if that would cause it to be in the state that it is or not. My transistor theory is kinda rusty at this point.
      Can you please upload the PDF of this training manual?
      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

      • drkthundr
        Member
        • Feb 2016
        • 45
        • United States

        #63
        Re: LG 55LV5500-UA no picture or sound

        I think the training manual he is talking about is this page.
        Attached Files

        Comment

        • drkthundr
          Member
          • Feb 2016
          • 45
          • United States

          #64
          Re: LG 55LV5500-UA no picture or sound

          I'm having the same issue different model.
          https://www.badcaps.net/forum/showthread.php?t=55572

          Comment

          • Dgtech
            E. Technician
            • Apr 2009
            • 1462
            • Steeler

            #65
            Re: LG 55LV5500-UA no picture or sound

            Here are both the SERVICE MANUAL and the TRAINING MANUAL. Very similar models that use the same boards with the same part numbers and pinouts.
            Attached Files
            The strong-minded rise to the challenge of their goals,the weak-minded BECOME HATERS

            Comment

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