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Samsung LA40C530F1RXXA Backlight Shuts Off

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    Samsung LA40C530F1RXXA Backlight Shuts Off

    Hi All.
    I have the above Samsung LCD TV,
    When first plugged in and powered on, it works fine for 20 minutes or so. The backlight then shuts off (but sound is still fine, and I can still see the image working by shining a flashlight into the screen.)
    If i restart it shortly thereafter, the Backlight only stays on for at most a minute or 2, then shuts off.
    WHen on, the backlight looks even.

    I have cleaned both the PSU and inverter boards.

    LD (Pins 7 and 8) are 9.6vdc when the backlight is on. It then drops low (maybe to 2vdc), at which time the Backlight turns off, they then go back up to 9.6v. But the backlight remains off. I think the other day I actually noticed the voltage drop twice before the backlight cut out.

    B13V is 12.52v stable

    FB1 and FB2 are both 0v constant (unless there is a spike too short for my multimeter to detect)

    Any suggestions on where to look. I believe it may be heat related, either Capacitor or one of the CFL tubes, But on the PSU board, I do not notice any large electrolytic caps in the Inverter Section for the CFLS.

    I have a diagram for the PSU board and it's interconnects, but I am stumped.

    I was told if I could get it working, I could keep it, and the wife would really like a larger TV for the Lounge, So I am trying my best.

    Thanks for any info you can provide.

    Peter

    #2
    Re: Samsung LA40C530F1RXXA Backlight Shuts Off

    Try turning down the backlights NOT the brightness, see if tv stays on longer, can also try heating powerboard a small section at a time, see if tv comes on after it goes out.

    Comment


      #3
      Re: Samsung LA40C530F1RXXA Backlight Shuts Off

      You set has balancer board, so look at these two videos:
      https://www.youtube.com/watch?v=oE6K4xBVweA
      https://www.youtube.com/watch?v=Dh01ZepjDp0
      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


        #4
        Re: Samsung LA40C530F1RXXA Backlight Shuts Off

        Thank you, the 2nd YT video looks the most promising.
        I assume that (like the problem he had), my Multimeter is too slow to catch the spike....
        Guess I have something to do tonight then...

        Comment


          #5
          Re: Samsung LA40C530F1RXXA Backlight Shuts Off

          Notice about 16:30 mark, he goes with a ground out method, the green wire, you don't have to solder a "tab" on, can just hold the clip in place on the sense line, if tv stays on you found the problem, HEED THE 1000 VOLT WARNING ON THE RIGHT SIDE THAT'S A DEADLY VOLT.
          Last edited by nomoresonys; 02-26-2019, 04:29 AM.

          Comment


            #6
            Re: Samsung LA40C530F1RXXA Backlight Shuts Off

            Thanks all. I came right. It was CFL tube no 9 or 10.
            I have bypassed the transformer for it, and the TV is working great now.
            And I have made a video of fixing it :
            https://youtu.be/RshRABoAhqE

            Comment


              #7
              Re: Samsung LA40C530F1RXXA Backlight Shuts Off

              Comment


                #8
                Re: Samsung LA40C530F1RXXA Backlight Shuts Off

                Originally posted by kolbep View Post
                Thanks all. I came right. It was CFL tube no 9 or 10.
                I have bypassed the transformer for it, and the TV is working great now.
                And I have made a video of fixing it :
                https://youtu.be/RshRABoAhqE
                Thanks for the follow-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

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