LG FLATRON W2240T-PN Backlight works only for 1 sec.

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  • BeginnerLVL1
    Senior Member
    • Apr 2015
    • 58
    • Czech Republic

    #1

    LG FLATRON W2240T-PN Backlight works only for 1 sec.

    Hello,
    i have lcd monitor LGFlatron W2240T - PN, on this LCD backlight light-up only for 1 sec.
    Please help me.

    I tested capacitors - OK
    Voltages is OK
    Mosfets - OK
    CCFL Tubes - OK
    HV Transformerc - i cant test it
    Invertor power on signal is ok, when i disconnect inv. ON signal an connect it back it lights up for another second.

    Thanks for any help
  • budm
    Badcaps Legend
    • Feb 2010
    • 40746
    • USA

    #2
    Re: LG FLATRON W2240T-PN Backlight works only for 1 sec.

    How did you test the CCFL tubes?
    Did you use test tubes to verify the board function?
    https://www.badcaps.net/forum/showthread.php?t=19987
    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

    • BeginnerLVL1
      Senior Member
      • Apr 2015
      • 58
      • Czech Republic

      #3
      Re: LG FLATRON W2240T-PN Backlight works only for 1 sec.

      Yes i tried to connect another new tubes.

      Comment

      • BeginnerLVL1
        Senior Member
        • Apr 2015
        • 58
        • Czech Republic

        #4
        Re: LG FLATRON W2240T-PN Backlight works only for 1 sec.

        Originally posted by budm
        How did you test the CCFL tubes?
        Did you use test tubes to verify the board function?
        https://www.badcaps.net/forum/showthread.php?t=19987
        No way. I cant find whats wrong. Have someone service manual?

        Comment

        • BeginnerLVL1
          Senior Member
          • Apr 2015
          • 58
          • Czech Republic

          #5
          Re: LG FLATRON W2240T-PN Backlight works only for 1 sec.

          Hello, i have now two pcs of these monitors with the same failure.
          I think its bad transformer for ccfl tubes.
          When i cut-off inverter protection it works, but the transformer heats up rapidly.
          I leave for test one monitor running for 30mins, transformer gonna melted.
          May i buy 2pcs of this? http://www.ebay.com/itm/IT-011-EBJ42...-/151287502952

          Comment

          • stj
            Great Sage 齊天大聖
            • Dec 2009
            • 30963
            • Albion

            #6
            Re: LG FLATRON W2240T-PN Backlight works only for 1 sec.

            check any high-voltage ceramic caps around the transformer & tube connectors.

            Comment

            • BeginnerLVL1
              Senior Member
              • Apr 2015
              • 58
              • Czech Republic

              #7
              Re: LG FLATRON W2240T-PN Backlight works only for 1 sec.

              Originally posted by stj
              check any high-voltage ceramic caps around the transformer & tube connectors.
              Thanks, I try it here is 4x 3kV 10J, all of them is OK, tested with capacity tester.
              I tested windings on the transormer, primary has 0,3Ohm and secondary1 has 1kOhm, secondary 2 is probably bad... It has infinity resistance.
              Look at pictures, secondary2 looks burned.
              Attached Files
              Last edited by BeginnerLVL1; 12-01-2015, 07:10 AM.

              Comment

              • BeginnerLVL1
                Senior Member
                • Apr 2015
                • 58
                • Czech Republic

                #8
                Re: LG FLATRON W2240T-PN Backlight works only for 1 sec.

                But why is the transformer gone?

                Comment

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