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
    Tags: None
    • 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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