LG Flatron L194WT inverter board; light flicker

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  • uengin
    Member
    • Jan 2014
    • 32
    • Australia
    #1

    LG Flatron L194WT inverter board; light flicker

    Hello everyone,

    Here I have the board only from a an LG Flatron L194WT. When a friend gave this to me because it was playing up and I didn't have time to fix it nor did I want it taking up space, so I just took the inverter board and tossed it out. So, for a learning experience I'd like to fix it.

    Tied BL_ON high to 5V rail. Hook it up to known good CCFLs. CCFL light flickers and slightly fainted. Capacitors are SAMXON, no bulging evident but not always have to bulging. Voltage rails are all good.

    I know I can test component, but I don't want to start testing at random. Where to start trouble shooting?

    Thanks everyone.
    Tags: None
    • budm
      Badcaps Legend
      • Feb 2010
      • 40746
      • USA
      #2
      Re: LG Flatron L194WT inverter board; light flicker

      Post good clear pictures of the board, both sides, will be a good start.
      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

        • uengin
          Member
          • Jan 2014
          • 32
          • Australia
          #3
          Re: LG Flatron L194WT inverter board; light flicker

          yeah, photos coming soon

            Comment

            • selldoor
              Slow Learner
              • Dec 2010
              • 7870
              #4
              Re: LG Flatron L194WT inverter board; light flicker

              You may need another jumper resistor from 5v to dim (if there is a dim pin)

              Test the secondary windings (Ohms 2000 range) on the inverter transformer/s
              Please upload pictures using attachment function when ask for help on the repair
              http://www.badcaps.net/forum/showthread.php?t=39740

                Comment

                • uengin
                  Member
                  • Jan 2014
                  • 32
                  • Australia
                  #5
                  Re: LG Flatron L194WT inverter board; light flicker

                  Ok, here's the photos. I don't know if it's the lighting or what, had so much trouble getting focussed images. Probably because I'm using a Nikon, I much prefer the Canons... Anyway, that's another story.
                  Attached Files

                    Comment

                    • uengin
                      Member
                      • Jan 2014
                      • 32
                      • Australia
                      #6
                      Re: LG Flatron L194WT inverter board; light flicker

                      Originally posted by selldoor
                      You may need another jumper resistor from 5v to dim (if there is a dim pin)

                      Test the secondary windings (Ohms 2000 range) on the inverter transformer/s
                      Ok, so there is a DIM line. Question is is it active high or active low? Pulling it high seems to me it will make it dim out? No?

                        Comment

                        • Davi.p
                          Hobbist Tech
                          • Sep 2009
                          • 4367
                          • Italy - Milan
                          #7
                          Re: LG Flatron L194WT inverter board; light flicker

                          Dim is not a digital signal, you have minimum brightness at 1,5v for example (i don't remember) and maximum at 3v so test which voltage you have with the resistor to 5v. Anyway i see there are output values printed near output connector, test those and compare to what's printed.

                            Comment

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