Top half of monitor is darker then bottom

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  • 1supertech
    Badcaps Veteran
    • Apr 2012
    • 384
    • USA

    #1

    Top half of monitor is darker then bottom

    Hello Everyone,
    I received a LG Flatron L1942 from a customer as a trade in on a monitor purchase.
    On the back of casing there was a burn mark due to over heating, when I opened the case up I found a very toasted power inverter board with a big cap 68uf 450v with bottom bulged out. I did a full recap except for one cap which I didn't have but tested well.

    I reassembled the monitor. It works but one problem - the top of screen is a few shades darker then the bottom. I am assuming some other component is burned or not enough voltage is going to the top bulbs, but I'm not sure. Would be grateful for any help.
    Thanks
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  • Rtech
    Badcaps Legend
    • Jul 2010
    • 1095

    #2
    Re: Top half of monitor is darker then bottom

    I have come across,the same symptoms before, and had to change the Screen to resolve it.

    Comment

    • 1supertech
      Badcaps Veteran
      • Apr 2012
      • 384
      • USA

      #3
      Re: Top half of monitor is darker then bottom

      Originally posted by Rtech
      I have come across,the same symptoms before, and had to change the Screen to resolve it.
      I connected my test monitor to the to powerboard and mainboard all is well
      your right I need a new screen.
      Thanks Rtech

      Comment

      • tom66
        EVs Rule
        • Apr 2011
        • 32560
        • UK

        #4
        Re: Top half of monitor is darker then bottom

        Could be the upper CCFL is dimmer than the other? Does black backlit screen look uniform?
        Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
        For service manual, schematic, boardview (board view), datasheet, cad - use our search.

        Comment

        • momaka
          master hoarder
          • May 2008
          • 12164
          • Bulgaria

          #5
          Re: Top half of monitor is darker then bottom

          Originally posted by tom66
          Could be the upper CCFL is dimmer than the other? Does black backlit screen look uniform?
          I agree, check the top CCFLs and the top inverter.

          If you have 2 spare CCFLs, unplug one of the CCFLs on the bottom of the monitor and one on the top. Plug in your spare CCFLs in those spots and see if there is any difference in brightness. Repeat with the other 2 CCLF bulbs. If no significant difference, the top CCFLs in your monitor may be just dead or dying.

          Comment

          • Rtech
            Badcaps Legend
            • Jul 2010
            • 1095

            #6
            Re: Top half of monitor is darker then bottom

            In my case the screen was split into 2 parts top being excellent and the bottom totally Black.so maybe in your case it could be CCFLs !! as the difference between the two halves is not total.

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