Lg flatron l1917s

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  • aquele
    New Member
    • Jan 2020
    • 3
    • Portugal

    #1

    Lg flatron l1917s

    Hey guys/girls,

    I have an old LG L1917S which doesn't work (doesn't turn on nor the LED turns). I would like to repair it (as a project and to learn more, since it is an old LCD monitor).

    I started by opening it, separate the power supply (AIP-0108) and the controller and check the power supply. The power supply seems to be all okay (fuse was ok, capacitors seem ok - C0204 can have a little bulge, not sure). Then i measure the outputs from the power supply (between GND and the pin). 5V had 4.998V (ok!) and 12V had 17.84V (it seems a value too high, but from what i read in other posts here in the forum, the 12V is not regulated without the controller connected - https://www.badcaps.net/forum/showthread.php?t=62426, so i guess this value is correct - correct me if i'm wrong).

    Everything seemed ok. I then connected the controller to the power supply and something very strange happened. Measuring the 5V i now had 0.178V and the 12V rail was constantly decreasing in value from the 17.84V. When disconnecting the controller from the power supply, the problem persisted. If i disconnected the power supply from mains (230V) and reconnected (without controller) i had 5V and 17.84V, again, in the power supply's pins.

    From what i have seen, the main problem from power supplies are the capacitors. My problem seems a capacitor problem? Also, can i use capacitors rated for 25V in my 5V rail (in the 5V rail they are rated to 16V and in the 12V rail for 25V)? I don't know any reason why not to use, but since i don't understand much about this system (power conversion).

    Best regards
    Attached Files
    Last edited by aquele; 01-21-2020, 05:45 PM. Reason: Images as an attachment
  • petehall347
    Badcaps Legend
    • Jan 2015
    • 4425
    • United Kingdom

    #2
    Re: Lg flatron l1917s

    one looks swollen change those 4 .
    its ok to go over voltage .but never go lower unless you know its ok for that particular circuit .

    Comment

    • aquele
      New Member
      • Jan 2020
      • 3
      • Portugal

      #3
      Re: Lg flatron l1917s

      Originally posted by petehall347
      one looks swollen change those 4 .
      its ok to go over voltage .but never go lower unless you know its ok for that particular circuit .
      Yeah, that was what I know from electronics but is better to confirm with the specialists

      Which 4 are you talking about? The ones inside the red square?
      Attached Files

      Comment

      • petehall347
        Badcaps Legend
        • Jan 2015
        • 4425
        • United Kingdom

        #4
        Re: Lg flatron l1917s

        yes . might be best change those other 2 as well

        Comment

        • R_J
          Badcaps Legend
          • Jun 2012
          • 9532
          • Canada

          #5
          Re: Lg flatron l1917s

          I would also change the 2 small electrolytics in the primary while you have it apart, these two primary caps won't show any bulging or leaking but just dry out over time.
          Attached Files

          Comment

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