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    #1

    Lg w2234s

    Hi there,

    I have an LG W2234S screen that doesn't work. When plugged in it does not power on when the power button is pressed. No power LED, no display - nothing.

    I have replaced all the caps on the board with Panasonic FM series parts (apart from the small cap which was a generic equivalent model of the correct capacitance) with the exception of the large one which remains the original.

    I have tested the power to the logic card from the power board and it appears to be correct. The two voltage regulators on the logic board also appear to be within spec at 1.8V and 3.3V. There is also a voltage drop across the power switch as I would expect but obviously the screen isn't powering up.

    I have also noticed that the large cap on the board takes a long time to discharge, ie a couple of days to drop from the measured 320V - i'm having to manually discharge it prior to working on the board.

    Thanks for your advice as to the next troubleshooting stages.

    (Picture of the power board after recap).
    Attached Files
    Last edited by bob12345; 05-30-2011, 07:15 AM.
    Tags: None
    #2
    Re: Lg w2234s

    Originally posted by bob12345 View Post
    Hi there,

    I have an LG W2234S screen that doesn't work. When plugged in it does not power on when the power button is pressed. No power LED, no display - nothing.

    I have replaced all the caps on the board with Panasonic FM series parts (apart from the small cap which was a generic equivalent model of the correct capacitance) with the exception of the large one which remains the original.

    I have tested the power to the logic card from the power board and it appears to be correct. The two voltage regulators on the logic board also appear to be within spec at 1.8V and 3.3V. There is also a voltage drop across the power switch as I would expect but obviously the screen isn't powering up.

    I have also noticed that the large cap on the board takes a long time to discharge, ie a couple of days to drop from the measured 320V - i'm having to manually discharge it prior to working on the board.

    Thanks for your advice as to the next troubleshooting stages.

    (Picture of the power board after recap).
    Possibly corrupted U108 on the signal board. Did the original caps show signs of failure? Also, I can't locate U104 on the signal board. Is it on the back? Or did they skip that number?

    PlainBill

    PlainBill
    For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

    Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

    Comment

      #3
      Re: Lg w2234s

      Visually the original caps appeared to be fine however I replaced them just in case. There doesn't seem to be any components on the back of the signal board - so U104 seems to be missed out.

      Comment

        #4
        Re: Lg w2234s

        Is there a way to test U108? - do you also reckon the power board is working?

        Comment

          #5
          Re: Lg w2234s

          Originally posted by bob12345 View Post
          Is there a way to test U108? - do you also reckon the power board is working?
          I believe the power board is working; certainly after recapping and your verifying the voltage are correct there is little I can suggest checking on it.

          U108 almost certainly contains the firmware (the blue dot is a dead giveaway). The only way to check it would be to remove it from the board, hook it to an appropriate programmer and adapter, extract the code and disassemble it. This is well above my skill level.

          This board and others like it use a 'fly by wire' approach - the power LED and everything else is controlled by the processor, U105. The datasheet on it is not available. There was one other possibility. There was a run of problems due to a failed reset controller. This would be a 3 pin package much like Q103, but with a U designation. That is why I asked about U104.

          PlainBill
          For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

          Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

          Comment

            #6
            Re: Lg w2234s

            Ok thanks PlainBill, I'll try and source a replacement logic board then.

            Comment

              #7
              Re: Lg w2234s

              Thank you for this thread and the clear pictures! I was able to source a new logic board for my W2234S, that was going all kinds of crazy colours and turning off.


              Don't really want to post a link but ebay seller called goldpart sells the logic boards from china.

              Comment

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