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Snowy Picture on LG Plasma TV

Discussion in 'Electronic Repair' started by Randy, Jan 16, 2009.

  1. Randy

    Randy Guest

    My LG plasma (42px50) has a "snowy" background. By "snowy" I mean
    that a constantly changing random pattern of isolated pixels flash - a
    little like the old days when you would see static on the screen if
    your antenna wasn't positioned properly. This isn't as pronounced as
    that, but the idea is similar. This applies across all inputs (cable
    box, DVD, etc.) I have component cables from the DVD and HDMI from
    the cable box. I have tried replacing the cables and the cable box,
    but he problem is consistent. Even during that momentary black screen
    that occurs when switching between inputs, the snow remains. It seems
    clear to me that this problem is not coming from the components or
    from the cables, but must be with the tv itself. Even when I select
    an input that is not connected to any device, the snowy picture
    continues.

    Does anybody know why this might be happening or what I can do to
    correct it? Thanks.
     
  2. Sjouke Burry

    Sjouke Burry Guest


    A noisy or oscillating powersupply?
     
  3. Randy

    Randy Guest

    How would I test for this? The TV is plugged into a power strip which
    is plugged into the wall.
     
  4. Sjouke Burry

    Sjouke Burry Guest

    Inside the tv.
    Your incoming power is converted to 1 or more
    internal supply voltages.
    Check with an oscilloscope.
     
  5. Jerry G.

    Jerry G. Guest

    This could be internal power supply noise. If you are experienced at
    TV service you can use a scope and go through all the power supply
    distributions to see if any of them are noisy.

    Another cause could be a defect somewhere along the digital signal
    path. There could be some system clocking errors, or some noise
    generation taking place.


    Jerry G.
     
  6. f825_633

    f825_633 Guest

    Does it do this on the menus also?,
    if you go to the menu and select white wash or invert does
    it seem to disappear ?, could your 'snow' be 'sparkles' ? if
    so sounds like its the same fault mine had and it turns out
    to be lots of 33uf caps on the power inverter board.
    The board with four little transformers on, three in a row
    at the top and one in the middle.

    Test with an ESR meter and change, but I now need a manual
    to set a couple of voltages to make it go away completely.

    I'm told the board in these LG sets are the same on used in
    Philips Plasmas?,
     
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