Colorful patches/lines on screen after 10 mins of turning on. Model KLV-32EX300

Discussion in 'General Electronics Chat' started by DjKrish, Dec 21, 2010.

  1. DjKrish

    Thread Starter New Member

    Dec 18, 2010
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    Hello folks. My Sony bravia LCD TV started giving me problem after 3 months of purchase. One fine day lightning striked and my TV gone blackout. Boom. Found out a couple of components spoiled in the power board including the rectifier. Replaced the fuse and rectifier, power working perfectly fine now. But there's another problem. After turning on for 10 minutes, picture goes rainbow and colorful, not picture but all patches and lines. Nothing can be done except to shut it off. Turn it on back again, works fine, but it starts again. Power board is confirmed working perfectly fine now. I doubt it could be the signal board Could it be? Even i have updated the firmware. Still no luck. Someone please help me tell me whats the problem could be?

    I have attached and uploaded the video to youtube. Please have a look.

    http://www.youtube.com/watch?v=nl_mOHZq4xY
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
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    Is it still under warranty? If so, it needs to go back to the dealer for a replacement.
     
  3. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
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    Lightning can do strange things but since this appears to be heat related a can of freeze spray might find the defective IC. Problem here is that if the lightning got that far into it other components may have been marginally damaged and present problems later.
     
  4. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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    +1 opening it will probably void any warranty.
     
  5. kubeek

    AAC Fanatic!

    Sep 20, 2005
    4,670
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    Not as much opening as changing components.
     
  6. tom66

    Senior Member

    May 9, 2009
    2,613
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    So when it goes wrong it makes a loud pop on the speakers and the video fails. This would seem to indicate it is likely to be in the signal chain of things - converting HDMI or other video inputs to the signals the TV uses. It's quite likely that the TV uses the same chip for audio decoding. Also, it's clear that after restarting it the picture only remains for a few seconds, because it warms up to whatever critical temperature it fails at.

    I'd therefore suspect a dry joint or thermal contact problem. Consider the framebuffer memory, if any, as being a possible cause. Could you take a picture of the controller/signal board? An interim solution would be to keep the TV cool (with an extra fan), but this probably wouldn't last long and only delays the problem.

    For the moment - ignoring the lightning - it's possible that the fault always existed and it is a coincidence. I would find it unlikely due to the high isolation in most power supplies. It is possible that the lightning or surge increased the temperature of the unit, or turning it off for a few days while servicing it could have also caused problems, because the unit cooled down and this led to thermal stress.
     
    Last edited: Dec 21, 2010
  7. marshallf3

    Well-Known Member

    Jul 26, 2010
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    As I mentioned get some freeze spray.
     
  8. retched

    AAC Fanatic!

    Dec 5, 2009
    5,201
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    Get a hammer, a six pack and a few friends.

    Charge $20 a whack. You should have enough for a new TV in no time.


    ;)
     
  9. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,750
    760
    Get freeze spray.

    And check the Display driver assy for heat ups.

    The DSP chip could be the culprit or the LVDS drivers.

    I have to see inside to tell you where to check.

    But first get the freeze spay or may be ur finger cud do the trick

    It also could be a DC to DC converter failing at certain temperature. Restarting resets it.
     
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