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Head scratching fault.

Discussion in 'Troubleshooting and Repair' started by dmmarchy, Jun 7, 2013.

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  1. dmmarchy

    dmmarchy

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    0
    Jun 7, 2013
    Hi I have a Cheap Technika 22" lcd tv.. I have a Passion for fixing things etc and cannot fathom out latest problem.. TV turns on, very dim screen almost black. but you can just make out menu etc. I was told to check for blown caps (ie bulging heads ) these all seem okay. I was then told to change the inverter card. which i did and still the same.. Odd thing is when i hold down display button on the remote the screen appears for a couple of seconds, then goes again until i press display button again.. 2 seconds then off... any pointers or clues would be much appreciated .. I know its only a cheap telly but love tinkering and fixing things .( hate to see waste electrical gear in this throwaway society ) Many thanks.
     
  2. GreenGiant

    GreenGiant

    842
    6
    Feb 9, 2012
    its possible its a setting, the Backlight setting to be precise, try increasing this.

    Measure the voltages to the inverter board, there may be something faulty there.
     
  3. sheldonstv

    sheldonstv

    68
    0
    Jul 17, 2007
    it may be that you have a faulty ccfl backlight...........
     
  4. dmmarchy

    dmmarchy

    2
    0
    Jun 7, 2013
    Many thanks for your replies .. Ive been through all the settings and all set correctly. ( was quite tricky had to keep pressing remote display to see screen then 3 secs before it went off. took me about half a hour ! ) I purchased the inverter board new. off Ebay. Could it be the infra red detector ? If i constantly keep pressing the display button screen stays on. but if i stop 3 secnods later goes back to black screen ? Many thank guys.
     
  5. davenn

    davenn Moderator

    13,833
    1,950
    Sep 5, 2009
    I agree with green giant and sheldon

    the chances are its either the inverter board or the CCFL tube that the inverter board drives
    I have seen very few CCFL failures, 99% of the time its the inverter board

    Dave
     
  6. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,271
    Nov 28, 2011
    It seems odd that the backlight comes on for a few seconds then turns off, with a new inverter board. I guess it could be a problem with the CCFL tube that causes the inverter to detect a problem and shut down... Have you checked for compromised insulation on the CCFL connections? Run it face down in a dark room and look for arcing or corona on the wiring to the CCFL tubes? Also, check the enable signal from the main board to the inverter and/or force the inverter's enable input active.

    Those are just suggesitons. I have little experience with LCD TVs. YMMV. Good luck!
     
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