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polaroid tv no picture

Discussion in 'Troubleshooting and Repair' started by gaas12, Mar 29, 2011.

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  1. gaas12

    gaas12

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    Mar 29, 2011
    i have a polaroid model tda03211c lcd. the blue light come on the back light comes on and when u first turn it on you can here noise from the speakers, but no picture just backlight light on screen. when i check voltag a cross the 2 450v caps i only get 400v across both and 200v on each one. could this be the problem.also dont know why when i touch any part of the transformer it arks really bad and turns my meter off, it arks like it shorted. it does this just using one lead. by the way this is just a project im trying to learn how to fix lcd tv
     
    Last edited: Mar 29, 2011
  2. SeasonedTech

    SeasonedTech

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    Mar 31, 2011
    Do yourself a favor and let an experienced tv technician handle the problem.
    You're obviously not educated as to the dangerous voltages inside those sets, and poking around will do you and the set more damage.
     
  3. gaas12

    gaas12

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    Mar 29, 2011
    how bout educating me if your so smart.instead of being a smart a$$. i do know the high voltage it takes to work the tv but i should be able to check it with a meter. i ask a question i dont want your opinion.
     
  4. davenn

    davenn Moderator

    13,671
    1,892
    Sep 5, 2009
    dont be like that, he is giving you sound advice, to try and stop you from killing yourself

    if you were poking you meter into places and producing arking and causing your meter to switch off you obviously dont know ahat you are playing with.
    Most meters WONT be able to measure the larges voltages present in a LCD monitor

    but if you have that strong urge to join the Darwin Awards list, just ignore the saftey advice and keep doing your own thing

    cheers
    Dave
     
  5. gaas12

    gaas12

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    Mar 29, 2011
    sorry about the remarks, i know there high voltage on all tvs and take the nessary precaution, i was just wanting to know what techs on this site think it might be. im trying to learn about lcd tv.
     
  6. davenn

    davenn Moderator

    13,671
    1,892
    Sep 5, 2009
    your lucky I wasnt a moderator I would have probably banned you for your response
    but if you would delete your last post it would be appreciated :)

    I'm not directly familiar with that model..
    is it a TV or a computer monitor ?
    if a computer monitor...does it have just a VGA input? or are there other inluts like DVI or composite video?
    have you tried it with another different input ?
    you need to confirm that its not a faulty output from your computer, or the cable between the computer and the monitor

    ohhh and if a capacitor is rated at 400V then it wont have 400V across it. when designing circuits capacitors would usually be rated at twice the voltage that they were expected to be operating at in a cct.

    Having confirmed that the computer output and the connecting cable are ok. You need to confirm if the monitor itself is working on any other input. It may just be one of the inputs that has failed.
    you need to confirm the presence of all low voltage power rails +5., +12V etc
    there should be markings on the cct board for testpoints etc

    Dave
     
    Last edited: Apr 2, 2011
  7. SeasonedTech

    SeasonedTech

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    Mar 31, 2011
    As an Experienced Professional Tech..... It's either a video processor problem OR a defective inverter board.
    Are you capable of scoping out the problem?, perhaps injecting a signal into the processor chip?
    Measure the frequency of the inverter too.
     
  8. gaas12

    gaas12

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    Mar 29, 2011
    i have a oscope just havent used it in a while, could u tell me what to do?
     
  9. mahmoud

    mahmoud

    1
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    Apr 6, 2011
    hi , the sound is ok ? and you have backlight right ? did you check the LVDS cabel and t-con board ?
     
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