Help Required. No Picture, Got Sound, Got Backlight

Discussion in 'LCD & LED LCD TVs Forum' started by sv2evo, Dec 22, 2011.

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  1. sv2evo

    sv2evo
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    Hi all,

    47" Wharfedale TV. Got backlight and sounds, don't have picture. Feed has no impact, whether from HDMI, or anywhere else.

    I have taken it apart, and noticed the following:

    • Visual check of capacitors for bulge/leaks ok
    • Everything else as it should be

    Going one step further, when I disconnect the TCON board cable and reconnect, I get the picture back perfectly for 10 seconds or so, and then it dissapears. It goes off gradually, like an invisible hand is sweeping it away.(not in a all at once fashion).

    From reading online, I either need a TCON, main board, or inverters. However, I would like some help to narrow it down a bit...

    :lease:

    Many thanks in advance!
     
  2. JayCee

    JayCee
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    Report back with the number printed on the power pcb...and the model no of the Tv?
     
  3. sv2evo

    sv2evo
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    The model number is LCD47F1080P.
    I am at work so can't check the power pcb number, is this significant?
     
  4. JayCee

    JayCee
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    Yes, very.
     
  5. sv2evo

    sv2evo
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    Ok, will do as soon as I get home... many thanks :)
     
  6. sv2evo

    sv2evo
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    Power Supply Board is 17PW17-4

    TCON is V420H1-CO7

    Mobo is 17MB26-2 followed by 260207

    Master Inverter is VIT70042.50 Rev3

    Slave inverter is VIT70042.51 Rev3


    I have measured every cable coming in to the inverter from the mobo and I get 12V on some, 3.5V-ish on others and some signal values 0.7V, 1.2V, 0.3V on others. I was under trhe impression that I should be getting 5V +-10% on one cable at least?

    I am now reading that some TCON boards are indeed fed by 12V DC. It seems that the power supply is working ok and that the TCON board is suspect...?
     
    Last edited: Dec 22, 2011
  7. JayCee

    JayCee
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    If the backlight stays on that rules out the invertors.
    Check C877/C878 on the psu pcb (usually 15nF/630v)...on some models these have been substituted with a single 33nf/630v cap.
    you would need to measure them with a capacitance meter or just replace them if you don't have a meter.
     
  8. sv2evo

    sv2evo
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    Thanks for the comment, will do so when I get home. I am intrigued, how did you come up with the suggestion above? Is it a common fault or did you deduce it from the symptoms I have described?
     
  9. JayCee

    JayCee
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    These particular caps are known to cause problems on several variations of these Vestel power supplies...I'm not saying 100% that they'll be the cause of your fault but it's best to rule them out.
    I've changed them many times on these chassis.
     
  10. sv2evo

    sv2evo
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    Tested C877 and C878 and both healthy:thumbsup:. Shame as it would have been a cheap and easy fix...

    Any other ideas I can try?
     
  11. jaseredjacket

    jaseredjacket
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    - did you manage to fix this problem? my tv has come up with the exact same issue- c788 and c877 are both fine- thanks jase.
     

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