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Vestel Based JVC no picture, leds on

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    #1

    Vestel Based JVC no picture, leds on

    Hoping someone has troden this path before !
    I'm looking at a JVC LT-39c790 - a vestel based unit.
    So, the remote turns it on, led's light up but no picture at all.

    I have a spare mainboard, so I know its not that. The PSU seems ok too.
    On the AUO T-Con I've got 16v on HAVDD_H but nothing on HAVDD_L - which I'm assuming should also be 16v ?

    So, Ive resorted to testing eveything I can on the board as I can't find any schemas for it (AUO 39T15 C04 Ctrl Bd) and I think I've found a diode gone short. it marked D005 on the board and E1 on the package but I've no clue as to whether this is a standard diode or a zener etc.

    Any pointers greatly received.
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    #2
    Re: Vestel Based JVC no picture, leds on

    Originally posted by nick4275 View Post
    Hoping someone has troden this path before !
    I'm looking at a JVC LT-39c790 - a vestel based unit.
    So, the remote turns it on, led's light up but no picture at all.

    I have a spare mainboard, so I know its not that. The PSU seems ok too.
    On the AUO T-Con I've got 16v on HAVDD_H but nothing on HAVDD_L - which I'm assuming should also be 16v ?

    So, Ive resorted to testing eveything I can on the board as I can't find any schemas for it (AUO 39T15 C04 Ctrl Bd) and I think I've found a diode gone short. it marked D005 on the board and E1 on the package but I've no clue as to whether this is a standard diode or a zener etc.

    Any pointers greatly received.
    Regarding the diode maybe remove it or lift one side and re test it for a short.

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      #3
      Re: Vestel Based JVC no picture, leds on

      E1 - MMSZ5231B (Zener diode at 5.1v)
      Attached Files

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        #4
        Thanks for the responses. Although I think Ive been "off the tools" too long. It wasn't the diode, I forgot to unplug the logic board before testing !

        So ignore what I said previously ! - This is what's happening........

        The AUO 39T15 CO4 Ctrl Bd has virtually no voltages on it apart from the incoming 12v from the logic board. If I unplug the daughter board ( 39T15 SO 8 XL) then AVDD, VGH and VGL return to normal although VCOM is only showing 1.9V
        Long shot I know but does anyone have a clue where to start !
        Are there no schemas for these AUO boards at all ?
        TIA

        Comment

          #5
          Have you tired disconnect one side of the panel to see which side may be bad?
          Then block ckv lines with tape

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