Vestel Based JVC no picture, leds on

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  • nick4275
    New Member
    • Nov 2023
    • 4
    • UK
    #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.
    Tags: None
    • vinceroger69
      Badcaps Legend
      • Mar 2012
      • 6714
      • uk
      #2
      Re: Vestel Based JVC no picture, leds on

      Originally posted by nick4275
      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.

        Comment

        • lotas
          Badcaps Legend
          • Jan 2016
          • 4555
          • Russia
          #3
          Re: Vestel Based JVC no picture, leds on

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

            Comment

            • nick4275
              New Member
              • Nov 2023
              • 4
              • UK
              #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

                • zwarder
                  Member
                  • Oct 2013
                  • 45
                  • United Kingdom
                  #5
                  Have you tired disconnect one side of the panel to see which side may be bad?
                  Then block ckv lines with tape

                    Comment

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