Panasonic LED TX-40AS640E no video w/ B.L. and sound

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  • Davi.p
    Hobbist Tech
    • Sep 2009
    • 4409
    • Italy - Milan

    #1

    Panasonic LED TX-40AS640E no video w/ B.L. and sound

    Hi to all, i have picked locally this smart 3D tv, unfortunately no remote for the moment , i have ordered it so no service functions now, i have tested only the tcon since i think the prob. is between it and the panel, it lacks some basic voltages, AVDD, VON, VOFF (alias vgh,vgl), the panel brand is unknown to me, Briview and tcon has the main chip by Samsung, also the card code remembers me a little those Samsung codes... the stepup for avdd is supplied trough a six-terminals/3-tracks component, surely a mosfet switch, but the 12v at the drain/source dont passes to source/drain apart probably for an instant at the start when i see about 3,3v on the output cap for the Avdd(with a DMM). Then, since i suspected an abnormal draw on the tcon itself or the panel, i have disconnected the panel, same thing, then short- circuited the mosfet and 12v are on the Avdd output cap but no smoke anywhere. Testpoint for Vcc 3,3v and 1,2v measures good and also the output of the 1117-adj chip (1,8v as marked on pcb). I have suspected a pulled down i2c but it measures 1,5v both clock/data. Connecting output ribbons one at a time makes no difference. What to do now taking in consideration i have bought only 1 board for all my tv's repairs and i dont liked to do it...
    Thanks verymuch Bye.
    Last edited by Davi.p; 10-15-2017, 11:18 AM.
  • tomartronica
    New Member
    • Mar 2013
    • 2
    • PORTUGAL

    #2
    Re: Panasonic LED TX-40AS640E no video w/ B.L. and sound

    Hi, did you solve this issue with this model ?
    I have exact model, no picture, backlight ok, TCON replaced but still no picture
    Maybe mainboard ?

    Comment

    • Davi.p
      Hobbist Tech
      • Sep 2009
      • 4409
      • Italy - Milan

      #3
      Re: Panasonic LED TX-40AS640E no video w/ B.L. and sound

      Faulty screen, must remove diodes one by one on small boards to see if it get better, you can use the Samsung panel trick to jumper trdy-1 and trdy-3 on tcon to disable protection

      Comment

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