Sony KDL-40S4100 No picture, sound

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  • Magno Grail
    New Member
    • Oct 2013
    • 2
    • US

    #1

    Sony KDL-40S4100 No picture, sound

    Hi All, I read the other posts on this LCD TV and have the manuals. The screen flickers cycling through green, blue, red and R/G/B/W bars with the CN303 connector disconnected as in a previous post. All the regulators on the main (A) board are working. With CN303 connected, I measure the following:
    pin signal volts measured
    1 BL-ON 3 0
    2 BL-DET 0 0.19
    4 BL-DIMMER 1.4-3.2 0

    The BL-DIMMER and BL-ON are from the A board to the G (power) board, BL-DET is from the G to A board. When I disconnect the CN303, I measure on the A board:
    1 BL-ON 3 3.3
    2 BL-DET 0 0.08
    4 BL-DIMMER 1.4-3.2 0

    The manual says to replace the A board if the 12 and 3.3 volt supplies are good on CN301. They are. I just want to be sure the problem is not in the T board before replacing the A board. I do not see any obvious problems with the A board (bulging/leaking capacitors, burned parts, cold solder joints). The manual does not give any other voltages/signals than at the connectors and regulators. Anything else that I could check?
    Thanks.
  • capkid
    Badcaps Legend
    • Oct 2010
    • 1339
    • United States

    #2
    Re: Sony KDL-40S4100 No picture, sound

    It looks like a bad main board to me. I'd either have it repaired or purchase from a company with a good warranty, such as Shopjimmy or Tristate Module.
    LG Plasma Mal-Discharge Correction Service

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