Sony KDL-32NL140: Powers On w/ Backlights, Black Screen - Bad TCON?

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  • JDC
    Badcaps Veteran
    • May 2015
    • 273
    • USA

    #1

    Sony KDL-32NL140: Powers On w/ Backlights, Black Screen - Bad TCON?

    Got a Sony KDL-32NL140 that turns on to a black screen w/ backlights. I've pulled the back cover and confirmed that they are on. No sound to be heard.

    Attached are the top and bottom pictures of the TCON from ShopJimmy (not enough light right now to take decent photos of mine). Readings are as follows:

    F1 fuse:

    00.2 ohm while unplugged
    OL diode mode
    Using chassis ground as neg, both ends measure 11.97v. Shouldn't this be 12?

    On the bottom on the TCON are measure points. They are as follows:

    GND
    INSDA_1 3.32
    INSCL_1 3.32
    FWP_1 3.33
    VCC_1 3.33

    There are two tabs connecting to the LCD.

    Removing the left one shows a screen of gray on the left, white on the right. At first, it almost looks like denim jeans. After a minute,
    both sides become smooth with the gray side almost on par with the white side.

    Removing the right one shows a 2 inch white vertical bar on the left side, followed by gray until the middle,
    then another 2 inch white vertical bar, ending with gray til the end of the screen. No "denim" effect is shown.

    Ordering a new TCON is around 20 bucks. I'd like to rule out a bad panel first.

    Questions:

    What else can I test to rule on the TCON?

    What can I do to test the panel, especially in checking for good tab bonding?
    Attached Files
  • Electronic Handyman
    Senior Member
    • Apr 2016
    • 58
    • Canada

    #2
    Re: Sony KDL-32NL140: Powers On w/ Backlights, Black Screen - Bad TCON?

    I'd check the power supply board's voltages and the main board too.By the way 11.97v is close enough and with the voltage tolerance range.
    Last edited by Electronic Handyman; 05-23-2016, 07:25 PM.

    Comment

    • budm
      Badcaps Legend
      • Feb 2010
      • 40746
      • USA

      #3
      Re: Sony KDL-32NL140: Powers On w/ Backlights, Black Screen - Bad TCON?

      Look for VGL, VGH, AVDD, VGMA with and without cables between the LCD and the T-CON connected.
      Last edited by budm; 05-23-2016, 09:49 PM.
      Never stop learning
      Basic LCD TV and Monitor troubleshooting guides.
      http://www.badcaps.net/forum/showthr...956#post305956

      Voltage Regulator (LDO) testing:
      http://www.badcaps.net/forum/showthr...999#post300999

      Inverter testing using old CFL:
      http://www.badcaps.net/forum/showthr...er+testing+cfl

      Tear down pictures : Hit the ">" Show Albums and stories" on the left side
      http://s807.photobucket.com/user/budm/library/

      TV Factory reset codes listing:
      http://www.badcaps.net/forum/showthread.php?t=24809

      Comment

      • JDC
        Badcaps Veteran
        • May 2015
        • 273
        • USA

        #4
        Re: Sony KDL-32NL140: Powers On w/ Backlights, Black Screen - Bad TCON?

        Originally posted by budm
        Look for VGL, VGH, AVDD, VGMA with and without cables between the LCD and the T-CON connected.
        With cables connected:

        VGL -6.32
        VGH 26.80
        AVDD 15.73
        VGMA 15.29

        Without:

        VGL -6.34
        VGH 26.80
        AVDD 15.75
        VGMA 15.28

        Pretty much the same both ways.

        Comment

        • JDC
          Badcaps Veteran
          • May 2015
          • 273
          • USA

          #5
          Re: Sony KDL-32NL140: Powers On w/ Backlights, Black Screen - Bad TCON?

          Bump.

          Comment

          • JDC
            Badcaps Veteran
            • May 2015
            • 273
            • USA

            #6
            Re: Sony KDL-32NL140: Powers On w/ Backlights, Black Screen - Bad TCON?

            Yikes, I'm in the wrong forum.

            Comment

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