Complex Backlight Issue. Please advise Asus DA0BKXMB8D0

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  • IamPritesh
    Badcaps Veteran
    • Aug 2017
    • 356
    • India

    #1

    Complex Backlight Issue. Please advise Asus DA0BKXMB8D0

    So I have this Asus TUF laptop ( BOARD ID : DA0BKXMB8D0 ) which has no backlight. tested this with multiple screens and each has different result.

    Original Screen ( FULL HD ) :
    Has Data
    No Backlight
    0V on EDP connector Pin 39,40
    Backlight Enable has 3.3V

    TEST Screen 1 (ONLY HD)

    No data
    No Backlight
    8V on EDP connector Pin 39,40

    TEST Screen 2 (ONLY HD)

    No data
    No Backlight
    5V on EDP connector Pin 39,40

    LDVS CONNECTED TO MB BUT NOT TO LED SCREEN

    19V on EDP connector Pin 39,40 and also on the display cable ( So probably not a cable issue I think )

    Attaching schematic .Would love to know what exactly is causing the drop in 19V Vin that is connected to the LDVS .
    Attached Files
    Last edited by SMDFlea; 02-16-2022, 07:29 AM.
  • mcplslg123
    Badcaps Legend
    • Jun 2015
    • 7262
    • india

    #2
    Re: Complex Backlight Issue. Please advise Asus DA0BKXMB8D0

    Display cable is likely burnt.

    Comment

    • IamPritesh
      Badcaps Veteran
      • Aug 2017
      • 356
      • India

      #3
      Re: Complex Backlight Issue. Please advise Asus DA0BKXMB8D0

      Originally posted by mcplslg123
      Display cable is likely burnt.
      If I dont connnect the led screen I get full 19V on the both the ends of display cable.

      Comment

      • mon2
        Badcaps Legend
        • Dec 2019
        • 14076
        • Canada

        #4
        Re: Complex Backlight Issue. Please advise Asus DA0BKXMB8D0

        Does the original screen work on another logic board?

        You can see the text / graphics with a flashlight?

        Remove all power. Meter in resistance mode. Check the resistance to ground for the lcd pin 39,40.

        Then check the same in diode mode. Meter in diode mode, red probe to ground. Black probe to pin 39,40.

        Post the readings.

        Comment

        • piernov
          Super Moderator
          • Jan 2016
          • 4435
          • France

          #5
          Re: Complex Backlight Issue. Please advise Asus DA0BKXMB8D0

          Of course fuse is good…?
          OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

          Comment

          • mcplslg123
            Badcaps Legend
            • Jun 2015
            • 7262
            • india

            #6
            Re: Complex Backlight Issue. Please advise Asus DA0BKXMB8D0

            Originally posted by IamPritesh
            If I dont connnect the led screen I get full 19V on the both the ends of display cable.
            This doesnt proves cable is not bad.

            Comment

            • IamPritesh
              Badcaps Veteran
              • Aug 2017
              • 356
              • India

              #7
              Re: Complex Backlight Issue. Please advise Asus DA0BKXMB8D0

              Originally posted by mon2
              Does the original screen work on another logic board?

              You can see the text / graphics with a flashlight?

              Remove all power. Meter in resistance mode. Check the resistance to ground for the lcd pin 39,40.

              Then check the same in diode mode. Meter in diode mode, red probe to ground. Black probe to pin 39,40.

              Post the readings.
              Originally posted by piernov
              Of course fuse is good…?
              Originally posted by mcplslg123
              This doesn't proves cable is not bad.
              The original screen was bad and only specific screen works on this asus machine. Something to do with the panel_id signal maybe ?

              The machine is no more with me. Since I could not source the new compatible screen, had no choice but to return the laptop.

              Comment

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