LCD backlight Issu Z8A REV D

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  • kalilinux25
    Badcaps Legend
    • Mar 2018
    • 2084
    • ZAMBOANGA SIBUGAY
    #1

    LCD backlight Issu Z8A REV D

    Hi good day i have a quit a bad issue of this board , I alrady change the scren but I can only ssee a dim light od display showing acer logo. Ive tsted the pins showing
    CN8
    Pin 40 19v
    Pin 36-34 has 3.3v
    Pin 32-33 has 3.3v
    Pin 30 has 0v

    Im very new with this issue and I dont want to add more damge to the board hope somoen can guide me..
    Attached Files
    Tags: None
    • mon2
      Badcaps Legend
      • Dec 2019
      • 14086
      • Canada
      #2
      Re: LCD backlight Issu Z8A REV D

      Hi. Is the replacement display a 100% new display or at least confirmed to be a working unit with a working backlight?

      The computer works fine with an external HDMI monitor?

        Comment

        • kalilinux25
          Badcaps Legend
          • Mar 2018
          • 2084
          • ZAMBOANGA SIBUGAY
          #3
          Re: LCD backlight Issu Z8A REV D

          Originally posted by mon2
          Hi. Is the replacement display a 100% new display or at least confirmed to be a working unit with a working backlight?

          The computer works fine with an external HDMI monitor?
          Yes the Lcd is new and it works in hdmi out

            Comment

            • mon2
              Badcaps Legend
              • Dec 2019
              • 14086
              • Canada
              #4
              Re: LCD backlight Issu Z8A REV D

              According to CN8 schematic, pin 30 should not be zero volts. Please see attached.

              Can you trace back this pin 30 and confirm if there is a stuffed resistor @ R6 or R9?

              Only one resistor should be present on the logic board.

              Respectively, when this resistor is found, check the OTHER side of the resistor to confirm if there is a voltage rail present @ +3V (R6) or +5V (R9).

              Also, investigate the hall effect IC (lid sensor?) as per the attached schematic. Is this working correctly?

              What is the voltage on BLON_CON?

              Perhaps the host CPU believes the LID is closed so it is dimming the display accordingly to save on power.
              Attached Files
              Last edited by mon2; 04-07-2021, 10:56 AM.

                Comment

                • kalilinux25
                  Badcaps Legend
                  • Mar 2018
                  • 2084
                  • ZAMBOANGA SIBUGAY
                  #5
                  Re: LCD backlight Issu Z8A REV D

                  Originally posted by mon2
                  According to CN8 schematic, pin 30 should not be zero volts. Please see attached.

                  Can you trace back this pin 30 and confirm if there is a stuffed resistor @ R6 or R9?

                  Only one resistor should be present on the logic board.

                  Respectively, when this resistor is found, check the OTHER side of the resistor to confirm if there is a voltage rail present @ +3V (R6) or +5V (R9).

                  Also, investigate the hall effect IC (lid sensor?) as per the attached schematic. Is this working correctly?

                  What is the voltage on BLON_CON?

                  Perhaps the host CPU believes the LID is closed so it is dimming the display accordingly to save on power.
                  The =3v and 5v is preent into the end of the two resistor
                  The r9 and r6 are no stuff
                  check the BLON_CON 3.3V

                    Comment

                    • mcplslg123
                      Badcaps Legend
                      • Jun 2015
                      • 7262
                      • india
                      #6
                      Re: LCD backlight Issu Z8A REV D

                      What about the LID switch as suggested by @mon2??

                        Comment

                        • kalilinux25
                          Badcaps Legend
                          • Mar 2018
                          • 2084
                          • ZAMBOANGA SIBUGAY
                          #7
                          Re: LCD backlight Issu Z8A REV D

                          Originally posted by mcplslg123
                          What about the LID switch as suggested by @mon2??
                          when I tried to check the pins of q38 im not getting any voltage on all pins

                            Comment

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