A1707 820-00928 Backlight issue

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  • mon2
    Badcaps Legend
    • Dec 2019
    • 13940
    • Canada
    #1

    A1707 820-00928 Backlight issue

    hi. have an a1707 that appears to work ok if the lid is partially open @ 30 degrees or so. At 90 degrees or more , the backlight always goes off.

    Confirmed that the LCD is ok by using my phone as a flashlight and shining on front face at an angle - can see the desktop text / icons, etc.

    If we attempt to close the lid, the backlight comes back on again at about the 30 degree mark.

    Is this related to FLEXGATE?

    Can check for the boost regulator operation next but thought to ask for ideas.

    Thanks.

    PS: Did hear the fans spin quite loudly when the screen was dark but not sure if this is an issue or not be concerned with for now.

    PS#2: Sure looks to be flexgate issue - OMG, the repair guide:

    https://www.youtube.com/watch?v=JLrKuK7IK3I

    No stage light issue but could very well be the break of the flex cable as noted.
    Last edited by mon2; 02-12-2021, 04:15 PM.
    Tags: None
    • MobileXT
      Senior Member
      • Oct 2012
      • 196
      • USA
      #2
      Re: A1707 820-00928 Backlight issue

      Originally posted by mon2
      hi. have an a1707 that appears to work ok if the lid is partially open @ 30 degrees or so. At 90 degrees or more , the backlight always goes off.

      Confirmed that the LCD is ok by using my phone as a flashlight and shining on front face at an angle - can see the desktop text / icons, etc.

      If we attempt to close the lid, the backlight comes back on again at about the 30 degree mark.

      Is this related to FLEXGATE?

      Can check for the boost regulator operation next but thought to ask for ideas.

      Thanks.

      PS: Did hear the fans spin quite loudly when the screen was dark but not sure if this is an issue or not be concerned with for now.

      PS#2: Sure looks to be flexgate issue - OMG, the repair guide:

      https://www.youtube.com/watch?v=JLrKuK7IK3I

      No stage light issue but could very well be the break of the flex cable as noted.
      Send it to apple is under recall program here https://support.apple.com/13-inch-ma...klight-service

        Comment

        • piernov
          Super Moderator
          • Jan 2016
          • 4435
          • France
          #3
          Re: A1707 820-00928 Backlight issue

          This is only for 2016 13", not 2017 15", even if they have the exact same problem. There have been a few reported cases of Apple replacing the LCD assembly for free even on 15", but you have to be extremely lucky.
          OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

            Comment

            • mon2
              Badcaps Legend
              • Dec 2019
              • 13940
              • Canada
              #4
              Re: A1707 820-00928 Backlight issue

              Thanks. This is a large 15" from what I can tell.

              There is a youtube video on the issue which is that the flex cable breaks the connection near the bend. The repair is to cut the ribbon cable and attach extensions and solder directly onto the backlight connector pads.

              Sounds like the same issue. Opening and closing the lid must have broken the rather rigid cable that is from the display.

              Master Liu has a video on the display repair but not sure that we want to do this. Using very thin disks, remove the the lcd and replace the cable.

              Root cause...If apple / Foxconn are listening...drop this flex cable vendor.

              If this is NOT flexgate, any other ideas to test?

              The display has the contents but backlight goes off.

              Can review the backlight power rail and its enable pin on Monday.

              If power rail is on then all related to contacts and flex cable.
              Last edited by mon2; 02-13-2021, 08:36 AM.

                Comment

                • mon2
                  Badcaps Legend
                  • Dec 2019
                  • 13940
                  • Canada
                  #5
                  Re: A1707 820-00928 Backlight issue

                  Looks to be another amateur design flaw by Apple. Promote these engineers...

                  https://www.ifixit.com/Answers/View/...6+no+backlight

                  Would show them the door with a cattle prod at our company.

                    Comment

                    • mon2
                      Badcaps Legend
                      • Dec 2019
                      • 13940
                      • Canada
                      #6
                      Re: A1707 820-00928 Backlight issue

                      As per my last post, this appears to be a flexgate related issue.

                      Observing that when the lid is open, backlight is on while the display is < 90 degrees to the keyboard.

                      After this range of open, the backlight is dark. However, the backlight voltage is @ 58v.

                      When the backlight is working, backlight is 48-49v.

                      Concerned about the dual fans are spinning like mad - temp is 104F using an IR temp on the bar-style heatsinks.

                      Need to apply fresh heatsink compound to cool this down?

                      Any ideas or is a replacement of the display assembly the only solution?

                      We may attempt the dissection of the screen as shown by Master Liu but I for one may leave footprints in the rice paper and am very nervous about such a delicate operation. We are ok to order the proper tools from Asia once they open..

                      https://www.youtube.com/watch?v=fVVq...ature=emb_logo

                        Comment

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