Macbook pro 820-00928-A Power but no Image

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  • Comp_Pro
    Member
    • Jun 2020
    • 33
    • USA
    #1

    Macbook pro 820-00928-A Power but no Image

    Hello all,

    I have this macbook pro board number 820-00928 which appears to power on fine and charge the battery but does not show any other signs of life. I can see the fans spinning and the heatsink get hot. Most of the coils on the board have voltage except for PPVCCGT_CPU_PH1 and PPVCCGT_CPU_PH2 as well as P5VUSBCT_LL. There is no chime, no caps lock light, no nothing.

    Something very peculiar is that with the battery disconnected, the motherboard is drawing a steady 1.31Amps at all times. It is not showing typical fluctuations as one would expect. I attempted DFU restore but it will not show in configurator 2. I will be inspecting further.

    Has anyone come across this issue?
    Tags: None
    • mon2
      Badcaps Legend
      • Dec 2019
      • 13936
      • Canada
      #2
      Re: Macbook pro 820-00928-A Power but no Image

      Static current draw could mean a shorted cap or another component.

      Remove all power. Meter in resistance mode. Measure the resistance to ground at each and every coil. Each coil is linked to a buck regulator that accepts a higher input voltage and lowers it to another voltage.

      A low resistance could be due to a shorted part.

        Comment

        • reformatt
          Badcaps Legend
          • Feb 2020
          • 1400
          • Australia
          #3
          Re: Macbook pro 820-00928-A Power but no Image

          At face value, sounds like a damaged CPU. Common on these models is liquid damage to the LCD connector or the CPU VRM's. In my experience, Vcore present with no CPU activity with this high current is normally indicative of a damaged CPU.

          Check the LCD connector both ends for any liquid damage. Crap design with 50V backlight leaking into the adjacent EDP data line pin to the CPU. Have one here last week where the CPU still works, but the EDP line is shorted to ground (and thus no image on the LCD but works external via USB-C/HDMI). I would have expected the CPU to be dead, but this one survived. Maybe because one of the USB-C controllers had a shorted cap on it as well.

            Comment

            • piernov
              Super Moderator
              • Jan 2016
              • 4435
              • France
              #4
              Re: Macbook pro 820-00928-A Power but no Image

              No T2, no DFU restore. Regular SPI ROM for UEFI on this board.
              OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

                Comment

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