Macbook A2681

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  • bryceonrice1111
    New Member
    • Jan 2021
    • 4
    • United States

    #1

    Macbook A2681

    Macbook A2681
    USB meter cycles between reading 19.93v and 0v every 5 seconds.
    PPBUS_AON cycles between 0v and 11.9v when plugged in.
    Not sure what to check/replace.
    Any help appreciated.
  • mon2
    Badcaps Legend
    • Dec 2019
    • 13834
    • Canada

    #2
    What is the history of the unit? Liquid spill?

    Using the Apple original and recommended power adapter for this macbook?

    Remove all power. Disconnect the battery. Meter in resistance mode. What is the resistance (ohms, not diode mode) to ground of PPBUS_AON @ fuse F5200?

    What is the resistance to ground of:

    SMBUS_BATT_1V8_SCL
    SMBUS_BATT_1V8_SDA

    Comment

    • bryceonrice1111
      New Member
      • Jan 2021
      • 4
      • United States

      #3
      Laptop is in great physical condition, no liquid damage or any signs of damage to the board. The owner says the laptop died in the middle of using it.

      Yes using the original charger. Same behavior between usb c port and magsafe ( when connected to magsafe blinks orange light on/off every 5 seconds).

      Resistance to ground of PPBUS_AON on fuse F5200 reads O.L on the multimeter.

      SMBUS_BATT_1V8_SCL reads 127.6k ohms
      SMBUS_BATT_1V8_SDA​ reads 123k ohms

      Comment

      • MobileXT
        Senior Member
        • Oct 2012
        • 191
        • USA

        #4
        Look like your PPBUS_AON is shorted to ground. You need to inject voltage on ppbus I would recommend start with 1volt and look on the cpu if not getting hot. If not getting hot then you adjust the voltage to 5v then 12v.

        Comment

        • mon2
          Badcaps Legend
          • Dec 2019
          • 13834
          • Canada

          #5
          No. Resistance to ground is OL = over limit so select a higher resistance scale on the meter. Not to be confused with 0 ohms like when the probes are shorted or touching each other.

          Be sure to test the resistance to ground on each side of the fuse, in case the fuse is blown. That is rare for the fuse to be blown.

          Comment

          • bryceonrice1111
            New Member
            • Jan 2021
            • 4
            • United States

            #6
            TIL how to manually set the range of my multimeter lol.

            Its reading 2.9 Megaohms on both sides, I tested the fuse for continuity I believe its fine.

            Comment

            • bryceonrice1111
              New Member
              • Jan 2021
              • 4
              • United States

              #7
              mon2 any idea what to check?​

              Comment

              • mon2
                Badcaps Legend
                • Dec 2019
                • 13834
                • Canada

                #8
                Try a DFU.

                A2681 repair after water damage | Rossmanngroup Forums

                Comment

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