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Macbook A2251 820-01949A - 20v not powering on or charging

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  • tccyo22
    Senior Member
    • Oct 2019
    • 79
    • UK

    #1

    Macbook A2251 820-01949A - 20v not powering on or charging

    Hi there, this one has me stumped. Quick back story is this macbook had a very small liquid damage on one side of charge ports which burnt the connector. I've currently got that side of USB ports disconnected and I've replaced the connector and the CD3217 that was stopping the macbook from transitioning to 20v. (It was originally stuck at 5v 0a) and I'm using the other side to diagnose this board.

    I now get 20v and it appears as though the macbook is attempting to boot but it's failing? On connection of usb power I watch the voltage swap from 5v to 20v and sit at 0.1a for 2-3 seconds then it will jump to 0.2a for a second then 0a and will not repeat unless I cut power and supply again.

    All my main power rails are mostly present from the power aliases however

    PPBUS_G3H = 12.65v (Schematic suggest 13.1v so this seems a little low)
    PP1V8_S5 is missing entirely. looking at U7700 the enable signal PM_SLP_SUS_L is missing. R7715 is 0.1ohms.

    I'm a little stuck where to go from here since it looks like PM_SLP_SUS_L comes from the CPU/PCH. Resistance on PM_SLP_SUS_L is 65k ohms.
  • mon2
    Badcaps Legend
    • Dec 2019
    • 15928
    • Canada

    #2
    Test the nand flash power rail for voltage and also resistance (without power).

    PPVCCQ_ANI_SSD0 (1.8V): This is for the NAND. Shorting here is a common failure.

    Attempt a DFU.

    Comment

    • tccyo22
      Senior Member
      • Oct 2019
      • 79
      • UK

      #3
      Originally posted by mon2
      Test the nand flash power rail for voltage and also resistance (without power).

      PPVCCQ_ANI_SSD0 (1.8V): This is for the NAND. Shorting here is a common failure.

      Attempt a DFU.
      No short on this rail. I've managed to get it to boot after finding 1 resistor that was partially failed around the damaged area. Always worth going back to double check sometimes as I had missed one or as they say, can't see for looking.

      Comment

      • mon2
        Badcaps Legend
        • Dec 2019
        • 15928
        • Canada

        #4
        Excellent.

        Comment

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