A2485, A2780(820-02100, 820-02890) PP3V8 short

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  • JxxK
    New Member
    • Jan 2024
    • 3
    • Korea

    #1

    A2485, A2780(820-02100, 820-02890) PP3V8 short

    Hello
    I am repairing the A2780 (M2Pro 16").
    There is no schematics and board view of A2708 yet, so I am referring 820-02100 (A2485).

    Stuck 5.2V, 0.02A
    'PP3V8_AON' short on diode mode and no voltage.
    'PP3V8_AON_MPMU' short on diode mode.
    'PPBUS_AON' looks fine. 12.3V
    'PPVIN_P3V8AON' looks fine(not short on diode mode), 12.3V

    I tried to remove the U5700, Q5800, Q5820, Q5840 and PP3V8 aond still stuck.

    It seems to be a problem in the process of moving from 'PPBUS_AON' to 'PP3V8_AON'.
    Even if I check with thermal image after energy injection, there is no heat. All I need to do is save the data. Where should I check it?
    Last edited by JxxK; 05-27-2024, 07:14 AM.
  • mon2
    Badcaps Legend
    • Dec 2019
    • 13894
    • Canada

    #2
    With no power to the board, measure the resistance to ground of PP3V8_AON.

    Comment

    • JxxK
      New Member
      • Jan 2024
      • 3
      • Korea

      #3
      Originally posted by mon2
      With no power to the board, measure the resistance to ground of PP3V8_AON.
      Thansk to reply.

      PP3V8_AON: 0.2Ω

      Comment

      • mon2
        Badcaps Legend
        • Dec 2019
        • 13894
        • Canada

        #4
        That is a dead short. Inject 1 volt only but at 3A or more here. Someone will heat up.

        Comment

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