A2179 PPBUS_G3H low

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  • Gueric
    Member
    • Feb 2025
    • 43
    • France
    #1

    A2179 PPBUS_G3H low

    Hey mon2. I’ve got another crazy case for you that never happened to me before.

    A2179 board, PPBUS_G3H short, 2 ohms.
    injected voltage, 1V 5A limit, 200mA draw.
    decided to increase to 2v, amperage draw instantly dropped to a few mA.

    the resistance of the rail actually went from 2 ohm to 100 after that, and PPBUS went from 0mV to 700mV.

    checked the resistance of the 4 current sensing resistors around the ISL, all fine. Removed the ISL, went from 100 to 160 ohm.

    Replaced it, still 160 ohm.
    Removed the 2 ISL mosfets. Still the same resistance. Replaced them both, still nothing.
    Replaced the ISL AGAIN, went to 220 ohm.
    PPBUS went from 700mv to 900mv.

    im really confused now.

    Also, PPDCIN_G3H is 5v as expected.
    Tags: None
    • mon2
      Badcaps Legend
      • Dec 2019
      • 13898
      • Canada
      #2
      Hey. What is the 820-**** # you are referencing?

      Remove F7000 (for now).

      Remove all power. Meter in resistance mode. Measure the resistance between CHGR_CSIR_P and CHGR_CSIR_N. You can measure using the meter tips @ C7021 and C7022.

        Comment

        • Gueric
          Member
          • Feb 2025
          • 43
          • France
          #3
          mon2 I'm talking about the 820-01958 2020 Intel MacBook Air.

          Remove F7000? the fuse that connects PPVBAT_G3H_FUSE and PPVBAT_G3H_CONN ?

          Regarding the resistance measurement between CHGR_CSIR_P and CHGR_CSIR_N, I measured 2.6 ohm.

            Comment

            • mon2
              Badcaps Legend
              • Dec 2019
              • 13898
              • Canada
              #4
              Resistance is fine.

              Yes on the F7000 fuse.

              Measure the voltage to ground of VDDA and also VDDP.



              ​

                Comment

                • dellxps15
                  Badcaps Legend
                  • Feb 2014
                  • 1588
                  • italy
                  #5
                  if u have a thermal camera would be much easier to spot where the problem is.... also sometimes a caps get shorted only when a certain of voltage is appikied, with all the risks that it give...

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