820-00165-A no SMC_PM_G2_EN

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  • cruiser_
    Senior Member
    • Nov 2019
    • 124
    • Ireland

    #1

    820-00165-A no SMC_PM_G2_EN

    Hi everyone, dealing with this 'fiddly' board here. No sign of corrosion anywhere. Board on bench with no battery.

    First inspection - shorted PP3V42_G3H which was strange - 3V voltage injection initially took no amperage, after a few tries though the short was gone. Now I am getting a stable PP3V42_G3H of 3.42V.

    I have all PPBUS_G3H / PPBUS_S5's however they are only 8.15V.

    PP3V3_S5_AVREF_SMC is there,
    SMC_BC_ACOK, SMC_RESET_L are high
    PM_BATLOW_L is low
    some activity on SMBUS_SMC_5_G3_SCL/SDA & SYS_ONEWIRE (singular spikes).
    bias voltage around 1V on SMC_XTAL_R & SMC_XTAL (my tiny oscilloscope doesn't capture anything - but it did not capture anything on another board either).

    At this point I can't get to S5 state - no SMC_PM_G2_EN means no S5_PWR_EN and no PP3V3_S5 and no PP5V_S5- as there is no SMC_PM_G2_EN for U7501 to start it off.

    I replaced U7501 thinking it pulls down SMC_PM_G2_EN, no joy.

    Reflowed SMC, no joy either.

    Original Magsafe - LED stays off. It turned orange once (?!).

    Anything else to try please?
    Last edited by cruiser_; 04-23-2023, 05:45 AM.
  • mon2
    Badcaps Legend
    • Dec 2019
    • 14004
    • Canada

    #2
    Re: 820-00165-A no SMC_PM_G2_EN

    What is the voltage to ground of ALL_SYS_PWRGD?

    Comment

    • piernov
      Super Moderator
      • Jan 2016
      • 4435
      • France

      #3
      Re: 820-00165-A no SMC_PM_G2_EN

      ALL_SYS_PWRGD is irrelevant at this point.
      Sounds like just a bad SMC.
      OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

      Comment

      • reformatt
        Badcaps Legend
        • Feb 2020
        • 1400
        • Australia

        #4
        Re: 820-00165-A no SMC_PM_G2_EN

        It does, although you should check the clock circuit for the SMC for damage, bias etc. But the short that disappeared points to a bad SMC.

        Comment

        • cruiser_
          Senior Member
          • Nov 2019
          • 124
          • Ireland

          #5
          Re: 820-00165-A no SMC_PM_G2_EN

          thank you gents,

          all nice and clean around Y5110.

          i went ahead an pulled an SMC from a donor board and am struggling to get this properly reballed. tried 0.45 balls, tried 0.3 balls, tried paste as well. disaster. tried 280, 300, 350C full blast - getting half of the balls fluid at best.

          must be missing something obvious :{

          Comment

          • cruiser_
            Senior Member
            • Nov 2019
            • 124
            • Ireland

            #6
            Re: 820-00165-A no SMC_PM_G2_EN

            it seems that the metal holder i have for chips is pulling heat too fast from this little SMC, especially in the corners. trick was to just put the chip on the bench...

            anyway, it wasn't the SMC. after the replacement still no green light.

            would SMC_*TAL be needed at this phase of operation?

            Comment

            • mon2
              Badcaps Legend
              • Dec 2019
              • 14004
              • Canada

              #7
              Re: 820-00165-A no SMC_PM_G2_EN

              Do you mean crystal? Yes, it is required.

              Comment

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