820-00850 20V 0.0amps

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  • iMuhtaseb
    Senior Member
    • Jan 2017
    • 122
    • Palesine
    #1

    820-00850 20V 0.0amps

    - 820-00850 came in does not power on
    - cleaned it up by prior shop
    - takes 20v, then 0.200mA - 0.150mA and drops down to 0.00A
    - 20V is OK board, tested PPDCIN
    - PPBUS is 12.6V
    PP3V3_G3H is 3.3v
    PP3V_G3H_RTC is 3V
    PP5V_G3S is 5.1V
    PP3V3_G3S is 3.3v
    PP1V8_G3S is 1.8V
    PP3V3_AWAKE is 3.3V
    PP0V8_SLPS2R IS 0.78V
    PP1V2_AWAKE is 1.2V
    PP3V3_G3H_PMU_VDDMAIN is 3.3V
    PP1V8_SSD is 1.8V
    PP0V9_SSD is 0.9V
    PP3V3_S5 IS MISSING

    PMU_ONOFF_L = 3.3v
    PMU_RSLOC_RST_L = 3.3v
    CHGR_RST_IN_R = 0.0V


    From the schematics, PP3V3_S5 is generated by U700 the PMU..

    I'd appreciate a hint or lead on something I may have missed

    Checked for shorts, no shorts..
    Tags: None
    • mon2
      Badcaps Legend
      • Dec 2019
      • 14034
      • Canada
      #2
      Re: 820-00850 20V 0.0amps

      Hi.

      1) Do the posted voltage rails remain ON when you attach the adapter or do they power cycle ?

      2) Are you using the suitable power adapter for this logic board ?

      3) Post the voltage readings for:

      I2C_PWR_SCL
      I2C_PWR_SDA

      4) Remove all power. Meter in resistance mode. What is the resistance to ground for PP3V3_S5 ?

        Comment

        • iMuhtaseb
          Senior Member
          • Jan 2017
          • 122
          • Palesine
          #3
          Re: 820-00850 20V 0.0amps

          1) Do the posted voltage rails remain ON when you attach the adapter or do they power cycle ?

          • Yes, very nice and stable.

          2) Are you using the suitable power adapter for this logic board ?

          • Yes, an Apple original 97W USB-C with an Apple original USB-C to USB-C cable.

          3) Post the voltage readings for:

          I2C_PWR_SCL is 1.79V
          I2C_PWR_SDA is 1.79v

          4) Remove all power. Meter in resistance mode. What is the resistance to ground for PP3V3_S5 ?[/QUOTE]

          Resistance mode: PP3V3_S5 110 kOhms (black probe on ground, red probe on PP3V3_S5.
          Diode mode: PP3V3_S5 0.360 (red probe on ground, red probe on PP3V3_S5).

            Comment

            • mon2
              Badcaps Legend
              • Dec 2019
              • 14034
              • Canada
              #4
              Re: 820-00850 20V 0.0amps

              Do you see any voltage on PP3V3_S5 ?

              Perhaps PP3V3_S5 is pulsing during power up ?

              Also, review this thread:

              https://www.reddit.com/r/mobilerepai...rails_missing/

              which notes that from Louis' youtube videos, corrupt T2 firmware could be the root cause.

              The linked above case looks similar to yours. Do update this thread for future readers, either way.
              Last edited by mon2; 12-23-2021, 12:29 PM.

                Comment

                • iMuhtaseb
                  Senior Member
                  • Jan 2017
                  • 122
                  • Palesine
                  #5
                  Re: 820-00850 20V 0.0amps

                  Perhaps PP3V3_S5 is pulsing during power up ?

                  Sadly, my multimeter is not advanced to good enough to detect quick pulses.

                  Also, review this thread:

                  https://www.reddit.com/r/mobilerepai...rails_missing/

                  which notes that from Louis' youtube videos, corrupt T2 firmware could be the root cause.

                  I've attempted DFU revive but haven't gone to restore, since it has important data on the logic board.

                  This is the error I get after revive:
                  "The operation couldn’t be completed. (AMRestoreErrorDomain error -1 - Failed to handle message type StatusMsg (Generic error)) [AMRestoreErrorDomain – 0xFFFFFFFFFFFFFFFF (-1) [sys = 0x3F, sub = 0xFFF, code = 0x3FFF (16383)]]"

                    Comment

                    • mon2
                      Badcaps Legend
                      • Dec 2019
                      • 14034
                      • Canada
                      #6
                      Re: 820-00850 20V 0.0amps

                      Have you tested all Type C connectors ? Same behavior ?

                      How does this logic behave with a charged battery ?

                        Comment

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