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A2289 (820-01987) 3v3_G3H_RTC

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    #1

    A2289 (820-01987) 3v3_G3H_RTC

    As always with nearly every T2 board, board is squeaky clean.. 3v3_G3H_RTC had a short..
    Of course in TPS chip.. I replaced it..
    Found another short in 3v3_G3H_RTC in SoC PMU; replaced..

    Board was taking 5v 0.40a on one port and another port is erratic.. ammeter turns on and off.. In thermal camera found TBT ROM was getting warm up to 38c.. PP3V3_UPC_XB_LDO had low diode mode reading..
    Replaced TBT ROM from another known-good A2289..

    Now board switches to 20v and consumes low wattage.. gets into DFU revives and restores successfully without errors..

    But nothing on screen.. only the trackpad is clicking..
    Tags: None
    #2
    Caps key led toggles?

    Test with an external monitor.

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      #3
      I put the board under the thermal cam again, found U8510 heating.. tested the pads and found SMCRST_TIEOFF almost direct short to ground instead of 0.721 in diode mode..

      No caps lock toggle.. nothing on external monitor.. put the board again under the thermal cam.. PMU, T2, TPS are all getting warm which is normal.. I found wifi chip around 31c.. idk if it has anything to do with the issue..

      PMU bucks are present.. 5v G3s present.. 1.8v G3S present.. SSD rails available and stable.. no volt in CPU coils

      Hate this machine hate this model hate all T2sssssssssss

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        #4
        What is the voltage to ground of PPBUS_G3H @ F7000? If you can DFU, this is a good start. Is the PPBUS_G3H stable or power cycling?

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          #5
          PPBUS_G3H 12.61v nice and stable

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            #6
            What is the current draw of the 20v from the power adapter? The power adapter is suitable to power this unit? Always suggest 100W rated USB C adapters with 100W rated (or higher) USB C cabling - if not using the original OEM adapter by Apple (no clones).

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              #7
              Using Apple Original 96W power adapter ofc.

              Power draw:
              After it switches to 20v
              Amp consumption goes into a pattern:
              0.11 > 0.22 > 0.14 > 0.23 > 0.43 (just for a sec) then drops > 0.11 > then to 0.06 and stays there

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                #8
                Suggest to test each inductor - the resistance to ground.

                Is this your case?

                https://repair.wiki/w/MacBook_Pro_A2..._at_20V_repair

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                  #9
                  I went on each inductor all around the board.. no shorts found..

                  I will look into that article tomorrow cause I'm leaving in a bit, although it does not quite match my board's symptoms but nevertheless, worth the shot.

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                    #10
                    RIP

                    PP3v3_S5 short to ground..

                    After volt injection PCH is warm..
                    Attached Files

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