Logic Board 820-01987-A missing PP3V3_S5

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  • mferna14
    Badcaps Legend
    • Jun 2018
    • 1006
    • Canada

    #1

    Logic Board 820-01987-A missing PP3V3_S5

    Hi good Friends., today working on a Macbook Pro A2289, Logic board 820-01978-A. The history was liquid spill, Cleaned & replaced all corroded components & now the logic board shows 20v & .01amp on the meter. Not taking in any amps. Upon trouble shooting I get the required stable voltages 5V, PP3V3_G3H 3.3V but no PP3V3_S5. Checked the schematic, assume that this is generated from U7800. Checked all the Input/Output voltages on this chip. All is fine, except PP3V3_S5 is missing. Resistance from GND to PP3V3_S5 is 146 Kohms. First I need to make sure whether PP3V3_S5 is generated from this chip??? Thanks in advance
  • mon2
    Badcaps Legend
    • Dec 2019
    • 13829
    • Canada

    #2
    What is the exact voltage to ground of PPBUS_G3H @ F7000?

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    • mferna14
      Badcaps Legend
      • Jun 2018
      • 1006
      • Canada

      #3
      PPBUS_G3H @ F7000 = 12.61V (no fluctuations at all)... Do you think that this logic board has gone into DFU or Recovery mode as it's Pulling ~0.03-0.06A current at 20v from USB-C as measured by USBC meter​
      Last edited by mferna14; 06-08-2025, 12:13 PM.

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      • mon2
        Badcaps Legend
        • Dec 2019
        • 13829
        • Canada

        #4
        It could be but personally cannot keep up with the madness of each model as it varies with the direction of the wind. THIS model does require a charged battery to boot. Would you have a battery connected? Ghettoware.

        reference:
        https://boards.rossmanngroup.com/thr...harging.64804/

        See post # 10.

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        • mferna14
          Badcaps Legend
          • Jun 2018
          • 1006
          • Canada

          #5
          Ok mon2., at last I figured out ths problem. This laptop had to be put in DFU mode & all restored back to factory default. Now at least I will remember that with 20V & drawing 0.03 ~ 0.08 amp, mostly it is to be rectified with DFU Mode. & one thing more for these models logic boards PP3V3_S5 will be missing & once restored all the require point with have 3.3V. Case done. Thanks dear for your help

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