Macbook pro 820-2879 no 5V rail

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  • andiukas223
    New Member
    • Oct 2019
    • 8
    • Lithuania
    #1

    Macbook pro 820-2879 no 5V rail

    Hello, I'm trying to fix a macbook 820-2879 that is not turning on, green light on the charger is present.
    ppbus_g3h is 12.57V
    pp3v42_g3h is 3.42V
    No liquid damage
    i tried to power on the machine by shorting the pins- no fan spin.

    On L7220 3.3V is present, on on L7260 5V not present so i checked Q7221 pin 2 and p5vs3_en_l is 3.27V, pin 5 is low. Next i checked Q7891 for PM_SLP_S4_L and it is not present. I tough't it might be bad q7891 so i replaced it, but still no 5v enable signal.

    I am certain that because of lack of knowledge and skill i am missing something.

    I ask you to help a young noob
    Last edited by andiukas223; 10-29-2019, 06:31 AM.
    Tags: None
    • piernov
      Super Moderator
      • Jan 2016
      • 4435
      • France
      #2
      Re: Macbook pro 820-2879 no 5V rail

      You need to trigger power button (short power button pads) while measuring PM_SLP_S4_L.
      Also, confirm all G3H/S5 rails are ok, confirm you are using a known good 60W/85W Magsafe, and confirm you are troubleshooting without anything connected to the board, except DC-in and fan.
      OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

        Comment

        • andiukas223
          New Member
          • Oct 2019
          • 8
          • Lithuania
          #3
          Re: Macbook pro 820-2879 no 5V rail

          Thank you for replying Piernov, i seem to have shortened something in attempt to test PM_SLP_S4_L and it got my quite sad at this point. I will get back to this in the near future .

            Comment

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