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820-3023 green light, warm cpu

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  • 820-3023 green light, warm cpu

    figured i'd ask before i spend another few hours messing around with it
    have a 13" 820-3023 which had liquid damage, cleaned

    initially PPBUS_G3H was jumping around between 8.5 and 3.4V, so I replaced R7051, R7052, and R7002

    magsafe is green and CPU gets warm within about a minute but doesn't get as far enough for fans to spin

    saw visual damage and put a wire between R2822 and Q2820 (PM_MEM_PWRGD)

    wasn't sure if I should still be looking around there and whether that voltage divider wasn't working right because they read as 15k in circuit

    getting diode reading .000 on R2801 pin 1
    my working comparison board is giving .081

    or should i be look at other S5 and S0 rails?

  • #2
    i'm guessing a CPU mosfet or cap in that area is shorted. Is PPBUS_G3H a steady 8.5v now? Is the machine in an S0 state, meaning S0 rails are present?

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    • #3
      g3h is steady now, yes def in S0 state
      getting 5.17V on PP5V_S0_CPU_VCCIO probe 371

      you even hear the board make a super faint little power squeak as it tries to turn on

      not getting the 1.5V on PM_MEM_PWRGD probe 379

      you think it's Q2820 shorting it to ground? or something else. not really any caps in that area, just a whole bunch of mosfet gates

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      • #4
        Let's look at this logically. Q2820 is going to short PM_MEM_PWRGD to ground if voltage on pin 2 is too high.

        So what is PM_MEM_PWRGD_L measuring? This means PM_MEM_PWRGD is present when the signal is LOW, so when it's HIGH it will short it to ground.

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