Please help!!! Macbook 820-2936b ppbus_g3h stuck at 4-4.5v

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  • justin35
    Senior Member
    • Jan 2019
    • 149
    • It
    #1

    Please help!!! Macbook 820-2936b ppbus_g3h stuck at 4-4.5v

    I have this annoying board who is trolling me
    First it was no green light no pp3v42_g3h no ppbus_g3h
    I restored pp33v42_g3h but no green light
    I changed smc but still no green light, because i was missing smc_bc_acok
    I changed u7000 again and i got green light and ppbus_g3h went at 4v fluctuating a little
    I checked
    r7051/52 both ok also traces from and to and they are good
    R7020/21 both ok also traces from and to and they are good
    Replaced q7030/35 no luck
    Reheated smc and lost green light...
    Pulled out smc but ppbus_g3h is now 4.1 to 4.5v...
    Changed u7000 from a donor that has no smc but ppbus_g3h 12.3v my ppbus stil 4.something (((
    Everything looks fine...

    I don’t know that to do next...
    Any ideea?
    Last edited by justin35; 05-23-2019, 02:15 PM.
    Tags: None
    • justin35
      Senior Member
      • Jan 2019
      • 149
      • It
      #2
      Re: Please help!!! Macbook 820-2936b ppbus_g3h stuck at 4-4.5v

      If i put a battery ppbus_g3h is 11.4v....

        Comment

        • piernov
          Super Moderator
          • Jan 2016
          • 4435
          • France
          #3
          Re: Please help!!! Macbook 820-2936b ppbus_g3h stuck at 4-4.5v

          Check again current sensing by measuring resistance between pin17 and 18, and between pin27 and 28.
          Check voltage on drain of high-side MOSFET of PPBUS_G3H.
          Disconnect the fuse and check voltage of PPBUS_G3H before the fuse.
          Check voltage on ACIN, DCIN, CELL, VDD, VDPP, ACOK.
          OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

            Comment

            • justin35
              Senior Member
              • Jan 2019
              • 149
              • It
              #4
              Re: Please help!!! Macbook 820-2936b ppbus_g3h stuck at 4-4.5v

              Fuse was disconnected long time ago, no short on either side...
              Smc is off the board... but i am sure i should get 10-12v without smc...

              17-18 2,86 ohm
              27/28 20.08ohm
              Q7035 pin5 drain 4.05-4.35
              Q7030 pin5 drain 16.38
              Chgr_acin 3.9-3.98
              Chgr_dcin 16.2-16.4
              Chgr_cell 3.46
              Pp5v1_chgr_vdd 5.04
              Pp5v1_chgr_vddp 5.02
              Smc_bc_acok 3.31

              I'm lost...

                Comment

                • justin35
                  Senior Member
                  • Jan 2019
                  • 149
                  • It
                  #5
                  Re: Please help!!! Macbook 820-2936b ppbus_g3h stuck at 4-4.5v

                  Ok, case solved, the board was missing c7025, dumb me because i did not inspect the u7000 area closer... as i found other ic missing on the edge of the board...
                  I have 12.28v now... with or without smc...
                  i've put back the old smc as the new one got 2 lifted pads while reballing...
                  I am also missing pp5v_s5 but i assime this is why the smc is not turning on, right?
                  Thanks a lot!!!

                    Comment

                    • justin35
                      Senior Member
                      • Jan 2019
                      • 149
                      • It
                      #6
                      Re: Please help!!! Macbook 820-2936b ppbus_g3h stuck at 4-4.5v

                      Pp5v_s5 and pp3v3_s5 is restored improper solder to u7200
                      Seems like someone else was here )
                      Ppbus_g3h still steady 12.28v
                      Looks like the smc was bad?!?

                      Will an smc from a core2duo doard work? (820-2879)?
                      Never tried before this kind of swap...
                      Thanks!

                        Comment

                        • piernov
                          Super Moderator
                          • Jan 2016
                          • 4435
                          • France
                          #7
                          Re: Please help!!! Macbook 820-2936b ppbus_g3h stuck at 4-4.5v

                          Yeah wouldn't have thought of C7025, it's not one of the common culprit, good catch.

                          Do you have green light on Magsafe? PP3V42_G3H is exactly 3.42V? SMC_RESET_L is high?

                          If ever the SMC needs to be swapped, it has to be from the same model donor board. An SMC from a 820-2879 won't work. There are a few select cases where an SMC from a different board will at least allow POST, but that's not the case here as far as I know.
                          OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

                            Comment

                            • justin35
                              Senior Member
                              • Jan 2019
                              • 149
                              • It
                              #8
                              Re: Please help!!! Macbook 820-2936b ppbus_g3h stuck at 4-4.5v

                              Thanks!
                              Pp3v42 is 3.4598 super pinpoint steady...
                              Of course green light is present, SOLID green.
                              I found out smc_manual_rst_l is 2,87v and on a working board is 0.1v...
                              U5010:
                              Pin1 3.45
                              Pin2 0
                              Pin3 3.45
                              Pin4 2.87
                              Pin5 3.42
                              Pin6 3.45
                              Pin7 3.45
                              Pin8 3.29

                              I am worried about pin4 2.87v is it normal?

                              Thanks again!

                                Comment

                                • justin35
                                  Senior Member
                                  • Jan 2019
                                  • 149
                                  • It
                                  #9
                                  Re: Please help!!! Macbook 820-2936b ppbus_g3h stuck at 4-4.5v

                                  Quick question, how do you bypass smc? I never knew that...
                                  Before i change smc again, not that i have another right now... i want to bypass smc and see if it goes further
                                  Thanks again!

                                    Comment

                                    • piernov
                                      Super Moderator
                                      • Jan 2016
                                      • 4435
                                      • France
                                      #10
                                      Re: Please help!!! Macbook 820-2936b ppbus_g3h stuck at 4-4.5v

                                      If you have green light (and you are using a genuine Apple Magsafe) then SMC should be somewhat working.
                                      SMC_RESET_L is high so nothing wrong there (if it was low you wouldn't get green light).

                                      If you have green light but PPBUS_G3H is 12.3V instead of 12.6V there's a communication issue between SMC and charger IC. The battery, the battery indicator LED, the charger IC, the pullup resistors of the SMBUS or the SMC can be the cause. You can check voltage and diode mode measurement to ground on SDA/SLC going to charger IC.

                                      For SMC bypass, you have to disconnect all source of power, hold power button then plug Magsafe in, and release power button 5-10 seconds later.
                                      OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

                                        Comment

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