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MacBook Air 820-3437 green light won't turn on. Missing PP3v3_SUS

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    #1

    MacBook Air 820-3437 green light won't turn on. Missing PP3v3_SUS

    This is a liquid damaged board that was dead with no green light.

    Replaced SMC and have green light and S5 rails including pp3v3_s5.

    No S4 rails because BIOS chip is not getting power from pp3v3_sus

    But pp3v3_sus is not short.

    It looks like pp3v3_sus is enabled by p3v3sus_en, which is missing.

    It looks like p3v3sus_en is created by pm_slp_sus_l which is also missing.

    And it looks like pm_slp_sus_l is supposed to be coming from the CPU/PCH.

    I also noticed PM_RSMRST_L is missing, but that looks like pp3v3_sus is required before that signal is present. Maybe I am wrong though.

    PPVRTC_G3H is good.

    RTC_RESET_L is good.

    PM_DSW_PWRGD is good.

    Can't find any shorted rails.

    That's about as far as my amateur brain can go. Any tips?
    Last edited by mattpd; 01-08-2020, 02:52 PM.
    Tags: None
    #2
    Re: MacBook Air 820-3437 green light won't turn on. Missing PP3v3_SUS

    PM_BATLOW_L?
    SMC_ADAPTER_EN?
    PCH_SRTCRST_L?
    PCH_INTVRMEN?
    PCH_DSWVRMEN?
    PCH_INTRUDER_L?
    32kHz RTC clock?

    PM_RSMRST_L is for PM_SLP_S5_L, not PM_SLP_SUS_L.
    OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

    Comment

      #3
      Re: MacBook Air 820-3437 green light won't turn on. Missing PP3v3_SUS

      Originally posted by piernov View Post
      PM_BATLOW_L?
      SMC_ADAPTER_EN?
      PCH_SRTCRST_L?
      PCH_INTVRMEN?
      PCH_DSWVRMEN?
      PCH_INTRUDER_L?
      32kHz RTC clock?

      PM_RSMRST_L is for PM_SLP_S5_L, not PM_SLP_SUS_L.
      Thank you for the reply.

      SMC_ADAPTER_EN = 3.3v
      PCH_SRTCRST_L = 3.3v
      PCH_INTVRMEN = 3.3v
      PCH_DSWVRMEN = 3.3v
      PCH_INTRUDER_L = 3.0v
      32kHz RTC clock = No scope unfortunately

      Comment

        #4
        Re: MacBook Air 820-3437 green light won't turn on. Missing PP3v3_SUS

        BATLOW# is missing from that list.
        OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

        Comment

          #5
          Re: MacBook Air 820-3437 green light won't turn on. Missing PP3v3_SUS

          Originally posted by piernov View Post
          BATLOW# is missing from that list.
          Sorry, also 3.3v.

          Comment

            #6
            Re: MacBook Air 820-3437 green light won't turn on. Missing PP3v3_SUS

            Oh and PM_PWRBTN_L too.
            Everything else sounds good there (except the RTC clock that's not confirmed).
            What's the resistance to ground on PM_SLP_SUS_L? No pulse at all on PM_SLP_SUS_L? Where was the liquid?
            OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

            Comment

              #7
              Re: MacBook Air 820-3437 green light won't turn on. Missing PP3v3_SUS

              Originally posted by piernov View Post
              Oh and PM_PWRBTN_L too.
              Everything else sounds good there (except the RTC clock that's not confirmed).
              What's the resistance to ground on PM_SLP_SUS_L? No pulse at all on PM_SLP_SUS_L? Where was the liquid?
              PM_PWRBTN_L = 3.41v

              I will be able to confirm the clock tomorrow.

              PM_SLP_SUS_L resistance is about 100k.

              No pulse using analog meter.

              I should have taken pictures or notes on this board. I have had it for over a month waiting on a donor SMC so I forget the original condition.

              SMC area for sure had liquid because it was bad.

              A tiny bit around BIOS area, but all traces and vias look fine.

              Some red probe points around J1800 which makes me wonder if it went under CPU. I flowed from flux under the CPU at low temp but it didn't help anything.

              Comment

                #8
                Re: MacBook Air 820-3437 green light won't turn on. Missing PP3v3_SUS

                It was crap under the PCH.

                I flowed flux for a second time under it and I got fan spin now.

                EDIT: and now back to being dead after it sat for a while...

                EDIT: Randomly get 1/4 fan spin when plugging in but most of the time not.

                EDIT: Cleaned the flux out with 99% iso and dried. Got fan spin again and confirmed CPU was warm. Didn't have LCD connected so I shut down to connect it. Now no fan spin again. Could it be bad PCH or am I still dealing with crap underneath?
                Last edited by mattpd; 01-09-2020, 12:34 PM.

                Comment

                  #9
                  Re: MacBook Air 820-3437 green light won't turn on. Missing PP3v3_SUS

                  It seems as long as I keep it warm I can get fan spin every time I plug it in. If it cools, back to being dead.

                  BUT when the fans are spinning its giving 3 beeps for bad RAM and no video.

                  So it looks like this thing had an SMC problem, still has a CPU/PCH problem, and probably a RAM problem too. Nightmare...

                  Comment

                    #10
                    Re: MacBook Air 820-3437 green light won't turn on. Missing PP3v3_SUS

                    Sounds all related to the CPU package. Could be simply dead, or the balls are too corroded to work properly.
                    Those are a real nightmare to rework, but if you have the equipment you could try to reball it (as I still have some hope it's not completely dead). Reflow will definitely kill it so don't try that.
                    OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

                    Comment

                      #11
                      Re: MacBook Air 820-3437 green light won't turn on. Missing PP3v3_SUS

                      Originally posted by piernov View Post
                      Sounds all related to the CPU package. Could be simply dead, or the balls are too corroded to work properly.
                      Those are a real nightmare to rework, but if you have the equipment you could try to reball it (as I still have some hope it's not completely dead). Reflow will definitely kill it so don't try that.
                      Well that stinks.

                      All I have is a nice hot air station. Is it impossible to do it safely without having a real BGA machine?

                      After flowing flux under the CPU 3 or 4 times it seems to turn on and give fan spin every time now, even when cold, but still 3 beeps. Kind of makes me think corrosion is more likely than failed CPU. Maybe 3 more cleanings and an extra long ultrasonic will bring back RAM

                      Comment

                        #12
                        Re: MacBook Air 820-3437 green light won't turn on. Missing PP3v3_SUS

                        Nope, even with a BGA rework station those CPUs are difficult to rework…

                        It could still be a separate issue with RAM, but no way to tell if it's RAM or CPU. You can at least confirm RAM is getting the 1.35V and 0.675V power rails, and then you can try to reflow RAM as well if you cleaned all you could under CPU.
                        OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

                        Comment

                          #13
                          Re: MacBook Air 820-3437 green light won't turn on. Missing PP3v3_SUS

                          Originally posted by piernov View Post
                          Nope, even with a BGA rework station those CPUs are difficult to rework…

                          It could still be a separate issue with RAM, but no way to tell if it's RAM or CPU. You can at least confirm RAM is getting the 1.35V and 0.675V power rails, and then you can try to reflow RAM as well if you cleaned all you could under CPU.
                          Are these the rails you speak of?

                          I see one called PP0V6_S0_DDRVTT but the schematics say it should be 0.75v. The actual measurement is 0.61v.

                          And another called PP1V35_DDR_CLK that measures 1.31v.

                          Comment

                            #14
                            Re: MacBook Air 820-3437 green light won't turn on. Missing PP3v3_SUS

                            Ah yes sorry on this machine they are 1.2V and 0.6V. Called PP1V2_S3 and PP0V6_S0_DDRVTT.

                            Voltage indication on schematics are often incorrect so don't fully trust them.
                            OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

                            Comment

                              #15
                              Re: MacBook Air 820-3437 green light won't turn on. Missing PP3v3_SUS

                              Originally posted by piernov View Post
                              Ah yes sorry on this machine they are 1.2V and 0.6V. Called PP1V2_S3 and PP0V6_S0_DDRVTT.

                              Voltage indication on schematics are often incorrect so don't fully trust them.
                              Sadly both rails are present.

                              I also re-flowed the RAM chips until they floated but still 3 beeps.

                              Is there a 100% chance of death if I hit the CPU with more heat? It's a junk board anyway so I figured it's worth a shot.

                              Comment

                                #16
                                Re: MacBook Air 820-3437 green light won't turn on. Missing PP3v3_SUS

                                @mattpd do you remember if it helped at all?
                                I have a 820-00165 board with same readings as you had initially, however there was no corrosion of any sort on mine.

                                From 11+1 prereqs I'm missing (no pulsing) PP3V3_SUS & PM_RSMRST_L with steady 0.19V PM_SLP_S4_L.

                                Comment

                                  #17
                                  Re: MacBook Air 820-3437 green light won't turn on. Missing PP3v3_SUS

                                  What is the voltage to ground of ppbus_g3h ?

                                  Comment

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