Macbook 2008 A1728 820-2327 No greenlight No power

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  • platinumsteel
    Badcaps Veteran
    • May 2019
    • 234
    • Trinidad&Tobago
    #1

    Macbook 2008 A1728 820-2327 No greenlight No power

    Hi again guys I have a tricky one.Macbook 2008 No greenlight when i got it.I am using bench power supply at 16.5V to power it up. It draws 0.02 amps .First measurement I took was PPBUS_G3H and sometimes i get 12.26V and sometimes i get 8.25V.Today i got 12.26V and decided to take some measurements on the U7000 ISL and also the 1 wire circuit which is responsible for the green light. I am having a lot of trouble understanding this model 1 Wire circuit. Hoping you guys can point out what doesn't look right and feel free to point me in the right direction. Especially with the 1-Wire circuit. I have a donor board which i can use to replace components.

    These are the measurments I took of the 1-Wire



    U7000 results below
    (Replaced R7010 and R7011 on Pin 3 .Those resistors were bad)

    Pin 1=0v
    Pin 2=16.27v
    Pin 3=3.8v
    Pin 4=3.1v
    Pin 5=1.3v
    Pin 6=0v
    Pin 7 =1v
    Pin 8 =2v
    Pin 9 =0v
    Pin 10 = 3.4v
    Pin 11 = 3.4v
    Pin 12 = 3.4v
    Pin 13 = 0v
    Pin 14 = 3.3v
    Pin 15=0v
    Pin 16 = 12.23v
    Pin 17 = 12.23v
    Pin 18 = 12.26v
    Pin 19= 5v
    Pin 20= 5v
    Pin 21= 0.642V
    Pin22=0v
    Pin23= 12.26V
    Pin24 =13v
    Pin25 =16.56v
    Pin26 =0v
    Pin 27 =16v
    Pin 28 =16v
    Tags: None
    • piernov
      Super Moderator
      • Jan 2016
      • 4435
      • France
      #2
      Re: Macbook 2008 A1728 820-2327 No greenlight No power

      Voltage on PP3V3_S5_SMC_AVCC, SMC_RESET_L, ADAPTER_SENSE, SYS_ONEWIRE?
      OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

        Comment

        • platinumsteel
          Badcaps Veteran
          • May 2019
          • 234
          • Trinidad&Tobago
          #3
          Re: Macbook 2008 A1728 820-2327 No greenlight No power

          PP3V3_S5 = 0v
          (SMC_AVCC) <<not shown GND_SMC_AVCC =0v PP3V3_S5_SMC_AVCC=3.41V
          SMC_RESET_L =3.42v
          ADAPTER_SENSE =2.864V
          SYS_ONEWIRE = 2.863V

          I now noticed a good bit of corrosion around the SMC area..Not sure if it means anything.

            Comment

            • piernov
              Super Moderator
              • Jan 2016
              • 4435
              • France
              #4
              Re: Macbook 2008 A1728 820-2327 No greenlight No power

              Of course it does, this is liquid damage, the SMC isn't working right now… Clean the dirt and corrosion, fix traces if need be, reflow the SMC and look for other corroded area.
              OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

                Comment

                • platinumsteel
                  Badcaps Veteran
                  • May 2019
                  • 234
                  • Trinidad&Tobago
                  #5
                  Re: Macbook 2008 A1728 820-2327 No greenlight No power

                  Yo piernov you are great. Thanks a lot for leading me in the right direction. When you told me to check the voltage on SMC_AVCC i noticed the corrosion in that area as you see in the picture. So i cleaned it up..and checked R5070 resistance.R5070 belongs to SMC_ONOFF_L As you can see in picture below.I replaced it with one from donor board and plugged in and immediately got a green light.I was so excited i didn't even bother too see if i get fan spin..and needed to report back here.Cause had you not told me to check those areas i would of still be groping in the wrong places.lol Thanks a lot man.Only issue i have now is PPBUS_G3H is still saying 9V so the fight continues. But i'm so grateful to even get a greenlight.lol Will keep working on it.PP3V3_S5 is now 3.322V.

                    Comment

                    • platinumsteel
                      Badcaps Veteran
                      • May 2019
                      • 234
                      • Trinidad&Tobago
                      #6
                      Re: Macbook 2008 A1728 820-2327 No greenlight No power

                      Okay my friends. Machine is finally up and running now...Didn't go tru with the reflow of SMC.Today it gave me PPBUS_G3H 12.57V instead of 9V and i decided to try and power it up..Machine powered on and seems to be working fine. So thanks again Pier for the help on this one.It's really good not to give up on any machine that you think may not be able to be resurrected. lol

                        Comment

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