MacBook 12" A1534 2017 820-00687-B

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  • mferna14
    Badcaps Legend
    • Jun 2018
    • 1046
    • Canada

    #1

    MacBook 12" A1534 2017 820-00687-B

    I am working on MacBook 12" A1534 2017 820-00687-B assuming that the logic board is same as 820-00244-B. It was not powering on. I did a ultra sonic cleaning of the motherboard since I saw some traces of liquid spill. Tested out of the casing, all worked fine & display was working 100% well. When I installed it again, no display. So I again was removing the logic board & while removing the keyboard connector I saw little smoke off the connector. I started to check the voltages again. 3.3volts is perfect but 5 volts rail fluctuates on & off on coil L7670 (PP5V_S4)., 5V come & goes again. I did not find any short to ground on this rail. Any tips or guidance will really be appreciated. Thanks in advance.
    Last edited by mferna14; 04-27-2021, 05:08 PM.
  • mferna14
    Badcaps Legend
    • Jun 2018
    • 1046
    • Canada

    #2
    Re: MacBook 12" A1534 2017 820-00687-B

    Anyone there to help... Thanks

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    • mon2
      Badcaps Legend
      • Dec 2019
      • 14662
      • Canada

      #3
      Re: MacBook 12" A1534 2017 820-00687-B

      Remove the keyboard / trackpad cables.

      Check the EN pin on U7650 - does it also toggle ON / OFF with the pulsing of this rail?

      Check the components on pins 7 & 8 on U7650. Anything missing ?

      Comment

      • mferna14
        Badcaps Legend
        • Jun 2018
        • 1046
        • Canada

        #4
        Re: MacBook 12" A1534 2017 820-00687-B

        Thanks "mon2" will do so & report... thanks for the help

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        • mferna14
          Badcaps Legend
          • Jun 2018
          • 1046
          • Canada

          #5
          Re: MacBook 12" A1534 2017 820-00687-B

          Ok 'mon2"., on the EN1 pin of U7650 (PM_SLP_S5_L) the voltage toggles on & off, even on pin 7 & 8 same thing voltage toggles.. But EN2 (S5_PWR_EN) pin 21, here the voltage is constant 3volts, this is why I am getting the 3.3v perfectly. Next to check I think "PM_SLP_S5_L" from where it genereating or some rail. Please inform me.. Thanks

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          • mon2
            Badcaps Legend
            • Dec 2019
            • 14662
            • Canada

            #6
            Re: MacBook 12" A1534 2017 820-00687-B

            1) PM_SLP_S5_L is generated by U0500, ball BH14 - sheet 15/67 of the PDF.

            2) What is the voltage on PM_SLP_S5_L ?

            3) With the power off, battery removed, what is the resistance to ground on L7670, pin # 1 ?

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            • mferna14
              Badcaps Legend
              • Jun 2018
              • 1046
              • Canada

              #7
              Re: MacBook 12" A1534 2017 820-00687-B

              2) What is the voltage on PM_SLP_S5_L ? nearly 2.9 & then drops
              3) With the power off, battery removed, what is the resistance to ground on L7670, pin # 1 ? 350.5k ohms & its keep on decreasing ohms

              Comment

              • mferna14
                Badcaps Legend
                • Jun 2018
                • 1046
                • Canada

                #8
                Re: MacBook 12" A1534 2017 820-00687-B

                Do think the CPU got defective???

                Comment

                • mon2
                  Badcaps Legend
                  • Dec 2019
                  • 14662
                  • Canada

                  #9
                  Re: MacBook 12" A1534 2017 820-00687-B

                  The CPU may be defective as reported by more seasoned techs on this forum but hate to believe it. It is a show stopper of an issue if true.

                  Our fancy BGA rework station should land next week and we are looking forward to complex repairs like CPU rework / reflowing. Has multiple HD vision cameras to perfectly align the balls once we clean the drop site.

                  2) What is the voltage on PM_SLP_S5_L ? nearly 2.9 & then drops


                  What is the voltage reading once this rail settles ?

                  Comment

                  • mferna14
                    Badcaps Legend
                    • Jun 2018
                    • 1046
                    • Canada

                    #10
                    Re: MacBook 12" A1534 2017 820-00687-B

                    Thanks "mon2"
                    "What is the voltage reading once this rail settles ?" the voltages never settles & it keeps on toggling on & off...

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                    • mferna14
                      Badcaps Legend
                      • Jun 2018
                      • 1046
                      • Canada

                      #11
                      Re: MacBook 12" A1534 2017 820-00687-B

                      Mr. "piernov" any thoughts on this repairs... Hope you can give me some good tips. Thanks in advance.

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                      • Erat
                        Member
                        • Mar 2015
                        • 13
                        • Greece

                        #12
                        Re: MacBook 12" A1534 2017 820-00687-B

                        I know its an old post but did you manage to find what was it? I have the exact same problem pp5v_s4 make spikes every so.

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                        • mferna14
                          Badcaps Legend
                          • Jun 2018
                          • 1046
                          • Canada

                          #13
                          Re: MacBook 12" A1534 2017 820-00687-B

                          This was a 11" Apple laptop, you know I could not find the problem, eventually I purchase a new motherboard, got for $200, worth it. You look for a new motherboard too, very difficult to find where the problem would be. Thanks

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