MacBook A1466 820-3437-B No power

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  • AlexVG
    Senior Member
    • Apr 2022
    • 134
    • SPAIN

    #1

    MacBook A1466 820-3437-B No power

    Hi.
    I have MacBook A1466 820-3437-B
    PDDR_S3_REG is 1.2V
    PP3V3_S5_REG is 3,3V
    PPDCIN_G3H_ISOL is 16V
    PPBUS_G3H is 8,6V
    Looks like everything ok,


    BUT
    On PP5V_SRS3 instead of 5V I have only 3.1!
    L7630 only 0.06V

    Other interesting things are:
    - On L7320 (PPVCC_S0_CPU) is 280 Om instead of 18 Om
    - I dont see the exchange on SPI at all. There is only the first drop to zero, but there is no answer.
    Who should ask SPI?

    SMC or Processor?



    So, I have already replaced

    SPI, SMC, U7501, Q7520
    U8130 I restored after liquid damaged.
    But have nothing changes!
    Would you help me please. I have not any ideas.
    Thank you.
    Last edited by AlexVG; 01-20-2023, 07:07 PM.
  • mon2
    Badcaps Legend
    • Dec 2019
    • 14023
    • Canada

    #2
    Re: MacBook A1466 820-3437-B No power

    Remove all power. Meter in resistance mode.

    For any rail that is low in voltage, check the resistance to ground first.

    Post the measurements.

    Comment

    • AlexVG
      Senior Member
      • Apr 2022
      • 134
      • SPAIN

      #3
      Re: MacBook A1466 820-3437-B No power

      Hi,
      Of course, I have them.
      PP3V42 jumps from 35 kOm till 50 mOm
      Thank you
      Attached Files
      Last edited by AlexVG; 01-20-2023, 07:10 PM.

      Comment

      • mon2
        Badcaps Legend
        • Dec 2019
        • 14023
        • Canada

        #4
        Re: MacBook A1466 820-3437-B No power

        That rail is ok on the resistance. Do you read 3v42 on that rail ? If yes, it is fine. If you see a green / orange light on your magsafe head, this rail is working.

        Measure the resistance to ground of PP5V_SRS3 since the voltage is low. With no power of course.

        Comment

        • AlexVG
          Senior Member
          • Apr 2022
          • 134
          • SPAIN

          #5
          Re: MacBook A1466 820-3437-B No power

          Yes, I can see green/orange light.

          I cant find PP5V_SRS3
          If you mean PP5V_S5 (L4820) it is 0.5 mOm

          Comment

          • mon2
            Badcaps Legend
            • Dec 2019
            • 14023
            • Canada

            #6
            Re: MacBook A1466 820-3437-B No power

            On PP5V_SRS3 instead of 5V I have only 3.1!
            L7630 only 0.06V
            From your first post...the above are at a lower voltage? If yes, check their resistance to ground but with no power to the logic board. Check each.

            Comment

            • AlexVG
              Senior Member
              • Apr 2022
              • 134
              • SPAIN

              #7
              Re: MacBook A1466 820-3437-B No power

              It is L7630
              It has 220 Om,
              Its OK

              Comment

              • AlexVG
                Senior Member
                • Apr 2022
                • 134
                • SPAIN

                #8
                Re: MacBook A1466 820-3437-B No power

                Who asks SPI first?
                CPU or SMC
                I guess problem is here, because SPI does not answer. There is no exchanging.

                Comment

                • mon2
                  Badcaps Legend
                  • Dec 2019
                  • 14023
                  • Canada

                  #9
                  Re: MacBook A1466 820-3437-B No power

                  SMC is ok since ppbus_g3h is 8v6.

                  What is the voltage to ground of ALL_SYS_PWRGD?

                  Review the mix of articles here:

                  https://www.it-tech.com.au/mac-q-a/m...npocDVXMXdZbC0.

                  https://www.it-tech.com.au/mac-q-a/pm-slp-s4-l-timing/

                  https://www.it-tech.com.au/mac-q-a/macbook-smc-circuit/

                  Comment

                  • AlexVG
                    Senior Member
                    • Apr 2022
                    • 134
                    • SPAIN

                    #10
                    Re: MacBook A1466 820-3437-B No power

                    Hi.
                    It is very useful information.
                    Thank you.
                    In my case ALL_SYS_PWRGD is down of course, because missing 5V and 1.05V
                    I checked all rails.
                    I am sure I have 5V problem, but i dont understand why.
                    Instead of 5V I have 3.31V
                    The resistive divider (R7520/R7521) was damaged by fluid, but I restored it.
                    The calculation shows that it works correctly (in case 5V on out).
                    But if I set 3.19V to out from resistive divider I get 623 mV instead of 1.012 that I have really (on calculation)
                    if I look at gates responsible for 5 volts with the osciloscope, I can note rare pulsation.
                    I have not idea why U7501 works not correctly.
                    Attached Files
                    Last edited by AlexVG; 01-22-2023, 04:43 PM.

                    Comment

                    • mon2
                      Badcaps Legend
                      • Dec 2019
                      • 14023
                      • Canada

                      #11
                      Re: MacBook A1466 820-3437-B No power

                      Remove all power.

                      Measure the resistance to ground of PP5V_S4RS3 rail @ L7520, pin # 1.

                      There may be a low resistance (high load) on this rail causing the voltage to be a lower output.

                      What is the resistance value ?

                      Comment

                      • AlexVG
                        Senior Member
                        • Apr 2022
                        • 134
                        • SPAIN

                        #12
                        Re: MacBook A1466 820-3437-B No power

                        Hi,
                        Problem was in R7521 resistor!
                        I have replaced R7520 and R7523 before.
                        R7521 looked perfectly, and showed 10 kOm and I have left it.
                        However according my calculation the divider did not work right.
                        I removed R7521 and found out that it is floating.
                        I replaced it with a new one.
                        All runs!
                        Thank you for your help. These posts answered for all my questions.

                        Comment

                        • mon2
                          Badcaps Legend
                          • Dec 2019
                          • 14023
                          • Canada

                          #13
                          Re: MacBook A1466 820-3437-B No power

                          Very nice! Thanks for the updates and closure.

                          Comment

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