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    Macbook Air A1466-No Display

    Logic Board#820-00165A

    Consumption on dc supply goes upto 590mA ,then drops to 390 and then again rise to 560mA with not much variation.(Using original magasafe2 65W cable)

    All the rails are present. No liquid spill or corrosion noticed under microscope.

    CPU_VCCST_PWRGD-Present
    ALL_SYS_PWRGD-present
    PLT_RST-Present
    R1540/41/42/43/44-33 Ohms
    Minor pulses on LPC lines with scope.
    Bios clean me flashed.
    Battery is charging. can be turned on/off with keyboard.

    What to check further? Any ideas are welcome.

    PS:Customer is going on a vacation-so 15 days time to solve the puzzle.
    Last edited by mcplslg123; 01-22-2023, 01:55 AM.

    #2
    Re: Macbook Air A1466-No Display

    What is the voltage to ground of PPBUS_G3H ?

    Measure at F7140 (both pins).

    Comment


      #3
      Re: Macbook Air A1466-No Display

      PPBUS_G3H is 8.62V measured on F7140-both pins.

      Comment


        #4
        Re: Macbook Air A1466-No Display

        Check resistor R1275.

        Also here:

        https://logi.wiki/index.php/820-00165_Pulsing

        Comment


          #5
          Re: Macbook Air A1466-No Display

          With no SSD present and just naked on the bench, these boards usually pull about 550 to 600ma, then settle to 350ma when they are trying to boot (e.g. USB ports are probed every 5 secs or so).

          Is there any SPI activity around U6100? Is the PCH/CPU at least trying to load code? I've seen other issues post BIOS load with bad HSIO or SPI to peripherals like audio etc in the U8005/Q1920 area.

          Comment


            #6
            Re: Macbook Air A1466-No Display

            Originally posted by mon2 View Post
            Check resistor R1275.

            Also here:

            https://logi.wiki/index.php/820-00165_Pulsing
            R1275/R1270/R1280 are all ok.

            The link you gave is perhaps not applicable here as all rails are stable and not pulsing.

            Comment


              #7
              Re: Macbook Air A1466-No Display

              Originally posted by reformatt View Post
              With no SSD present and just naked on the bench, these boards usually pull about 550 to 600ma, then settle to 350ma when they are trying to boot (e.g. USB ports are probed every 5 secs or so).

              Is there any SPI activity around U6100? Is the PCH/CPU at least trying to load code? I've seen other issues post BIOS load with bad HSIO or SPI to peripherals like audio etc in the U8005/Q1920 area.
              Yes, the consumption pattern mentioned here is only naked board with fan and dc-in board-no ssd/wifi etc.

              Yes, Spi activity is present on U6100.

              Q1920
              pin2-3.3V
              pin3-1.5V
              pin4-0V
              pin5-0V

              Q8060,pin4-HSIOFET_EN-0V
              Q8062,pin2-PCH_HSIO_PWR_EN-3.3V
              U8005-Working ok.

              PS:The fan goes to max speed after 30 seconds of power on.
              Last edited by mcplslg123; 01-23-2023, 11:03 PM.

              Comment


                #8
                Re: Macbook Air A1466-No Display

                many board with all volt present (cpu 1,79volt present, cpu not getting hot)but no post on a1466 board got fixed by replacing u1950.

                Comment


                  #9
                  Re: Macbook Air A1466-No Display

                  Ok, went back through my notes. The fault I found was a bad pullup resistor on the AUD_SPI_MOSI data line (R1663). This appeared to have caused the CPU to hang during the boot process. So check the data lines pullups/pulldowns as a sanity check (R1660~R1677).

                  Also check resistance of the PCH (when its at ambient temperature) at L7630. They usually read over 200 ohms, but anything 150 ohms generally indicates some kind of damage.

                  Comment


                    #10
                    Re: Macbook Air A1466-No Display

                    Originally posted by dellxps15 View Post
                    many board with all volt present (cpu 1,79volt present, cpu not getting hot)but no post on a1466 board got fixed by replacing u1950.
                    In this case, cpu is heating up. Still try replacing U1950??

                    Comment


                      #11
                      Re: Macbook Air A1466-No Display

                      Originally posted by reformatt View Post
                      Ok, went back through my notes. The fault I found was a bad pullup resistor on the AUD_SPI_MOSI data line (R1663). This appeared to have caused the CPU to hang during the boot process. So check the data lines pullups/pulldowns as a sanity check (R1660~R1677).

                      Also check resistance of the PCH (when its at ambient temperature) at L7630. They usually read over 200 ohms, but anything 150 ohms generally indicates some kind of damage.
                      R1660-R1673 all checked and resistance values are all ok. The ones which are pulled up by PP3V3_S0 are all 3.3V on both sides.

                      L7630 resistance is more then 200 Ohms.
                      Last edited by mcplslg123; 01-24-2023, 11:05 PM.

                      Comment


                        #12
                        Re: Macbook Air A1466-No Display

                        did u try on external display ?

                        edit: about u1950 i almost replace it in all board because it's cheap and many time make macbooks work again.

                        Comment


                          #13
                          Re: Macbook Air A1466-No Display

                          Thursday was holiday for Indians as we celebrated our 74th Republic Day.

                          Will replace U1950 and see if it makes any difference.

                          Comment


                            #14
                            Re: Macbook Air A1466-No Display

                            Replaced U1950 but didnt helped. No changes in any signal/behaviour. I'm out of ideas for this particular case and may let it go unrepaired.

                            Comment


                              #15
                              Re: Macbook Air A1466-No Display

                              bad news...

                              did u try usb for activity ? or caps lock light if working or not when pressed ?
                              Last edited by dellxps15; 01-30-2023, 12:26 PM.

                              Comment


                                #16
                                Re: Macbook Air A1466-No Display

                                Caps lock light not working when pressed. There is activity on usb lines. I even see slight communication on LPC lines but the pulses were not usual. Anyway, i returned it to the customer UNREPAIRED. Perhaps someone more skilled and experienced may fix this unit.

                                Comment

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