MacBook A1989 missing rails PP3V3_S5 and PP1V8_S5

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  • Nikan.e
    Member
    • Nov 2023
    • 17
    • Germany
    #1

    MacBook A1989 missing rails PP3V3_S5 and PP1V8_S5

    Greetings and Salutations,

    I have gotten an A1989 Macbook board number 820-00850-A which has two missing rails -> PP3V3_S5 and PP1V8_S5.
    PBUS is at 12.6V every other voltage made by the PMIC is just fine.

    Resistance to ground -> PP3V3_S5 ~ 220Ω
    Resistance to ground -> PP1V8_S5 ~ 220Ω

    PP1V8_S5 and PP3V3_S5 are not shorted together.

    Voltages up to PP2V5_NAND_SSD0 seem to be fine.

    Can anyone confirm if these resistances are normal for this board?
    What could be causing this issue?
    Is there a way to rule out a defective PMIC without replacing it, as I do not have a donor.

    Thanks in advance and best regards from Germany,
    Nikan​
    Tags: None
    • Answer selected by Nikan.e at 12-04-2023, 05:09 AM.
      mon2
      Badcaps Legend
      • Dec 2019
      • 13850
      • Canada
      T2 has booted since ppbus_g3h is 12v6.

      try dfu on this unit.

      what is the voltage and current draw on the usb c meter?

      https://repair.wiki/w/A1989_2018_13”_Touchbar_MacBook_Pro
        • Selected Answer

        Comment

        • mon2
          Badcaps Legend
          • Dec 2019
          • 13850
          • Canada
          #2
          T2 has booted since ppbus_g3h is 12v6.

          try dfu on this unit.

          what is the voltage and current draw on the usb c meter?

          https://repair.wiki/w/A1989_2018_13”_Touchbar_MacBook_Pro
            • Selected Answer

            Comment

            • Nikan.e
              Member
              • Nov 2023
              • 17
              • Germany
              #3
              DFU does indeed work; it shows up on a PC running a virtual machine - Sonoma, with the latest Apple Configurator installed.
              However, the restore option does not complete. Could this be due to the virtual machine, or is it because the trackpad is missing?

              The schematics also show that a sensor is located on the trackpad. Is that relevant for a restore, or does the software not check for the trackpad while trying to restore?

              The voltage does go up to 20V but the current draw is very funky. It stays sometimes at 44mA, sometimes it goes up to 300mA, and sometimes it goes all the way up to 1.9A. But it is always cutting off after some time and - power cycling. Disconnecting and reconnecting the power supply does get the current draw back up, if it is stuck at 44mA.
              Last edited by Nikan.e; 12-04-2023, 05:47 AM.

                Comment

                • mon2
                  Badcaps Legend
                  • Dec 2019
                  • 13850
                  • Canada
                  #4
                  Yes. Had exactly this case with A2141 last week. Killed too much time on it but yes, the trackpad MUST remain connected. If missing, the sensors will not be detected over smbus lines which will result in high fan spin and power cycling. We thought that some part was overheating but nothing was over 52 degrees C. We used the same board in target mode to extract the client's data off which was very valuable to their company. Attempt the same process with the trackpad. For us, the dfu process did complete (4/4 steps). We applied a revive process.

                  btw - press T key during boot and you should see the logon screen on the remote unit. If that works then your nand is ok. Login to see the drive letter and contents.

                  Also, we used a known good A2141 for the dfu process which the client purchased after the data migration.
                  Last edited by mon2; 12-04-2023, 05:02 AM.

                    Comment

                    • Nikan.e
                      Member
                      • Nov 2023
                      • 17
                      • Germany
                      #5
                      I do not get any fan spin or a hiccup on the fan, not even when it is trying to revive/restore. Does the fan kick in even without the trackpad?

                      Wow, that is crazy. I really did not expect this, but well, what do I know? It's Apple after all...

                        Comment

                        • mon2
                          Badcaps Legend
                          • Dec 2019
                          • 13850
                          • Canada
                          #6
                          Yes, we had normal fan spin with trackpad and hyper fan spin without the trackpad. Had boot chime always on the A2141. Attempt the target mode using your external remote unit to check for the logon screen.

                            Comment

                            • Nikan.e
                              #6.1
                              Nikan.e commented
                              12-04-2023, 05:34 AM
                              Editing a comment
                              The configurator does not show anything at all when holding the t key while booting, but I am able to see it as an apple macintosh peripheral device.
                              Also, I do not get the boot chime. But DFU does show up, when using the debug jumper as well as the keyboard combination.
                              Last edited by Nikan.e; 12-04-2023, 05:39 AM.
                            • mon2
                              Badcaps Legend
                              • Dec 2019
                              • 13850
                              • Canada
                              #7
                              It is our belief that the quality of the usb cable and the host are important. We attempted to use an A1534 and that failed to logon to the Sonoma target. We did use a 40G rated usb cable from Amazon. Do test other quality cables unless this cable is a known good one used for the dfu process. The use of the fresh A2141 was key for us.

                                Comment

                                • Nikan.e
                                  #7.1
                                  Nikan.e commented
                                  12-27-2023, 11:01 AM
                                  Editing a comment
                                  I was finally able to test it, but unfortunately, it did not work.
                                  The trackpad does indeed function, and the haptic feedback works while the device is not in DFU mode.

                                  - The trackpad was connected while trying to revive and also restore.
                                  - A similar Mac, just with a different RAM/SSD configuration, was used.
                                  - Different cables were tested, from Apple and other brands.

                                  I always get an error saying the following:

                                  "Gave up waiting for the device to transition from DFU state to DFU state. [com.apple.MobileDevice.MobileRestore - 0xFCA (4042)]"

                                  I am thinking that this error means the following:
                                  The device is in DFU mode -> the host device restarts the target device -> the host device is waiting for the target device to turn on the rails so that the CPU can be used.

                                  What are the next steps to take on this Mac?
                                  I really want to get this working; it is really bugging me. I hate it whenever I can't figure out what's going on!
                                  Even if it is doomed to be unreparable, I want to know the reason -> what is hindering the S5 Rails from showing up...
                                • Nikan.e
                                  Member
                                  • Nov 2023
                                  • 17
                                  • Germany
                                  #8
                                  Alright, Thank you very much!!! I'll try it as soon as I get the trackpad cable!

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