M1 MacBooks

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This page is a stub article, but it is time to start gathering information about M1 repair practices. For now it is simply to throw things i learn during the repairs (i got 5 M1 macbooks which i cant repair but thats NOT a dead CPU / SSD, so i wont give up untill i fix them). DO not use it as a repair guide or reference of any time, i have probably no idea what i am talking about - @inwerp#2476

  1. There is no S5-S0 sequence anymore, Do not look for it, forget everything you knew about power rails, sequence. Finita. Like on T2, SSD is always powered on.
  2. The most important power rails now are 3v8 and 5v_S2. G3HOT is now called AON (Allways On?)
  3. If you have waterdamage and you need some ICs, stock donorboards. Go google AONE36196, thats a simple double mosFet with customized footrpint. I successfully substituted it with two standard N-fets for test purposes but thats not a repair.
  4. all CPU power rails are now generated with Apple proprietary PMU. This might be a good thing because you won really see high side-shorts to VCORE anymore. Bad thing, again - donor only.
  5. if you look at 13 inch logic board, there are WAY less chips and components compared to older devices.
  6. Backlight circuit is the same as on older models. Same LP8549/49 as described in this article
  7. wifi/bt module is a bliss. Check its fooprint and smile.
  8. For now 820-02020 is basically almost a development board. SV004. SV000, SV010, SC002 e.t.c are debug buttons. There are all sorts of resets, power button and force DFU on edge of the board, both sides. There are also debug leds which i plan to stock and test. Switching Fet , 6.8K 201 resister, LED 0201

Power Rails

as mentioned, PP5V_S2 substitutes 3v3 _g3h rail from previous modell. It is generated by UC300(LT8642EV-2 Stepdown converter with integrated fet). If this rail is unstable, you will get all sorts of issues like weird 3v8 Rail (next rail to power up CPU PMU), blown backlight switch, etc. If any sign corrosion, check all surrounding area, especially Feedback circuit. Unlike many other power ICs we seen before, this one has 5 Resisters and 1 Capacitor on feedback line. 1 Corroded feedback and you have PPBUS on your 5vRail. Not good at all.

Possible damage from bad Feedback: UP700(Display power switch), U5700 (3v8 driver, there will be a very weird short 5V to Phase 3 low side gate which looks like hot Q5840 BUT some random voltage on L75840 )

Power Consumption during boot: 19v. 0.1-025 is a normal during POST / Boot phase. It also POSTS with 5V-1A if PD is disabled on USB Meter(weird but true).