submerged Macbook A2141 - no power on, no voltages

[Sanevent]

I checked the following G3S voltages:

PP5V_G3S - 0v
PP1V8_G3S - 0v
PP3V3_G3S_T - 0v

PP5VG3S_EN - 0v
PP1V8G3S_EN - 0v
PP3V3G3S_T_EN - 0v

Those are the lines that I thought were important to measure.
For the SSD lines, please tell me which ones are the important ones. There are at least 100 lines that include SSD somehow and I can't quite make up which ones could be important.

I you could tell me which G3S lines are important that I did not cover, please also let me know.

 

[2informaticos]

"100 lines that include SSD somehow"
All of them are power rails???

You have two SSD0/1 areas, each with 3 power rails: 0.9V, 1.8V and 2.5V (pages 87 & 92).

 

[Sanevent]

Thanks for clarifying.
I took the measurements and got:

PP0V9_SSD0/1 - 0v
PP1V8_SSD0/1 - 0v
PP2V5_NAND_SSD0/1 - 0v

So no power on that rails too.

 

[2informaticos]

Is the machine recognized in DFU mode?

 

[Sanevent]

When connecting the Board will it be recognized immediately or do I need to set the board into DFU mode?
As for setting the board to DFU Mode, there are 2 ways I've read about. One method uses the assembled mac and the keyboard and the other uses the Force DFU jumper. Which way is the preferred method here ?

 

[2informaticos]

External switch method is the best to try with board alone on the desk.

Making sure you're not a bot!

Now only need to check if it is recognized in DFU.

To successfully complete DFU, battery and trackpad may be needed; requires to put board back on the shell.

 

[Sanevent]

ok got it. I will try the method with the switch, mentioned in the article. Is it enough for the first test to test if the DFU_STATUS line becomes 1.8v?
I only ask because gathering a second Mac will take me until next week. My colleague has the Mac from the lab for the time being.

 

[2informaticos]

Yes, that signal also unveils if DFU mode is achieved.

 

[2informaticos]

Impossible to access DFU without 1V8_SLPS2R present.

Keep tye board alone on the desk, for test.
Do you get 3V3_G3H_RTC and PPBUS_G3H now?

BTW, F7000/1 must be soldered.

 

[Sanevent]

The fuses are soldered back in place.
PPBUS_G3H is 12v
3V3_G3H_RTC_X is 3.3v

 

[2informaticos]

What about U7800's LDOs (page 76)?

 

[Sanevent]

I measured around the U7800 and found the following voltages:
LDO_CORE 1.47v
PP0V8_SLPS2R 0v
PP3V0_G3H_RTC 0v
PP1V2_AWAKE 0v
PMU_LDO3_OUT 1.8v

I also measured the input side, because i dont know which voltages are derived from which - so maybe this is helpful.
PP1V1_SLPS2R 0v
PP3V3_G3H_RTC 3.3v
PP1V8_SLPS2R 0v

 

[2informaticos]

What about LDO_RTC and 3V3_G3H_SOCPMU?
If not present, check voltage at C7907.

 

[Sanevent]

LDO_RTC is 1.49v
P3V3_G3H_SOCMPU is 0.94v

So I measured at C7907 but there was 3.3v present.

 

[2informaticos]

Check diode mode to ground at P3V3_G3H_SOCMPU.

 

[Sanevent]

I measured 1.1, which increased over time, and as I reversed the prongs, I measured 0.4.

 

[2informaticos]

Should replace U7800.

 

[Sanevent]

Ok. I will order a new part. This will take 7 to 10 days.

 

[2informaticos]

Write down diode mode readings around actual U7800.
Compare with new readings, once replaced the chip.