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820-01521 A1932 no power 20V @ 75-85mA

J

jadao

Member
I have this board with no liquid damage, stopped on its own as customer reports.

PPBUS_G3H 12,62V
PP3V3_G3H 3.3v
PP3V3_G3H_RTC 3.3V

PP5V_G3S 5V
PP3V3_G3S 3.3V
PP1V8_G3S 0V / 0.318


PP1V8_S5 0V / 0.466
PP3V3_S5 0V / 0.320
PP1V1_SLPS2R 1.1V
PP1V1_SLPDDR 0V / 0.365
Coils around PMIC
PP1V8_SSD: 1.8V
PP0V9_SSD: 0.9V during around 15 seconds and then 0V
PP1V_PRIM: 1V comes 11 seconds after board is plugged in to power, it stays on 2 seconds and goes back to 0V
PPVCC_PRIM_CORE: 1V comes 11 seconds after board is plugged in to power, it stays on 2 seconds and goes back to 0V
PP1V8_SLPS2R: 1.8V
PP0V9_SLPDDR: 0.9V comes for a couple of seconds and goes back to 0V
PP1V1_SLPS2R: 1.1V
PP0V8_SLPS2R: 0.8V
PPVDDCPU_AWAKE: 0.75V 2sec->0.9V 2sec -> 0,55V 2sec -> 0V
PP0V82_SLPDDR: 0.82 for couple of seconds and goes back to 0V
PPVDDCPUSRAM_AWAKE: 0.8 to 1.04V during couple of seconds and goes back to 0V

I can provide more voltage if needed.
I am not able to do DFU, it is not detected.

Thanks
 
J

jadao

Member
Compared with good board all big coils have same diode mode reading, the only one a little bit off is PP1V2_S3 (L8100) 0.245 (950ohms) vs 0.175 (600ohms) on faulty board.

P1V8G3S_EN is present 1.8V and so sorry PP1V8_G3S is also present 1.8V, I think I just didn't probed the right place yesterday.
 
J

jadao

Member
Ok some progress to report: after a dfu I tried the revive option and now I have all voltages except CPUGT_PHASE1/2 no image no backlight no usb light, external monirtor or capsLock.
UBC meter shows 20V 0,560A without battery wich seems to me ok.
Fan spins when cpu is hot, when I power off it will restart again. I am considering doing a DFU restore... Do you have other idea before wiping the sdd?
 
2informaticos

2informaticos

Administrator
Staff member
iGPU voltage is not expected yet, so that is normal.

If there is important data, it can be recovered in DFU by an authorized Apple workshop.
 
J

jadao

Member
There was no important data and I did a restore via dfu. All process went ok but still laptop is not booting...
The strange thing is when I turn it off with power button, it turns off but will restarts on its own...
I have no more idea
 
J

jadao

Member
I have already tested it without anything plugged in, I have 20V 0.650A on usb-c meter and CPU core voltage always comes on 0.965V, but it is brain dead.
I don't know if I try another T2 ROM image, but I think the one I have must be good if I can perform the complete dfu restore process.
I Inspected carefully the board for any physical damage missing component but I found no evidences. Thanks!
 
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