820-01598 bootloop

ajdoc

Member
Board have liquid damage around R6900, U6903, Q8401.

No chime, trackpad clicks, no caps lock LED.
Got 20V on charger and after 15 seconds take 0.15A and reboot.

Readings from board only.
PPDCIN_G3H = 20V
PPBUS_G3H = 12.7V
PP3v3_G3H = 3.30V
PP1V8_SLPS2R = 1.79V
PP1V8_AWAKE = 1.79V
P3V3MAIN_PGOOD = 3.25V
PP3V_G3H_RTC = 3V
P5VG3S_EN = 1.79V
PP5V_G3S = 5.10V
PMU_PVDDMAIN_EN =3.30V

Any idea?
 

ajdoc

Member
Same issue on both USB port on source Mac. On target Mac it is detected only on one port which is nearer to trackpad (thats as it should)

SSD/NAND voltage:
PP3V3_G3H_SSD0 = 3.3V
SSD_PMU_RESET_L = 1.8V
PPVCCQ_ANI_SSD0 = 1.8V
PP0V9_SSD0 = 0.9V
SSD0_VR_P2V5_EN = 1.8V
PP2V5_NAND_SSD0 = 2.5V
SSD0_OCARINA_WP_L = 0V
SSD0_OCARINA_RESET_L = 0V

No voltage on big coils.

Used thermal camera and thats what I got (rest of the board is cold):
 

Attachments

ajdoc

Member
Found short on PPVCC_S0_CPU (0.001V in diode mode).
Injected low voltage and on thermal camera only part of CPU went warm so thats it I think.
 
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