820-00840 Liquid damaged PP3V3_S5 short to ground

[aplas]

Liquid damage around U7650, visible corrosion cleaned and replaced C7650.

From charger 20,2V 0,03A

Power rails:

PPBUS_G3H - 13.7V
PPDCIN_G3H - 20.35V
PP5V_S5 - 0V
PP3V3_G3H - 3.426V
PP3V3_S5 - 0V shorted
PP1V8_S3 - 0V
pp3v3_sus - 0.00v
pp3v3_s5 - 0.00v
Buf_smc_reset_l - 3.424V
smc_pm_g2_en - 3.420v
PPBUS_PMIC - 13,2V
PP3V3_LDO3V - 3,2V
PMIC_SHUTDOWN_L - 3,2V

U7890:
1 ssd_pwr_req - 0,5v (when measuring the line, zizzly noise appears from Q7680)
2 pmic_en_p3v3s5 - 0,0v
4 pm_en_pvxs5 - 0,00v
6 pp3v3_g3h - 3,42v

Removed Q7680 and U7650 resistance still 1,2ohm.

 

[2informaticos]

Be aware, do not apply power without U7650!!!

1.2 ohm at 3V3_S5 is low enough to get something hot injecting voltage.
Start with 1V and go up (if needed), no more than 4V...