820-00850 no power - 5v

Liquid damage. Lots of minor blue everywhere.
components around u3100 has minor corrosion. u7650 looks like it might have been hit the hardest.
When plugged in I get 5.12v-5.16v on each port. No amps.

Looking around u7650 I noticed PPVIN_G3H_P5VG3S had .02v to ground. Traced it back to u7600. Replaced that and short was gone. Plugged in the board and had 5v with .3 amps then 19.8v with 0 amps. Checked a different port and it was back to 5v 0 amps. Checked PPVIN_G3H_P5VG3S again and back to .04v to ground.
Short is on pins 6,7,8 of u7600. so something on PP5V_G3S at .016v. Removed r5410 to confirm not on PPBUS_G3H.

The only thing with serious corrosion on PP5V_G3S was pin 22 of j5100. Removed connector and 4 connecting caps but no change.

Safe to inject PP5V_G3S??
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If I remove u8110 the short goes to .7v. Poking around I found a short on pp5v_usbc. If I also remove rb706, rb701, r3506, and r3501 - then my short on pp5v_g3s goes away.

Pulled a replacement for u8110 from an 820-3787. Is this ok?
Short is gone - .295v to ground on pp5v_g3s.

replaced u3500, ub700, qb701, and q3501to eliminate short on pp5v_usbc.
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Plugged in and fried PP5V_G3S again...
5v, 40amps then 19v 0amps. unplugged and plugged again - 5v 0amps.

PP5V_G3S - .02v to ground. (not u8110 this time).

pp5v_usbc - no short.

Stopping on this until I get a reply... Please help
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Staff member
Allow 15-20s after power removed, before measuring diode mode.

Be sure R/C7609 are good, as traces/solders too.


Staff member
That is the system side.
Start injecting 1V and go up slowly, if needed.
You may need 20A PSU, to heat something...
u8400 got hot. Replaced and board is no longer pulling amps from psu.
pin 1 of L7600 is only up to 0.084v to ground.

Edit - now its at .340v... going to test the board.

Short was on U8400 again. When testing the board I use naked board out of case with only one charging port attached.

Should I go ahead and apply power again or test something else prior?
Any chance charging chips are somehow frying this line?

R7678 shows as 8.3k. Replaced and get the same. Other board starts at 8k and climbs to 40k..


Staff member
Be sure R7677/78/79 are all good, as their traces too.
Open feedback network can cause overvoltage on 5V_G3S!!!

High value resistors must be checked out of board.
Onboard measurment will cause lower reading than nominal.
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R7677/78/79 are all good.

Applied power - 5v .25a then 19v .08a up to .21a then back to .08a. This time it doesn't short and when plugged back in it does the same thing.
5.135v on 5V_G3S
PP5V_S4SW_ISNS is 0v but there isnt anything there..
PP3V3_S4SW_SNS is slightly low at - 2.925v

PPBUS_G3H - 12.6v
PPBUS_HS_CPU - 12.6v
PPVIN_G3H_P5VG3S - 12.6v
PPVIN_G3H_P3V3G3H - 12.6v
PPVIN_G3H_P3V3G3HRTC - 12.6v
PPDCIN_G3H - 20v
PP5V_G3S - 5.135v
PP5V_S4SW - 5.135v
PP5V_S0SW_LCD_ISNS_R - 5.133v
PP5V_S5_LDO - 5.130v
PP3V3_G3H_RTC 3.38v
PP3V3_G3H - 3.356
PP3V3_S4SW_SNS - 2.925v
PP3V3_G3S - 3.392
PP3V3_TBT_X_S0 - 0v
PP3V3_TBT_T_S0 - 0v


Staff member
"PP5V_S4SW - 5.135v
PP5V_S4SW_ISNS - 0v"
Check R5950 and traces; be sure no short there.

Try to understand a schematic to earn time.
Im actually getting 0v on PP5V_S4SW. Looked around and noticed r3501/06 were bad. Replaced these and u3500/q3501 but still nothing on PP5V_S4SW.
Doesnt see shorted - .293v to ground.
Could this be u3100/3200?