820-00165 PPBUS at 1V

[Bouba148]

WD, No Green Light

PP3V42_G3H: 0.8V
In diode mode reading 0.002V: short to GND
Pin2 of J6100 and C5008 shorted to GND
Removed J6100 and C5008
PP3V42: 3.336V and green light OK
trace broken between C5001 and L5001, rebuilt:OK

PPBUS: 1V
PPBUS to GND: 3MOhms
in diode mode: 0.139V should be : compared with another board : 0.142V
remove F7140: 0.137V at pin 1 and 0.465V at pin2, doesn't seem shorted to Gnd

at U7100 R17/18: 3.5Ohms and R27/28: 21.2Ohms
1:0V
2: 14.17V
3: 3.803V
4: 3.233V
5: 2.570V
6: 0V
7: 2.658V
8: 0.171V
9: 0.033V
10: SDA, pulsing OK ( burst square signal at scope )
11: SCL, pulsing OK ( burst square signal at scope )
12: 3.333V
13: 3.304V
14: 3.304V
15: 0.050V ( battery not plugged)
16: 1.300V
17: 1.020V
18: 1.020V
19: 5.035V
20: 5.020V
21: 0.027V
22: gnd
23: 1.014V
24: 4.875V
25: 5.025V
26: 1.066V
27: 1.031V
28: 1.031V

Voltage at R7180 is 1.034V which means that Q7180 doesn't close his second fet.
normally I should read something like 13.7V on pin 1 and 13.9V on pin 2.
Is my U7100 bad?
At 7180 pin 7,8,9 and 10 reading 14.15V

 

[2informaticos]

Change Q7180.
Once removed, check traces to its resistors.

 

[Bouba148]

Hi 2Informaticos,

just to update you, I replaced Q7180 and rebuit some traces around R7180 and R7181 and I had a nice PPBUS at 8.58V.
Unfortunately the WD went to the CPU, which directely fried when I had ppbus present, I had smoke coming out of the PCH.
Maybe directely shorted to CPU. so good to go in donor bin.

Again it was a good catch from you, and again thank you