Casestudy 1_From_Badcaps

1.Hp 14 day11amb6e0 no Mainon

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Im working on this board day11amb6e0. On the KBC Im gettting
RSMRST# 3.3v then to 0v immediately
S5_ON 3.3v then 0v immediately.
No +3v to KBC
Mainon stays at 0v

Also theres no +5vs5 or +3vs5

PU11
vin is ok
+3vpcu is ok +3v
S5_on 3.3v then 0v immediately
Pgood 0v
En2 4.5v


PU12
S5_on 3.3v then 0v immediately
+5VPCU ok 5v
pgood 0v.

What would cause the S5_on to drop to 0v ?
When S5_on is 3.3v then I get +5VS5 and +3VS5 for a couple of seconds then both drop to 0v because s5_on goes low.

2.do you have on/off fastly symptom ?
check secondry section for short like vcc_Core vgfx 1.05 and vtt

3. What about SUSC, SUSB and SUSON?

4.CN9

Pin 1 =3v drop to 0v
Pin 2 =0v
Pin 3 =1.28v
Pin 4 =0v
Pin 5=0v
Pin 6=0v
Pin 7=3.3v drops to 0v quickly
Pin 9=0v
Pin 11= 3.3v then drop to 0v
Pin 13=0v
Pin 15=0v

5.Seems like the board won't go to an S4 state, it's stuck in S5. The PCH is not doing its job even though it has the required voltage (indicated by the presence of RSMRST#).

Voltage on BIOS pins?
I'm not sure about RTC_RST#, could you measure it elsewhere? Also which schematics are you using?

6.Hi pin 9 of Cn9 is rtc _rst 0v

Im using schematic attached its close enough I think even though mine is Uma version.

7.Voltage on both sides of R277? (just above CN9)

8.2.6v one side and 0v on other side

9. Resitance to ground of RTC_RST#?
Voltage on pin 2 of Q19?

10.53ohm and pin 2 of q19 0v

11. 53ohm is way too low, RTC_RST# is partially shorted to ground.
Try removing Q19 and C367 and see if the resistance goes up. If it does not, the PCH (on the CPU package) is most likely dead.

12. C367 was leaky alright I removed it and the voltage came back up. its switching on now just need to check if everything else is ok.

Your help is much appreciated.