820-00840: not powering up P5VS4_EN missing

[macRepairAmb]

Originally PP20V was present but no PPBUS_G3H_CPU. Replaced Q7900 which restored PPBUS_G3H_CPU, but the board still isn't powering up. Missing PP5V_S4 due to P5VS4_EN being at 0v. PM_SLP_S5_L is also at 0v.
Other voltages i noticed was PM_EN_P3V3S4 which is reading 0.024, PMIC_EN_P3V3S5 is present @ 3.3v.
I've replaced U7800 with the same result.
Any suggestion as to why PM_SLP_S5_L is 0v or what else to check.

 

[2informaticos]

Do you get 3V1_RTC?
If yes, check the PCH's RTC signals.

 

[macRepairAmb]

Yes to PP3V1_RTC @ 3.1v
and i'm only seeing one PCH's RTC signal, PPDCPRTC_PCH @ 1.66. Every other PCH RTC signals are omitted in the schematic and board.

 

[2informaticos]

RTC signals are not clearly delimited in this schematic, as in older platforms.
But you should be able to catch them, as they have the same names.
RTC_RESET_L, PCH_SRTCRST_L and PCH_INTRUDER_L.
PCH_INTVRMEN is not used anymore by this PCH generation.

 

[macRepairAmb]

These are all the PCH RTC signals

PCH_INTRUDER_L - 2.8
PCH_SRTCRST_L - 3.08
RTC_RESET_L - 3.08
PP3V3_SUS_PCH_VCCRTCPRIM - 3.3

 

[2informaticos]

Do you get 3V3_S5 (L7690)?
If yes, check PM_DSW_PWRGD.

 

[macRepairAmb]

L7690 - yes @ 3.3v
PM_DSW_PWRGD - 3.4

 

[2informaticos]

Any history fail available?

 

[macRepairAmb]

Not much history just that it stopped working. No corrosion or sign of liquid spill or damage. There was a short on PPBUS_G3H_CPU which was resolved by replacing Q7900.

 

[2informaticos]

Good enough to fry the PCH...