820-3435 jumping sleep signals

[MUUK]

820-3435

pp3v42 present
green light
damage to R6120/6121
ran wire and replaced.


ppbus 8.58v
PPBUS_S5_HS_COMPUTING_ISNS 8.58
PPBUS_S5_HS_OTHER_ISNS 8.58
PPVRTC_G3H 3.3v
PP5V_S5 5.01v
PP3V3_S5 3.28v
PP3V3_SUS 3.3v
SMC_PM_G2_EN 3.4v
SMC_LID 3.4v



PP3V3_S4 jumping high then low.
PP5V_S4RS3 jumping high then low.
PM_SLP_S5_l jumping
PM_SLP_S4_l jumping
the above 4 jump 3 times (so its trying to turn on) then goto 0v.

PM_BATLOW_L 0v


u7501

enables
pin12 3.4v
pin21 3.4v
pin4 0v
pin 20 - S5_PWRGD 0v

Tried replacing U7501, no change. No further evidence of liquid damage.

PCH dead ?

 

[dukefawks]

So it is power cycling. The usual suspects apply, U1900, U1950, J6100, U6100 and termination resistors/traces. Is CPU Vcore pulsing too?

 

[MUUK]

Thank you Duke. Yes Vcore is also pulsing. J6100 was removed already. Board was clean apart from the damage trace and R6120 / R6121. I replaced area and ran a jumper wire. I've checked for continuity between all the termination resistors to the right of U6100 and the relevant pins. U1950 ALL_SYS_PWRGD pulses also along with SYS_PWORK_R and CPUVR_PGOOD_R .
On U6100 i get steadt 3.32v on pins 1,2,3 6,7,8 the only voltage jumping there is pin 5 SPI_MLB_MOSI which goes from 2.2 to 3.3v regularly.

 

[dukefawks]

Must be a corroded trace or via to U6100 or termination resistors. Check all traces, remove U6100 and resistors if necessary and then check diode mode to verify continuity to CPU and SMC.