820-00165 PP3V3_SUS pulsing 1.1-1.4V

[BCN_Techs]

Got this board with water damage near U6100.

Changed U7600, U6101, U7400 and some small components near that had wrong values.


Now all main rails are ok, but all rails near efi chip are pulsing from 1.1 to 1.4 V. Board is trying to enter S0 and all S0 rails are pulsing (Ex: 3v3_S0 is pulsing 0.5-0.8.)


I tried new bios DUMP and same. Without bios it is pulsing too. Checked traces and all are ok.


What else i can check?

 

[2informaticos]

Is not BIOS issue.
PCH doesn't access BIOS before PLT_RESET_L goes high.

Did you try SMC bypass mode?
Did you reball SMC?

 

[BCN_Techs]

SMC By pass not turning on

Right now trying reball smc because i see that also there is issue with pm_slp_s5_l. Will back once finish

 

[BCN_Techs]

Reballed and sames happening. Exactly same. Change SMC?

 

[2informaticos]

ALL_SYS_PWRGD pulsing too?
Remove Q8150 and try again.
Check U1950 for corrosion; does it get pulse at pins 7 & 3?

 

[BCN_Techs]

ALL_SYS_PWRGD and pins 7 and 3 not pulsing. Removed Q8150 and the only difference is that after it is pulsin between 0.9 and 1.2


NO corrosion under U1950, but changed it anyway, now ALL_SYS_PWRGD is pulsing very lightly 0.00-0,002V ( dont know if this information is useful or not)

 

[2informaticos]

Do you get pulse on all S3 and S0 power rails?
An o-scope can catch the faster peak pulse.

 

[BCN_Techs]

pp3v3 s3 and s0 are pulsing 0.5-0.8V and all other rails s0 and s3 pulsing too.


Right now i am without o-scope :-(

 

[2informaticos]

If trigger SMC_ONOFF_L repeatedly, you must be able to catch higher pulses.
Need to be sure which points have pulse or not.

 

[BCN_Techs]

"higher pulses" you mean the highest value of pp3v3_sus?

 

[2informaticos]

I'm talking about all power rails.
An o-scope can always catch the expected peak.
DC voltmeter will catch lower peaks, depending by the moment of the reading.
Repeated readings allow you to catch different values, some of them higher.