820-2850 no PP5V_S3

[Sr. Robot]

Hi, hope you guys are doing great.

820-2850 not turning on, green light on charger, no visible liquid damage. PPBUS_G3H, PP5V_S5, PP3V3_S5 are prensent but PP5V_S5 is missing. PP5V_S5 pulses to about 2.5v for a fraction of a second.

 

[2informaticos]

"PP5V_S5 ... prensent but PP5V_S5 is missing"
Can you clarify your post???

 

[Sr. Robot]

Sorry, I meant PP5V_S3

 

[2informaticos]

If 5V_S3 pulses, then check for pulse at other coils.
Try starting in SMC bypass mode also.

 

[Sr. Robot]

All coils pulse except for C1689 and C1690.

With SMC bypass the fans only spin for a sec.

 

[2informaticos]

These caps are associated with 1V05_S0, which comes from one of the coils you've said pulsing!
Maybe not all pulsing; what about VCORE?
Can you catch a pulse at ALL_SYS_PWRGD?

 

[Sr. Robot]

Sorry, i meant L7030, not those caps. L7030 not pulsing.

PPVCORE_S0_CPU pulsing.

PP3V3_S0GPU pulsing.

ALL_SYS_PWRGD pulsing.

 

[2informaticos]

L7030 should have stable voltage, no pulse of course.

Change C9560, just in case.

Any pulse at PLT_RESET_L?

 

[Sr. Robot]

Replaced C9560, still nothing.

No pulse at PLT_RESET_L

 

[2informaticos]

So PCH doesn't know if power on sequence is acomplished.
Check for pulse at CPU_PWRGD, PM_MEM_PWRGD and CPUVTTS0_PGOOD.

 

[Sr. Robot]

CPU_PWRGD pulsing

PM_MEM_PWRGD pulsing

CPUVTTS0_PGOOD pulsing

 

[2informaticos]

Looks like bad PCH then...

 

[Sr. Robot]

RIP...

Thank you so much. Have a good day.

 

[piernov]

Try to flash the BIOS.

 

[Sr. Robot]

Replaced U6100 with known working from another board of the same model but still no fan spin. Thank you very much for all of your help.