820-01958 not turning on. Only 5.25v on both USBC ports. PP1V1_S3 only 2.3Ω

joshAU

Member
Hi all.
Looking at a 820-01958 board that was extensively water damaged.
After cleaning, I'm only getting 5v on both USBC ports.

With the AC adaptor connected to the primary (REAR) USBC port:
PP20V_USBC_T_VBUS 0.00v
PP20V_USBC_X_VBUS 5.25v
However,
With the AC adaptor connected to the secondary (FRONT) USBC port:
PP20V_USBC_T_VBUS 5.25v
PP20V_USBC_X_VBUS constantly fluctuating/cycling between 0.00v and about 0.50v

I would normally assume that the fluctuating voltage would indicate a short on PP20V_USBC_X_VBUS, however as it shows 5.25v on the other port, it cannot be shorted.
Would this indicate a problem with the Secondary USBC controller?

I also just noticed that PPDCIN_G3H also fluctuates from about 2.98v to 5.05v ONLY when connected to the secondary USBC port.

Checking coils, PP1V1_S3 also seems to be too low.
In diode mode, red to ground, it measures 008.
In resistance mode it measures 2.3Ω to ground.

Any suggestions appreciated, thank you.
 

2informaticos

Administrator
Staff member
1V1_S3 powers up the RAM and CPU.
CPU is the most sensitive there; probably dead now.

You have a problem on USB-C area too.
Anyway, not worth to spend time there, with dead CPU.
 
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