820-00165 S0 state no cpu vcore

No-Clean

Member
Board looks clean no water damage at all, but it looks like the computer was dropped from a high distance.

Sometimes the fan spins and looks like the computer is on, but no cpu vcore at all even while there is fan spin, most of the time it stays in S0 state but wont turn on at all.

Starts up everytime in SMC bypass but no vcore either.
 

2informaticos

Administrator
Staff member
Dropped machines are nightmare, I don't recommend to waste much time on it.
Check if pins 7 & 3 of U1950 stay high.
Possibly broken traces/solders underneath CPU...
 

2informaticos

Administrator
Staff member
Post all secondary voltages; big coils from the MLB.
You cannot get VCORE, without ALL_SYS_PWRGD.
One secondary power supply pulls it down...
 

No-Clean

Member
Now the board is not entering S0 state anymore. so I started troubleshooting all power rails and PP5V_S4RS3 was missing, I gave U7501 new solder joins and walla! board now turns on and works as expected.
 
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