A1466 820 3437 Board No Power , No Chime, No Fan Spin

mdc2018

Member
Power rails measure normal, am getting .46 V on PPVCC_S0_CPU

No visible corrosion but signs of water damage.

Not sure how to diagnose low voltage on this line, how should I proceed?

Thankyou!
 

2informaticos

Administrator
Staff member
Do you get all other normal voltages, excepting CPU core?
Check if U7310/20 are correctly powered and look if R7311/21 and C7311/21 are all good/present.
Also check U7200 area, VR_ON, VIN, VDD.
Is sufficient one corroded small resistor; and there are many, too many...
You may also consider to change the MOSFETs from CPU power supply.
 

mdc2018

Member
R7311/21 = 4.8V
C7311/21 = 4.8V

U7310 Pin 8 (Phase) is getting the same .46V as PPVCC_S0_CPU

These readings do not match my known good board. Is this a step in the right direction?
 

dukefawks

Administrator
No use in measuring Vcore if there is not even fan spin. Check all S4/S3 rails first if present then all S0 rails. S0_CPU will be the very last rail to come on and the fan should spin first.
 
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