820-00164

[ComputerOverhauls]

fan spins for a second then shuts off

corrosion around u7400 area
mostly between u7400 and c7400

tried replacing u7400 with a known good. no change.
all_sys_pwrgd is 0v

r8168 is 99oms
noticed that if r8168 is removed then all_sys_pwrgd is 3.3v and fan stays on
still no chime or image on screen tho.

 

[2informaticos]

Problem on DDR power supply.
Its power good pulls down to ground ALL_SYS_PWRGD.

Post resistance to ground at L7430 and some voltages for U7400; pins 6, 12, 16, 17.
Be sure R/C7425 and traces are good.
You may need to change U7400 and/or Q7430...

 

[ComputerOverhauls]

L7430 pin1 0.7K ohms
L7430 pin2 0.7K ohms

U7400 pin6 0v
U7400 pin12 5v
?????U7400 pin16 0v
U7400 pin17 22.8mV

from c7425 to r7425 is OL.

 

[2informaticos]

"from c7425 to r7425 is OL."
Do you mean no connection between R/C7425???

"?????U7400 pin16 0v"
Check voltage on both sides of R8111...

 

[ComputerOverhauls]

sorry for late reply.
yes fromc7425 to r7425 there is no connection
voltage is 0v on both sides of r8111

 

[2informaticos]

As per schematic R/C7425 are both connected; supposedly corroded trace in your case.
Be aware, Q7430 gets usually fried in such case...