820-00165 Fan Spins for 3 sec

[Don Anton]

Hi ,

This is not a liquied dmged board.
resi
I get cpu v_core for 3 secs with fan spining then no pp5v_s4. I replaced the SMC, Tried with same board different bios isl 625 and current sensing resistors . Still the same. any clue?

 

[2informaticos]

Did you try to start in SMC bypass mode?
Pin 3/U1950 goes high in these 3s?
Also check if PLT_RESET_L reacts.
Check if all voltages from page 58 come on.

 

[Don Anton]

Thank you for your reply.

Pin 3/U/1950 goes to 3.3v for 3sec and also PT_RESET_L goes 3.3v only for that fan spining 3 secs. I dont know how to bypass SMC.
I checked with same 820-00165 bios to see whether it turns on but same situation. I check with 820-3437 bios then I get continue fan spining no chime no display.

 

[2informaticos]

Then reflash original, don't waste time trying 3437 file.

SMC bypass has already been explained here several times; even Google helps you...

 

[Don Anton]

solder wire on R5115/16 for SMC bypass still same.

 

[2informaticos]

Did the fan spin at max when you tried?
If not, wasn't in SMC bypass mode...

 

[Don Anton]

yes fan whent max high speed then stop as before.

 

[2informaticos]

Then should be some CPU issue.
Check if you get correct all voltages on the L/C blocks near CPU; at the edge of the board.

"Check if all voltages from page 58 come on."
Don't forget...

 

[Don Anton]

Hi,
Thank you for your reply. Sorry couldnt mention I did check all the power rails and all are exactly the way it should be including CPU_VCORE. checed voltages on Blocks newar CPU edge of the board and they are getting the voltage suppose to get. Do you think this is CPU by itself?

 

[2informaticos]

Could be anything else, like just a small resistor.
But is probably internal CPU problem...