820-00426 in S0 state but no chime

sekidata

Member
I have an A1398 820-00426 board that apparently has all power rails and is in S0 state, with fans spinning, but refuses to chime or start up. USB mouse shows a brief flash, then nothing. No apparent liquid damage. Where would you look next?

ALL_SYS_PWRGD: 3.2V
PPVCC_S0_CPU: 1.8V
SYS_PWROK_R : 3.4V
 

2informaticos

Administrator
Staff member
Any history available, what the client said about the failure?

Could be FDMF6808 problem.
Try known good BIOS, before touching CPU power supply.
 

sekidata

Member
The client stated vaguely "The machine developed some sort of heat sensor issue and it quit booting."

I replaced the BIOS chip twice with no change.
 
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