820-3662 - No post

[rvanpruissen]

MacBook starts, fan spin, no chime, no backlight, no light on optical mouse.

• No liquid damage,
• all voltages present,
• PPBUS_G3H = 12,58v
• VCORE = 3x 1,7v
• SYS_PWROK present,
• PM_S0_PGOOD present,
• No short between VCORE and PPBUS_G3H.

All suggestions (except dead CPU) are welcome

 

[Alan.L]

could be a dead bios chip. i would try a bios chip from a donor first before doing any ME stuff.

 

[JohnB8812]

I agree with Alan try BIOS

 

[rvanpruissen]

Sorry, forgot to mention this. Tried the following yesterday:
* Donor BIOS from 2013 board
* Reprogrammed the original with new 2014 bios.

Both produced no difference.

 

[2informaticos]

How did happen?
Previous random shutdown, or other weird issue reported?

 

[rvanpruissen]

According to the customer, he closed the MacBook one night and it would not boot anymore the next day. No mention of previous problems.

 

[2informaticos]

These boards are known for CPU power supply issue.
You get VCORE now, but CPU could get damaged by wrong job of one FDMF6808 in time.
You can try to change them with FDMF6708, but will not help in case of internal CPU damage...