820-3662 no chime

[Kyle93]

Arrived with no liquid damage. Turns on with fan spin but nothing else happens. USB mouse light comes on.

L7310 1.790v

L7320 1.795V

L7330 1.807V

Should all three FDMF6808N chips be replaced?

 

[2informaticos]

If board doesn't boot at all, I doubt it will revive changing these chips.
Can you confirm USB activity for sure?
Use macOS installed on pendrive with Link LED; if flashes, is OK 100%.
Also do PRAM reset 2-3 times, if possible.

 

[Kyle93]

pendrive with macOS does not flash.

3 pram resets did not help

 

[2informaticos]

PLT_RESET_L comes up?
Pins 5 & 6 of U6100 go to 9V after 2-3s?
If yes, try known good BIOS.

 

[Kyle93]

PLT_RESET_L 1.3V

pins 5&6 of U6100 0V

 

[2informaticos]

"PLT_RESET_L 1.3V "
Reset must be disabled, 3V is required there.
PCH doesn't finish power on sequence correctly.
Check PM_SYSRST_L, PM_PCH_PWROK and PM_PCH_SYS_PWROK.

 

[Kyle93]

PM_SYSRST_L 3.3v

PM_PCH_PWROK 3.4v

PM_PCH_SYS_PWROK 3.4V

 

[2informaticos]

"PM_SYSRST_L 3.3v "
Then was a misstyping previous post?

Check all SPI Bus Series Termination resistors and their traces,
Clean J6199; or/and remove it if you don't use Medusa.
Try known good BIOS...

 

[Kyle93]

Do you have a known good bios to share?

 

[2informaticos]

Try and comment.
I don't remember if any really good...

3662 test.rar

drive.google.com

 

[Kyle93]

Same syomtoms with new bios file. No blinking led light on oxs pen drive

 

[2informaticos]

Looks like CPU issue; probably damaged by (in)famous FDMF6808 chips...