820-00138 FAn Spins for 5 Sec and stop then fans spins continuously No chime.

[Don Anton]

Hi,

There is no any damaged on this board.
I get all the power rails accurately. Initial issue was quater fan spin. How ever I replace the bios with same model board bios to check then it chimes and could get display.
Then I tried to clear me Reagan on that bios using medusa. And back to old problem fan spins and stop. I tried original bios with clean me , complete new bios, bios from same type of board.replaced
smc. with all this same issue now fan spins for 5 sec, then fan spins for ever no chime. Checked bios traces and resisters and they are fine. All the tests with no USB light,

PLT_RESET_L and PLT_RST_BUF_L is 3.3v and stable.

Tried with out bios no fan spins, USB light blinks.

 

[2informaticos]

So board doesn't boot now, even testing with BIOS file which worked before?

You could have CPU issue, as these boards suffer because of CPU power supply problems; read about FDMF6808 chips.

 

[Don Anton]

Hi , Thank you for your reply. yes it doesnt boot now. fan spins then stop and fanspins again for ever. No usb mouse light. regards FDMF6808 chips, If i have replace these do i have to replace all 3 of them?

 

[2informaticos]

Should be all replaced, but damaged CPU will not come back to life; if that is the case.
Inspect first for knocked off components around SPI chip; if you removed it from the board.
Also check integrity of all SPI Bus Serie Termination resistors and traces.