820-00165 Macbook air Cpu_vcore is there but no chime no image

[Ciki]

Reflow the smc ,flash new bios smc2925 clean,still no image
all rail present
all_sys-pwgrd 3.3v
cpu_vcore 1.8v
only i notice that is spi_clk is low 0v (maybe thats normal)

 

[KC Micro Tronix]

SPI_CLK will only momentarily operate and you can only really see it with a scope.
All your rails are good?
You have checked for a waterdamged resistor pad? Something like that hiding somewhere?

 

[Ciki]

I didnt found any rail missing

 

[2informaticos]

Any history available?
PLT_RESET_L high?

Which new BIOS did you try?
Some links are posted on the forum.

Did you test USB activity?

 

[Ciki]

PLT_RESET_L 3.3v
When i connect usb keyboard get light on trackpad but no caps lock(have keyboard with small mouse ball) ;-)

 

[Ciki]

Is it normal that my SMC_THRMTRIP is 0v

 

[2informaticos]

"Which new BIOS did you try?
Some links are posted on the forum."
???
Let us know what you've really tested...

Use USB pendrive/HDD with Link LED and preinstalled OSX to confirm, or not, USB activity.

 

[Ciki]

I use 2 different bios from donor board ,try usb and get lights for about 30 sec then off ,if you unplug and recconect lights is on again for around 30 sec

 

[2informaticos]

USB mouse can trick you sometime.
Always best to test USB activity in the other manner.

Did you pick BIOS chips for test from working boards?

 

[Ciki]

There were dead board cant confirm working bios,and when is on its drawing 650mA on power supply ,I remember the working one was around 350mA ??

 

[2informaticos]

Hard to think you've got bad BIOS chips from different boards.
But cannot discard BIOS issue, untill try known good working file.

Check all voltages from pages 57/58 and also voltage on all (big) L/C blocks near PCH/CPU area.

History fault can give a clue, but not reply from you.
Also no USB activity confirmed 100%.