820-00165 No damage not turning on

[wgaca]

Another one that just died on it's own.

No visible liquid or any other damage. Reported by the user that just died.

The fan will spin for 5-6 seconds and all rails are present
No short found on any big caps or coils

Once the fan stops all the pch signals are there, s5 pwrgd is there but no sus_l

 

[2informaticos]

PLT_RESET_L goes high?

 

[wgaca]

PLT_REST_L goes to stable 3.3V for the time the board is on 5-6 seconds

 

[2informaticos]

Check then CPU_VCCST_PWRGD and CPU_VR_READY.

 

[wgaca]

CPU_VCCST-PWRGD is at stable 1V and VR_READY at 1.05V steady

The CPU also gets hot in these 5 seconds.

 

[2informaticos]

Try starting in SMC bypass mode.
If still the same, try known good BIOS.

 

[wgaca]

I forgot to mention that I already tried SMC bypass and there was no difference
I tried a known good efi chip just to see if there is any difference but it's the same behaviour.

 

[2informaticos]

Any pulse at L8304?

 

[wgaca]

With LCD connected nothing for the first few seconds and then jumps to about 20 mV, it's very low for very short not sure if i can call that a pulse.

 

[2informaticos]

Did you note the fan starting with full speed in SMC bypass mode?

 

[wgaca]

Yes, the fan is starting at full speed in SMC bypass and normal speed in normal mode.

 

[2informaticos]

Looks like bad CPU...