820-00840 20v 0.45a no chime, no image

[Outofwhack]

This board had corrosion on components C7101, R7101, R7132 and tracks connecting to U7100
After replacement of above and U7100 I have
0.95v on L7410/20/30
all_sys_pwrgd 3.2v
pm_sysrst_l 3.3v
put_rst_l 3.3v

Fan spins initially then stops then spins long time. Currents remains at 0.45a with SSD inserted. 0.36a without SSD.
No USB activity as indicated by snow edition stick.

 

[2informaticos]

Very strange to get iGPU core voltage, but no CPU core.
Are you sure no voltage at L7210/20?

 

[Outofwhack]

0v at L7210/20
4.5ohm to gnd at each one
pp5v_s0 5v
ppbus_g3h_cpu 13.06v

 

[2informaticos]

May have CPU problem.
Try known good BIOS, just in case.

 

[Outofwhack]

Just tried known good BIOS - no difference still 0v on L7210/20

How could a cpu problem explain why 0v at L7210/20 ?
Surely lack of voltage here means no power to cpu.

 

[2informaticos]

PCH, BIOS and CPU are involved there.
Can also be other problem, like a simple corroded resistor...

820-00840 8HV22 Medusa clean ME + PRAM.rar

drive.google.com

 

[Outofwhack]

I have to say my 'known good BIOS' should really only be 'assumed good' as it was from another yet to be repaired 820-00840.
Worth trying a reprogrammed BIOS. Late here in Oz - something for tomorrow. Thanks

 

[Outofwhack]

Replaced 95828, board now boots