820-2915 no CPU VCORE

[G.Beard]

No corrosion.

Power rails all present and correct aside from:

PPVCORE_S0_CPU = 0V
PPVCCSA_S0_REG = 0.98 (not sure about this one)

Checked U7400
Pin 1, CPU_IMVP_VR_ON = 3V3
Pin 2, CPUIMVP_TON = 12V5
Pin 15, 24, PP5V_S0 = 5V

No idea where to go from here.

 

[dukefawks]

This is going to suck. Try a donor BIOS and inspect board for physical damage. Also heat the GPU first to eliminate that.

 

[G.Beard]

Tried GPU but no go.
Tried replacing U7400 because it's not putting anything out to FET gates.
SPIROM is good.

Guess I'll check current sensing and look deeper into what's going on around U7400 circuits.

Any other ideas?

 

[dukefawks]

Nooooo, U7400 is fine. U7400 needs communication with CPU to turn it on. This could really be anything. Check damaged components, was it dropped? Did you really try BIOS? Again this board will probably be a rabbit hole...

 

[G.Beard]

Nooooo, U7400 is fine. U7400 needs communication with CPU to turn it on. This could really be anything. Check damaged components, was it dropped? Did you really try BIOS? Again this board will probably be a rabbit hole...

Had to test ROM in the TL866 as no donor chips with correct BIOS here. Reads good 3 times with same checksum so I guess it's OK since it reads. Checked the reads in UEFI tool too.

Everything I get from this guy recently is either a clean shiny rabbit hole or a corroded crusty asshole resulting in wasted time. I can't see that it's been dropped but who fucking knows man.... It's going back dead.
My time is worth more than figuring out this problem.

Appreciate the help Duke, thank you.

 

[dukefawks]

Uhm, if the chip was corrupted how would reading it 3 times confirm it is good? Flash it with a known good file and see if it works.....

 

[G.Beard]

Uhm, if the chip was corrupted how would reading it 3 times confirm it is good? Flash it with a known good file and see if it works.....

OK that's a good point, I was only testing if the chip itself was working. I'll try that first.... Do you have good EFI?