[SOLVED]820-3437 - Fan spins, No chime, No image on screen

[aprendiz]

COuld be corrosion under J6100, also check values for all resistors arround U6100....

 

[Sykulski]

I removed J6100 from board. All resistors around U6100 measure correctly according to schematics.

Still same issue.

 

[dukefawks]

Did liquid get to the clock chip? Replace it just to be sure.

 

[Sykulski]

No liquid or signs of it on clock chip. Switched it anyways. Issue persists :-(

 

[dukefawks]

Only thing I can think of is another corroded trace from U6100 to the CPU or SMC. Remove U6100 and measure diode mode on all pins.

 

[Sykulski]

Diode mode U6100 (off the board)

Pin1: 0.497
Pin2: 0.477
Pin3: 2.017 - (should this be so high? R6101 = 3.3KΩ, diode mode pin1 = 0.412)
Pin4: 0.002
Pin5: 0.508
Pin6: 0.508
Pin7: 0.462
Pin8: 0.408

 

[dukefawks]

Now remove R6114-17 and measure again. Only pin 1,2,7,8 are of interest.

 

[Sykulski]

OK.

Diode mode. R6114-17 removed. U6100 still off board

Pin1: 0.501
Pin2: 0.480
Pin7: 0.468
Pin8: 0.408

 

[dukefawks]

Shit I meant 1,2,5 and 6, sorry.

 

[Sykulski]

No problem.

Pin1: 0.501
Pin2: 0.480
Pin5: 0.514
Pin6: 0.514

 

[Sykulski]

Hi Duke

Do you have any new advice to this one?

 

[dukefawks]

Measure diode mode on both side of R6114-17. Resistors should be removed.

 

[Sykulski]

Diode mode with resistors R6114-17 removed:

R6114: p1 = 0.735, p2 = 0.484
R6115: p1 = 0.736, p2 = 0.515
R6116: p1 = 0.735, p2 = 0.515
R6117: p1 = 0.735, p2 = 0.505

 

[dukefawks]

That all looks ok. Still looking at that 3V on pin 7. It should either be 3.3 or 0, have you checked the pull up resistor and traces are ok?

 

[dukefawks]

I'm out if suggestions then, anywhere else that had corrosion?

 

[Sykulski]

Nothing obvious. I will inspect carefully. Thanks for your time.

 

[Sykulski]

I got this one up and running after a long and lasting fight. It was the BIOS after all. I missed it because I accidentally flashed an A-revision BIOS but it is a B-revision board. But because the A-revision BIOS made same issues as the corrupted original BIOS it trolled me. After flashing correct BIOS for 820-3437-B and updating ME it is running smoothly. Thanks again for your time and effort Mr Duke. Please mark solved.