820-3437 Fanspin, no post

Received this one pre-cleaned by another company and it actually worked when I got it. After doing some touch up work, returned it to the customer. It didn't work when the customer tested it and now that I've got it back, is doesn't work either. The fan spins, but I get no chime...

All voltages are present (CPU voltage 1.75, don't these normally measure 1.8?);
Tested another BIOS;
Replaced clock chip;
JTAG removed;
SMC replaced;
Some touch up work.

Any brilliant ideas?
 

2informaticos

Administrator
Staff member
Do you get the normal 3 start attempts, when plug in the charger?
Did you check all SPI Bus Series Termination resistors and their traces?
BIOS tested good for sure?
PLT_RESET_L is steady hihg?

If board was affected by liquid, maybe need to reball SMC.
Also try to heat CPU with quality flux; no more than 180-200 degrees, no need to melt the balls.
 
Top to bottom:
* No, it stays on at the second attempt (points to BIOS issue?)
* Checked, all fine.
* I've just tested with a BIOS from the ghostlyhaks repo, without changing ME-region. No difference.
* PLT_RESET_L steady high
* SMC was replaced earlier, made no difference
* CPU heated with Louis' flux, no sigar
 

2informaticos

Administrator
Staff member
Link for clean BIOS should be already posted on the forum; didn't check that first?

Was SMC replaced with correct one?
 
* Nope didn't know people share them on here, I'll have a look later
* SMC was replaced by a 820-3437-A while this is a -B board. These are interchangeable right?
 

2informaticos

Administrator
Staff member
Possibly CPU area affected by corrosion.
Heat it with quality flux; try to clean eventually crap accumulated underneath.
 

2informaticos

Administrator
Staff member
Test the board alone on the desk; disconnect any device/cable, apart of 5 pins power.
Use onboard USB for activity test.
 

2informaticos

Administrator
Staff member
Could be CPU, or just a knocked off resistor, or broken trace from previous repair attempt.
Working on boards which someone messed before, is a nightmare...
 
Last edited:
Top