820-00165 Pulsing. No Fan spin. Liquid damage near U7600 and the Bios chip

[dukefawks]

In TL866 software you can enable it under the "config" tab I believe. EZP2010 can not do this.

 

[phuketmymac]

That was already enabled. I've replaced every single resistor next to the Bios chip but same behavior.
It quarter fan spins.

Duke, do you believe it could be something other than the Bios area?
I am getting .4A once I plug the charger which makes the quarter fan spin, then simple pulse on PM_SLP_S4_L.
Does it sound like a short on some random rails?

Also I am wondering what that U6101 does?
Do you know which values I should get on SPI_MLB_CS_L, SPIROM_USE_MLB and SPI_MLBROM_CS_L when the system is pulsing please?

 

[dukefawks]

U6101 switches between SPI and quad SPI. The SMC talks SPI to U6100 and the CPU uses quad SPI. Is CPU Vcore coming on?

 

[phuketmymac]

Yes it does.

I am getting 2 pulses of PPVCORE_S0_CPU to 1.7V.

 

[dukefawks]

Picture of U6100 area, good quality plz.

 

[phuketmymac]

I already did put 4 pictures a while ago. Yes that area has been abused, mostly by corrosion.
I did, like you advised, check every single resistor value, even replacing them all + checking the continuity from any signals going to U6100 and U6101 and I got them.

Now I am seriously thinking I am getting trolled by the CPU...

That board has been liquid damaged around U6100 (Bios), U3210 (Thunderbolt circuitry) and U7600 (PP1V05_S0).
During my last test, I have had these behaviors:

-Tried a different Bios for the same board model on the Vietnamese website and the board did start but I got no picture.
Reading the comment, the guy had the same issue using this Bios so I thought "Yeah that's it!"
Tried a different Bios, but wouldn't start.
Tried to go back to the same Bios which did start to do some measurements but it wouldn't start...
I've tried all the different Bios I could find but again, wouldn't start.

Put back the original Bios and now, here is what is happening:
Either I am getting 2 pulses on All_sys_pwrgd or I am getting a 0.235V on PP1V05_S0 (remember U7600 was liquid damaged) with 0.1A of current usage.
Now I've checked and replaced U7600 twice + all the surrounding resistors and even compared the U7600 diode mode measurements with a known working board and the values are very similar.

I am just not getting how come I am getting 0.235V on that rail?!...
When I am getting the pulses, I can see it reaching 1.05V using my oscilloscope.

 

[dukefawks]

You are getting Vcore so there is no reason to mess with any power rails really. Vcore will only come high once all other rails are ok. It is power cycling and that could be anything. The usual suspects are U6100 traces and resistors, crap under SMC.