820-3437 try to spin. All rails are ok.

BCN_Techs

Member
Hi there,

Got 820-3437 that try to spin the fan but immediatly shut down. It seems like there is a short on S3 or S0 lines but i cant find it out.


All rails i checked are giving correct value. S3 and S0 rails give correct value at the moment fan tries to spin ( spin quarter and stop). Also all sys good giving 3.3 at the moment of fan spins.


No water damage just someone didnt screwed it well and there was a screw going up to down over logic board that must make short something somewhere.


Any idea?
 

BCN_Techs

Member
CHanged now boot and on half logo progress bar it stays darked with backlight lcd ON. Also tried from USB, internet recovery mode etc and same, when it arrived about 50% of progress bar computer hungs with lcd's backlight on. Seems be hardware. What can i do:D?
 
Last edited:

2informaticos

Administrator
Staff member
First of all, disconnect internal SSD and test it witk known good OSX through USB.
Also try clean ME BIOS.
 

BCN_Techs

Member
tried with usb with capitan installed on it ( boot on other macs) and same happens. About Clean me BIOS i have never did it. Where i can find info what is that and how it works?

Do you mean new efi chip? I must have some in my chips for this model.
 

BCN_Techs

Member
Tried clean me bios and same. Boot untill apple logo and than stay black screen. It's like when machine must ask user password it stopped showing image.
 

BCN_Techs

Member
Sorry for delay. Checked with external monitor and right when internal shuts down, same happens on external. About usb , with mouse conected i get red buttom light.
 

BCN_Techs

Member
i had extraced EFI chip from working macbook air and soldered it on broken one. Not booting. After returned it to donor board and board booting fine.
 

2informaticos

Administrator
Staff member
Did you resolder the same PCH???
I don't think.
Any piece is DIFFERENT.
I don talk about model number!
Any chip has its differencies due to manufacture process.
ME region correct these differencies.
When boots, if PCH detects clean ME region, will configure data area.
If ME region is already configured (by other PCH), data area is not changed; even if it doesn't correspond to actual PCH.
 

2informaticos

Administrator
Staff member
We already have posted links for BIOS with clean ME region for your board.
You will need to replace serial number at the end, but use downloaded file as is, just for test.
 

BCN_Techs

Member
Hi again,


Finally i tried CLearme and DUMP EFI and the result is same. Computer boots begin to load and after that no image only backlight. The only way i got into installations was with CMD+R but after download all and restart to install same thing happened.


Any idea what else it can be?
 
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