820-00840 No Power

brunomotter

Member
Hello. Got this board here with no power. 20V on charger. If I let it plugged off for some minutes, the first time I plug it in it negotiates 20V with charger and draws around 300mA for some seconds. When this happens I have 1.05V on L7370 but no voltage on L7220 or L7210. Then, after some seconds the board stops drawing current and stays 20V with 0A. If it plug it off and let it sit on the bench for some minutes the same thing occurs again, 0.3Amps for some seconds then nothing. Where should I start?
 

2informaticos

Administrator
Staff member
Try starting in SMC bypass.

Did you test the board alone on the desk?
Nothing connected, apart of charger; no LCD, nor even SSD.
 

brunomotter

Member
Just board on the desk with nothing but charger/ampmeter connected to it. Original 96W Apple Charger with original cable. Will try SMC bypass.
 

brunomotter

Member
Tried SMC bypass. Machine turns on with fans maxed out but no chime, no video output and no POST. On SMC bypass I get 0.8V on L7410, L7420 and L7430 but still no voltage on L7210/20.
 

brunomotter

Member
Flashed with known good BIOS. Now board keeps drawing continuously 325mA from PSU when connected and CPU gets warm. I have voltage on L7410/20/30 but still nothing on L7210/20
 
Last edited:

2informaticos

Administrator
Staff member
That's really strange, because iGPU doesn't come on until high graphics load is detected.
VCORE should be there always, dropping from up 1V to 0.6V approx.
I suppose bad CPU in this case...
 
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