820-00840: No powering up

[macRepairAmb]

Have a 820-00840 that isn't booting up. Owner said it was running fine the previous day and all of sudden won't power up.
I've checked the board for corrosion or sign of spill, none.
The board does get warm with PP20 present and about 70mA of current draw. I've flashed new ME as well with the same result. Any suggestions on where to start looking on this one?

 

[2informaticos]

What about PPBUS_G3H and 3V3_S5?

 

[macRepairAmb]

PPBUS_G3H - 13.1
PP3V3_S5 - 3.3
CPUVR_SW1 - 0.95
CPUVR_SW2 - 0.95

 

[2informaticos]

"won't power up"
How not, if you get even VCORE???
Please, make difference between boot and power on!

Your board turns on, but doesn't boot.
VCORE should drop to 0.6V approx, when the board boots.
Check PLT_RST_L level.
You can try known good BIOS.
Be sure SMC_LID_LEFT/RIGHT and LID_OPEN are all high.
Check VCORE with the board alone on the desk; nothing connected, apart of USB.

 

[macRepairAmb]

YEah, correction on that, the board does power up, just doesn't boot.

PLT_RST_L - 3.3
SMC_LID_LEFT - 3.3
SMC_LID_RIGHT - O.1
LID_OPEN - 3.3
The CPUVR readings were from the board out of the unit.
Flashed good bios with same result

 

[2informaticos]

"SMC_LID_RIGHT - O.1"
Try to fix this; disconnect J6600 and check it again.

 

[macRepairAmb]

With J6100 cable connected, HALL_SENSOR_RIGHT is now 3.4 with lid open and 0.0 with lid closed.

 

[2informaticos]

So all lid signals stay high now?
CPU core voltage drops now from 0.95V to 0.6V?

 

[macRepairAmb]

yes with the board in the frame, all lid signal is high when the lid is open.
CPU core voltage doesn't drop from 0.95v

 

[2informaticos]

Did you try the board alone on the desk?
Notthing connected, nor even SSD; keep only charger.

 

[macRepairAmb]

Yes. Got the same results.

 

[2informaticos]

Probably bad CPU...