820-00165-A "Baby bounce and nothing" S0 state for maybe 0.25 sec.

[KC Micro Tronix]

I have another bouncing POS board.. I hate bouncers. This one is more like a drop. It only bounces once then nothing.

I checked the S5 rails.. All normal.
Unit enters a S0 state for a split second. 0.25 sec. Appears to pull normal current but it's hard to tell with such a short sample time.

U1930 does register (CPU_VCCST_PWRGD) and the input (ALL_SYS_PWRGD) does come up to the proper 3.3v
PCH_SRTCRST_L is 3.3V
PCH_RESET_L is 3.3v
PCH_INTVRMEN is 3.3v
PCH_INTRUDER_L is 3.0v

Unit will register a SMC reset.


I am looking at the SMC lines trying to figure out how it is being shut down.
Suggestions?

 

[2informaticos]

Try first to start in SMC bypass mode.

 

[KC Micro Tronix]

ok. From what I gather SMC bypass is done like this....l

Hold down the power button and connect the MagSafe.

The machine does try to boot but in the same quarter second shuts down.

 

[2informaticos]

Check if all voltages from page 58 try to appear.
Be sure no short after the Power FETs.
Also check U4600.
And of course, test the MLB alone, disconnecting LIO flex.