820-2915 No Power

Hi all,

I have a nightmare board - quite literally was destroyed by another company.

History is liquid damage and some poor rework.

Current symptoms: Green light and draws 0.26 amps (CPU/GPU are warm)

I have replaced the SMC twice now as I thought the above was caused by that and most of the 3.42v net as it was all missing. Q7030 was also shorted and now replaced.

PPBUS_G3H = 12.59v
PP3V42 = Present along with SMC_BCACOK

Can anyone think of a possible cause for 0.26amps --> i'm starting to think the CPU/GPU has a short :-(

Any ideas welcome before I say goodbye to this board?
 

2informaticos

Administrator
Staff member
Maybe some magician can completely solve an issue looking at the ampers only..
You've wasted time changing SMC in base of an assumption, without basics measurements.

First step, BEFORE powering a MLB, check resistance to grouind on all (big) coils.
A short, or low value on any, will show you where to continue; no need to power board to eliminate short/low value on power rails.
Maybe is not your case now (to have short), I just wrote it as general rule.

To get more than 25-30mA, the board should exit from S5 state.
Check 3V3_SUS, 5V_SUS, 3V3_S5.
To get warm, CPU/GPU need some S0 voltages.
If not present, then some leakage on their power supplies maybe...

Check PM_RSMRST_L and PCH's RTC signals.
See if PM_PWRBTN_L and PM_SLP_Sx_L signals react when simulate pressing power button (R5015/16).

Then come abck with more information...
 
Top