820-3332 PM_SLP_SUS_L Missing

SMMRepair

New member
Working on an 820-3332 with no power; s5/g3h/3v42/vrtc all present, but found PM_SLP_SUS_L missing...oh no. PP3V3_S5_PWRCTL present at C7940. SMC_BATLOW_L is present at Q5040.

At Q5040 things are a bit weird, and I checked several times (a dozen+). Sometimes when I measure Q5040, pin 1 and pin 2 are both .522v and pin 3 is 3.3v, all stable. Other times, pin 2 cycles from .017v to .202v, and pin 1 cycles from .188v to .228v. Pin 3 (SMC_BATLOW_L) is stable all the time at 3.3v. Diode readings at Q5040 match a working board. No battery connected of course, but a working board has 3.3v on all three pins of Q5040, so I assume I don't need a battery to figure out the issue that's present. Changed Q5040 and U7940 "just because".

PM_SLP_SUS_L missing scares me since it comes from the PCH. Any help appreciated--thank you in advance as always!
 

SMMRepair

New member
I have a bad habit of finding new information shortly after posting:

I was looking over Q5040 area on schematics and saw several signals come from (of course) the SMC, and combined with the inconsistent readings at Q5040, and finding no shorts to explain the cycling/bouncing signals, I decided to reflow the SMC. Low and behold Q5040 readings stabilized and I got fan spin! Great. So now my question is this; could this have been cracked solder balls, or do you think the SMC is on the way out? I'd prefer to not replace it unnecessarily, but I've not seen cracked solder balls on the SMC on this model very often, so makes me think it may be failing. This is a customer mail-in repair, so might go ahead and replace it to be safe. Any input appreciated!

Thanks again!
 

SMMRepair

New member
Hey Duke! Yeah, I feared there may be crap under there, and in the interest of not having this unit come back, I went ahead and pulled SMC. There was a tiny bit of crap, so I went ahead and replaced SMC and unit is working well so far! :)

Thanks, Duke!
 
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