820-00239 Missing SMC_PM_G2_EN.

SMMRepair

Member
Clean 00239, no liquid, with no power. Board has ppbus (13.2v) and 20v on USB-C power input (0W/0A draw), but not much else. SMC_PM_G2_EN is missing completely. Thought it might be the SMC since signal was missing completely, but replaced SMC and symptoms persist. Also replaced U7650 to be safe. SMC power (3v3_g3h_SMC_vdd) is present. I have .4v at L7960, and no damage or anything around U7800. All related pull-up resistors for SMC_PM_G2_EN (R5192, R8110) measuring fine. SMC_RESET signals all high.

Is this possibly a U7800 power issue? Nothing gets warm, no shorts on S5_HS, etc. Everything stops at SMC_PM_G2_EN. All help appreciated!
 
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SMMRepair

Member
I can't tell if battery is charging; how would I determine that with no board life? I have 0W/0A draw on all USB-C ports.

If the SMC isn't at fault for the missing SMC_PM_G2_EN, what else should I be looking at? Could U7800 be pulling SMC_PM_G2_EN down, which is why it's missing? Would love to not screw around with U7800 if I don't need to. ;)
 

2informaticos

Administrator
Staff member
Check if possible to cut off the trace, before U7800.
If not, should remove it and see if signal comes high.

If no current drawn from charger, battery is not charging; secondary effect of missing SMC_PM_G2_EN I suppose.
 

SMMRepair

Member
Sounds good, I'll do that. But quick question: Obviously I don't want to apply power with U7800 removed; how should I check if signal comes high with U7800 removed?
 

2informaticos

Administrator
Staff member
Puah, good question...
You MUST remove several MOSFETs from the secondary power supplies controlled by U7800; U7900/60, U8000/50.
Be sure I didn't forget any to mention...
 

SMMRepair

Member
Sure thing, thank you; I'll try that. I may even just replace U7800 since I'm having to pull it, and I have spares. Will try that and let you know--thank you!
 

SMMRepair

Member
Bit of a newb question here, but what all is required by the SMC on this model to actually produce SMC_PM_G2_EN? I replaced U7800 and no dice, exact same behavior. Curious if I'm missing an input for SMC that should be present. These touchbar boards really throw me for a loop.
 

2informaticos

Administrator
Staff member
Very strange, as getting 20V from charger means SMC talks with it.
So SMC is in working condition.
SMC_PM_G2_EN must be high on S5 state if charger is connected.
If SMC already talked with tthe charger I don't know if needs other signal about charger presence; which looks like redundant in such case.
However check SMC_AUX_OK; corresponds to ACOK.
 
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