I've become pretty comfortable (I though) with this type of issue, but this board is kicking my ass right now. Symptoms and order of attempts:
1. Board had liquid damage that was cleaned at some point in the past, before I got it. Nothing looked too ugly except for one small area near the oft-shorted C6405. I cleaned that area up, and still had a short on 3v42 (.000).
2. Traced short to SMC, replaced and short was gone, but no green light still.
3. Checked ppbus_g3h and it's missing (.7v) but has no short.
4. pp3v42_g3h missing. SMC_BC_ACOK is 0v at U7000.
5. This led me to check voltages at U7000; pins 2 and 3 are both present, but pins 23 (chgr_phase) and 14 are zero. Resistance at pins 17/18 and 27/28 is normal (2.0ohm, 20.0ohm)
6. I replaced U7000 again, along with Q7080, Q7085, Q7030, Q7035 and Q7055 just to be safe. I know liquid was in the area, and didn't want to waste time. However...
7. Same results; missing ppbus_g3h (.7v) and pp3v42 (0v)
8. ppbus_g3h is present at 12v with battery installed (a bit low), and 3v42 is still missing but does jump up to .4v on battery (compared to 0v on charger).
9. PPDCIN_G3h present and steady at 16.6v @ R6990. R6990 and R6905 both measure fine, and voltage is missing completely on R6905.
So I was leaning towards the SMC again, but power isn't even getting to the SMC yet. I've found no shorts on ppdcin_g3h or anything else. I'm not entirely sure where to go from here; I'd suspect the ISL again since my dcin and acin are both present (pins 2 and 3), but still no ppbus voltage. Rather than waste MORE time here, I thought I'd post about it!
Help me out, Aprendiz/Duke! Thank you in advance.
1. Board had liquid damage that was cleaned at some point in the past, before I got it. Nothing looked too ugly except for one small area near the oft-shorted C6405. I cleaned that area up, and still had a short on 3v42 (.000).
2. Traced short to SMC, replaced and short was gone, but no green light still.
3. Checked ppbus_g3h and it's missing (.7v) but has no short.
4. pp3v42_g3h missing. SMC_BC_ACOK is 0v at U7000.
5. This led me to check voltages at U7000; pins 2 and 3 are both present, but pins 23 (chgr_phase) and 14 are zero. Resistance at pins 17/18 and 27/28 is normal (2.0ohm, 20.0ohm)
6. I replaced U7000 again, along with Q7080, Q7085, Q7030, Q7035 and Q7055 just to be safe. I know liquid was in the area, and didn't want to waste time. However...
7. Same results; missing ppbus_g3h (.7v) and pp3v42 (0v)
8. ppbus_g3h is present at 12v with battery installed (a bit low), and 3v42 is still missing but does jump up to .4v on battery (compared to 0v on charger).
9. PPDCIN_G3h present and steady at 16.6v @ R6990. R6990 and R6905 both measure fine, and voltage is missing completely on R6905.
So I was leaning towards the SMC again, but power isn't even getting to the SMC yet. I've found no shorts on ppdcin_g3h or anything else. I'm not entirely sure where to go from here; I'd suspect the ISL again since my dcin and acin are both present (pins 2 and 3), but still no ppbus voltage. Rather than waste MORE time here, I thought I'd post about it!
Help me out, Aprendiz/Duke! Thank you in advance.
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