820-3330 SMC_BC_ACOK Missing when Battery Connected

[SMMRepair]

Working on an 820-3330 and can't get it figured out:

1. Board originally had no green light, no power, ppbus/dcin missing, no liquid.
2. Replaced Q7080/30/35, ISL, R7021/22 and got my green light and fan spin.
3. Noticed that with (known-good) battery connected, board won't show green light. If I unplug battery, then connect charger, green light is present.
3. Board has green light without battery connected, and will keep green light if I connect battery after board is powered, and board will run from battery. If I plug charger in at this point, no green light again. If I connect battery then connect charger, I get no green light and no power (SMC_BC_ACOK missing).

Thought this was a pretty clear damaged SMC issue, but even a replacement SMC doesn't resolve issue. What am I missing here? I figured if green light works fine without battery, issue shouldn't be with U6900/U6990, right?

Any help appreciated, as always. Thanks!

 

[dukefawks]

I would more suspect an issue with U7000, pull and inspect/replace again. Also check ACIN voltage, R7005 and pull up resistor on ACOK line.

 

[SMMRepair]

Hey Duke! Thanks so much; you were right on as usual. I checked R7005 and it was actually showing me 18.8 kOhm and I did not notice that at first. Replaced it, got proper ~19.7ohm, but issue persisted. Realized that with the proper resistance there, D7005 then got scorching whenever I'd have battery/charger connected (a hint I wouldn't have had without your tip on R7005!). Replaced D7005 and all is well now.

Any idea what would damage D7005/R7005? Shit charger, or maybe proxy-damage from ISL (from shit charger), or something more? Really appreciate this one, one more for me to document! Thanks so much, Duke.

 

[dukefawks]

This was done by a shit chinese charger for sure.

 

[SMMRepair]

Thanks, Duke.

I actually am still having a bit of trouble with this one; it works about 80% of the time. I checked back at my D7005, and noticed some odd diode readings (machine off for 10 minutes before these taken):

D7005 diode: pins 1/2: .627; pin 3: .540

D7005 on a working board: pins 1/2: 1.80; pin 3: .548

So, pins 1 and 2 are way off of a working board. I'm not quite sure where to go from here; is this maybe an issue with Q7080?

 

[dukefawks]

Usually Q7080, U7000, R7005 die, also current sense resistor circuits are suspect so check the usual pin 17/18, 27/28.
As you said D7005 got hot, that means the ISL is possibly damaged again or C7005 is shorting.

 

[SMMRepair]

Knock-on-wood, I think I got this one resolved finally (hopefully). I ended up replacing Q7080, and noticed my diode readings were back to normal. I also replaced a few of the caps around ISL because they just looked "dark", like they had seen a lot of heat. Since doing so, all seems well. Hopefully this will be my last post on this one!

Thanks duke, really appreciate the help.