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[SOLVED]820-3437 Won't power on without charger

H

Hellfiya

Member
No water damage, no obvious drops, tried two batteries, one of which is known-good. Any ideas where to start? ASD EFI shows no errors except the usual when the battery is low(sensor vb0r) which I know is normal.
Can't see any fried chips or anything.

R7120(pp dcin in rush etc,) voltage steadily drops from around 16.7v downwards, thought it may have been a bad charge port board but i disconnected it and it still drops. The device charges normally, however. Or is it just the caps draining? Resistance to ground is around 300k then drops to 220k then goes back up slowly

two solderballs sticking out from C1031(ppVCC_CPU_s0) - Resistance to ground 66.5ohm on pin 1.
Also, same with c1060(ppmain_io_cpu) - resistance to ground .880k
both of these are in close proximity to cpu of course.

maybe some humidity or heat damage since some test points are slightly rainbow throughout the board. But no water drops or corrosion marks anywhere in housing or on board.

I will get more powerline measurements when I get back to my workshop:

voltages with fully charged battery only plugged in(no charger connected):
battery connector:
pin 1-3 ppvbat - 8.47v Diode mode - OL to ground***
pin 4 smbus smc 5 g3 scl - 3.416v diode mode - .5v to ground
pin 5 smc sda - 3.416v Diode mode - .5v to ground
pin 6 - sys detect l - OL Diode mode - OL to ground - Resistance is 9.94k(r6950 ok)
pin 7-9 ground diode mode 0v obv

still only battery connected:
ppbus_g3h = 8.43v
pp5v_s5 = 0v
pp3v3_s5 = 0v

With charger and battery(machine on):
ppbus_g3h=8.55v
pp5v_s5 = 5.13v
pp3v3_s5 = 3v338v

after machine turns on with charger, it can stay powered on until shutdown or power loss
 
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J

JohnB8812

New member
When you power on the machine with the charger and battery plugged if you boot into the OS, does it recongize the battery or is there an X through the battery?
 
J

JohnB8812

New member
Ok how are you turning it on with just the battery I would assume keyboard? If so, tried known good keyboard and inspected trackpad for corrosion or damage? If so, my guess would be to check R7006
 
H

Hellfiya

Member
No corrosion detected, I use the power button. Won't work when completed shut down but when it's on it works normally, puts it to sleep, or I can hold to force shut down. Also smc reset works when charger is plugged in or Mac is on
 
J

JohnB8812

New member
All kinds of things what is your voltage on PPBUS currently with just the charger and then with the battery and charger?
 
H

Hellfiya

Member
Charger Only(amber light): 8.56v
Battery(100%) Only: 8.45v(machine off), 8.39v(machine on - after being turned on by charger then disconnecting charger)
Battery(100%) and Charger(green light): 8.56v

I also noticed that when turning on from a completely off state, the machine the fan spins on and off twice before remaining on and chiming the third time(testing out of housing with nothing except battery or charge port connecting and reacts same in housing with everything connected)
 
J

JohnB8812

New member
The on off on off on thing is normal for this model. I’m gonna defer to Duke and others because I don’t know why that’s happening tbh and don’t wanna give you any bad information. My only thought is maybe corrosion under the battery connector or the SMC
 
D

dukefawks

Administrator
Disconnect trackpad flex cable and connect the battery. Now short the power pads on the board, R5115/6 and see if that works.
 
H

Hellfiya

Member
Hello Duke, yes it does turn on when shorting smc_onoff_l to ground with the trackpad disconnected. No reaction when trackpad is connected and smc_onoff is shorted. So does this imply the trackpad is bad?
 
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