820-00840 Not working if battery connected [SOLVED]

nik1981

Member
Hello, I'm stuck as I have an A1708 which powers up fine on the charger alone but won't boot if the battery is connected.

I've tried a known good battery but still no change.

On USBC alone, F7000 is 13v
On Battery and USBC F7000 climbs from 11v to 12.96v and drops back in a cycle roughly every 6 seconds.
On battery alone F7000 sits around 10.6 and very slowly drops

Resistance on R7061/62 + R5438 + R5439 are all as schematic.

Q7065 diode mode
from pin 5 to pins 1-3 is .219v
from pin 4 to pins 1-3 is .634v

I'm not sure where to check from here
 

nik1981

Member
Thank you for the reply 2informaticos.

R6905 is reading 2.5 ohms while on the board

On a known good board, my multimeter shows 2.5 on that one also so I think my meter is just slightly out
 
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2informaticos

Administrator
Staff member
The value is correct.

Do you get 3V3_G3H with battery alone (no charger)?
Did you check R7021/22 too?

Check for corrosion at J6951.
 

nik1981

Member
Yes I get 3.344v for 3v3_g3h on battery alone

Yes I forgot to mention I checked R7021/22 and they're both as 1.3 ohms

J6951 looks clean inside and around it
 
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nik1981

Member
No, the MacBook came in with a non genuine battery but that seems to work.
No history of liquid etc. Just wouldn't power on one day apparently.

I disconnected the battery and tried with just the charger and it turned on as if nothing had happened. reconnected the battery and two others and it won't start.
 

2informaticos

Administrator
Staff member
Start with charger only and connect J6951 once logged into macOS.
Tight battery screw first, of course.
Check if battery is detected correctly then.
 

nik1981

Member
Well thats weird.

I connected the battery and charger but not J6951, booted to MacOS and logged in.
I connected J6951 but it didn't see the battery

I left it all connected and hit restart, on once restarted, it sees the battery and is charging it.

PPBUS_G3H on F7000 very slowly creeped up to 12.22v

If I unplug the charger, it stays on the battery perfectly with PPBUS_G3H fluctuating between 9.5v-10.8v

If I plug the charger back in, it begins charging again 2.7a and PPBUS_G3H slows climbs back to 12.2v

It will now start on the battery alone.
 
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