820-01814 20v, but amps…

Zebulon

Member
The MacBook was working fine, but then it seemed like the battery was dying fast, almost suddenly, then it just stopped turning on. The guy that owns it did a battery replacementI, but had no luck getting it running. After opening it up I noticed the lock clip missing from the battery connector on the battery controller board and the flex cable was just sitting there. I fixed the connector and the battery is now working, although I’m not sure if it’s charging or simply running off the power that was in it from out of the box. I get 20 volts but once the amps ramp up to 0.72, then zero out and start again. In a loop. It does not power up. I only see one big coil get warm under thermal cam, but not hot. Any ideas?
 

Zebulon

Member
I just checked and it is 87w charger. No power to CPU rail with or without board connected. With everything connected in the housing it goes to 20v then ramps up to around 0.77a then goes back to zero and starts again. Board alone goes to 20v and goes up to around 0.05a and bounces around from 0.03a to 0.05a.
 

2informaticos

Administrator
Staff member
Check for knocked off components, or other damage that could be caused by customer changing the battery.

Do you get all AWAKE and SLPS2R voltages and steady?
 

Zebulon

Member
AWAKE voltage is 1.206 at pin 1 of C7914 and SLPS2R voltage is 0.799 at pin 1 of C7905 ... and both go to zero and back to those voltages after around 20 seconds. i do not see any knocked off components, but the MacBook died while it was being used and that's why he replaced the battery in the first place. A friend told him that would fix it. He took it to Apple and they said it needed a new logic board of course. In the attached image you can see L7030 and the T2 are the only components getting warm.
 

Attachments

  • 20220503T194040.JPG
    20220503T194040.JPG
    493.5 KB · Views: 0
Last edited:

2informaticos

Administrator
Staff member
There are more AWAKE and SLPS2R voltages on the board.
Look at the small coils surrounding U7800.

What is PPBUS_G3H behavior?
Check it when the mentioned voltages drop to 0V.
 

Zebulon

Member
PPBUS_G3H is at 12.64v then drops to 12.33v when the amps drop to 0.00a from 0.05 now that it's just the board. When i first plug the board in it starts at 5.17v and 0.25a then goes to 20.2v and 0.05a. Coils look ok around U7800.
 

2informaticos

Administrator
Staff member
"Look at the..."
I said that to point you where AWAKE and SLPS2R voktages to check; not too "look" at them.
Check if all G3S and SSD voltages appear too.
Also check diode mode to ground on all big coils; including the "small" ones corresponding to SSD.
 

Zebulon

Member
Ok, thanks for the info. I understand what you mean now. I had checked the diode mode to ground on all big coils, including the small ones corresponding to SDD, but wasn't sure exactly what the readings should be. I get some of the small ones that are 4.11 and some that are 0.11. The big ones seem to be higher numbers. I am pretty sure that I should have CPU power even while the board is out and just using the 87w charger, but the CPU rails are missing. Is there anywhere I can safely inject voltage or something to look for a short. Unfortunately I'm running out of time with this one.
 

2informaticos

Administrator
Staff member
Before searching for CPU core, did you check RAM voltage at least?

You can't get the board working if no voltage at L7600 first.
 
Top