820-3115-B PP3V42 dead short - how to find it?

2informaticos

Administrator
Staff member
You should start from 1V and go up, but maintain ampers bellow power supply current limit.
The limit could be reached at 2V/5A maybe and then a 5A power supply will get blocked directly if you try to inject 3V.
In such case you cannot inject more than 2V.
A 10A power supply can go up, supporting 3.5V/8A, for example.

Remove the black sponge near BIL connector and check the caps there...
 

djdblaster

New member
Started with 1V, nothing was heating, bumped to 2V, SMC got a little bit warm and DCPS showed around 250mA draw.
Tried again 3V, draw was 150mA. SMC was again little bit warm.

PP3V42 is now present, PPBUS_G3H is 12.54V. Green light present. No fan spin.

When I connect the charger, SMC is warm, around 35-40C. As far as I can see, the bottom half of SMC gets warm, from pins 75-157.

Following schematics, page 3 "Revision History", I don't have P3V3S5_EN_L from U7941. Both input signals are present.
 
Last edited:

2informaticos

Administrator
Staff member
"Remove the black sponge near BIL connector and check the caps there..."
???
Increasing resistance after voltage injection is usually sign of bad cap in that area...

But if you now have stable 3V42 there is other problem.
Do you get green light for MagSafe?
 

2informaticos

Administrator
Staff member
Check SMC_ADAPTER_EN, PM_BATLOW_L, PM_SP_SUS_L, 3V3_SUS.
Try to start in SMC bypass mode.
If SMC gets hot, should be good to try another one...
 

djdblaster

New member
SMC_ADAPTER_EN ----------------- 3.42V
PM_BATLOW_L ------------------------0.006V
PM_SP_SUS_L ------------------------ where is this?
3V3_SUS -------------------------------- 0V

Doesn't start in SMC bypass mode.
 

2informaticos

Administrator
Staff member
"PM_SP_SUS_L ------------------------ where is this?"
Sorry, try PM_SLP_SUS_L.

"PM_BATLOW_L ------------------------0.006V"
Try another charger first...
 
Top