Macbook A2337 Stuck at 5V Amps Cycling Between 0.01 to 0.45

[Instafixx]

Board Clean.
PPBUS is Fluctuating between 0V to 12.2V.

Did thermal imaging when connected to charger.
Found something near U7700 heating up. It's either R8001 and L7800.

Diode mode readings of both are as per the Openboarddata.

R8001 resistance across pins is 1M Ohms

 

[2informaticos]

R8001 can't overheats; is 1 Mohm resistor.

U7700 is first suspect if L7800 overheats.
Just in case, try replacing the coil first.

 

[Instafixx]

Replace L7800.
Now stable at0.45Amps.
But still the Coil Heats.

U7700 ? Replace or Reball ?

 

[2informaticos]

Replace it...

 

[Instafixx]

Replaced U7700 . Still the same.
L7800 still heats up.

PP3v8_vddmain diode mode is .220 - is that ok?

 

[2informaticos]

PPBUS_AON still fluctuating?
Remove F5200 and check if C5254 voltage is stable.

 

[Instafixx]

PPBUS is stable at 6.6V.
Removed FUSE - Get stable 12.29V.
I thought bad fuse so replaced it. still the same.
Have good diode mode readings of .560 on both pins.

 

[2informaticos]

What about 3V8_AON now?

 

[Instafixx]

Without Fuse. 0V

 

[2informaticos]

Of course; you must connect the fuse.
6.6V is enough to generate 3V8_AON; if its power supply is good.

 

[Instafixx]

PP3V8_AON is 1.7V

 

[2informaticos]

That's the problem.
Not easy to fix, as you don't have short there.
Check all components around U5700 and adjacent MOSFETs.

 

[Instafixx]

While checking I found C7800 is getting hot. Removed it. Short Gone. PP3v8 is 3.8V now.
PPBUS is 12.3V.

 

[2informaticos]

What is actual board behavior?

 

[Instafixx]

It works now.