A2337 MacBook Air 820-02016 - 5V - 0,04 Amp

[samstown]

Hi,

No liquid, board looks super clean.

MBA doesn't start up, power stuck at 5v 0.05-0.1 amps.
On the thermal camera, U5200 pulses. No short on U5200 and surrounding components,


PPBUS_AON - F5200 - 12.25 pulse down to 11.74 every seconds

U5700:
pin 8 PPBUS_AON - 12.25 pulse down to 11.74 every seconds
pin 7 PP5V_AON_P3V8VRLDO - 5V
pin 5 P3V8AON_PVCC - 5v
ENABLE - 5v both sides of R5710

U8100
C81F6 - PP3V8_AON_VDDMAIN 3.8V

Would appreciate your help on this.
Thanks

 

[2informaticos]

Check all secondary power supplies.
If any doesn't pulse, check there for short.

 

[samstown]

Thanks.

I found a short at
PP5V_BSTLQ_VOUT_SPMU
C7893
C7892
C7800
C7801
C7831

So now I need to inject 1V to find culprit ?

 

[2informaticos]

What is the exact ohm value of that short?

 

[samstown]

Diode Mode, red probe on ground.
.098 on both side of each cap
0.0v

 

[2informaticos]

That doesn't look like a short.
Did you compare the value with good board?

 

[samstown]

Good board
.421 diode mode red probe on ground.
.024 GND

 

[2informaticos]

That is lower reading than normal, but not short.
Inject voltage may not help in such case.
Possibly high performant IR camera can detect something injecting up to 5V.

You can remove mentioned capacitors, one by one, and see if reading goes up.
If not, then change U7700.

 

[samstown]

Problème was Coil on U7700. thanks

 

[palmtree]

Problème was Coil on U7700. thanks

What coil number was bad and how did you find it?