820-00165 - Green - Amber - PP3V3_S5 = 0.59V

[samstown]

Hello,

Got this Macbook Air. Board is clean. When connected I get green and orange led, fan doesn't spin. SMC looks ok.

I am suspecting C7500 but before removing anything i want to make sure.

C7500 Pin1 = Diode mode = 0
C7500 Pin2 = Diode mode = 0

U 7501
23 = 0.0 V
22 = 0.00 V
12 = 3.4V
13 = 2.64 V
29 = 0.33 V
21 = 3.4 V

PM_BATLOW_L NON = 0,59

U1900 2 = 0.59V

R1405 1 = 0.59V PP3V3_S5
R1405 2 = 1.45V PM_PWRBTN_L
R1410 1 & 2 = 0.59V PM_BATLOW_L
R1452 1 = 0.59V
R1452 2 = 0.59V PCIE_WAKE_L
C1845 = 0.59V PP3V3_S5




thanks
Sam

 

[2informaticos]

"C7500 Pin2 = Diode mode = 0"
Any reason to check ground to ground???

"I am suspecting C7500"
There are many more components connected to PPBUS_G3H, apart of C7500.

Post exact ohm resistance to ground.
Compare with the resistance on the big coils.

 

[samstown]

right... GND to GND...

so Diode Mode, red probe on GND
C7500 PIN1 = ohm resistance 0.000 ( i know you won't like it : )

L7139 = .112
L7520 = .112

 

[2informaticos]

No other big coils visible on the board?
The VCORE ones are first to check.

 

[samstown]

L7310 = .18
L7320 = .18
L7360 = .144

those looks ok.

 

[2informaticos]

Being pure short to ground, is very likely a filter cap.
However, always discard first a short between PPBUS_G3H and a big coil.

Should be safe to use voltage injection method now.
1V is probably good enough to find the culprit.

 

[samstown]

Thanks.
It was C7376.
Fan still not spin after replacement. I'll have to keep searching.

R7006 = 1.04V now at PPBUS_G3H

 

[2informaticos]

Did you change F7140?

 

[samstown]

no, I should ?

 

[2informaticos]

Should be bad now; just check it.

 

[samstown]

I don't know how you know that but you were right . I've changed it and now fan spin ! Thank you very much