[SOLVED] 820 2838 A not powering up

[diode]

Hi to everyone

I have one macbook air late 2010 with board 820 2838 A

It charges perfectly, and then the light stays green (no dim, full light!), but it won't power up.
Already reinstalled C1301 because i've found it ripped off!
Already checked all G3Hot rails and everything is fine!

What i can do in your opinion?
thanks!

 

[dukefawks]

Voltage on L7260?

 

[diode]

on L7260 i have 3,320v

thanks

 

[dukefawks]

Disconnect trackpad cable and power on the board by shorting the pads (R5014 or R5015).
Any history of liquid damage?

 

[diode]

already tried, nothing happens, no chime, no fan spinning!
No, only thing that i forgot to mention is that U4690 seemed to had a very little corrosion, i've cleaned and resoldered it

 

[dukefawks]

Voltage on Y2810?

 

[diode]

PIN1: It floats from 1.460 to 1.510
PIN4: 1.747

 

[dukefawks]

That seems ok. Getting anything on L7220 after powering on? Could be a short pulse so measure while shoring power pads. Also have you checked all coils for shorts to GND?
Also check if SMC_LID is high.

 

[diode]

Yes, L7220 gives 5.10v
No shorted coils!
SMC_LID (PIN7 on J4700) is shorted to GND

 

[dukefawks]

If 5V is there then a whole lot more voltages must be there. Go and check all coils for power. SMC_LID ignore for now, first need to have all power and CPU getting hot

 

[diode]

Checked voltages on all coils: first value is for power down state, second value is taken after pressing power button

L9701:
0.001
0.001

L7260
3.3
3.3

L7220
0.0
5.10

L7030
8.40
8.40

L7560
0.0
0.0018

L7330
0.0
1.065

L7630
0.0
1.5

L7550
0.9
0.9

L7400
0.0
0.0


What you think?
thanks!

 

[dukefawks]

Well L7560 stands out. Same enable as all the other power rails. Check for short on L7560 and check around U7500, could be dead or corrosion.

 

[diode]

ok, i'm changing L7560.
In your opinion i can change U7500 from one taken another air board? I have a Late2010 10" board.

Codes are on the 13":

9563BHZ
R5400
H040BBM

Other one is:

9563BHZ
R5400
H021BCS

 

[dukefawks]

L7560 is fine! Is there a short to GND on L7560? And yeah an ISL9563B is an ISL9563B. Diagnose why this isn't working don't "just" replace stuff

 

[larossmann]

L7560 is an inductor. A large inductor. That is like a spool of wire or a slinky. Slinkies don't break. Think about this and follow duke's advice!

 

[diode]

thanks guys for helping me, you were right!
board working perfectly now, i had to change C7576 around U7500, it was blown.

have a nice day!