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820-3437-B with liquid damage

1

1phone.cl

Member
Hello friends, I get a Macbook Air 820-3437-B with liquid damage in the sectors
U4650
U5000
U7501

Only with the charger connected the light goes from green to orange and does nothing

I did a thorough check and changed all the damaged components and reballing the U5000
Also reviewing in other posts I saw that they made some measurements in the U7100 so to advance something I did these measurements

u7100

Pin 1 0V
Pin 2 14.6V
Pin 3 3.8V
Pin 9 0.037V
Pin 12 3.4V
Pin 13 3.37V
Pin 14 3.37V
Pin 15 0V
Pin 17 4.04V
Pin 19 5.05V
Pin 20 5.03V
Pin 27 14.4V

PP5V_S4RS3 Isn´t present
 
Last edited:
2informaticos

2informaticos

Administrator
Staff member
First of all, welcome to the forum!

Start posting diode mode reading at PPBUS_G3H (red probe at ground).
Check the resistance value between pins 17/18 and 27/28 of U7100.
 
1

1phone.cl

Member
Thanks for the welcome, I am very excited as I have experience repairing iPhone and I am just entering the world of Mac

PPBUS_g3h 0.122

Resistance between Pins 17/18 = 3.2 ohm
Resistance between Pins 27/28 = 20 ohm
 
Last edited:
2informaticos

2informaticos

Administrator
Staff member
I'm not sure about the values; diode mode readings?
We need ohm scale measurments; should get very low values, as per schematic.
Check R7121/22 and R7151/52 with their traces.
 
1

1phone.cl

Member
sorry, I edited the answer with correct information

Diode mode PPBUS_g3h = 0.122V

Resistance between Pins 17/18 = 3.2 ohm
Resistance between Pins 27/28 = 20 ohm

R7121 = 10 ohm
R7122 = 10.3 ohm

R7151 = 2.5 ohm
R7152 = 0.2 ohm
 
2informaticos

2informaticos

Administrator
Staff member
No need to check the resistors, if the asked values are good.

Remove F7140 and check C7140 voltage.
Be sure R7113 is good, as its traces too.
Check all components and traces related with pins 5, 7, 8.
 
2informaticos

2informaticos

Administrator
Staff member
So you have a problem on the PPBUS_G3H, after F7140.
Resolder F7140 and check voltage on its pin 2.
If still low, check diode mode to ground on all big coils, apart of L7130.
See if any gives the same value as in PPBUS_G3H.
 
1

1phone.cl

Member
Thank you for your answer but i am a little confused, in Rossmann Repair Training Guide it says

  • On Macbook Airs and old Macbook Pro 17” PPBUS_G3H is 8.5v when
  • the SMC is able to communicate with the ISL, 8.16v when the SMC
  • cannot.

  • On Macbook Pros PPBUS_G3H is 12.56v when the SMC is able to communicate with the ISL, 12.23v when the SMC cannot.

taking this into account the voltage of PPBUS_G3H in the model I'm looking at would be fine
 
2informaticos

2informaticos

Administrator
Staff member
Your problem is not caused by communication between SMC and ISL6259.

You've said to have 4V at PPBUS_G3H, when F7140 is in place.
Confirm if is true...
 
2informaticos

2informaticos

Administrator
Staff member
"Pin 17 4.04V"
We need accurate and consistent information, in order to help you.

Do you now get 3V3_S5/SUS?
 
2informaticos

2informaticos

Administrator
Staff member
Post SMC_ADAPTER_EN, PM_PWRBTN_L, PM_RSMRST_L and SMC_ONOFF_L.
Trigger SMC_ONOFF_L (using R5115/16 pads, instead of power button) and check for drop pulse at PM_PWRBTN_L (at same time).
 
1

1phone.cl

Member
SMC_ADAPTER_EN 3.3V
PM_PWRBTN_L 3.4V
PM_RSMRST_L 0V
SMC_ONOFF_L 3.4V

Drop pulse 3.4V to 0.352V when SMC_ONOFF_L isTrigger
 
1

1phone.cl

Member
R8133 it´s ok
i changed u8130 and now it gives me these values
PIN 1 3.3V
PIN 2 3.3V
PIN 3 1.4V
PIN 4 3.2V
PIN 6 3.2V

still does not turn on
 
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