820-3023 - Keyboard / Track Pad Issue

[mccafe]

Hello,

I have a 820-3023 MacBook Air with a keyboard / track pad issue. I found corrosion on the trackpad connector which I replaced and trackpad started working as well as most of the keyboard keys. I replaced the whole keyboard and now both the trackpad and keyboard works. After a day of testing, both keyboard and trackpad suddenly stopped working. I checked voltages and was getting weird USB _TPAD_CONN_P / USB_TPAD_CONN_N voltages (2.8 volts / 1.9 volts). I replaced U5700 and now I get 3.3 volts / 0 volts and trackpad / keyboard works again. However after 1 day of testing again, it stopped out of no where USB _TPAD_CONN_P / USB_TPAD_CONN_N abnormal voltages again. After a bunch of measuring, seems the only thing left is the U2650 which I replaced. Worked for a little bit, and again back to weird issue. I replaced trackpad to make sure that might not be it and UC'd the board. Same issue. I even tried with the keyboard disconnected and just the track pad, but seems to have nothing to do with the newly installed keyboard.

Any thoughts?

 

[2informaticos]

Check if both USB ports are working.

Do you get correct voltage at pins 1, 10, 13 of J5700.
Also check pin 12 level.

 

[mccafe]

Hello, both USB ports are working.


14. SMC_TPAD_RST_L 3.42
13. PP3V42_G3H 3.42
12. SMC_LID 3.42
11. SMC_ONOFF_L 3.42
10. PP5V_TPAG_FILT 5
9. SMBUS_SMC_MGMT_SCLK 3.3
8. SMBUS_SMC_MGMT_SD 3.3
7. GND
6. USB_TPAD_CONN_N 2 (this is when it stops working)
5. USB_TPAD_CONN_P 2.8 (this is when it stops working)
4. GND
3. GND
2. SMC_PME_S4_WAKE_L 3
1. PP3V3_TPAD_CONN 3.3

 

[2informaticos]

Check pin 5 & 6 disconnecting trackpad flex; voltage and diode mode to ground.