820-3332 Keyboard and track pad not working

[tlough75]

I got in yesterday and 820-3332 that I originally changed the backlight fuse and LCD cable on. I was unable to test the computers functionality before I returned it because I saw corrosion on the trackpad cable and the trackpad was not working. I told the customer to replace the cable and trackpad and they said they but the keyboard and track pad are not working. I looked at the cable and everything and it looks ok. Do I need to just do an SMC reset or something? or are there bigger issues?

 

[2informaticos]

I recommend you to test known good working TP flex, becuase "new" chines flex always nightmare; maybe TP board too.
If still same, check basic voltages and signals to TP connector.

Next steps, check R5701-04 and change U5701...

 

[tlough75]

So I checked the voltages to the TP connector and they appear to be in order. I get 3.3V on pins 17 and 19 and 5v on pin 18.

 

[tlough75]

would SMC Lid have anything to do with it?

 

[tlough75]

I'm checking voltages on u5701

 

[tlough75]

So I checked pin 2 and pin 23 of the keyboard connector and i have both present.

 

[2informaticos]

J5700 power pins are 18 and 22.

"SMC Lid have anything to do with it?"
In fact you must check BUTTON_DISABLE signal.
High voltage will disable TP/KB.
And Q5701 is driven by SMC_LID...

Did you check all in U5701 area?

 

[tlough75]

BUTTON_DISABLE is at 0 volts. I am however showing a short to ground on the caps surrounding u5701. Also, PP3V3_S3_PSOC is 2.9v instead of 3.3v

 

[tlough75]

those caps are on the two VDD pins of U5701. 13 ohms to ground.

 

[2informaticos]

R5704 has correct value?

 

[tlough75]

yeah. pin 2 is 3.2v on PP3V3_S4_TPAD

 

[tlough75]

2.9v on pin 1 side of r5704

 

[tlough75]

I'm wondering if U5701 is dead. I did note allot of corrosion on the TPAD side of the connector and TPAD flex

 

[2informaticos]

Has R5704 correct 1.5 ohm value???
Higher value points to bad U5701...

 

[tlough75]

yes, it measured 1.6 ohms

 

[tlough75]

can you tell me what the outputs of U5701 are? I cannot tell but wanted to check.I measured TP_PSOC_SCL and TP_PSOC_SDA but do not have a frame of reference on if that is good or not.

 

[2informaticos]

0.4V over 1.5 ohm is too much current consumption.
U5701 is bad, or you have some corroded cap filters on its power rails.

 

[tlough75]

Should I bother changing the Caps? or just replace U5701?

 

[tlough75]

I should also note that Pin 51 which is PSOC_WAKE_L is at 3.3V. does this mean U5701 is not AWAKE?

 

[tlough75]

Ok so I pulled off U5701 to measure the caps around it and with the chip on they were all measuring 13 ohms to ground and now they are all measuring 14K ohms to ground. So is this definitive proof that U5701 is bad?