820-02016 trackpad and kb not working

[Dozer]

î got this device with not working keyboard and not working trackpad.

i replaced all the stuff like traclpad tp-cable, controller and so on.

now i got a known good working mainboard.

with the good mainboard keyboard and trackpad are working
with the faulty mainboard kb and trackpad not working.
after turning on for a short while it it possible to "click" the trackpad then its like dead

no idea where to look first. the area around JT400 and other boardside loooks prtity good.
All pins from JT400 shows in diode mode almost the value from openboarddata

 

[Dozer]

i tryed no the faulty mainboard without backlight cable. now its working all like it should be.
but intresting, for doubleckeck i pluged the keyboardbacklight in again and now ALL is working without problems.

i dont know now what was the problem, oh how i hate such things...

i tryed the faulty board with the trackpad from the faulty device in a known good working case

so the backlight is ok, maybe the flexcable from trackpad is damaged, thats the only thing i can imagine. what do you think?

 

[Dozer]

i have now reassembled everything with a new trackpad cable. the device now works flawlessly.

 

[2informaticos]

Be aware of new chinese cables for trackpad; not good as should be.

 

[Dozer]

ok, thanks for the hint

 

[Dozer]

I now found out that in normal mode everything is working but all time after wake up from sleep mode trackpad is like "dead"
Now I found on the trackpad a tiny bit of old fluid . I cleaned the trackpad in ultrasonic and now all is good, after sleepmode is still working fine
So I think that was the problem. Solved.