820-3437 Trackpad and keyboard not work

[raainxx]

Hi i have this board who don't find trackpad and keyboard.
I try new one trackpad same problem, no liquid spill, no trace very clean.
the customer say, trackpad work & sometimes not. now not work all the time
i find PP3V3_S4_IPD = 2V is too low, if i compare with another board.
i find PP3V3_S4 on C5560 =3v3 but PP3V3_S4 on R4830 = 2V (with & without the trackpad), R4830=0ohm.
why it PP3V3_S4 is different? normally is the same on all the board no?

 

[dukefawks]

Should of course be 3V3 on R4830. Sounds like a bad trace to me, run a wire to the nearest 3v3_s4 point.

 

[raainxx]

Sorry but PP3V3_S4SW_SNS is different of PP3V3_S4?
who is create PP3V3_S4 because when i put a wire between this signal, all fall at 2V, after some minutes, the keyboard work at start after 1 minute, stop working.

 

[dukefawks]

U8050 may be bad then if 3v3_s4 is low everywhere on the board.

 

[raainxx]

i find the problem is R8115 is dead, i change it and keyboard & trackpad work well.