820-3476 trackpad movement not working

Revive

Member
Very clean board no apparent liquid damage, the trackpad does not move the cursor but it does register the clicks.
Tried a new pad and cable no change, there were some crumbs magically around the SMC so I reflowed and ultrasonic'ed, no change.
Not really sure what lines control the pad movement.
Fails detect trackpad in ASD 162

R4808 - 3.33v
L4807 - 5.14v
U4801 Pin 24 - up and down 1.6 to 3.33, which Im guessing isn't right?

So is it likely the U4801 (looks clean on surface) needs to replaced or the SMC needs to be replaced/reballed? anything else to look at?
 

Revive

Member
J4800
1: 3.15V
2: 1.6 - 3.3
3: 3.3
4: 5.14
5: 5.14
6: 0
7: 3.13
8: .01 - .09
9: 3.3 - .05
10: .01 - .22
11: .01 - .107
12: 0
13: .001
14: 3.13 - 2.3
15: 3.31
16: 3.13
17: 2.8 - 1.1
18: 3.13

Unfortunately I don't currently have another ME866LL/A to compare it to. Any insight is greatly appreciated.
 

dukefawks

Administrator
Pin 5 can of course never be 5V but that would only affect the thermal sensor and trackpad should work. Double check pin 5!
Also do a diode mode on all the pins. Voltages look ok besides pin 5 for now.
 

Revive

Member
Yep you are of course right pin 5 is 3.3v

Diode mode J4800
1: .625
2: 1.26
3: 1.18
4: 1.67 and seems to keep ticking up slowly
5: 1.18
6: .0
7: 1.26
8: 1.26
9: 1.26
11: 1.26
12: 0
13: 1.26
14: 1.26
15: 1.26
16: 1.26
17: 1.22
18: 1.26
 
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