820-3476 no trackpad/keyboard

[rob777]

Changed trackpad and flex already. Was minor water damage but not there trackpad or keyboard areas.

keyboard has 3.3v at pin 30
and 3.4v at pin 4
trackpad has 5v pin 4 and 3.3v at pin 1

at one stage when testing pin1 on trackpad I touched ground too and it shorted and I had to replace r4808 when it shorted though the keyboard stared working.
put r4808 back and no keyboard again.

Keyboard pin 5 smc_onoff_l is 3.4v

 

[rob777]

Smc_lid is 3.42v

 

[rob777]

Put a new u4801 on - no change
found it wasn’t doing a smc reset changed q4801 u4850 and u5110 started doing an smc reset but no working keyboard or trackpad.

Smc reset has stopped working again now. Reflowed smc cause getting desperate. No change.

So as of right now. External mouse works. No power button to turn on. No smc reset happening. Once on no track pad or keyboard still.

 

[dukefawks]

Randomly replacing parts without diagnosing is just adding more variables to the mix. Was power at U4801 checked?

 

[rob777]

Yeh I know better. You are exactly right. Unfortunately because I have no patience, frustration at myself and then desperation lead here..
Anyway yes 3.3v is there as well as tpad_vbus_en 3.3v
Have traced all keyboard and trackpad pins back to U4801 too.

 

[dukefawks]

Don't care about the keyboard, the trackpad needs to work first. Check all connection from U4801 to the end of the trackpad cable so you know traces/connector/cable are good.

 

[Hellfiya]

Did you perhaps plug in/disconnect the tpad while the battery was plugged in? I just had another a1502 come in with no tpad/kb after the last person tried hotswapping the tpad connector. I also have the issue on a 3662 where I may have plugged in the tpad while the macs battery was connected. Could 3v3(pin 1 on 3476; 22 on 3662) fry the adjacent z2_clkin(pin 2 on 3476; 20 on 3662) when plugged in misaligned?