(347) 552-2258 [email protected]

820-00928-A missing trackpad force feedback

F

Fanfwe

Member
Hi,
I've got this 15-inch MBP which came in with no working keyboard and trackpad.
Turns out the trackpad was bad. I replaced the trackpad with a known good one, and a new flex cable too.
Now keyboard works, and trackpad works, only it doesn't provide any force feedback, which makes it feel very weird to use.

Other things I noticed: CB700 was blown, it probably shorted internally and burnt down. I removed it but it was probably already dead open after burning. It is just a cap on PPBUS though, so I don't see how that would affect the trackpad force feedback while the rest of the machine works just fine.

Anyone has encountered issue with trackpad force feedback before ? I'm not quite sure where to look at since I'd expect this to be fully contained within the trackpad, but I've got it tested in another machine and it works fine.

And of course, I've already tried PRAM reset, SMC reset, and the option in Trackpad settings in MacOS is properly turned on.
 
F

Fanfwe

Member
Yeah, I should have mentionned that I checked it too. The fuse is good.
PPBUS_G3H is only 11.2V. Isn't that too low ? I don't have a reference for this machine. But really other than the touchpad feedback, this machine works just fine, so I assumed it wouldn't be a bad PPBUS, but maybe it is after all ?
 
F

Fanfwe

Member
I checked it at F4500, but also at F7000 and F7001. All read the same voltage.
The 11.2V was with the battery connected (and no charger connected).
I've just measured without the battery, and this time it gives me 12.6V at all three fuses.
 
2informaticos

2informaticos

Administrator
Staff member
I suspect the actuator doesn't get the voltage.
Maybe bad contacts, or even bad flex.
Do not trust new chinese flex, try another.
Connect the trackpad direct to MLB, outside of the shell.
Then check contacts between TP board and MLB.
Don't forget to check SMC_VIBE_L continuity.
 
You must log in or register to reply here.
Top