[Shop-talk] Chamberlin Garage Door Opener

[Bob Nogueira]

Kind of a stab in the dark here but the group has never failed me so let me
give it a go.
I have a Chamberlin Garage door opener  (chain drive)  that I have converted
to open my driveway gate. It has worked great for several years with minimum
problems. Recently it started reversing just before it reaches full close.
The  "obstacle in the way reversing"  is activated by  one what looks like a
Hall effect sensor you would find in a car,  a cup which turns inside the
head that has windows which turn with the drive shaft.
I believe my problem is with that sensor. Problem is I have no idea how that
system works. Anyone have any notion as to how such a sensor would work in a
Garage Door opener?

I'll take even WAG's.

Bob Nogueira