The Liftmaster/Chamberlain/Craftsman still use limit switches & always
have. The limit switches are under the motor cover & not on the track.

There are/were some units that counted motor revolutions but they were
a real pain & had to be reset (re-learned) every time the power went
out.

Doordoc
www.ActionDoor.com

On Mar 3, 8:45 am, wrote:
On Mar 3, 8:27 am, "Joseph Meehan" wrote:





wrote:
On Mar 2, 8:15 pm, "Joseph Meehan" wrote:
RBM wrote:
It sounds like the limit switches need to be readjusted. At the
moment thedoorreaches bottom or top, a limit switch should stop
the motor

Or replaced. In any case that seems to be the problem. Take a
good look at the wires to make sure they are intact.

--
Joseph Meehan

Dia 's Muire duit

I don't think there are limit switches in any current vintagegarage
dooropeners. They measure movement by counting pulses from the gear
drive.

I just checked the Genie site and they still show limit switches on
their description of how they work.

Interesting. I wonder why they still use them. I've had several
Craftsman over the years as well as a 20 year old LiftMaster. Neither
brand used actual switches on the tracks to set the limits. I think
they track movement by counting pulses from the gear train, which
sounds like a simple design, less wires to run, switches to go bad,
etc.





--
Joseph Meehan

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