At 06:00 PM 1/22/2008 -0600, Bob Nogueira wrote:
>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.
Bob,
I thought most obstical sensors were photoelectric beams. An LED either
visable or IR would emit a light beam to a photo receiver. If the receiver
does not get the light it opens the circuit so the opener doesn't work or
reverses.
I don't understand how/why they'd use a Hall effect sensor. Unless they
are counting time between pulses. If the time is too long, it figures
that something is stopping or slowing the opener (while it's closing) and
it stops and reverses.
You didn't say what model you have, but I did a google search (Chamberlin
Garage door opener) and found: http://www.liftmaster.com/
Under the garage door openers, I was able to find the owners manuals for
several units. It infers that the sensor is an "eye" so I'd expect it
to be a optic system not a magnetic system.
I didn't spend a lot of time looking to try and find a repair manual or
schematic.
In their manual it states:
3. My door reverses for no apparent reason: Repeat safety reverse test after
adjustments to force or travel limits. The need for occasional adjustment
for the force and limit settings is normal......
Hope this helps.
John
John T. Blair WA4OHZ email: jblair1948@cox.net
Va. Beach, Va
Phone: (757) 495-8229
48 TR1800 48 #4 Midget 65 Morgan 4/4 Series V (B1106)
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