Kurt Ullman wrote:
In article . com,
"irish" wrote:

Do you have the light sensors at the bottom of the door to stop it if a
child or other object blocks the light. That will do exactly what you
decribe. it will go up but not down. Maybe the sensor has been blocked.

Second thing I checked. The closest thing to the sensor is more than 2
feet away. Is it possible that maybe one side or the other got knocked
out of kilter so the light isn't getting to the sensor?

I doubt that would affect it one way only. However, watch the lights on
the sensors to see if they flicker when closing and not opening. Can be
just alignment. Maybe the frame shakes a bit when closing.

I had a Chamberlain that did something similar but it most likely was in
both directions. I decided it was the rpm sensor control board. A
little board that fastened at the rear of the motor shaft with an LED
and a slotted cup. I took a chance and bought one and that fixed the
problem. It was obviously better built than the original.

If it happens to be a Chamberlain they have a pretty good web site with
downloadable manuals:

http://www.chamberlain-diy.com/diy04/home/