No range of Motion for my garage door opener

Kevin100

I've replaced all the gears in my Craftsman garage door opener and the broken cable that caused the gears to be stripped. Now when I operate the opener with or without the door engaged the chain moved 3"-4", stops and then reverses itself. The safety sensors seem to be okay and the limit switch does not make contact. I'd appreciate any ideas on what to check next...

Kevin100

Ron6519

It would help if you mentioned the model # of the unit, how old it was and if it had the electric eyes.
Ron

Kevin100

It's a Craftsman 139.53973SRT 1/2 horsepower. It's about 10 years old but as I said I have just replaced all of the gears.

It does have the safety sensors but they are both solidly lit.

Thanks.

firehawkmph

Kevin,
If both eyes are lit solid, about the only other thing to check is the opening and closing force adjustments. Turn them all the way up and see if the operator will travel back and forth like it's supposed to. If the clutch adjustments are set too light, it will do what yours is doing. If that doesn't do it, I would replace the opener. If you got 10 years out of a newer sears, you did pretty good. Even though they are made by Liftmaster for sears, they are not specced the same. I don't usually recommend even replacing the plastic gears. About the time they go, it's about time to replace it.
Mike Hawkins

Kevin100

Mike,

Thanks for the advice. In retrospec I should have asked before replacing the gears although I've done that on my other bay about 4 years ago and it still works fine. I'll do as you suggest first checking the clutch adjustments and then replacing.

Thanks again.

Best regards,

Kevin

Thurman

When changing a new gear care should be taken to assure the relationship between the driveshaft (the gear attaches to) and the "full open/full close" adjustments are not disturbed. This relationship can be re-established with a few adjustments. You didn't state which direction the chain is moving when it stops. IF the chain is moving as to open the door, when it stops this may be meeting the "full open" adjustment. Then if it moves only 3"-4" and stops the unit may be meeting the "full close" adjustment which may have gotten out of adjustment. Try removing the chain also to take it out of the equation, it may be binding on something. You state that you have another unit of this type. Carefully watch the gear on the good unit to determine the revolutions, then compare with the faulty unit. This will tell you if the faulty unit is turning enough revs or the stops may need to be adjusted. David