Lynx 455 No Sensors Closed on an Object

[Hoggy]

My Lynx 455 opener has no sensors and the door closed on a lawnmower that was not in the clear. The motor ran for some time before I realized it and quit working. I took the cover off and the drive belt was broken. I replaced the belt but when I push the open button the motor only hums. I can turn the pulley and motor by hand and it moves the chain and manually opens the door. So what have I done to my poor old door opener? We been together a long time.

[HayZee518]

check the start capacitor. with the overload, it could have burnt up. the motor has a set of movable contacts inside that disconnect the capacitor when the motor is up to full speed. continuous operation on the start winding could have burnt up that winding also. if you need a new motor go to grainger supply - best bet for replacements.

[Hoggy]

check the start capacitor. with the overload, it could have burnt up. the motor has a set of movable contacts inside that disconnect the capacitor when the motor is up to full speed. continuous operation on the start winding could have burnt up that winding also. if you need a new motor go to grainger supply - best bet for replacements.

Well that gives me a clearer understanding of how these capacitor and motors work together. Thanks for the information.

When I first removed the door opener cover the drive belt was broken. When I pushed the "open" button the motor hummed but didn't turn even though there was no load on it. Would the motor require the assistance of the capacitor to start even without a load on it? If not, then this would point to the motor as being part of the problem, no?

Hoggy

[HayZee518]

the motor is called a poly-phase motor. it has two windings in it, a start winding and a run winding. a capacitor is inserted inline with the start winding to get the motor spinning as near to full speed it offsets one phase by 90 degrees and then disconnects by means of the centrifugal start switch inside. every motor that starts presents almost a dead short to the circuit. high currents are present until full speed is attained then this current drops to almost zero. most motors draw 125% more than nameplate current. smell the motor for an acrid smell. this will give you an indication of a burnt up winding necessitating a new motor. if you can take it apart look for blackened or brownish windingd. you check same with a meggar or analog meter. digital meters can't tell you much.