Mikey
Aspiring Old Fart, EE, computer & networking geek
A neighbor had me over to fix his garage door -- it would go back and forth from full open to down-a-little and back to open. It looked like a safety circuit issue. His door has two such circuits -- a photocell sensor across the lower opening, and a pneumatic switch on the bottom of the door. According to the diagrams, each of these circuits is NO, then go to closed when they activate. I tried disconnecting them altogether, making the circuits permanently open, but the problem persisted. I eventually found a small wirenut had worked loose from one of the wires on the pneumatic switch, permanently opening the circuit. When I reconnected the wire, everything worked OK.
Why?
That was a commercial roll-up door. On my own door, I have a Sears system with a similar photocell sensor thing across the door opening, connected to the controller by a 2-wire cable. There appears to be no easy way to disable this system -- neither a NO nor a NC hookup will allow the door to operate. Somehow, the system knows whether the photocells are connected are not. Anybody know how this works?
Why?
That was a commercial roll-up door. On my own door, I have a Sears system with a similar photocell sensor thing across the door opening, connected to the controller by a 2-wire cable. There appears to be no easy way to disable this system -- neither a NO nor a NC hookup will allow the door to operate. Somehow, the system knows whether the photocells are connected are not. Anybody know how this works?