Hello,
I bought a roller door from a well known auction site ;(
The problem is that the box of electronics controlling it has got two relays. I imagine one for up and one for down. The "up" relay is sticking so that the door will not open. I have opened the box of electronics and given the relay a tap and it is working for now but I expect it to stick again soon. How can I prevent it from sticking in the future? Is there anything I can do? I guess I really need to get out the soldering iron and replace it before it fails completely.
Does anyone know the schematic for these boxes of tricks? I presume the relays isolate the electronics from the motor? Is the switch side of the relay connected to the mains on one side and the motor on the other? Is the relay output open circuit when he door is stationary? If so I was wondering whether I could put a switch in parallel with the relay so that I have an emergency override? Is this possible?
My worry is that if the relay output is connected to ground when stationary, I don't want to blow a fuse when I switch the override!
I notice there is a spark when the relays open. I'm not sure whether that's the reverse emf in the coil or just the mains jumping the contacts as they separate. Possibly this is welding the relay stuck. Do you think I should add diodes?
The box is branded Nico IIRC.
Thanks, Stephen.