Garage Door Openers:

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rattus

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Early models of the Genie garage door openers used a rotary switch of sorts on the end of the drive screw as part of the low voltage circuit. Does anyone know the function of this thing?

They also used a 4 position stepping relay in the high voltage (120V) circuit. Does anyone know the function of the third wire coming from the relay coil?

My newer opener works fine. I am asking simply because I am curious.

Rattus
 
My guess is that the rotary switch was a safety backup for turning off the motor, in the event that the limit switches on the door did not stop the motor first. Perhaps there were no limit switches, and this was the only way to stop the motor. I have no guesses for the second part of your question. I am not even certain I know what a ?four position stepping relay? might be.
 
The rotory switch is most likely used to set the upper and lower stop positions. the third wire may have been used for locking the opener out. I've seen several with this option, for example if you leave for vacation you have the option of locking the opener by mearly pressing the lock button which opened the circuit.

LHarrington
 
Yes, this one does use limit switches located on the rail which holds the drive screw. They are not located on the door itself.

The stepping relay works something like a pull chain switch. Each time it is energized, it moves a cam to operate the switches as follows:

OFF--CCW, light ON--OFF--CW, light ON

The limit switches are only active when the motor is ON.
 
I am guessing the stepping relay gives you one contact control from either a wall button or a radio transmitter of OFF--CCW, light ON--OFF--CW, light ON.
 
My guess is that the rotary switch would reverse the door if the motor is running and the drive shaft isn't turning. (I.e. something is stuck under the door while it is trying to close, so the motor would reverse and open the door).

Steve
 
iwire said:
I am guessing the stepping relay gives you one contact control from either a wall button or a radio transmitter of OFF--CCW, light ON--OFF--CW, light ON.
Click to expand...

Right! That part I understand. There are two motor windings connected by a capacitor. Power is applied alternately through one and then the other of two contacts to effect motor reversal. A third contact operates the light, and a fourth connects the limit switches.

I think the rotary switch has something to do with automatic reversal if the door hits an obstruction. There is an adjustable overload clutch next to the switch.
 
Half an answer:

Half an answer:

OK, here is part of it. If the moving door hits a solid obstruction, the overload clutch slips. This allows a centrifugal switch to close which jogs the relay to the OFF position. The rotary switch is part of this circuit.

Still don't see any automatic reversal though.
 
That must be a really old one. I had one, probably from the late 70's that I rebuilt a time or two. There are two limit switches on the rail. Loosen the screw and slide them to where you want the door to stop for down and open. I assume you are talking about the spring adjusted clutch on the back of the motor that couples it to the screw. Yes, that has a centrifugal switch contact that senses when the clutch slips and screw stops turning which means the door hit something.

In mine the control was a PC board with a couple of ice cube relays. The door would reverse if it hit something.

Oh, make sure you use the specified aircraft grease on the screw. I tried just about everything else and it had a hard time turning. Had to take the screw and rail apart and wash them in solvent to get it off then use the right stuff.

-Hal
 
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hbiss said:
That must be a really old one. I had one, probably from the late 70's that I rebuilt a time or two. There are two limit switches on the rail. Loosen the screw and slide them to where you want the door to stop for down and open. I assume you are talking about the spring adjusted clutch on the back of the motor that couples it to the screw. Yes, that has a centrifugal switch contact that senses when the clutch slips and screw stops turning which means the door hit something.

In mine the control was a PC board with a couple of ice cube relays. The door would reverse if it hit something.

Oh, make sure you use the specified aircraft grease on the screw. I tried just about everything else and it had a hard time turning. Had to take the screw and rail apart and wash them in solvent to get it off then use the right stuff.

-Hal
Click to expand...

This one is even more ancient. No PC board. Sequencing is done with a stepping relay which was rather expensive I think. Otherwise, it is similar to your description. Not using this one, so I don't need to worry about the lube, but your point is well taken.
 
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