I let the magic smoke out of a wire *or* the Magic Door (Linear Actuator, Part 2)

So you might remember that when I put in the linear actuator for the door it had a handy remote that could easily both open and close the door.  Now, as much as the remote controller unit was a black box, its exterior functions were really simple – the two wires for one channel either are pos/neg to open or neg/pos to close, thus sending the 12 VDC through the linear actuator’s motor one way or the other to get the desired result.

And, in understanding that, I had thought that I could just put a DTDP switch in place and be able to electronically open and close the door with the switch.  My thought was that I would use the positive power and ground that the controller was hooked to, and that way, the circuit would connect in parallel to the linear actuator’s wires, but bypass the controller entirely, and all would be good.

It was easy enough to hook up, and after double checking the circuit, I tested it.  The door was closed, and I flipped the switch, and the actuator whirred and the door opened, leaving me happy, until I flipped the switch back and as the door started to close, one of the wires from the controller to the linear actuator let out all its magic smoke as the insulation melted away.  I quickly flipped the switch off and examined the system.  All was as it should have been, the polarity to the linear actuator just being put to the opposite wires.

A quick check on the remote showed that the controller unit was still clicking along with the use of the remote’s buttons, but the wire was fried, and the linear actuator wasn’t working.  As I needed to clean up the bus to move it, I quickly disconnected the switch, cut out the damaged wire and spliced the ends.  The controller clicked but again the actuator didn’t twitch.

I tested the actuator wires by making a circuit to the positive and ground, and the actuator slide the door closed, much to my relief.  And then I decided to test out the second channel of the remote.  I quickly wired it to the actuator (with no additional switch in the circuit), and tested it out with the remote.  Again to my relief, the door opened, and then closed again with the remote.  So the system worked, and I buttoned it all up.

So now I’m left with a DTDP switch, which I think may end up running some lights, a controller board that (I discovered after the fact) needs a new wire soldered to it so the first channel will be usable again, and a quandary about why one wire of the controller shorted the circuit while the other didn’t.  But, the door still works with the remote, which is the important part.

2 thoughts on “I let the magic smoke out of a wire *or* the Magic Door (Linear Actuator, Part 2)”

    1. Yes, it is true. Since the smoke keeps everything running, it’s a real shame to waste it. But that’s why they make new smoke-filled components … 😉

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