Wiring for the near novice, awesome gift at stake.

December 15, 2020 8:11 PM

My husband and I picked up this awesome clock at a thrift store years ago. but it isn't in working order. He would love for it to work, perhaps you can help?

I originally thought I'd just replace the inner workings with a long arm torque battery kit. That is an option, I have purchased one, but we would lose the cool switches in the back. It is a little hard to see, but it is two black stripped wires coming out the back.Pictures

I have basic wire strippers, tape, and probably even a cord replacement kit for a lamp laying around, but honestly haven't done any wiring in a few years. Any thoughts? If you were going to rewire this guy what would be your concerns?

posted by stormygrey to Technology (7 answers total)

Well, you could just splice up a some lamp wire and a plug and see what happens ...

but something that old I would be concerned about shock hazard. You don't know what is inside that motor housing and it looks to be metal. There could be deteriorated rubber insulation or cracked shellac on the motor winding.
posted by JackFlash at 8:54 PM on December 15, 2020

Best answer: I'd put a new plug on it, wrap any bare wires in electrical tape, and plug it in. In my experience electrical equipment dies quietly a lot more than it dies with sparks and smoke. I have a switched outlet I plug stuff into, step out of the way, and turn it quickly on and off. You can make something like that up with a light switch and an old extension cord, and an electrical box if you feel like being elaborate.
It's possible that it won't work anyway, but I'd say it's worth a try. Lots of thrift stores cut plugs off stuff to reduce their liability, which is a questionable thing to do, because most people aren't going to buy an appliance they can't test, and lots of people don't want to spend the time and money putting on a new plug.
posted by AugustusCrunch at 10:33 PM on December 15, 2020 [1 favorite]

Please, if you try splicing a new plug at least use wire nuts or wago connectors to connect the two pieces.
posted by drezdn at 6:11 AM on December 16, 2020 [1 favorite]

I'd be less concerned about electrical issues and more about the possibility of radioactivity from that white dial.
Glow in the dark dials can still be dangerous decades after they stop giving off any visible glow.
posted by Lanark at 6:12 AM on December 16, 2020

Response by poster: Thanks all, I will break out the tools and try to rewire it after he goes to sleep. The face is a print on kraft paper/cardboard, not the slightly glow in the dark scary radioactive thing. (Which I had in an old fire exit in an old building.)
posted by stormygrey at 7:16 AM on December 16, 2020

Best answer: That's a Hammond clock mechanism - it uses a synchronous mains motor, like the ones used in Hammond organs.

Rod Elliott's site has a pretty good discussion of how they work and the electrical safety concerns from a modern perspective (he's in Australia so the Hammond clock he shows is 240V/50Hz not 120V/60Hz, but the idea is the same). Based on comments about how the coil insulation degrades, I don't think I'd want to power up your clock without rewinding the coil first.
posted by offog at 7:41 AM on December 16, 2020 [2 favorites]

Best answer: I would be very careful in attempting this. I would drill a small hole in the motor housing and tap it for a grounding screw or self-tapping sheet metal screw. Then I would attach a three-prong cord and connect the grounding wire to the screw. Note that you have to twist the starter knob to get the motor running which means touching the metal housing. You don't want to be the short to ground.

I would also get a combination arc-fault/ground fault outlet and plug it into that. The combination outlet will detect a ground fault but will also detect a power fault that could cause a fire that won't trip your panel circuit breaker.

In addition to the risk of crumbled rubber insulation and cracked enamel on the coil winding, you also have the possibility of frozen bearings or gelled lubricants that could cause excess heating in the motor.
posted by JackFlash at 4:39 PM on December 16, 2020 [1 favorite]