Electric Clock Help

Discuss clock projects, repair techniques; exchange tips and advice.

Electric Clock Help

New postby Geoff_O » Tue Apr 14, 2015 1:31 am

Hi All,
I normally work on pocket watches, so this one is a bit new to me. My parents were helping a neighbour clean out their shed, and they were going to throw out an old art deco electric clock that wasnt working. Anyway, they have asked me to see if I can get it working.
I have taken a photo showing the movement, and will take a picture of the front tonight when I get home from work.
The clock plugs into mains power, and you flick and release the spring loaded lever on the back to start spinning the notched "balance" wheel at the centre of the movement. I assume the alternating mains current flowing through the coil induces a magnetic current that keeps the 'notched balance wheel' rotating.
This notched wheel spins freely, but the movement is dirty and will be cleaned.
Can anybody help with any information on this type of clock? What commonly goes wrong with them? With the mains power running through it, is it safe?
Any help would be greatly appreciated.
Thanks
Geoff

Clock.jpg
Last edited by Glyn Meredith on Tue Apr 14, 2015 8:04 am, edited 1 time in total.
Reason: Pic placed inline.
Geoff Osborne
Geoff_O
Member
 
Posts: 33
Joined: Tue Mar 10, 2009 1:12 am
Location: Adelaide, South Australia

Re: Electric Clock Help

New postby cannon pinion » Tue Apr 14, 2015 2:05 am

It looks to have been newly rewired. Take an ohmeter and make a step by step check of continuity, starting at one leg of the plug to the soldered lug where the cord meets the brass bar. Oftentimes I find in repairing old electrical appliances that the power cord is the culprit.
Once you are sure both legs of the cord are good, continue checking continuity thru the circuit. Check the coil resistance - you should have two windings, tho how the terminals will be set up is different depending on application. You should get two sets of resistance readings. An open reading means the coil is burnt out. You do all this with the clock UNPLUGGED, of course.
I doubt that the clock works on a magnetic flux - tho it might. It's hard to tell from the photo, but is there not a conventional motor in there somewhere, with the coil being a stepdown transformer to a low voltage DC?
Setting up a fluctuating magnetic field would require a precisely timed make break switch like the points ignition in the old automotive distributors.
Hope this helps, and post a few more snaps.
Andrew Yale
cannon pinion
Super Member
 
Posts: 643
Joined: Mon Dec 30, 2013 1:22 am
Location: Jersey City, NJ

Re: Electric Clock Help

New postby cannon pinion » Tue Apr 14, 2015 2:07 am

On closer look, it seems your right hand lead is severed or partly severed just prior to where it's soldered to the bar.
Andrew Yale
cannon pinion
Super Member
 
Posts: 643
Joined: Mon Dec 30, 2013 1:22 am
Location: Jersey City, NJ

Re: Electric Clock Help

New postby Geoff_O » Tue Apr 14, 2015 2:15 am

Hi Andrew, Thanks for the help. I'll try to test the continuity through it tonight, you're right, the wiring of the lead does look suspect. Hopefully it is just a matter or cleaning and resoldering the lead.
I'll take some more photos tonight and post them, I'm curious to nut out how it works.
Cheers
Geoff
Geoff Osborne
Geoff_O
Member
 
Posts: 33
Joined: Tue Mar 10, 2009 1:12 am
Location: Adelaide, South Australia

Re: Electric Clock Help

New postby Geoff_O » Wed Apr 15, 2015 12:43 am

Ok, here is a photo of the front of the clock, you can thank my daughters for the Frozen placemat background!!
I reckon with a bit of a polish this would look pretty cool, though my wife thinks it looks horrible!! :D

Clock1.jpg
Last edited by Glyn Meredith on Thu Apr 16, 2015 11:16 am, edited 1 time in total.
Reason: Pic placed inline.
Geoff Osborne
Geoff_O
Member
 
Posts: 33
Joined: Tue Mar 10, 2009 1:12 am
Location: Adelaide, South Australia

Re: Electric Clock Help

New postby Geoff_O » Wed Apr 15, 2015 1:13 am

Anyway, I sat down last night to have a closer look at the movement on this one, Andrew you were spot on, there wasn't any continuity across the coil. Once I had the movement out, it was clean that there had baan an attempted repair to one end of the coil which appeared to be coated with glue from a hot glue gun. I removed the glue and found a bakelite core with a copper coil wound around it and a number of steel plates fed through it bolted at either end. I assume this induces a magnitic field from the AC current which keept the notched wheel turning.

Anyway, at one end of the coil was a terminal and at the other end the bakelite with the terminal has broken away (I assume the clock has been dropped or the cable has been pulled) see attached photo.

I tried to solder the lead directly to the coil and tape it up with electrical tape, but I could not get connectivity so I have accepted defeat. Unless someone has another suggestion, I will just have to try and keep my eye out for a possible donor clock with a coil.

Clock3.jpg
Last edited by Glyn Meredith on Thu Apr 16, 2015 11:16 am, edited 1 time in total.
Reason: Pic placed inline.
Geoff Osborne
Geoff_O
Member
 
Posts: 33
Joined: Tue Mar 10, 2009 1:12 am
Location: Adelaide, South Australia

Re: Electric Clock Help

New postby Geoff_O » Wed Apr 15, 2015 1:13 am

Closer photo of the movement.

Clock2.jpg
Last edited by Glyn Meredith on Thu Apr 16, 2015 11:17 am, edited 1 time in total.
Reason: Pic placed inline.
Geoff Osborne
Geoff_O
Member
 
Posts: 33
Joined: Tue Mar 10, 2009 1:12 am
Location: Adelaide, South Australia

Re: Electric Clock Help

New postby cannon pinion » Wed Apr 15, 2015 2:54 am

You should be able to take the old coil to a good electrical supply house and get it specked out and some equivalent found. They are fairly standard. And simple.
I still dont understand how the clock works, unless the center wheel is magnetized. Is there an escapement in the movement?
Andrew Yale
cannon pinion
Super Member
 
Posts: 643
Joined: Mon Dec 30, 2013 1:22 am
Location: Jersey City, NJ

Re: Electric Clock Help

New postby cannon pinion » Wed Apr 15, 2015 3:01 am

One more idea - take a close look at the one intact terminal and see what connects to it. The coil has 2 windings - one of thick wire, one of thin. Determine which wire is attached at the terminal. My guess is it is the thicker wire. Then very carefully, get some of the matching wire out on the broken side. It's allright to unwind it a little , just dont bust it. Strip an end and wrap it around a small screw, between two washer, bolts on either side of the washers. Solder the whole assemblage, and see what you get. Or some variant thereof.
Andrew Yale
cannon pinion
Super Member
 
Posts: 643
Joined: Mon Dec 30, 2013 1:22 am
Location: Jersey City, NJ

Re: Electric Clock Help

New postby 4brokenow » Wed Apr 15, 2015 11:35 am

Geoff,

The enamel wire should be easily soldered back to the cord. You have to clean it good with sand-paper on the end. Strip the cord and twist the two bare clean copper ends together. Use a good soldering iron and some 60/40 rosin core and you should have it. Tape up the solder splice and tape up the coil again. Andrew is right, a few turns off won't hurt. Just keep in mind the shorter the coil the hotter the coil gets. You don't want to create a fire hazard. You also don't want to use a coil that has been already overheated. If the enamel wire has it's enamel flaking off or looks burned, throw it in the garbage unless you want to rewind it or pay someone to rewind it.

That is a "synchronous" clock. The coil should be a single winding. The core (laminations) thansfer the field to the rotor where a counter-field is induced and this keeps the rotor going. You have to get it started with the lever.
Phil Rickert
User avatar
4brokenow
Super Member
 
Posts: 723
Joined: Thu Apr 30, 2009 10:33 pm
Location: De Pere, Wisconsin
NAWCC #: 170509

Re: Electric Clock Help

New postby cannon pinion » Wed Apr 15, 2015 10:06 pm

Phil - can you explain the workings of this syncronous clock in more detail? I get the induced field in the center wheel, but does the center wheel drive a typical escapement movement?
Andrew Yale
cannon pinion
Super Member
 
Posts: 643
Joined: Mon Dec 30, 2013 1:22 am
Location: Jersey City, NJ

Re: Electric Clock Help

New postby 4brokenow » Wed Apr 15, 2015 11:09 pm

Andrew,

Unless I'm mistaken with this style clock...the motor drives a gear box that connects to the Hour and minute hand and that's that. The gear box ratio is solely dependent on the utility company keeping the freq. at 60Hz. or 50hz.

The overall average frequency is managed by computers these days so it may be a little fast one day and a little slow the next, the overall average is pretty exacting though. So your synchronous clocks should keep pretty good time these days.

Early synchronous clocks were not self starting as this one looks to be that style. Later ones they figured out how to design the stator (dual winding) and rotor so they would self start. I believe this is similar to a shaded pole brushless fan motor that are widely used in all household fans.

I see the condition of that coil on my big screen now and personally I would not use it. The end of it looks like a dog chewed on it. Trying to fix it may facilitate the unintended construction of an incendiary device.

I've actually had success rewinding a rotor out of a obscure synchronous clock. I applied the enamel over the wound coil and insulated and secured with Kapton tape. It was more of an experiment just to see if I could do it.
Phil Rickert
User avatar
4brokenow
Super Member
 
Posts: 723
Joined: Thu Apr 30, 2009 10:33 pm
Location: De Pere, Wisconsin
NAWCC #: 170509

Re: Electric Clock Help

New postby cannon pinion » Thu Apr 16, 2015 2:05 am

Thanks, I get it now. I've only worked on one electric clock. And it had a conventional motor.
Do you think he can find a replacement coil?
Andrew Yale
cannon pinion
Super Member
 
Posts: 643
Joined: Mon Dec 30, 2013 1:22 am
Location: Jersey City, NJ

Re: Electric Clock Help

New postby Geoff_O » Thu Apr 16, 2015 7:22 am

Hi Phil,
You are right, I think this coil is beyond saving, the bakelite core is broken off at the end and the wire winding at the end is starting to unwind, is broken in a couple of places and will become a tangled mess if I am not careful. Unfortunately with the broken bekelite centre, I dont think I'll even be able to rewind the coil.
I'm not sure if I'll be able to find another coil, as it appears to be specifically sized to fit a number of steel flat bars through its centre.
Also, yes, the notched wheel spins and turns the clock works that drives the hands, no 'escapement' as such.
This one will have to be an ornament at my parents house until I can find a suitable coil.
Thanks again guys.
Geoff Osborne
Geoff_O
Member
 
Posts: 33
Joined: Tue Mar 10, 2009 1:12 am
Location: Adelaide, South Australia

Re: Electric Clock Help

New postby Stephan » Tue Aug 01, 2017 7:26 am

I would try to make up a plastic washer to slide over the end and keep the wires in position.
Easy enough to file a square hole in it.
A bit of plastic from an ice cream container or some other hard plastic box.
Make the outer diameter bigger than you need so you can put a small hole on the outer edge to take a brass screw and nut.
Run the coil wire to that screw to anchor it.
Remove the rest that is not needed.

It will not matter if you loose a couple of turns of wire. As long as you find a good end to connect to.
Learning all the time.
Stephan Gaal

Proud Member of Global Horology and Chapter 149
User avatar
Stephan
Super Member
 
Posts: 3255
Joined: Sun Jan 20, 2008 7:10 am
Location: Melbourne, Australia
Skype Account: stephan.gaal


Return to Clock Repairs - projects, techniques and tips

Who is online

Users browsing this forum: No registered users and 2 guests