Electric clock repair/service...

[Growler]

Hello,

I have a Smiths bakelite electric clock - I think from the 1950s - that has recently stopped working. I have tried to find somewhere to service or overhaul the clock but without success. I wondered if anyone in this forum might be able to point me in the right direction?

[Darren-UK]

Hi,

Assuming it is indeed 1950's it probably uses the 'Bijou' type movement. The field coil on these is notoriously prone to failure (open circuit). The simple answer is to find another battered old clock and salvage the coil from that. The nightmarish answer is to have the coil rewound (expensive and difficult with 48SWG wire).

If you have and can use a multimeter it takes two seconds to check the field coil; all you need do is check for resistance across the mains plug pins. Check the plug fuse hasn't failed too; the fuse should be no more than 3A by the way - 1A is more ideal but these aren't that easy to get nowadays unless via mail order.

The problem may not, of course, be the field coil but that's the most likely cause. If the coil is still ok, plug it in and you should be able to hear and/or feel a weak buzz coming from the movement. If you can, the trouble will be elsewhere. Dirt, gummed up oil etc.

The Bijou movement is normally (there are rare exceptions) in a pear-shaped black bakelite capsule usually mounted inverted. If unsure, post a picture and anyone who may be able to help will know for sure what they're dealing with.

[Growler]

Apologies for the long delay in responding - a couple of weeks camping in rainy Devon!

Thanks for your reply Darren. At this point I have to own up to not knowing for certain what a multimeter is, let alone how to use one! So now you know the extent of my technical ignorance, I'm attaching a few pictures of the clock; front, back and the movement. I was hoping that someone of the site might know of somewhere that fixes, restores or services these types of electric clocks. (I also have a battery-powered electric wall clock from the early 70s which has given up the ghost too, but it appears that regular/mechanical clock repairers don't want to know about electric movements).

Any additional advice appreciated!

[Station X]

This should do the job:-

http://www.maplin.co.uk/Module.aspx?ModuleNo=37279

Set it to the 200 ohm range. Plug in the leads and WITH THE CLOCK UNPLUGGED FROM THE MAINS, touch the test probes on the two brass screws where the mains lead terminates. If you measure infinite resistance (open circuit) then the movement is faulty.

If the coil is O/C it can be easily rewound with thicker wire and run off a small transformer or capacitive dropper. Getting the old winding off is best done with a knife, cutting through the windings. I did this for a Teasmade for the inlaws, worked well until I was told 'you where supposed to say it's unfixable', I still have the transformer.

[Darren-UK]

What you have is the more common version of the 'Croleigh' model (sometimes spelt 'Crowleigh') which dates from 1950 and was initially sold with a horrid little 30 hour timepiece-only mechanical movement.

The movement in yours is indeed the Bijou, or rather a cheapened-up version of it. The trouble with this movement is that the field coil was wound with 48SWG wire and is very prone to going o/c. They last only for 50-60 years; very poor indeed when compared to other synchronous movements.

As MM suggests, rewinding with 48 gauge wire is a near-impossible nightmare but rewinding with a heavier gauge wire is possible. You may, bear this in mind, need to compensate with the addition of a series resistor.

Sometimes, however, the break in the winding is at or very near to the terminals. If this turns out to be the case you can remove a couple of turns to be rid of the break without the need to do anything else. Unfortunately Sods Law usually applies and the break is deep within the winding, but you never know and may be lucky.

Quite frankly clocks using this movement remain very common and the simplest solution is to obtain another and swap the coil or entire movement but, of course, the risk remains of further failures. If you saw one for sale somewhere you also have to overcome the "It's Bakelite, you know" brigade but tatty woodies with this movement also turn up.

I would recommend obtaining the meter as per Graham's suggestion regardless of what course you follow. They're most frightfully useful things to have and they're very easy to learn the usage of. They also fit neatly in a pocket, so should you see another clock for sale somewhere you can test its coil there and then - via the mains plug if still fitted or via the cable stub-end if it's been cut off. That's what I do and if the vendor is awkward about it then he/she doesn't get a sale, simple as that.

As you've discovered, clock repairers won't touch these things. This is partly because they poo-poo them, partly because they probably lack electrical knowledge, partly because replacement parts aren't available new. The PAT testing twaddle most likely comes into the equation too.

Anyway, have a think about what you want to do. I can send you another coil for you to fit but remember that the same coil type means potential for the same problem to recur.

Hope that helps anyway.

[Growler]

Thank you very much for taking the time to respond to my question - it's very much appreciated. I'll invest in a multimeter as you suggest and see how things pan out from there. It sounds as if swapping the coil or the entire movement may be my best option; the idea of rewinding with a different gauge of wire sounds a step too far for me! Darren thanks in particular for the offer to send a coil - I'll see how I get on and let you know.

[M0FYA Andy]

Have a look at this site - http://sound.westhost.com/clocks/ocm.html
(I have no connections whatsoever with the site or author)
I have a number of synchronous motor clocks with o/c motors, and have seriously thought of rewinding them for low voltage operation as more feasible than rewinding for mains. On current project planning this might happen in the next couple of centuries!
Andy

[julie_m]

That motor looks a lot like the ones you find in central heating 3-way valves, which are 12-pole synchronous motors (500 rpm @ 50Hz). Should cost less than a tenner from any plumber's merchant; might be worth a try?