Fixing a broken pendulum/motor assembly with a CDM12.4 platter

[Mooly]

I managed to acquire an old quartz pendulum clock that had a non functional swinging pendulum... now this is the first time I've ever seen one of these things internally and it seemed to be missing some kind of metal or magnetic insert on the arm itself.

Time to get creative and see if I could cobble something together. Small magnets, so earbuds came to mind but they looked much to small and the magnet would need to be extracted somehow.

CD pickups have powerful magnets in them to drive the motor coils and that was certainly a possibility. I also had a couple of old CDM12 type platters and thought about using the magnet from one of these. I snipped around the platter with wire cutters and managed to wedge the remains into the slot on the pendulum and unbelievably it worked on a quick test.

To neaten it up a bit I managed to get the magnet out cleanly and then placing it on a pad of suitable height to bring it near the actuator coil I epoxied it into place. All good, the pendulum has a good amplitude and the average current draw seems to be around 400uA when averaged out on the AVO 8.

YouTube Repaired Pendulum Motor

[Graham G3ZVT]

I have a small grandfather (granddaughter?) style clock that's been standing on a landing for thirty years. Quite early on I made two changes, the original movement was one of those pre-quartz ones with a balance wheel and a transistor. It was very inaccurate so I swapped out the movement for a Quartz type.
The pendulum kept stopping, I think it worked with a pair of contacts that needed to be scrupulously clean. As you can see, my solution was to blu tack a dry reed-switch in a strategic position in the influence of the magnet armature, and has since worked reliably.

[Mooly]

That's cool. A little ingenuity goes a long way sometimes.

I remember the balance wheel type clocks, as a youngster I had one of those Bush Nightingale clock radios which tbh ran for many many years before the really heavy balance wore the bearings out.

[mike_newcomb]

Hi, I recently repaired a Wall-clock with a that quartz movement that frequently stopped.

Just replaced the movement complete as found exactly the same movement on ebay for 99p including postage from China.

Also I have a friend with a very nice Pendulum Wall-clock where the Pendulum does not work. It is the 50 year service award for her now deceased Husband. As these movements are also available I suggested it might be possible to do same for hers - awaiting decision.

Regards - Mike

[Robsradio]

Originally Posted by Mooly

That's cool. A little ingenuity goes a long way sometimes.

I remember the balance wheel type clocks, as a youngster I had one of those Bush Nightingale clock radios which tbh ran for many many years before the really heavy balance wore the bearings out.

I still have one of those clock radios, bought a few years ago but the clock didn’t work, serviced it and it’s been going a treat ever since.

[Mooly]

Eeee, now that brings back memories.

Good to know yours is working OK... and long may it do so. I also remember those yellow/gold so called 'clock batteries' from Eveready. C11 I think was the designation.

[Robsradio]

Originally Posted by Mooly

Eeee, now that brings back memories.

Good to know yours is working OK... and long may it do so. I also remember those yellow/gold so called 'clock batteries' from Eveready. C11 I think was the designation.

I remember the battery, you’re correct, it was the C11 for transistor clocks, I remember as a kid in the 70s being given the old batteries from the Smiths (tuning fork) wall clocks at school. I think they were changed before they had expired, and the caretaker knowing that I tinkered with batteries etc. gave them to me to totally expire them with a bulb probably!
Good memories

[Mooly]

Yes, bulbs and batteries... its how we all started... and look where we all ended up