Mains clock running fast

[MattyF]

We have a clock that has a synchronous motor that is intended to run on 50Hz

mains. It skips 5 or 10 minutes fast sometimes. I looked up this problem and

was advised that noise on the power supply could cause the clock to be wrong

(but only by a tiny amount). Before I taking the clock apart, I decided to

plug my power measuring device in to the power point, and got a reading of 158

volts and 32 Hz. It is supposed to be 237 v and 50 Hz!

Since the clock had been plugged into the power point for over 30 years I

pushed the plug in and out a few times and got the correct readings. I think

there was corrosion in the contacts.

However the clock still keeps skipping ahead. The minute hand keeps in step

with the hour hand so I don't think the hands are slipping.

The clock has earlier had an accident where it fell off the wall 3 metres onto

to a concrete floor. The adjustment spindle at the bottom broke off, so I made

a new part on the huge lathe out of a 1/4'" bolt turned down to 1/16" on the

lathe. I am amazed that it didn't break!

I now suspect that a cog in the clockwork is skipping teeth. So that is next

weekend''s job, unless anyone has brilliant suggestions. I think I need a

lathe 100 times smaller now that I seem to be fixing so many clocks.

I have uploaded pictures of all this but they seem to have vanished. I cannot

see where to put my user name and password. So this probably won't work!

[MattyF]

These are the pictures that have already gone somewhere else.

[Martin Brown]

Usually such clocks keep very good time long term although they can be

very slightly slow in the evening and fast in the early morning as mains

50Hz is guaranteed as a long term average but is load dependant.

I suggest you throw away your power tester then.

Anything outside of 50+/-1Hz and 230+/-15 would be very unusual.

Skipping ahead is unusual. Can you tell if it happens when the minute

(and/or hour) hand is on its way down the face? ie gravity assisted.

The bump might well have taken something out of alignment or chipped a

tooth. Whenever I have had trouble with synchronous motor clocks it has

been running slow or stopping because of worn teeth on the gears.

[Dave Plowman (News)]

Might it be easier to simply replace the guts with a battery quartz

movement? Unless rare and expensive - if such a synchronous clock exists.

[Brian Gaff (Sofa 2)]

My advice is to ditch Home owner club and use a real usenet client and use

Dropbox for your pictures and paste the public link in with the trailing 0

set to a 1.

I won't see it, but most will, and many people here won't reply to Home

owners club Usenet exported messages due to their portal software being

basically crappy.

I would say about your clock yes well clocks do wear out and missing or worn

teeth are a fact of life. Another common one is they suddenly start going

backwards, due to the motor stalling due to damaged gears and then starting

up the wrong way. The little ratchet kicker that normally stops this does

have a habit of not working if its been in a greasy kitchen for a few years.

Why not treat yourself to a nice radio controlled clock?

Brian

[Brian Gaff (Sofa 2)]

One thing I would also check is the actual wire fixings in the point its

plugged into. I've had funny things going on on clock points in the past

with daft measurements, and the wires under the screws on one half or the

other had worked loose and since there was not much current, the arcing did

not weld it together or set fire to the house!

Brian

[Robert]

I quite like the synchronous electric clocks, usually in Bakelite and

really not expensive for a "collectible" but useful item.

They can be a pain to get restarted though, not sure if this is down to

sticky oil or grease on the gears ?

I usually earth them when rewiring.

[Dave Plowman (News)]

All I remember of them was they usually got noisy with age. And not a

pleasant noise.

Do have a couple of mains clocks here - but they're LED. One in the

bedroom - large digits so easy to read even at my ripe old age.

[newshound]

Or throw the whole thing away and replace it with a radio controlled

one? I picked up one in a CPC sale several years ago and IIRC it's only

needed a couple of battery replacements since. Saves faffing around at

clock change time.

[Robin]

That could rather go against the spirit of the owners, especially if -

as I thought probable - the clock is at MOTAT.

[tabbypurr]

A bad contact would explain the low v reading, but 32hz means your tester is basically junk, at least as far as measuring f goes.

I've had a simlar experience with a 1970s quartz clock, very puzzling. No idea what's causing your problem.

Most regulars here have the website you're using blocked. Google groups is vastly better, much as it gets criticised. And re pic uploads, please use anything other than dripbox, it's so awful I frequently just don't bother to look.

NT

[Vir Campestris]

Yes, you ought to have a Congreve Rolling Ball clock... that would be a

project!

Welcome back Matty - but please ditch HoH!

Andy

[Bob Eager]

I first found out about them in a Nevil Shute book - Trustee from the

Toolroom I think. Always wanted one.

Very inaccurate, though!

[Steve Walker]

I read that many years ago. I must see if I can get hold of it again.

My bodged together, much simplified version at school came third in the

class for accuracy ... not that any of them were accurate :)

SteveW

[MattyF]

I think the clock has suffered from its fall. The second hand appears to be

loose and may sometimes be touching the other hands (but never when I am

watching it). If I can't fix it easily someone can buy a new clock. But it is

a nice clock.

I have recently fixed the clock outside by the tram stop. It needs to be wound

every 7 days. It was stopping because of rust on the two mainsprings. That was

probably why the other two clocks stopped working.

I found Tim's message on HomeOwnersHub, and this seems easier than Usenet that

died on me 5 years ago.

[Tim+]

Hi Matty, great to see you back here. We new more real DIY and less politics here!

Regarding HOH, it really is an abomination. It only exists to generate income for the site owner, not to provide a useful service. There are so many things wrong with it I'm not sure where to start.

If you don't want to use a dedicated usenet client, google groups is better than HOH, but a proper newsreader is the best option. I believe Thunderbird is supposed to be okay. Plenty of free news servers like Eternal September if you don't want to pay. Anyway, here's the link to this thread in google groups.

Many thanks for the tour earlier this week! I love places like MOTAT and it's always interesting to put a face to a name on the internet. Currently in Rotorua.

Tim

[Tim+]

Any possibility that there could be enough sub-50Hz noise in the power supply to the clock to cause a spurious reading (and to upset a synchronous clock)?

Tim

[tabbypurr]

if all else fails a new large hands mechanism could run it.

bad decision. This is usenet anyway.

NT