Goblin electric clock model 31 Alarm - working of sorts.

[Scotorvm]

Guys, recently acquired a nice Bakelite Goblin alarm clock.
Connected to a Variac and lamp limiter, it actually ran, but after 15mins the coil started to smoke on 230VAC.

The clock actually runs on 140VAC, no smoke but coil still 80 degrees under the thermal imager.

Windings are almost 1.2kohm, I think this works out at 44watts which is why the coil is so hot.

Would any member be able to rewind (obviously for payment) or know where I can have this work carried out?

Or is it easy enough to try and do. I can't locate a great deal of info so have know idea what the winding resistance should be.

There are no other electric components in this clock, live and neutral just go straight to the coil.

Thanks.

[Nickthedentist]

10k ohms and a couple of watts is more typical.

You can rewind the coil with thicker wire very easily, then power it from a low voltage AC supply.

Mike Barker or Ed Dinning are the rewinding experts here.

That is lovely, the low voltage fewer turns approach is the best way to go, more copper less insulation, better coil. That coil does look very cooked.

[Scotorvm]

Originally Posted by Nickthedentist

10k ohms and a couple of watts is more typical.

You can rewind the coil with thicker wire very easily, then power it from a low voltage AC supply.

Mike Barker or Ed Dinning are the rewinding experts here.

Thanks Nick.

I have 0.32mm enamelled copper wire, would this be suitable and how many turns would be required, I have never re-wound a coil so

I have a 9VAC PSU, would that be suitable?

Cheers
Lee

[Scotorvm]

Originally Posted by merlinmaxwell

That is lovely, the low voltage fewer turns approach is the best way to go, more copper less insulation, better coil. That coil does look very cooked.

Thanks merlinmaxwell, just trying to work out how many turns of thicker wire to do? I have 0.32mm enamelled wire, do I just wind it on to fill the spool to a similar capacity as the original?

Cheers
Lee

Fill the spool, then find out how many volts it needs to run and add 50% for luck. At a vague guess I would say 0.32mm filled would be 12V or so.

[Scotorvm]

Originally Posted by merlinmaxwell

Fill the spool, then find out how many volts it needs to run and add 50% for luck. At a vague guess I would say 0.32mm filled would be 12V or so.

Thank you, I will give this a try, fingers crossed.

[FIXITNOW]

Try these two sites.

Basic repair:-

https://www.teasmade.uk/clock-faults-and-repair/

Rewinding for low voltage:-

https://sound-au.com/clocks/ocm.html

[Scotorvm]

Originally Posted by FIXITNOW

Try these two sites.

Basic repair:-

https://www.teasmade.uk/clock-faults-and-repair/

Rewinding for low voltage:-

https://sound-au.com/clocks/ocm.html

This is ideal Fixitnow, great info, thanks.

[Mike Phelan]

Originally Posted by Scotorvm

This is ideal Fixitnow, great info, thanks.

Good to see that someone read my article!

[ex 2 Base]

Hello Mike, I showed my wife your article on "teasmade" and she couldn't believe what she read, an excellent detailed informative read. I wish I had located it before as I've fixed a couple in the past. Both needed a good clean up and away they went. ted

[Scotorvm]

Originally Posted by Mike Phelan

It's a great article Mike

[Scotorvm]

Just an update on this.

All old copper removed from the coil and rewound using a paint brush with the spool wedged onto the shaft, the shaft inserted into a battery variable speed drill which was held in a vice, a cable tie around the trigger just nipped to give the speed I was happy with, spool of 0.32mm wire on a screwdriver, just let it go until the spool was full.

The ohms measurement was 8.5.

Connected to the Variac, set at 16VAC and it worked perfectly.

So ordered a 16VAC plug in adapter, now this measured 20VAC, I assume as no load, but when connected to the clock it ran noisily and didn't work well at all, so not sure what was wrong, possibly the load is so small..??

Have ordered a 9VAC and 12VAC adapter to see if these are any better.

While the clock was running happily and quietly on the Variac at 16VAC, I connected my meter across the power connections at the clock, measured 4.5VAC

Any thoughts on this appreciated.

Thanks.
Lee

[Mike Phelan]

Probably the lack of load.

Better to have one of our members to wind the coil to 240v, Lee.

[Scotorvm]

Originally Posted by Mike Phelan

Probably the lack of load.

Better to have one of our members to wind the coil to 240v, Lee.

Thanks Mike.

Have this actually working fine now on a 9VAC supply, I have added 2 x 100mA fuses inside the clock, just need an enclosure to house the board.

Does anyone know how the alarm works? All I know is that when I turn the day / night dial a plunger pops up at 3 on the day side. The button on top of the clock when pushed depresses the plunger!

I can't see what would make an alarm noise

Thanks
Lee

[Brigham]

Originally Posted by Guest

That is lovely, the low voltage fewer turns approach is the best way to go...

NO IT ISN'T.

Can a 'sticky' warning be put on the site somewhere, refuting the falsehoods on that scare-mongering site, before all original synchronous clocks are either destroyed or turned into something else?
That fellow's a fanatic, and people need to be warned.

[Scotorvm]

Originally Posted by Brigham

NO IT ISN'T.

Can a 'sticky' warning be put on the site somewhere, refuting the falsehoods on that scare-mongering site, before all original synchronous clocks are either destroyed or turned into something else?
That fellow's a fanatic, and people need to be warned.

With respect, the work carried out on this clock is reversible. Before, the clock was smoking when plugged in..

[Brigham]

The request was made as a response to the wholesale condemnation of historic synchronous clocks IN GENERAL, and not to any specific example listed here.

The fellow starts his rant with:

"Making Old Synchronous Clocks Safe to Use"

As if they are somehow intrinsically NOT.
This isn't, in my view, an opinion which should go unchallenged.

[Station X]

You've both made your points for members to read and consider.

Thread closed. The OP can ask for it to be reopened if he needs further help.