Pul-syn-etic clock - advice on repair

[ian richardson]

I have acquired this clock via an auction, with no instruction manual. There is nothing to indicate the age of the clock and it does not bear a makers mark on the dial. It appears to be a master clock for a slave clock factory system. At the moment it does not run. It has a fluorescent tube around the dial and is approx 15 -16" in diameter. I have been able to light the fluorescent tube using main voltage (as I am in the UK our system runs using 240v supply), but I have been loath to introduce this voltage to the clock mechanism as I am concerned about burning out any of the components. However, on introducing a 12v supply to the clock contact, one pulse occurs causing the yellow contact shown in picture 4 to close, but nothing else. This is my first repair on an Electronic clock like this, and I wonder if anyone can advise me what to do next,or whether it is worth trying the higher voltage.

 

[Uhralt]

Reading the instructions in your first picture it seems to me that this is a slave clock, not the master. The voltage of the time train depends on how many slaves are connected in series. You need an ampere meter to find the correct voltage. The master would be the "time transmitter" mentioned in the instructions.
Uhralt

 

[shutterbug]

It appears that it is designed to run at 24VDC, which is common for American master clocks. Since it impulsed when you applied low voltage, that part must be working. It looks like it MIGHT be a master clock, but if so, the motor needs to run, and that part appears to require 210 VAC. So the clock motor will run, and send a signal to the the DC circuit every minute.
Does the motor move or hum when you apply power to it?

 

[bangster]

I'm moving this to Electric Horology

bangster
moderator

 

[ian richardson]

Thank you folks, so it looks like it could be a slave clock, which now having just looked further afield seems right. The master clocks all seem to look like long case clocks. Does anyone have any idea whether t can be used on it's own.

 

[rogerj]

never seen one like that ! As you are in UK and the clock is Gents the time loop will be for standard Implulse dials (every 30 seconds) current as per your photo.

That current would have to come from a separate source and the vloltage would depend on how many dials were in the loop in addition to the solenoid marked 18R - which must impulse the hands of your clock..
If the solenoid is 18ohms then that will require about 7.5 volts...Plus about 1.5 volts for every additional slave dial..
The master clock function appears to be provided by the 240V synchrous motor and an associated contact.
So if you apply 240v mains to both the input connectors does it motor around (slowly!)
Any additional dials would be wired in series..These series circuits are usually powered by a battery system of some convenienent voltage and the current in the loop adjusted with a variable resistor.If my guesses are correct then a 12 volt DC supply, with about 10 ohms included series would be a starting point to test the clock with no additional dials..IE Connect a 12volt DC power suply (or battery) with a 10 ohm resistor in one lead to the "Time Circuit" connector..
BTW I've just looked at the Gents story (A Conspectus of Clocks and Time Related Products Produced By Gent & Co Leicester) and can't find any reference to this type of clock..
Gents Pulse-Syn- Etic clock loops were usually driven by a C7 master clock....Roger

 

[ian richardson]

Thank you Roger, I will have a go at what you suggest tomorrow.

 

[Edwardo]

The ac motor is used to run the seconds hand which will stop at 00
when the clock receives a pulse on the minute from the master clock the second hand will
start again
these clocks were built mostly to run on the European train systems and not a standard Gents line

Apply 3vdc to the "time circuit" connections will advance the minute hand

Apply 240vac to the "Time" connections to make the seconds hand run to 00 position

Closing the switch under the plastic safety cover (MAINS VOLTAGE!!) will make the second hand start another revolution
Hope this helps

 

[rogerj]

Ah well..Looks like Edwardo has cracked it ! My guesses are all rubbish...And I couldn't even get ohms law right I would need 3.6 volts to push 0.2 amp through the solenoid, not 7.5V
By what means is the sync. motor stopped ? Is it permanently powered, but "jammed" at 00 by a catch of some sort ?
All external slaves would be pulsed every minute ....not 30 seconds ?

 

[Edwardo]

As I mentioned above this is not a standard Gents clock
It locks like a low production unit, built to comply with an existing system

I haven't worked on this exact model before but I would say it was a 30 seconds movement and operated in a similar way to some European station clocks.

The way they work is as follows;
The motor and its gears runs a bit faster than 1rpm
On the minute the red disk on the ratchet wheel lifts the switch which starts the motor
There should be a 2nd switch that closes before the next 30 second pulse which keeps the motor running
On that next pulse the top switch opens but the motor still runs through the 2nd switch
The 2nd switch opens at 00 position and the second hand waits for the motor to start again on the next pulse from the master clock
Remember the motor runs a bit fast

RE the correct voltage for the slave

After looking at you photos again I noticed the slave coil has 18k written on it
This may be because of the voltage used by their system and it probably wont work on 3v


Normal gent slaves where 4 ohm and need just under a volt to drive them
However from experience, old unserviced slaves often need a few volt more to get them moving
It is perfectly safe to test a 4 ohm slave on 9v for a very short while. We used to carry around a 9v batter in are toolbox for that purpose

NB I wouldn't trust the information written on the large round label
They stuck these on everything towards the end, even mains powered clocks!

I would be interested to see this clock in pieces if you choose to dismantle it

regard
Edd

 

[rogerj]

I read the solenoid as 18R thinking 18K was very high for a wound solenoid..I could easily be wrong about that as well...

 

[Edwardo]

18 ohms is a standard medium duty coil for Gents
approx. 4 Volts at .22a
You can safely test it at up to 12vdc for a few seconds at a time without any damage
or if you put a 100ohm 5w resistor in series you can run it at 12v permanently