Clock Repair Archive - -     Telechron:

This is a type of electric clock that, in most cases, works on 110 volt 60 cycle electric current. There are quite a number of different types of Telechron electric clocks but only a few will be discussed in depth here. The 2 most common problems with the telechrons are the rotors (including the coil) and the actual mechanical part of the clock. It has been my experience that if the coil is bad, it is usually because of a power surge, improper handling, or just plain age.

Rotors that have a flat side on the shaft, but no replacement listed, can often be replaced by those with no flat side if the rpm rating, the size, the direction of rotation ( ccw for counter clock wise and c for clockwise ), and the diameter of the shaft are the same. If the only difference is the flat side on the shaft then either rotor will work. Of course you must file a flat side if all you can get is one with a round shaft. Always check the power cord; if it is worn anywhere replace it. Be very careful where the cord enters the coil it will break very easily. When the sequence is set(generally done after you have finished the bushing replacement and check the pivots for fit)as you reassemble the mechanism, be sure that the trip pins on the centerpost are at the hour position. The hour position is where the minute hand is exacty at the 12 and the mechanism is ready to strike the hour this will be determined by where the rest of the gear train is set with respect to the hammer lift assembly. If this is not done, the chime and strike will not release at the correct time and the gear train will bind up or the tempo of the chime-vs-strike will not sound pleasant. The hour strike will start too soon after the last note of the chime.

It is normal for the coil to heat up slightly however, it should not get too hot to touch, if it does, something is wrong. More than likely the coil is shorted. This can be a fire hazard so be careful and be sure to check coils out carefully. Some alternating current hum is normal however it shouldn't be too noticeable. Sometimes the rotors are noisy; it is gear noise that causes this. Don't confuse this with hum. Sometimes there will be both hum and gear noise. As of 1997, replacement rotors were available from most clock repair supply houses however, these rotors are becoming much harder to find. As of the writing of this journal some of them are no longer available. The serial number will usually be the letter M followed by four numbers. The rpm will usually be stamped on the outside of the case along with the serial number. Most rotors are designed to run on 60 cycle alternating current. There were some for 50 cycle current. There were coils made for 220/240 volt operation ( stove clocks ), but most are 110 volt. There were some coils made for 24 volt operation and some for 480 volt operation so be certain you know what coil you are dealing with before you apply power to it. If you use a 50 cycle rotor on 60 cycle power the clock won't keep time, so be certain of the power frequency specification of the coil you are working on. If you have 50 cycle power, and change the 60 cycle rotor to a 50 cycle rotor, you must change the coil also; if you do not, the 60 cycle coil will heat up because it does not have enough inductance for the 50 cycle power and too much current will flow through it.

The old rotors were made of copper and were soldered together. They can be taken apart and repaired. Inside the capsule is a tiny ac induction motor that powers a reduction gear train. They are oil filled so I would not recommend opening them using any kind of heat. I have cut them open by chucking them up in a lathe and CAREFULLY cutting a groove in the top part of the capsule. If you look closely you can see where they have been soldered at the factory. The newer rotors can be cut open also. They are made mostly of aluminum. The gears inside the new rotors are plastic and so are some of the bushings. If you are very careful you can repair these rotors. The old rotors made of copper will usually have bronze bushings. These often wear and can be replaced. The gears also often wear. If these are worn the repair may not be as easy. Unless you have lots of time , and are very quick I would not recommend repairing these rotors as a general practice. As time goes on you may have no choice because as each year passes by fewer and fewer of them are available. They will usually have the rpm and direction of rotation stamped on the outside of the capsule.

Telechron electrics that don't have keyholes for setting the strike and chime sequence can be set up by lining up the indentations on the back with the holes in the hammer lift cam instead of using the key pins. You are doing essentially the same thing as putting the pins through the "indexing" holes. The difference is that it might take several tries before you get the shutoff exactly correct. What I mean by keyholes and "indexing" holes is small holes that a (steel) pin will fit through. These are usually designed to accept pins .040 thousandths of an inch diameter). The idea is that you set the hour trip with the setscrew on the drive gear loose, then insert the pins which go all the way through the plate that holds the chime hammer lift assembly ;then through holes in the assembly itself. This holds the lift assembly in the correct position. The pins go in both sides , by the way. Once you have the pins in place and the hour trip cam set on the centerpost , you tighten the setscrew on the drive gear and the clock will be in sequence.

There have been Telechron clocks made with rack and snail type of design for the strike. The main thing to keep in mind is that this style must have no load on the hammers when the strike shuts off , or they will continue to strike sometimes and sometimes not. The shutoff lever for the strike hits the long pin and pops the strike drive gear away from the main rotor / time gear (which gives it its power). That pin must not be loose. If it is even slightly loose (and they do get loose) the clock will not work correctly all the time. The strike shutoff cam hammers must just have dropped when the cam is in the shutoff position. If this is not set within ten thousandths of an inch the clock will not work correctly all the time.

The hammer pads on these clocks tend to become quite hard and make the clock sound "tinny". If you are repairing clocks for a living , DO NOT change these unless the customer specifically asks you to. If you change them you will change the sound of the clock and you will no doubt have a very angry customer in your store when they listen to their clock for the first time after you have repaired it and discover that you have changed their family heirloom. Trust me on this once you replace those old pads the clock will NEVER sound the same again and you will not be able to get the old sound back. You will be up to your backside in alligators and the swamp won't even matter any more!

If you own one of these and want to change it consider that the originals on the older telechrons were leather. It tends to harden up over the years. I would suggest using a plastic end such as the ones used in the modern European clocks. They can be made to fit and can be ordered from suppliers. And , yes , you are changing the clock. Keep that in mind before you decide to change it. I'm not recommending you change the clock, I am saying if you must change it to sound softer use plastic. However , it may not be much of a change. If you want it original , just be happy with a tinny sound. I cannot in good conscience recommend using leather replacements

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