Originally Web posted Wednesday, 27 May 2009.
Content last modified Wednesday, 27 May 2009 .
External links last verified Wednesday, 27 May 2009.

Telechron Electric Clock Repair Tips

A compilation of my own ideas and the best of what i have come across on the WWW, focusing on motor rotor relubrication.
3H98 Navigator and 7H162 Gay Hour undergoing work

Telechron/G.E. electric clocks tend to run for decades with no complaints, yet sometimes they get noisy and/or stop working. The intent of this page is to provide a(nother) source of informative tips on revitalizing these (usually) nice vintage clocks.

Relubrication

Background

These clocks are plenty old enough to have had their lubrication become gummy, dried out, or otherwise no longer viable for its original purpose. It’s pretty likely that the whole gear assembly will need cleaning and lubrication… this is (or should be) straightforward, so will not be covered on this page, beyond mentioning that i like to use a strong solvent (i’m presently using Fedron®) to remove the old lubricant, followed (once dry) by a good Teflon®-based light oil (i am presently using Tri-Flo®).

The tough, and often essential, challenge is lubricating the gears and whatnot inside the sealed motor rotor units on these clocks—the heart of the Telechron design. When these were current products, one could merely buy a new rotor assembly for some reasonable price (50¢? $1?, $2?). Not likely in modern times! The only opening is the very slight clearance between the output gear shaft and its bearing. Seem impossible? Read on!

Early Method

Some clever person in the 1950s or 1960s figured out that one can set this little “can” on top of an incandescent light bulb of, say, 60 to 100W. The old oil heats up, expands, and seeps out of the gear shaft opening (assuming there is any old oil left in any sort of fluid form!). One soaks up any old oil, then applies new oil and removes the assembly from heat. Suction is created, and the new oil is sucked in. One keeps adding oil until the assembly refuses to accept any more.

Improved Method

I have used the above method in the past, and it does work: my original 1970s treatment was good for over 20 years… especially noteworthy since i was using vegetable-based 3-in-1® oil and did not clean nor lubricate the exposed gearing.

Each subsequent attempt has included experimenting with different techniques to maximize the efficacy of the relubrication. While it is too early to tell if any of these will last as long or longer than the original method, the early results seem sufficiently good to keep using the improved methods. Here is an outline of my current optimized method of rotor treatment. It is assumed that the clock has been disassembled and the motor assembly removed:

  1. Push the rotor assembly out of the stator frame to separate the two.
  2. Apply solvent on and around the output gear, to remove whatever old lubrication is easily removable.
  3. Place the rotor, gear side up, on a source of heat. (I am liking a low-power coffee pot heating tray presently.) Plan to remain present during the heating process. Look for a temperature rating on the rotor case, and be sure to respect it! If there is no temperature rating mark, if the rotor still runs, it may be worthwhile to take a detour:
    1. Replace the rotor into the stator assembly.
    2. Attach a thermometer:
      A digital thermometer probe held to the rotor by a rubber band
    3. Run the motor until it has reached its full operating temperature, and note it.
    This may be useful knowledge anyway, perhaps to compare Before and After running temperatures.
  4. As the rotor assembly heats up, stand by with a dry rag and some cotton swabs and remove any and all old lubricant and/or other residue which manages to make its way out of the rotor case
  5. When the unit is piping hot and nothing more will come out (sometimes there are air bubbles, other times not), remove the rotor from the heat source and apply your choice of solvent (if it is safe to do so) or high-quality lubricant. Hopefully whatever you apply will be sucked in in short order… keep applying the chemical and allow the rotor assembly to “drink” as much as it wants, or 1.5 to 2 cc, whichever comes first.
  6. During the above cooling process, when you feel the rotor assembly is cool enough to put back into the stator assembly, do so, and run the motor. The movement of the internal parts will hopefully encourage chemical distribution and “shake up” as much of the remaining old oil as possible.
  7. Once the rotor is accepting no further chemical when running, unplug the motor and let the rotor fully cool down to room temperature… for best results, don’t rush this step. Stand at the ready to add more of your chosen chemical as the rotor continues to cool, unless you have already reached the 1.5 to 2 cc limit.
  8. Repeat steps 2-7, using your preferred lubricant this time.
  9. Put the rotor back into the stator, and test the motor: it should run smoothly and quietly. Expect that some lubricant will percolate back out; run the motor until it has reached its normal operating temperature, then a few minutes longer, continuing to remove excess oil as needed:
Using a cotton swab to soak up old/excess oil

Other Alternatives

One popular alternative method involves carefully drilling an access hole into the rotor housing. Another, a variant of the methods above, uses vacuum to assist pulling out what’s inside the rotor.

If you want to follow the current state of relubrication art, including the techniques mentioned in that last paragraph, i know of no better place than the Clock Talk Forum > Telechron & G.E. Clocks. (Not sure what happened to the old forum or if any of its content will ever come back.) Especially the topic “My rotor rejuvination machine - need some more bad rotors”.

Other Sources of Telechron/G.E. Information


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