Accutron Tuning Forks


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Most 214's can be adjusted to run properly through years of normal use without any difficulty but there are some movements which can only be described as over-active. The adjustment of an over-active movement is so tenuous that any external force will cause it to speed up. This explains why some watches run great on the dresser but too fast when worn while others will run well for a while until a hard bump causes them to slip out of adjustment. 

The bottom of each tuning fork tine was notched at the factory to set the frequency (photo). A relative few have tuning forks that were cut to the lower end of their tolerances. This was OK when the magnets were energized by 1.3 volts, but at 1.5 volts these forks are over-active. This causes them to  index two teeth instead of one either periodically or with every stroke.

Unfortunately, there is no way to know in advance which movements have this problem. The problem is usually found while adjusting the movement but it is possible for a very few to slip by undetected.

Previously the only way to correct the problem was to replace the tuning fork with one that has thicker tines but the supply of good forks is rapidly decreasing. Fortunately though, We now have a better way to eliminate the problem. A diode which lowers battery voltage in the circuit by 0.2 volts can be installed in the coil. This is really the best possible solution. The watch will
perform as it did when new and battery problems will not occur again. This inexpensive
modification is not noticeable and it is reversible.

Copyright  2002 by Martin Marcus. All rights reserved.
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