Two years back I serviced a Hamilton Electric Railroad Special 50, fitting a NOS contact, and a new battery -- and regulating it as close to time as possible.

After two years on the same battery, and still running, the watch has gained 4876 seconds in 730 days, an average gain of 6.68 seconds per day.

To eliminate some probable but unmeasurable variables I have kept the watch dial up on my bench the whole time.


Dan

Funny, in the same 2 years, I sure seem to have gotten more than 6.68 seconds a day slower. Perhaps this would not have happened if I had remained face up?

In all seriousness, I am not surprised. How does the formerly NOC contact now appear?

Regards,

Not possible to say while the watch is still running - but previous tests of 505 NOS contacts have resulted in them being worn out in anything from 15 months to several years.

However there was a solution which never got into the production watches -- reverse the polarity of the battery, and additionally use a diode to suppress sparks, and use platinum contacts instead of the gold alloy they did use.

Properly set up the 500 movement contacts can potentially last even longer.

A few days later than the above the watch finally stopped -- so 2 years running from a 301 battery.

dan