[time-nuts] Frequency trimming of Seiko wristwatches

[Michael Baker]

Max Robinson wished for a way to open up wrist-watches
and adjust the crystal trimmer.

I have owned at least two Seiko wrist watches which
had a simple to open screw-on back.  I opened the back
and tweaked the trimmer capacitor on both of them using
the ticks from WWV as a reference.  After watching for
a month to see which way the drift was, I re-tweaked
several times.  Ultimately, the best I could achieve
was around +/- a few seconds per month.  The problem appeared
to be one of temperature compensation-- seconds gained
or lost per month were different in the winter months
as opposed to the summer months.  These particular Seiko
wristwatches had a tiny o-ring to seal them against
moisture and I had no problems with leakage.

Mike Baker
Micanopy, FL USA
---------------------------