On Tue, 23 Nov 2004 11:36:47 +0000 (UTC), Hannahblot
wrote:

Hi, I wonder if anyone might be able to help me figure out the most
likely reason an old 1960's battery clock has stopped working.

The clock has an unusual battery powered movement so i can't just swap
it out for a more modern one. It's such a nice old retro design I
don't want to bin it either.

I have a link to a .jpg of the clock's circuit board below.

My first guess is that it is the capacitor but I am unsure how I would
go about testing this (I have a multimeter) or any of the other
components.

Runs off a single D cell battery, battery and contacts are fine.

http://home.btconnect.com/metaluna/clock/clockcirc.jpg


Thanks

Hannahblot

I'm very famillar with this design, no quartz, it uses the magnetic
impulses in both directions and hair spring (thin, fine coiled spring
with slot in the finger for the hairspring for setting clock (slowing
balance wheel down or speed it up to correct timing error). Coil has
two windings, trigger and impulse.

Couple caps is to give nice proper impulse to the magnets in the
balance wheel. Resistor limits the current or to bias the transistor
off. The triggering energy is done from one trigger winding that was
generated by the magnets when passing through that coil. This biases
the transistor on for a pulse to impulse winding to repel (or attact?)
magnets (balance wheel had moved sufficent by then trigger-impulse
happened). Happens on both directions.

I use to collect those type of movements when I was younger when they
were plentiful back then (1980's). Unfontunely don't have them. Try
the older clock/watch shops, they may have a bunch of those in all
kinds.

The red one is poly cap, reliable. The blue one is electrolytic and
tend to dry out. Change this one, watch the polarity. Black one with
3 legs is transistor. I think generic NPN transistor should do.

That coil, be very careful and gentle. Windings is made of very fine
gauge.

Cheers,

Wizard