[T3] Why early clocks fail

[Jim Adney]

Sure, I've got one car on a "maintainer" right now.

On 9 Aug 2011 at 8:22, crash 69 wrote:

> So using a trickle charger would be OK, right?
> 
> On Mon, Aug 8, 2011 at 9:41 PM, Jim Adney <jadney at vwtype3.org> wrote:
> 
> > I just fixed an early (up thru '70, the ones with the white plastic
> > backs) clock for someone who asked what goes wrong with them. I
> > thought this might be worth sharing with everyone.
> >
> > These early clocks use a solenoid to wind the clock every minute or
> > so. When the spring winds down a bit this lets a set of points make
> > contact, energizing a solenoid which "kicks" the winder and opens the
> > points. I believe this is typical for all car clocks up to around
> > 1970.
> >
> > There's a "fuse" in these clocks that opens up. This typically
> > happens if the car is left in storage with the battery installed. As
> > the battery discharges, it gets to the point where no longer
> > sufficient voltage to kick the winder, so the points stay closed and
> > draw current continuously until the fuse blows. The clock normally
> > draws current for only a fraction of a second, and that current
> > normally never gets large enough (or long enough) to trip the fuse.
> >
> > The "fuse" is actually a tiny rivet made of very low melting point
> > solder. I repair it by melting it and rejoining the connection. I
> > also add a diode across the solenoid to minimize arcing when the
> > points open. Then I flush out the works and lubricate each of the
> > pivots with clock oil. The repair is usually pretty straightforward,
> > but these clocks never kept very good time.
> >
> > In 40 years, I've only seen one of these clocks where the bearings &
> > pivots were actually worn out.
> >
> > The moral? Disconnect either the battery or the clock if you park the
> > car for a long time (months.)
> >
> >
> > --
> > *******************************
> > Jim Adney, jadney at vwtype3.org
> > Madison, Wisconsin, USA
> > *******************************
> >
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> >
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-- 
*******************************
Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
*******************************