Date: Thu, 6 Jan 2000 18:10:42 -0500
Reply-To: David Beierl <dbeierl@IBM.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: David Beierl <dbeierl@IBM.NET>
Subject: Re: Clock slows down
In-Reply-To: <3.0.6.32.20000106173556.007dadf0@mail.visuallink.com>
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At 17:35 1/6/00 , dan wrote:
>I have an 84 1.9L that when I go to it in the morning, if it is nice and
>cold, the clock seems to have died out because it tells me I am going to
>work when I went to bed:)
If the car starts then it's certainly not the battery. The clock will
probably run long after the dash lights have pooped out. Sounds to me
like a clock that needs a bit of cleaning and maybe oiling. I haven't been
inside one -- but electronic clocks are mechanically very crude and simple,
now that timekeeping accuracy doesn't depend on keeping the friction
down. In general they have a very small chunk of electronics that drives a
very simple little open-frame stepper motor whose rotor is a ferrite magnet
disk. The motor has two positions it likes to be in, and every time the
circuit gives it a kick it flips around to the other one. After that is a
series of nylon gears (self-lubricating) whose bearings are often molded
into the plastic case (so be very thoughtful taking the thing apart unless
you like to play 52-gear pickup). In general I'd expect the entire
mechanism to be running dry in plastic bearings. If VDO did it otherwise
then I think they were working too hard.
If the clock is twitching at all, then it's almost surely a friction
problem. If it's absolutely dead in the water, could be an electrical
fault, i.e. something opening up as everything contracts in the cold. If
there are solder joints available to be reflowed, try it -- otherwise
you're unlikely to fix a problem with the electronics (somebody supposedly
asked Mozart how to learn to compose music and M. told him to start simple
and gradually work up. The fellow said "but that's not how you did it,"
and M. replied "but I didn't ask..."). But bad solder is very likely,
especially in an automotive environment, so remelting it is definitely
worth a try if you have access to a small electronic-type iron. Bad
(fatigued) joints of this type are seldom visible to the naked eye, though
they show up pretty well under a 20-power stereo microscope.
david
David Beierl - Providence, RI
http://pws.prserv.net/synergy/Vanagon/
'84 Westy "Dutiful Passage"
'85 GL "Poor Relation"
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