I've got an Art Deco style clock, rather nice, but it looses a couple of minutes a week. Any way to adjust the crystal to speed it up. The movement is rather small and it's difficult to find a replacement that would fit (and the nickel hands may be non standard).
rusty
That is an error of 200 parts per million = huge for a crystal IME. Adjusting it would be an expert job and even if it could be pulled that far, is unlikely to be stable as the frequency would be too dependent on the external components. Possibly not a lot you can realistically do to be honest.
One of those "if you have ask the question, then you are probably not equipped to solve it" type queries :-)
AIUI digital clocks are either synchronised with the 50-cycle mains, or receive a synchronising time signal from the MSF time signal broadcast from Anthorn (see
One thing that's puzzling me - a digital clock with hands?
Do you mean an electronic one (i.e. crystal governed)? In that case you are SOL I do not think these are sortable(word?) by us mere mortals. So you have three choices; live with the two minutes a week, replace the movement or skip(Eeeek) the clock.
Seem to have a V hazy memory that old clock units had ,as well as the time setting 'wheel', a little 'wheel'/switch to speed up/slow down the movement this may be a dream or may apply to mechanical clocks (probably the latter).
Are you sure it is crystal controlled? What vintage is it?
It could be inductor/capacitor at that level of drift from reality.
200ppm off is a long way. Most of the better quartz movements have a small load capacitance adjuster that can pull the crystal a few ppm or tens of ppm at most. Speeding it up is harder than slowing down.If yours has one then it should look like a miniature screw head with marks around it and + 0 - annotations. Modern ones are supposedly trimmed close enough at the factory now and lack these adjusters.
So how does it work, one assumes mechanically somehow? If the xtal is old it can drift so if you can get a new xtal then do so, but it might be rather hard if its an obsolete movement.
People go to extremes to keep these old things going I'm told like making up special synthesized frequency generators to get them going again, probably cost more than a new clock!
Brian
Maybe it's got fingers? ;-)
Tim
I had a similar problem with my first digital watch, and cured it by replacing the faulty crystal. Which then lasted another couple of years....
Mostly, they use the same frequency 32,768Hz crystals, and aren't too fiddly to work on, as the crystal only has two connections to the PCB.
Usually it will have a 32.786kHz clock and a chip to divide this down by
2^15 to 1 pulse per second- sometimes two phase - to drive a tiny stepper motor. Gears thereafter as per a convention clock, driving hands. If you listen carefully, there is typically a quiet 1Hz tick.
There may also be a once per minute or half minute thump in the older ones which were a sort of hybrid pumped mechanical spiral hairspring driven by a quartz derived pulse to keep it going.
A picture is worth a thousand words here...
mechanical movements could have spring tensions adjusted.
Xtal stuff - well you CAN pull the crystal a LITTLE or replace it..but as you say, not for the faint hearted.
IN general reducing capacitance across the xtal will slightly speed it up.
If there is such a capacitor, removing it and then adding back little bits might work. Or it might stop the clock altogether.
Tricky things, crystals.
Not to Brian :-(
Some mechanisms have an adjustable capacitor in them. Fiddled with my alarm clock one once and it started gaining. Recently it's started losing though.....
I mention this as there's one thing been overlooked (and when I find my tuit, I shall investigate my clock) is the possibility of gooey old oil or bits of fluff in the works.
with a stepper motor, it either works or it dont and the time is generally down to the Xtal alone.
Just a thought, but it may be the mechanical side that is faulty, ie sticking through worn or damaged gears.
The cause of such clocks losing time by a small amount with age is sometimes as simple as dirt and grunge in the pivots of the few gears causing the stepper motor to miss occasional bits of rotation. Cleaning the mechanical side with isopropyl alcohol on a small soft paint brush may help.
I had a watch with this kind of mechanism - after a dunking in my ultrasoni c cleaner (not intentional - it should only have cleaned the expanding brac elet, but the support failed) it started working at double time... As long as you knew what was happening it was quite possible to work out th e time - I carried on using it for a while until it finally gave up the gho st. It really confused people who asked the time and happened to get a glim pse of the watch face as I was calculating it...
Yeay, thanks for all the replies. mechanical problems I hadn't thought of, so I'll give it a clean first.
I should have been clearer: the clock's only a few years old with a conventional quartz movement but made to look 1920's Art Deco with metal hands, fancy nickel plated scrolls etc. An option might be to replace the
32 kHz crystal with out of a different clock, or at least check the frequency with a frequency meter first, if a meter is sufficiently accurate. I vaguely remembered that xtal oscallators can be pulled a bit, but apparently only downward from the comments here which is the wrong direction.I'll also keep an eye out for a new clock that can be cannibalised for the movement, they only cost small change on Ebay.
rusty
You have changed the battery and/or given the battery and clock contacts a wipe with a cloth haven't you? I can't remember if you said this clock was running fast or slow, but low battery is a prime cause for slow with our quartz clocks.
John :
And you got the proper standard of timekeeping for a well-adjusted 1920s clock. That's extra authenticity, you ungrateful person.
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