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Posted

Hi Guys.

 

I need help to completely identify this watch.

 

It is a classic Omega.

 

I inherited it from my Grandfather.

 

I know nothing about this watch, but i can tell you the strap is not the original.

 

However the face/glass etc is all original.

 

I would like to know more about it and have it restored.

 

Would appreciate any assistance.

 

there are no markings on the back.

 

Looks like about a 1971 Chronometer with 12 Jewel movement.PM me the serial no and i will find out more.

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Posted

Looks like about a 1971 Chronometer with 12 Jewel movement.PM me the serial no and i will find out more.

It uses a battery and has a tuning fork that resonates to keep accurate time. Similar to Bulova Accutron I believe. The good old days before quartz crystal. I will dust mine off and post a pic.

http://forums.watchuseek.com/attachments/f20/623048d1328841182-my-new-connie-f300-electronic-battery-question-omegaad.jpg

Posted (edited)

Dont blame you, i would also hold on to a nice piece like that.

 

If you dont mind me asking, how did you come about it?

 

This was a birthday present to myself when I was younger, actually this watch has had a very hard life, it was used extensively in the day.

 

The watch was serviced by Omega about 2 years ago, now it is used for special occasions only.

Apart from a full cleaning,lubrication and regulation service, the following parts were replaced.

Strap.

Bezel.

Hands.

Crystal (glass).

The watch is otherwise completely and fully original.

Hope this answers your question.

Edited by Scooter69
Posted (edited)
It uses a battery and has a tuning fork that resonates to keep accurate time. Similar to Bulova Accutron I believe. The good old days before quartz crystal. I will dust mine off and post a pic. [/img]

 

The Movement

 

http://pippick.com/photos/accutron_fork_ad.jpgIt's the movement that makes this watch special, and so it deserves a section to itself. The heart of the movement is of course this little fellow (right). Well, not exactly, because the Speedsonic uses a modified fork design with additional weights near the magnets. These give superior performance by reducing positional error to virtually zero. Another difference is that in the early design (below left), adjustment of the fork's natural frequency (and hence the timing) is accomplished by turning weights on the inward-facing ends of the fork cups. In the modified design (below right) this is accomplished by rotating the weights mounted on the bottom of the tines by equal amounts in opposite directions. Omega also claim that by repositioning the driving click near the bottom of the tuning fork, the effects of wear are minimised leading to longer correct functioning of the indexing mechanism.

 

http://pippick.com/photos/accutron_fork.jpghttp://pippick.com/photos/spdsnc_fork.jpg

 

So how does it work? Well, to put it simply (very simply), the battery provides current to a transistorised circuit, which then pulses it at 300 times a second through many turns of fine wire forming a coil within each tuning fork cup. The coil of course acts like a pulsing electromagnet, causing the tines of the fork to resonate at 300 Hz. As the tines vibrate, a tiny finger or 'driving click' attached to a tine moves backwards and forwards over a toothed wheel—the 'index' wheel—pushing it round tooth by tooth. A 'stationary click' situated further round the wheel also bears on it and checks its position, while preventing it from moving backwards. The index wheel, the first in the gear train, has 300 teeth and thus makes one revolution in a second. This rotary motion is conveyed through the normal system of gears and pinions to finally turn the hands.

 

http://pippick.com/photos/spdsnc_mvt.jpgAs you can see, the view after taking the back off a Speedsonic is not particularly exciting. The dominant feature is the battery, of which more later. The coils of copper wire forming the electromagnets are plainly seen, as are the poise-adjusting weights at the foot of the tines. The movement has 12 jewels, and is 'unadjusted'. It was made by the Swiss firm Ebauches SA (ESA) under licence to Bulova. These ESA movements use index wheels made by Bulova, and are probably the finest tuning fork movements ever made. They were certainly expensive to make. Omega sent their movements for COSC testing and so they received the 'Chronometer' certification. Exactly the same movement (part of the "Swissonic 100" series) was used for the Longines Ultronic and the Certina C-Tronic, among others. Only 21,000 of these movements were made, between 1972 and 1976.

 

The Accutron movement embodied two major advances over all electric/electronic balance wheel movements made hitherto. The first advance was of course, the use of a tuning fork as a resonator. Instead of the lowly 2 or 3 Hz of a balance wheel, the tuning fork resonated at 300 Hz (or 360 Hz in the case of the original Accutron), giving much more stable and accurate time measurement. (Compare this with the usual quartz frequency of 32,768 Hz and you can see why quartz is so damn good.) Secondly, and perhaps more importantly, the use of the solid state transistor to rapidly control current flow was a major breakthrough. The Achilles heel of the Hamilton and similar electrics was always the contacts used in the make-and-break circuitry; they were subject to premature burning out and were thus unreliable. The Accutron did away with all that and replaced it with solid state reliability.

 

The early Accutrons were designed to use mercury batteries which provided an operating voltage of 1.35 volts. As the world's supply of mercury batteries diminishes for environmental reasons, these models can in most cases be kept going by using silver oxide batteries of 1.5 volts, although some adjustment of the watch might be needed. The ESA movements (such as that used in the Speedsonic) were designed to use either mercury or silver oxide, and if serviced according to specifications should run happily on either without any further adjustment. Rob B's Accutron website explains all this (and much more) in great detail. Rob also suggests servicing should be carried out every 5-10 years.

Edited by gummibear
Posted

Never been one for fancy watches, but this one I'd do a lance for:

http://craphound.com/images/versiona1.jpg

 

Of course at 17.5k USD, it's never going to happen.

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