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The CYMA Sonomatic

Bill241

By Bill241
in Your Walkthroughs and Techniques

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Bill241 Member

Bill241

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I’ve spent a bit of time learning about alarm clocks- particularly the higher end Swiss ones- as an inexpensive way of learning about complications.

Here’s my CYMA Sonomatic: a fairly rare alarm clock introduced in 1958. The ‘Elite’ model featured here was priced at 15 Guineas (£15 15 0 in British pre decimal days, I believe) at the time. About a week’s wages for a skilled factory worker at the time.

It’s an 8 day movement which is quite unique as the alarm itself is also an 8 day one, overcoming the limitation of all other mechanical alarms which will completely run down its mainspring unless manually stopped. On the Sonomatic, the alarm will sound for a few seconds every 12 hours and then automatically shut off (thus, no good for heavy sleepers!) It should sound up to 19 times on one wind. 

There’s very little on the ‘net about these so to assist others working on this calibre, I’ve posted some images of the strip down intended to show the movement and particularly the unique automatic alarm shut off mechanism.  Basically it is a cam with a small pin that makes a single revolution and then acts against the disconnect lever to stop the alarm. 

Within an hour or so, the hour wheel pushes the disconnect lever down a little further, eliminating the resistance against the cam pin, and so the spring loaded cam springs forward a few degrees and is ready for the next alarm cycle. That is, if it’s set up correctly.

It took me a while to figure out the set up as when I rebuilt it, the cam pin would briefly depress the disconnect lever then carry on revolving so the alarm would not shut off. The trick is to adjust the disconnect lever sideways to ensure just enough resistance to stop the cam. The disconnect lever is quite sophisticated but the two screws holding it in place can be accessed easily from the dial side (top marks for design!)  and then adjusted. With quite a bit of trisl and error, it’s now working perfectly. 
 

 

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oldhippy Distinguished Member

oldhippy

Posted
Posted

I remember repairing this type of clock. Well made as well. Someone has had a go at the bush for the hammer as it looks as if someone has used a punch on it, it is also filthy dirty. 

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Bill241 Member

Bill241

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The photos were taken during disassembly. Like all of these clocks I’ve looked at, filthy dirty. I doubt it’s been serviced in 30 years. The oil was so old it had turned green! The third wheel pivots were so gummed up the clock barely ran at all. 

I agree about the build quality and design. The movement is almost completely silent unlike the loud tick of lower quality clocks. 

Edited by Bill241
Nucejoe Distinguished Member

Nucejoe

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3 hours ago, Bill241 said:

The movement is almost completely silent unlike the loud tick of lower quality clocks. 

I find the loud tic of clocks, relaxing. 

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Bill241 Member

Bill241

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9 hours ago, watchweasol said:

Hi. Along with the Swiza movements these were good quality for alarm clocks. It will clean up very well. Use Windles clock oil on the rebuild is the best for clocks.

I haven’t worked on a Swiza yet- some inventive designs, certainly, but I’m not a fan of pin levers or the alarm/movement running off a single spring. I prefer CYMA, Looping (particularly the cal. 50-55) and Imhof from the 50s-70s period as they are more like pocket watches than clocks. They are usually very cheap to buy- I recently bought the smaller version of the Sonomatic, with calendar, for £6.

I avoid the prewar alarm clocks and 8 day timepieces having read the Horological Journal articles on the dangers of radium dials! 

For lubrication I tend to use HP1300, 9020 and 941 for the escape wheel/pallets with a thick grease like DX or 8300 on the barrel arbor pivots. I’ll get some Windles though as I do occasionally work on larger clocks. 

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    • Simeon
      9020 or HP500? Which would I get the most use out of?

      By Simeon · Posted

      Yes, this is on the basis of no epilam. Interestingly, the technical guide calls for using HP1300 instead of grease on a lot of stuff in the keyless works which might indicate an assumption that it had all been treated with epilam.    This, exactly I suppose . Literally trying to get a more, or less, viscous oil by mixing two different oils together. Obviously you would imagine using oils from the same 'family' would make them more compatible.    Actually, I knew this. Everyone seems to use HP1300 to substitute D5 but Moebius actually recommend their HP oils only for jewelled bearings. If it's a brass bushing D5 is best.  Interested what the outcome might be if I used 9020 on the balance/ escape wheel pivots of a typical wristwatch sized movement. The practical consequence of this would be having to service the movement again if it doesn't work but actually the real consequence is that you have bought 2ml of extremely expensive oil that you might not use again. 
    • AndyGSi
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      By AndyGSi · Posted

      What size is the movement and have you done the usual search with bestfit. To me it looks like something in the 10 series. The other option would be to measure the staff and try and trace it from their, or at least find an equivalent. Edit Just realised after a bit more digging the manufacturer is marked on the movement 'FREY'  
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      1mm copper wire can be tapered to fit. Softer than brass but it does work.
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      Looking to try servicing an old movement

      By Neverenoughwatches · Posted

      You would think so.....but maybe not. I did just that with a 50's Oris tank. 5 years ago.....stripped and polished...it hasn't tarnished and looks exactly as it did..I wear it often. Looks like brushed gold plate. 
    • GPrideaux
      Bulova Rubaiyat 1920/21

      By GPrideaux · Posted

      This poor watch now has a new escape wheel jewel. I got a jewel assortment and found one that fitted snugly in the setting, and whose hole was a neat fit on the escape wheel pivot, glued it to the flattened end of a 1mm drill bit and turned it on some brass with diamond lapping paste to give it a taper on one side. I used a sewing needle to gently close the setting over the jewel. It doesn't look too bad in the pic, but actually about the bottom third of the setting has nothing left holding the jewel down and I'm not sure whether it will hold. I'll have to see when I reassemble it. Before I reassemble, I thought I'd better have a look at the balance and check its poise. I put it on a pair of tweezers and found it did indeed want to always stop with the same point uppermost, swinging to and fro around that point. While I was thinking about timing washers and that I don't have the right tool to remove a timing screw, I noticed that one of the pivots didn't look straight. A closer look was called for: The right hand (upper) pivot is definitely bent. So, should I try to straighten it? It is likely to break, I suspect. Am I going to be able to buy a replacement balance staff for a watch more than 100 years old with no movement number? Seems unlikely. I have no lathe so I'm not in a position to make one myself. What are my options?
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