Cosmotron 7803A Movement – the Special Version

Posted on November 28, 2013 by sweephand

The X8 / Cosmotron electro-mechanical movements  first produced in 1966 were, for a short time, Citizen’s most accurate watches – capable of reaching chronometer grade standards.  They had a very limited life though, since quartz technology was developed soon after and by the mid-1970s they were obsolete.

The most sophisticated Cosmotron was the 7803A – with a 36,000 beat per hour speed they had an additional feature, indicated by a button at the 8 o’clock position. Known as the ‘special’, this button not only  zeros the second hand (to 12 o’clock) but also zeros the minute hand when it is within + or – 3 minutes of 12 o’clock. Currently I’m not aware of any other manufacturer that has employed this feature, which I believe is to allow exact synchronisation of the watch. Also, when the button is held in, the second hand is kept at 12 o’clock until the button is released. If the button is pressed and released the hand is zero’d and immediately restarts, as is found in a ‘fly-back‘ chronograph. Citizen also tells us that the Cosmotron Special is capable of chronometer grade accuracy.

The movement itself is differentiated from other versions by the gold plated finish:

I really like the Cosmotrons – in good condition they are a very accurate timepiece and the hybrid technology they utilise is pretty cool, in my opinion 😉

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This Week’s Featured Watch #54 – the Challenge Timer aka Citizen Bullhead, 4-901096

Posted on November 18, 2013 by sweephand

The Citizen Challenge Timer, usually known these days as a ‘bullhead’, was first marketed in 1972. It’s now probably Citizen’s best known vintage watch and there are often examples up for sale, however many have after market dials and refurbished cases. There were two case designs, one in base metal with a variety of finishes, and one stainless steel octagonal design. The base metal models were finished in three ways – satin polished, gold plated, and black coated.

This week’s watch is seen much less often than other models and is finished in black with a green dial. Citizen didn’t give this a model number, so it is identified by its case number – 4-901096:

Although the main dial colour is green, there are lots of other colours in the dial details and the hands, framed by the stainless steel bezel. The back is typical of the earlier Challenge Timers, with a serial number showing production in December 1973:

The movement is of course the high beat, fly-back 8110A (no movement shot since the back is on rather tight!). The case material code on this is BLS – black case, steel bezel. As can be seen from the above shot the black coating does wear and this means good examples are hard to find. Many are polished back to the metal underneath so it’s always worth checking what the case code tells you about the original finish.

The crown is signed, and mine is on a modern strap. I have found one pic of this model with its original strap, along with tag and instruction leaflet, with due credit for the image to the seller on Yahoo Japan:

For more info on the original Challenge Timer models please take a look here: https://sweep-hand.org/want-an-original-citizen-bullhead-a-quick-buying-guide/

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Coming Soon to a Blog Near You!

Posted on November 10, 2013 by sweephand

You may have come across the work of a certain watch maker known as 31 Jewels. There are several threads on the WUS Forum showing his restoration work on Citizen’s vintage mechanical chronographs (both the 8110 and 8100 models) and I have linked to them a couple of times from this blog.

I’m now pleased to say that I’ll be posting new pages in the not too distant future featuring some of his amazing work, sometimes on pieces you might otherwise have thought were probably not even good enough for parts!

I hope this new feature will be of interest since it will not only be about the aesthetics of these great watches  but also show their fine inner workings and just what 31 Jewels can do with them!

In the meantime, please watch this space 🙂

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UNI Automatic Problem

Posted on October 31, 2013 by sweephand

One of my favourite watches, a 19 jewel ‘UNI’ Auto Dater from 1965  with a ‘linen’ dial, stopped running a little while ago. Although I’m not a watch repairer I was able to diagnose the problem – it turned out to be a loose pallet fork jewel. I wasn’t able to fix it, so I looked out for a donor watch on Yahoo Japan, and recently I found one.  There were no other bidders and I got it for just JPY1200, about GBP7.50! Although the transaction via ‘Japamart’ doubled this, it was still a cheap buy….providing it turned out to be in working order as the seller had described.

The seller was absolutely right, the watch was in nice mechanical order, running accurately and changing date properly. As a result I simply swapped the movements, and I will keep the old movement for spares.

The donor watch was made in 1963, the year of the launch of the UNI which marked the beginning of the end for the Jet automatic. Here it is (after removing the movement):

The gold plate is well worn, as is the crystal (hence the blurred dial printing), which is no doubt why I got it so cheaply. The dial isn’t too bad at all:

Thanks to this donor I now have a fully functioning 19 jewel example:

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Right Tool for the Job

Posted on October 28, 2013 by sweephand

Removing and replacing rotors on many of Citizen’s vintage automatics has been something of a pain. Other than the SM and UNI models, and the Jets of course, they aren’t just a simple screw fitting i.e.:

[linked image]

By chance I came across the solution, on Yahoo Japan, a vintage screw driver with special fitting. Arrived today: 
[linked image]

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Jack’s Golf Updated

Posted on October 25, 2013 by sweephand

Jack reminded me that he had sent me more pictures! 🙂 So I’ve now added more to the post.

Stephen

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Jack’s Golf

Posted on October 25, 2013 by sweephand

No, not a motor car, but a rather special example of Citizen’s unique Challenge Golf watch. Jack has kindly allowed me to use his photos here – please do not reproduce them anywhere else (thanks). Jack found a mint example of the ‘TV’ style model:

As you can see it is in superb condition, and is on a very nice black Citizen bracelet. This may well be an original fitting, an alternative to a white leather strap I’ve seen in contemporary catalogs:

What is particularly special, and rare, about Jack’s watch is that it came in its original box, a hinged wooden example with a very nice outer cover:

Here’s the case back, showing production in 1973:

Inside lies the 7760 movement, unique to this model:

More detailshots of the dial:

This is a very nice collector’s item, and congratulations to Jack on his acquisition. And thanks for sharing the photos with us – again please do not reproduce these anywhere else.

(more information on the Challenge Golf here: https://sweep-hand.org/2011/06/07/this-weeks-featyured-watch-6-the-challenge-golf/)

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Diamond Flake – Power Reserve

Posted on October 16, 2013 by sweephand

This mini series on the Diamond Flake ends with a real positive 🙂  I fully wound the watch on Monday (14th October) at 14.10 hours. It stopped today (16th October) at 12.10. That’s an impressive 46 hours, not at all bad for a 50 year old watch – and for a movement that was hidden behind this:

The watch is also keeping excellent time, with no adjustment needed over several days.

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Diamond Flake problem….solved – Part 2

Posted on October 14, 2013 by sweephand

‘Ninja01’, a redoubtable member of the Seikoholics forum kindly contacted me about the Diamond Flake movement and the difference between the donor movement I’ve used to resolve the problem with my Diamond Flake. Ninja01 is a Seiko expert and told me that the Gold Feather model had at least two movement variants with differences in their architecture, so could this apply to the Diamond Flake?

Since I was concerned that my donor movement, although running well, might have been fixed in a non-original way I thought I’d dig a little deeper. I hoped that this would also confirm Marko’s view and reassurance that all is well!

First I checked my photo of the two movements and noticed that not only did the donor movement have a different top lever, but it was also missing a part held by a screw underneath it. So it is more than the top lever that is different. I soon found, via Ranfft’s archive, that there were several movement numbers for the Diamond Flake, from 0700 to 0705, but no differences are identified.

I then studied my original parts manual – here is the relevant area. Part 077 is the top lever and part 903-02 is the lower part, not present in the donor movement – note also alternative parts 067-12 and 068-09 :

In the parts list I see that the 0700 has part 903-02, whilst it is not required for the 0701 & 0702 movements. The full 077 part number for the 0700 is 077-11, whilst for the 0701 & 0702 it is 077-12, confirming that it is different, although not illustrated in the diagram. Also, part 067-12 is required for the 0700, whilst for the 0701 & 0702 it is 068-09 :

So there we have it – the 0701 and 0702, presumably later versions, use two different parts, and do not require the lower part. Clearly my donor movement is one of these (I didn’t see a movement number stamped on it) and all seems correct, as Marko advised 🙂

NB: the parts diagram shows a date wheel, this is for the 2700 Diamond Flake Date and the 2710 Date Flake models.

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Diamond Flake Movement – The Thinnest of its Day

Posted on October 13, 2013 by sweephand

Sorting the problems with my Diamond Flake gave an opportunity to get a side shot of the 0700 movement. According to Citizen, when this was first produced in August 1962, it was the thinnest watch movement in the world – that was certainly true in Japan since at 2.7mm it was 0.2mm thinner than the Seiko Gold Feather:

 

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