One corner of the watch world that attracts a particular niche enthusiasm is that of the military wrist watch. Issued watches have derived from all corners of the market heirarchy from Blancpain, IWC, Jaeger Le Coultre, Omega and Rolex at the higher end to Seiko and Pulsar at the somewhat more humble end. The British military watch holds a particularly revered position in that landscape, with specialist watch companies producing watches specifically for the armed forces. Companies with such pedigree include Smiths and Precista but perhaps the most well known contemporary brand is the Cabot Watch Company.
CWC was founded in 1972 and produced watches for all branches of the British armed services. Their range included mechanical and quartz chronographs, divers watches and general issue service watches. In this latter category, the CWC G10 is perhaps the most iconic and well known. The CWC G10 first appeared in 1980, fitted with the ubiquitous ESA 536.121 quartz movement.
Photocredit: Stock Ebay photo via Google
The watch face was designed for simplicity and clarity and this model in its various incarnations was supplied to the Ministry of Defence for more than 20 years. That first incarnation though was a thick old thing, needing to accommodate the considerable height of the ESA movement and subsequently acquired the sobriquet ‘Fat Boy’. Later editions of the watch used thinner movements, allowing for a lower profile, more discrete case design. From 1987 the watch was fitted with the ETA/ESA 955.114 seven jewel quartz movement and it is an example of this watch that forms the basis of this current entry.
I sourced my watch from a seller on a watch forum who advertised it as a non-runner. I snapped it up as a potential 14th birthday present for my eldest son, anticipating a little work to get it running again. With the watch in hand, the overall cosmetic condition is really very nice, with a clean case, sporting only the odd sign of wear, a mint dial and handset with nicely toned tritium lume and its original slightly scuffed crystal.
As advertised, the watch was not running when I received it. Looking at the caseback, we see the rather complicated combination of stock codes, item code, serial number and year of issue.
The stock code 0552/6645-99 comprises three parts: the first is the 0552 MoD code which means the watch was issued to the Royal Navy; 6645 identifies the item as a Time Measuring Instrument and the 99 is the UK country code. The number beneath is the item number which refers to this particular model of watch. The 5 digit number beneath that is the serial number of the watch and the two digit number at the bottom, the year of issue. So this particular watch was issued to the Royal Navy in 1990.
The case back is a snap on back but is fitted with a battery hatch, presumably to aid battery changes in the field. Removing the case back provides access to the movement, an ETA 955.114:
The seller had tried a new battery to no avail and just to confirm his conclusion that it was dead, I tried one of my own for good measure but no signs of life. A non-functioning quartz movement is not something that is easy to diagnose without the correct testing gear and, to be honest, my limited experience of quartz does not encourage me to pursue this. I can get my head around mechanical movements and reasons why they might not be working but electronic failures are generally not fixable by means other than replacing the whole circuit. That would be an option here because replacement circuits are still available but they cost a little more than a complete replacement movement and so that is the route I am going to take. While the 955.114 is obsolete, its direct replacement, the 955.112 is still in production and all but identical in appearance and dimensions and so this is what I order.
Taking the movement out of the case is straightforward and provides a clearer view of the dial and handset
All very neat and tidy with lovely creamy tritium lume. If we take the dial and hands off, we can take a look at the calendar side of the 955.114:
I say calendar side because, although this watch has no calendar function, the movement does, but in this application, the redundant calendar parts have been removed. What this does mean is that the operation of the crown still retains the central click stop for the quickset date function but, of course, without those parts it serves no function. To set the time, you have to pull the crown out to the second click stop. So, in the interests of retaining the spirit of the original, I will remove the calendar parts from the new replacement 955.112. Here’s a sequence of shots illustrating that process, with the original 955.114 at the end for comparison:
The case needs nothing more than a clean and fresh crystal.
You can buy replacement crystals direct from Silvermans who are the current supplier of CWC watches but it can sometimes be difficult to get a response from them and so I opt instead for a replacement acrylic from Sternkreuz. The original crystal is 31.6 mm in diameter and comes with a beadblasted metal tension ring. To keep the original look, I plan to substitute the chromed tension ring supplied with the replacement crystal with the original extracted from the old crystal. When I get the new replacement I find two problems: the first is that the original bead blasted tension ring shown here
is slightly smaller in diameter than the chromed tension ring in the replacement. The second issue is that the 31.6mm replacement does not sit particularly snuggly in the recess in the case
and cannot therefore be trusted to remain in position once fitted, particularly given the likely abuse it will suffer under the ownership of my oldest son. I order instead a 31.7mm diameter crystal which should sit securely in the case and whose compression when fitted might then better bridge the small gap to the original matt tension ring. With it fitted it seems very secure with no play at all with the tension ring so we’ll go with this compromise for the moment and perhaps try to source a crystal from Silvermans at some point.
Back to the movement and we can re-fit the dial and hands
and then fit the movement to the case ring
and the whole lot to the case.
With the new crystal fitted and the movement ticking happily away, we are finished.
Hi Martin, I came across your site while searching for more information about a vintage Seiko I recently acquired and absolutely love what you’re doing! Love the photos but more importantly, am loving the before and after results.
I was wondering if I can reach out to you about a particular question I had in regards to restoration. Please let me know if you’re available to speak! Thanks! -Noah
There is not an obvious mechanism for asking off-line questions via the blog but you could ask your question under the About tab at the top of the page and I’ll do my best to answer.
Mr Smoff said:
In the early part of this article you mention the ‘ubiquitous’ ESA 536.121 movement.
I have just received a non running Oris Executive quartz watch which contains one of these.
Any ideas where I can buy a replacement or alternative movement would be greatly appreciated.
Mr Smoff (UK)
As with any obsolete movement or part, the most likely source of a direct replacement has to be Ebay. When I was looking for spares for the one example of this movement I’ve worked on, I found complete movements as well as parts fairly easily and I think ended up sourcing what I needed from a seller based in the Netherlands. As to replacements, there is an ISA movement which is a direct drop in but you would need to replace the hands because the hole sizes are different. Alternatively, you could replace the movement with an ETA automatic – from memory I think the 2836 would work and has the advantage too that the hand hole sizes are the same as the 536.121.
Only the second hand is a slightly different size on the ISA 1198. It does the job but isn’t a patch on the ESA.
I’ve just received a watch expecting to find that lovely old ESA movement only to find someone had swapped it out for the ISA at some point in the past. From what I can tell they re-used all the original hands.
How did you fit the Crystal to the G10? Did you use a press to push it in or Crystal Lift tool? Equally how did you remove the old?
I used a crystal press to fit the new crystal and my fingers to push the old crystal out.
Surprised you took the easily route of new parts on this!
That crystal would have polished up very easily with T-Cut, Autosol and/or isopropyl alcohol. A little experimentation is required with acrylic crystals because they all respond differently to these types of polish.
The silver/green 955.114 is the Hong Kong assembled version of the gold/blue 955.112.
Before binning a movement it’s always worth checking the resistance of the coil (if infinite, it’s dead). Although, I’m not sure if that can be checked on these as the coil can’t be removed from the circuit.
A circuit can easily be checked by seeing it the coil is receiving an alternating voltage pulse every second. If it is and the coil is good then the problem is mechanical (sticky rotor/gears) same as any non quartz.
I still have both crystal and the original movement and will take a look at the latter when opportunity knocks. On both fronts though, as this was intended as a birthday present, I wanted it both to look as new as possible (in my experience, polished acrylic crystals often look like polished acrylic crystals rather than new!) and to function as a new watch. The latter achieved more easily (and probably more cheaply) just by swapping out the movement rather than trouble-shooting and replacing parts as required. Thanks for the advice on testing the coil though – I’ll certainly follow that up.
True, some acrylic crystals can be hard to get back to a new finish but with experience and the right materials I can get most near perfect to the naked eye. No different from polishing car bodywork really 😉 The ones I’ve done were most bespoke crystals that would be impossible to find new.
Good news is new Sternkreuz crystals polish up very easily with isopropyl alcohol and a soft cloth. Even if you’re careful acrylic can pick up scuffs and scratches after a while so it’s useful skill to have.
In my experience the circuit or coil are rarely a problem unless there’s been a battery/water leak or the coil has been scratched. ETA’s from the 80s and 90s seems to be pretty bad now for sticky gear trains and I’d bet that’s the only issue.
I picked up an very early 955 recently (badged ESA-ETA) and it’s running fine… Just needed a splash of oil to solve a bouncy second hand. Pretty soon servicing and donors will be the only option when Swatch wind down supply 😦
If I had the time and patience I would write-up my projects because many people still have an irrational fear of quartz!
Well, I’ve measured a resistance across the coil with my multimeter which suggests that the coil is ok but no impulses from the output of the integrated circuit. The movement itself just looks far too clean for it to be a gummed up drive train. My reluctance to dabble more with quartz derives from the fact that I’m not prepared to invest in the proper testing equipment when I only very rarely buy anything other than mechanical watches.
I’ve only ever worked on three quartz watches, one of which was about 30 years old and just needed a new battery; one which I serviced but which then continued to throw up random electrical problems until I replaced the circuit and this one. The faults that integrated circuits present don’t provide me with any traction at all when it comes to providing a fix and it seems like cheating to just replace wholesale the heart of the movement. If I’m going to do that, I might as well just swap the whole movement. Of course what path you take depends on the watch and whether it’s something worth preserving in as close to its original form as you can. In this particular case, given it’s fate as the watch of a teenage boy, I suspect it’s got greater challenges ahead!
I think you’ve just had bad luck with your quartz experience. So far I’d say only 20% of mine (all 15 to 35 years old) have needed surgery and then only half of those needing a complete or partial donor.
Of course all my watches are for myself and if problems persist I can revisit them. If I was fixing up a ETA 955 powered watch for someone else I’d probably throw in a new Swiss-made Ronda 705/715 instead for about a third of the price, even if it means a stem swap.
Still, even replacing with genuine ETA this probably owes you a lot less than the £145 CWC charge for a new one, which doesn’t even have the appeal of having seen miltary service.
I was wondering if an ETA 955.102 will work as a replacement movement
As far as I can tell, the 955.102 is just the 955.122 without the calendar parts and so I would expect it to be a straight drop-in for either the 955.112 or 955.114.
Thanks for writing. I think I’ll try one in mine.
How exactly did you remove the old crystal? I’m having trouble on mine using a crsytal lifter. Thanks
It’s been a while since I did this one but as I recall, I think I just pushed it out from the rear. This does sometimes require quite a bit of force but I don’t remember it being a particular problem with this watch.
Very appreciative of your post on the CWC G10. My own area of interest is steam engines but I have a fondness for the simplicity of the CWC G10 and recently acquired a somewhat tired but functioning 1989 Royal Navy model similar to the one featured in your post. It has an ETA 955.114 movement . May I trouble you with a couple of questions?
1. The dial and movement of my watch are a bit wobbly presumably because both the tiny screws that fix the movement to the movement ring are missing! Do you know the size and type of screws I need to order to fix it?
2. One of your images suggests that a rubber gasket is fitted to the outside of the movement ring. Do you know its size?
If you can answer my queries it will be most helpful but if not, thanks again for the article. This is my first step away from hammers, spanners and oily rags and towards taking off the back of a watch.
I have a feeling I am not going to be particularly helpful but here goes:
1. Case screws: Cousins reports the part number as ETA9564015101 and they want a slightly outrageous £5.95 + VAT +delivery per screw. You might have better luck seeing what you can find on Ebay. I don’t know, for example, whether the screws designed for the 2824 would work but you can find packs of 25 for about a tenner.
2. Yes, there is a case back gasket but I am afraid I don’t know the dimensions. I suspect that information may be out there somewhere given the number of these watches in circulation but you could also try Silvermans.
Thanks for your speedy response. My online search for a parts list has so far been fruitless so the part number is most helpful. I often machine my own screws and fixtures but I admit to being defeated by the size of watch case screws!
Great article, I wonder whether you could give me some advice.
How did you remove the crown and stem from the watch?
Thanks in advance paul
Hi Paul, I’m away at the moment but should be able to reply in a week or so.
Have a great time
Harry overton said:
I have an early 83 g10
Which I had serviced back in the 90s .
The guy that did it neglected to tell me that he had sustituted the movement with a cheap £1 unit .
By the time I realised he had moved shop .
My question is can a put a later movement in the old case ?
It is known as the fat boy .
I believe that your watch will originally have been fitted with an ESA 536.121. As far as replacements are concerned your options are limited to the following:
1) Locate another 536.121
2) Fit an ISA 1198/103
3) Convert it to an automatic and fit a, ETA 2836-2.
Option 1) is not out of the question. In the past I have seen NOS movements for sale on Ebay but not recently. You might alternatively source a movement from a scrap watch and have it serviced. I’ve written about this movement in the past here.
Option 2) may well be the route your previous watchmaker took although the ISA is not a £1 unit but probably closer to £15. The only problem with this option is that the seconds hand post is slightly smaller than on the 536.121 and so you may need to crimp the tube or source an alternative seconds hand.
3) Option three would work but probably be by far the most expensive option and again would compromise the original specification of the watch. I made a post recently about just such a conversion.
There may be other options but this is the extent of my knowledge currently.
Best of luck!
Steve Moore said:
Something of a fan of your blogs, in particular Seikos but looking for a CWC G10 ‘basket case’ for a little modding. In particular, I fancy dropping in a Seiko Auto movement (as they’re plentiful, generally pretty accurate and fairly robust ).
Any thoughts on a Seiko movement candidate for the CWC G10 case/movement swap)
Hi Steve, these were designed around Swiss quartz movements and the later ones will have been much thinner than your typical Seiko auto. I think you would struggle to get something one to fit and to be honest. It is not something I would contemplate.
Steve Moore said:
OK. Thanks for that Martin.
I might do some homework on sizes, just to see if it’s possible.
Thanks for the reply and keep up the good work in the blog.
You’ll need to consider not just the ligne but also stem height and the overall depth of the movement (to ensure that the rotor clears the case back). You’ll also need to consider how the movement will be secured in the case – i.e. what sort of case ring you would use.
Steve Moore said:
If I make any meaningful progress, I’ll report back.
Steve Moore said:
How do I contact you about looking at a Orient King Diver GS 469620 7C PT for me?
Hi Steve, I’m afraid that I don’t take on work for others. I’m not a professional watchmaker and just don’t have the time or indeed inclination to take in work. Sorry!
Steve Moore said:
OK, thanks for the response.
Keep up the good work on the blog!
Thanks and regards,
Steve Moore said:
Just picked up a CWC G10 (working) off that auction site, but it doesn’t have a crown.
Any ideas for an obvious screw down replacement?
Hi Steve, a screw down crown would require a replacement case tube which then throws up other logistical considerations. I would not be inclined to follow that path myself. Have you tried contacting Silvermans to see if they might supply a replacement crown?
Dave Barnes. said:
Hi Martin, cwc g10 related.. If 0552 relates to Royal Navy,, what are the codes for Royal Air Force and British Army,thanks ,Dave ..
I am no expert, but I believe W10 is British Army, 0552 Royal Navy, 0555 Royal Marines and 6BB Royal Airforce.
Dave Barnes. said:
Thanks very much Martin,i will quote this to a well known London supplier , see what they can supply. I may have to bother you again, thanks.
Ok, im a bit late commenting 3years after the article was written, but…
Just out of curiosity, have you ever heard of an ETA 955.411 being used in a cwc g10?
Picked up an impulse eBay buy, no description/blurry photo, but less than £40.
Turned out to be a 1984 issued Cwc “medium fatboy”, which id assumed would have the same ETA movement as most of my others (i’ve got a few, including an 84 precista model and a couple of mid 90s CWCs, all use the ETA 955.102 or 955.112 movements).
It doesn’t appear to ever have had a movement change, even if it had, the 955.411 was only around from 79-86 so it’s an odd choice if it was a movement swap.
Just a bit of a mystery…
I am no expert on these watches but the 955.411 is not a direct replacement for the 955.114 as the former is 10.5 ligne and the latter 11.5. If there an additional movement spacer in your watch, then it may be that the 955.411 was used as a substitute at some point but I can find no references to CWC’s being fitted with this movement in a quick dip into Google this morning.
Bill Lewsey said:
I have just won a cwc g10 on e bay and in the description it says that the hands jump to 1:45 when the crown is pushed in. Easy fix or new movement??
Bill, I can think of no reason why the hands should jump to the same position each time. If there is some slack in the setting train, then you might expect some movement of the hands when you push in the crown. If the hands are not properly secured onto their posts then they might also jump when receiving the shock of the setting click but if this were the problem then they would not retain their correct alignment with respect to each other. If the movement otherwise works, then I would have thought a watchmaker could correct any problems without the need to replace the movement.
Bill Lewsey said:
Thank you Martin
I have the watch in my hands and I cannot reproduce the fault. Maybe the postman fixed it in the sorting office! Lol
Glad to hear it!
In your post, you mentioned that the UK country code is 99, can you provide a reference? Cause I could not find it. Thanks.
There are numerous references, one of which, inevitably being Wikipedia: https://en.wikipedia.org/wiki/National_Codification_Bureau
I recently obtained a pretty knackered g10 and the case tube appears to be missing. This is my first foray into watch repair and I’m a little bit stumped as how to choose from the myriad tubes available. Any help as to which one to go for would be much appreciated. Hours of googling has not thrown up anything useful as yet…
The rest of the g10 article is extremely helpful and gives me a clear path to follow though, so thank you!
That’s a tricky one. In the absence of a tube from which to take dimensions, you’ll have to measure the diameter of the hole and estimate the length you’ll need. Alternatively, you could try contacting Silvermans either for the part or for dimensions. Sorry not to be of more help.
Hi again Martin,
I’ve now managed to get hold of a case with its tube… can you by any chance guide me towards what size crown I’ll need to order? Cousins list swiss/italian, long tube/short tube which once again leaves me stumped. I’ve tried to measure the space but don’t want to order the wrong diameter/width…
Hi Joe, you’ll need to measure the tube diameter and make sure that the width of the crown is narrow enough to clear the case crown guards. Looking at the photos on my blog, I would guess you’ll want a regular short pipe Swiss/Italian from Cousins selection but you’ll need also to check the stem tap. Lots of room for error and it may be inevitable that you end up having to buy more than one. Did you try Silverman’s to see if they can supply a correct replacement crown?
Billy Ray said:
Wonderful post! I have exactly the same G10 and am resurrecting it so I have something to wear while my tudor goes in for a service soon. Thanks for the inspiration. I’m also going to try and clean up the crystal. Great watch to give a 14 year old. Almost makes me wish I had children! I hope he liked it!?
He did but like most teen-agers, has got out of the habit of wearing a watch. So it sits quietly ticking away on his bedside table.
Great review. I bought a CWC G10 1991 from a local jeweller to temporarily replace my Rolex while being serviced. The Rolex stays in the drawer as I love the simplicity of the G10 (and accuracy). It’s just gone exactly 1 minute slow (pips still match on the radio but 12.59 rather than 13.00 on the watch. Everything working normally. Stumped – any ideas?
It sounds like you are suggesting that the seconds stays synched whilst the minute hand has drifted. This could just be some backlash being taken up from when you set the watch or it could be that it has lost/gained a minute over some period of time. You would expect a quartz to be able to keep time to a few seconds per month but you don’t say over what period the drift has occurred.
No drift. It changed and lost an exact minute between evening and next lunchtime. I normally subconsciously check the ‘pips’ on the radio. Perfect time evening before, to the second, then at 1pm next day, minute is exactly 1 minute behind, second hand spot on to the pips. Bizarre and hasn’t happened since. Time had not been adjusted on the watch since BST 25th March.
NICK BATES said:
i came across your blog just by chance and a great read it is.
I have to ask have you ever tried to renew the watches “Tritium”, lume or do know of anybody that has?
My G10 is an offset 84 battery case version who´s lume is all but dead, which is to be expected.
I wondered, as the “Tritium”, breaks down and crumbles (especially on the hands) with the passage of time, if it is safe to handle and is it restore able and if “Luminova”,paint be a good or better option.
I´d appreciate your thoughts
My understanding is that tritium paint may be a restricted material now and it is probably highly unlikely that anyone is either luming or reluming dials with tritium paint. The more pragmatic approach to selective repairing of tritium lume is to attempt to colour match with a non-luminous compound mixed in a matt binder. You can also undertake complete relumes with tinted luminova paint but the results can be very variable. My rule of thumb is don’t relume unless the lume is badly contaminated with mold or oxidation or generally detracts from the appearance of the watch. And if you have to relume, make sure you get it done by someone who really knows what they are doing. There are lots of very poor relumes out there. If you take a wander through this blog you will see examples of where I have relumed dials and hands myself and others where I’ve sent them off to third party relumers. The latter experiences have been variable; some very good, others disastrous. Good luck!
Hi, the movement how to out of the case
The case back is press fit and so just levers off. Press the setting lever button to remove the crown and then the case ring and movement.
Daniel Stewart said:
Would you possibly be able to describe what to look for to get the crown and stem out of the movement?
The setting lever button is the one adjacent to the arrow on the circuit. You press that in whilst pulling the crown and it should just slide out. Once the crown is out, the movement will drop out with the case inverted.
Daniel Stewart said:
Got it! Thank you so much. I didn’t think to look on the blue circuit.
I just wanted to thank you for this blog. I was issued a G10 in 1990 and broke it in 1997 (some of the North Sea got in!)
I have successfully replaced the movement and it lives again. My son is looking forward to inheriting it!
Just one question, and I apologise if it has been asked before, where can I get a new dial or the original re-finished please?
Thank you once again sgt (rtrd) Mat T.
Hi Matthew, I’m glad it’s been helpful for you. I can’t help you with a dial replacement other perhaps than to suggest you try approaching Silverman’s.
Martin Combes said:
Hi Martin I’ve got a G10 watch that was issued to me in 1989 new , it stopped about 6 months ago , I was on the verg of chucking it in the bin but was told that I could get new movement . I’ve read your bit about doing it but it’s not something I could do . Can you give me some ideas of who I could get in touch with to get it fixed.
Thanks , Martin Combes.
Hi Martin, if you are in the UK, then you might try Richard Askham. He is contactable through his blog, thewatchspotblog.com. Whatever you do though, don’t chuck it in the bin!
Hi Martin, I wonder if you could help me,
I have a 1982 CWC G10 with a faulty ESA 536,121 I purchased a ETA 955,112 to swap the movements, all went well until it came to fitting the hands the 955,112 hand size = 120,70,20 but the hands from the 536,121 are a lot bigger “hole size”
Also I have a CWC from 1983 with the ETA 947,111 this watch works well, the hand hole seizes are the same as the 536.. i have looked on ebay and the hands listed as CWC G10 hands don’t look right,
Can you help with any suggestions or info on if i am able to purchase proper G 10 hands size 120,70,20
Any help would be great, thank you sir.
Very best regards Peter.
Hi Peter, I’m afraid I have no experience sourcing correct hands for CWC G10s and no leads to offer. The CWC hands that I can see on eBay are not the correct style or finish and look to be very poor quality. My only suggestion would be to see if you can get anywhere with Silvermans. Sorry not to be of greater assistance.
Thank you Martin, much appreciated, all the best to you sir.
Ask on mwrforum