I have a soft spot for the Cosmotrons – these were electro-mechanical hybrid watches with a limited production life since their new technology was almost immediately superseded by quartz technology. The fact that they were doomed almost from day one seems a good reason to collect a few! 🙂
I also realised that I don’t have many square, or square-ish watches so a ‘tank’ case Cosmotron was a nice find:
This one, from 1973, is on a good solid link bracelet, and since it has a chunky case it has a nice heft about it. It’s also a Cosmotron ‘Special’ with a button at 8 o’clock which zeros the second hand – it also zeros the minute hand when close to the 12 o’clock position. See this video of another model with this movement:
The bracelet is in good condition (the same design can be seen on some of the Challenge Timer Chronographs) and is just the right size for me. Time keeping is very good from this 36,000 beats per hour movement , requiring no adjustment over a week or so 🙂
I have 2 new citizen Cosmotron for sale
Hi Kevin, thanks for visiting my blog. No sales are done here though I’m afraid.
Hi sweephand- I have a 7801A and was wondering about the balance adjustment. Do you simply turn the screw or do you move one of the arms? If it’s the screw do you know how many seconds one notch is? Sorry to post this here I wasnt sure how to contact you via a new post. Thanks
Actually my mistake, there are no lines near the + or – …..
Hi Jeff, thanks for visiting my blog. No problem about using ‘comments’ for your question, it’s the best way in fact since only I can create posts. The screw on the balance:
This screw is a fine adjuster typically used on high beat watches – the 78 Cosmotrons run at 36,000 beat per hour – which are capable of being finely tuned for very accurate time-keeping. Only a small movement of the screw will adjust by a few seconds or even less if you move it very carefully once the watch is already running fairly accurately. I can’t say that a certain amount of movement results in x amount of seconds – it’s a case of trial and error, so can require patience if you want to get very accurate timing. If your watch is currently running minutes out, say more than 2 minutes, then this adjuster is unlikely to provide enough adjustment, and I’d recommend getting the watch serviced first to make sure it is clean, oiled and checked for worn parts, so that it is in the best possible condition to get the most accurate time-keeping.
Thanks for the response Stephen. I suppose Iâll turn the screw all the way in one direction and then all the way the other direction, compare the results, then adjust accordingly. I have 6 Cosmotrons and they are among my favorite electronic watches. All except 1 are accurate and I havenât had to adjust until now.
Someday Iâd like one of those IC-12âs with the 5800 movement or a GX with the 3701B movement. The Hisonics are too expensive!
You’re welcome Jeff – nice to hear you have a few Cosmotrons, I’ve got a soft spot for them. I can’t remember seeing an IC12 model for sale, but it’s possible to find other models with the 5800 movement. I got hold of two, and they weren’t too expensive – see here: https://sweep-hand.org/2011/09/21/this-weeks-featured-watch-14-the-cosmotron-5800/.
Cool. I’ll be keeping a lookout for those 5800’s, and maybe some of those 36000bph models listed on your movement table. Nice site.
Thanks Jeff – good luck with your search 🙂
I recently acquired an cosmotron 7804 with movement inside but it little too fast so i try to fine tune it but without knowledge i accidently moving the hand instead of the screw, i managed to slow it down to -19s/d but now it have pretty bad beat error, is there any chance or advice for me that i can undo my mistake, i’m pretty much screw rn
Hi Binh Nguyen, sorry for my slow reply. I’m afraid I can’t help much – I’m not a watchmaker, and I’ve never tried to adjust the timing/beat on a Cosmotron. You’ve no doubt tried to carefully return the part you’ve moved on the adjuster to where it was before, and then tried to adjust accuracy using the fine adjuster. Other than that I can only suggest taking it to a reputable watchmaker if you know of anyone local to you for advice or a fix. This pic of the movement and might help to get it back to where it should be: