I’ve been looking out for the date version of the 0840 Cosmotron since I hadn’t previously found an example – designated the 4840, models with this movement were launched in 1970 and run at 21,600 beats per hour. Since my funds were limited,  I took a punt on a ‘junk’ model on Yahoo Japan, especially because it has the date window at the more unusual 6 o’clock position. Described as not working, even after a battery change, it also had a damaged crystal. After checking that a new crystal was still available, and knowing that I could get it looked at at a later date by Paul at ‘Electric Watches’ I nabbed it, the only bidder, at just ¥1,800 – about £10 ($15). So not a huge loss if it were to prove beyond rescue. On arrival I could see that the dial and hands were in good condition – the hands are an unusual ‘see through’ frame design:

The cracked glass and wear to the case show it has been well used – the case also shows evidence of an original brushed finish.  But the dial and hands are nice:

I have found before that it is always worth trying a new battery even when a seller has already tried one. Here’s a shot of the 12 jewel movement, which thankfully appeared to be in clean condition, with new battery installed:

And to my delight it fired up! 🙂  Not only did it start to run, but it also keeps good time, and the date change works just fine. So this was turning into a bargain – and a new acrylic crystal made specifically for this model was soon ordered, again at little cost. The damage to the old crystal is even more obvious with the movement removed:

There’s no guarantee that crystals are still available, but Sternkreuz still stock one for this model:

This is a compression fit crystal, and fits directly into the case without a bezel. I’ve not fitted one like this before, so the ‘crack’ as the press located it in place was a bit unnerving! But all was well:

I cleaned and very lightly polished the case to revive it a little, and after re-installing the movement, here’s the result:

The case back is good condition, and shows a production date of April 1970:

So, the gamble in buying a ‘junk’ watch has paid off – always a nice feeling 🙂