Seiko 7A38 - by the numbers



Post Reply
Forum Home > Parts Info, Tech Tips and Tinkering > Yema N7 / N8 (Spationaute III etc.) specific case-back tool anybody ?

Site Owner
Posts: 9954

I suspect most of us who change their own batteries in Seiko 7Axx's are quite happy (and reasonably competent) with the Jaxa (copy) 3-prong adjustable screw-down case-back opener. If you haven't already got one, then I strongly recommend you do. They can be picked up on eBay for around a Fiver, and once you've done your first couple of battery changes, the thing will have paid for itself - compared to the Fiver a time (minimum) charged by most high street jewellers.

But what about Yema N7's and N8's ? Not so easy. Sometimes you can get them undone with a 'Sticky Ball' - but not always.

Whereas Jaxa tools can be used, the various pins they usually come supplied with aren't the right size for Yema case-backs:

I saw Bry listing variations of his case-back tool on eBay a few months ago:

That particular tool is meant for use on Seiko 6119-xxxx case-backs. Yet those watches have 6 rectangular slots around the periphery of the case-back (the same as on Seiko 7Axx's). So I had my doubts about how well such a tool might work. But it did give me an idea.

So I've been talking to Bry, and yesterday gave him the dimensions: 6 pins - 1.85mm diameter on a 24.5mm P.C.D..

Anybody who's recently purchased a Spationaute III interested ? 

April 8, 2013 at 12:58 PM Flag Quote & Reply

Site Owner
Posts: 9954

5 years on from my original post, we may finally have got a step closer. :)

Earlier today, this came up in my saved eBay favourite search notifications:

I notice Bry is also now listing a dozen other variations of his tool for other watches.

I personally now own over two dozen Yema Spationaute III and N8 Flygrafs, plus numerous other various assorted Yema N8 models, like the dressy N81W63 (which springs to mind) that could certainly benefit from such a tool, specifically designed to fit the Yema 6-hole case-back. Hint. ;)

April 16, 2018 at 4:25 PM Flag Quote & Reply

You must login to post.