Around 1960, Tissot launched a tiny handwound movement series for ladies’ watches with a diameter of only 6 3⁄4 lignes (15.1mm). It was produced several years and got two subsequent versions. This was the Tissot 709 series and the Tissot 709-2 described here was the last modification of the base movement Tissot 709.Video on YouTube
It is a contemporary construction with a directly driven center minute wheel. The round shape of the plates made it possible to use a relatively large screw-less ring balance.
Unlike is predecessors, the Tissot 709-2 no longer uses a KIF Duofix bearing for the escapement wheel, but only a standard jewel. The seventeenth jewel is now used as bearing for the minute wheel on the dial side. You can see this jewel on the photo below - it’s the smallest ruby in the movement, located near est to the center.
The screw-less ring balance, which is beared in two Incabloc shock protection bearings beats with no longer top modern 19800 A/h and controls a conventional swiss pallet lever escapement.
On the dial side, you can easily spot the second Incabloc bearing of the balance, as well, as the yoke winding system with its setting lever spring.
The minute wheel (at 4:30) has got four holes, which allows oling of the underlying driving wheel without dismounting and it is beared in a ruby.
The changes to the Tissot 709-1 are, besides the now ruby-beared minute wheel with its own pivot, a slightly changed setting lever spring, larger cutouts on the dial side for the mainspring barrel, a smaller cutout for the setting yoke and the missing KIF Duofix bearing for the escapement wheel.
|Number of jewels:||17|
Nickel anular balance|
|Balance bearing / direction hairspring:||Clockwise|
|Adjust mechanism:||Long regulator arm|
|Construction type:||solid construction|
|Winding mechanism:||yoke winding system|
|Setting lever spring:||2 hole(s)|
|Size:||6 3/4''' (measured: 15,3mm)|
Flume: K3 -|