ETA/Valjoux Caliber A05.231

The ETA/Valjoux caliber A05.231 is an automatic bi-compax chronograph with 29 jewels.

In July 2022, Swatch Group made an announcement that the Tissot Telemeter 1938 would be powered by the ETA/Valjoux caliber A05.231.

“An Upgraded Movement: Tissot has chosen the Telemeter 1938 to house the newly upgraded Valjoux A05.231 automatic chronograph calibre. This is now equipped with a highly durable Nivachron balance spring and an extended 68-hour power reserve. It’s finished off with a new Tissot Heritage rotor design.” -Tissot Press Release: Relive the glory days of sports timekeeping with the stylish new Tissot Telemeter 1938 (source)

Editor’s Comments: The way Swatch Group is handling some of their marketing is interesting. Most enthusiasts already know that ETA is owned and operated by the Swatch Group conglomerate, and most know about the ties between Valjoux and ETA. By now, it is widely known that ETA movements are no longer for sale to non-Swatch Group brands. With this almost universal knowledge in the watch community, it is understandable that Swatch Group brands like Tissot are keeping the ETA branding and caliber numbers, rather than designating their own individually – as they did in the past. This decision seems to be a good marketing play for the group since it will strengthen all of the brands under the umbrella, and also does not limit them in terms of cross-brand usage and cross-brand sales/service training. But, what is especially interesting with the A05.231 is that Tissot specifically refers to it as a “Valjoux” caliber. This is a new direction from what we’ve seen in recent years where ETA strayed away from referencing anything as Valjoux, weaning away from the Valjoux Rohwerke “R” stamp in the late 1980s. Valjoux, along with a list of other companies was absorbed into ETA around 1944, and is associated with historical chronograph movements. The company was the designer of the 7750, and other calibers found in models like the Rolex Daytona, etc. However, to most collectors who entered the market in the past decade or two, Valjoux movements like the 7750 has largely become known as the “ETA 7750”, because that is how Swatch Group brands started marketing them. With the emergence of the Valjoux caliber A05.231, it is as if the Swatch Group aims to revive the Valjoux name (even though the movement is still stamped with ETA). This marketing move may help part of the community get past any animosity for the ETA name and feel good about buying a timepiece with an engine carrying the name of a legendary mechanical chronograph movement maker.  Let’s see what other “Valjoux” calibers will be released!

How to regulate the A05.231?

You don’t. You have a Swatch certified watchmaker do it for you. At least, that is what they are hoping for. Even more, they are hoping your watch just won’t need regualted before your next overhaul. The A05.231 (and other A05 calibres) doesn’t have an easily adjustable ETACHRON style regulator system. It has a variable interia balance with screws on the spokes of the balance wheel. To make adjustments, the screws need to be adjusted in a matching, asymmetrical fashion.

Additional Resources:

• Official Tissot Telemeter user manual (pdf)