7750 History & All official references.
The Valjoux 7750 (Valjoux= Vallée de Joux) is the most famous caliber, the most prevalent automatic chrono in Swiss watchmaking.
Sometimes compared to the Kalashnikov , because of its hardiness, its reliability, the number of its variations and of its low cost.
In 1969, Zenith presents the first automatic chronograph, the «El Primero», and even though the threat of quartz starts to hover, the announcement has the effect of a sensation. The competitive version of micro-rotor automatic chrono from Heuer/Breitling/Buren is not yet ready for the market…
The chrono from Zenith features a major double innovation: high frequency and automatic winding on a chronograph. «Ebauche SA», the previous name of Valjoux, regards this novelty with interest and launches the development of its own automatic movement.
The company chooses a young watchmaker to lead the project, Edmond Capt.
He will draw his inspiration from the 7733 caliber, the manual chrono from Ebauche SA, the rumor has it that, for the conception, he would have used management’s computer, the only one available at Ebauche SA.
Two years later, the 7750 is ready, immediately more rustic than an «El Primero», Ebauche SA made basic technological choices in order to reduce production and maintenance costs.
It translates into a lower frequency and into an inferior level of execution.
The caliber is released in 1973, with a jewelling of 17 rubies and 2 frequencies available, 21600v/h and 28800v/h. It is barely distributed, and because of the financial and commercial struggle induced by the success of Japanese quarts. the production of the 7750 is halted.
Nonetheless, Ebauche SA keeps the machine-tools necessary to manufacture the 7750.
At the beginning of the 80’s, the demand for mechanical automatic chronographs increased. The industrial production of the 7750 really started; That’s the reason why most of the variations were commissioned during the 80’s.
Most of time, it will be more jeweled than the initial model, with 25 rubies, and systematically set to 28800v/h.
Nowadays, the 7750 is a best-seller, it has powered watches amongst the most beautiful and interesting of the market. However, because of its modest origins and its large diffusion, it is despised by collectors.
This caliber is ridden with flaws, such as a prohibitive thickness (the manual version, 776x, enables a gain of 1.55mm in the rotor thickness), frequent rotor failures leaving the user with a manual winding system prone to induce arthritis, and a frequency ill adapted for a chronograph.
Regardless, it is relatively sturdy and reliable, (and doesn’t have serious competitors) and therefore was fitted in many of the chronographs produced, starting in the early 80’s.
We won’t be snobby, it is an entertaining caliber, which makes the automatic winding a noisy and convivial daily experience.
Here are the technical features of the initial version, 775-0
Diameter: 30mm (13 lines 1/2)
Thickness: 7.9mm
Jeweling: 17 or 25 Rubies.
Cam set off chronograph.
28800 v/h, 44h of P.res. (in average).
Tricompax chrono, 6-9-12, with date à 3 o’clock.
Valjoux 7750 (Since 1973) The chrono 6-9-12 with date à 3 o’clock.
Valjoux 7751 (Since 1986) Triple date (date, jour, mois)
Valjoux 7752 (Since ????) Extra GMT hand
Valjoux 7753 (Since 2002) 3-6-9 configuration, date switching at 10 o’clock.
Valjoux 7754 (Depuis 2003) Second hour hand on 24h.
Valjoux 7755 (1978-????) Amputation of the hours counter, no day disk (but yet with date).
Valjoux 7757 (1985-2003) Countdown function for boat racing.
Valjoux 7758 (1985-2003) Moon phases at 6 o’clock, replacing the hours counter.
Valjoux 7760 (1985-2005) Manual version of the 7750.
Valjoux 7761 (1986-1998) Manual version of the 7751.
Valjoux 7765 (1978-1998) Manual 7760 without the counter at 6 o’clock...
Valjoux 7768 (1985-1998) Manual version of the 7758.
Valjoux 7770 (Since 2002) 7750 integrated split-seconds.
Valgranges A07.111 (Since 2005) Three hands, 37mm, date.
Valgranges A07.161 (Since 2005) Three hands, 37mm, date, P.res indicator.
Valgranges A07.171 (Since 2005) Three hands, 37mm, date, GMT.
Valgranges A07.211 (Since 2005) Chronograph, 37mm.