The Creation of the Valjoux/ETA 7750

How a young team headed by a 24-year-old Edmond Capt pulled off a technological coup in that resulted in the Valjoux/ETA 7750 that still powers many of today’s automatic chronographs, nearly 50 years after its introduction.

From its introduction in the 1970s, the ETA/Valjoux 7750 is the most ubiquitous self-winding chronograph movement beloved of brands across a whole spectrum of price segments. How did the 7750 come to enjoy such broad acceptance? For starters, it worked, and it was engineered from the beginning to be practical, robust, and optimised for mass production at (relatively) low cost — exactly what the watch industry still reeling from the ravages of the Quartz Crisis needed to win back the consumer.

In retrospect, it seems both courageous and downright lucky that Valjoux, the ébauche manufacturer in the Vallée de Joux, decided to develop another mechanical chronograph movement simultaneously with Seiko’s cal. 6139, Zenith’s El Primero, Breitling-Heuer-Hamilton’s Caliber 11 and Lémania/Omega’s cal. 1040. A successful blend of tradition and innovation, the cal. 7750 also boasts an excellent cost-benefit ratio. Launched in 1973, this caliber was created during a difficult epoch when it seemed as though horological tradition was flourishing for one final time before it vanished into obsolescence.

Heuer Kentucky, one of the first to use the Valjoux 7750
Heuer Kentucky, one of the first to use the Valjoux 7750

Back to the Basics

Anyone who wants to launch something fundamentally new has no other choice but to rethink things. In 1970, this must have crossed the minds of the young people on the developmental team led by then 24-year-old movement specialist Edmond Capt.

Capt and his team had been asked to develop an unprecedentedly slim movement with an extremely small diameter. Valjoux had its sights set on creating a genuine horological superlative, so Capt’s team strove to invent a reliable ticking microcosm that would be able to succeed on the watch market during this turbulent era.

What gradually took shape during three years of developmental work was visibly different from every preceding caliber. Components for an affordably priced caliber that could sell to a wide range of potential customers had to be produced mostly by automated machinery, and the caliber had to be simple enough for trainees to assemble.

The laborious refitting and fine adjustment that were almost always required by classical chronographs built between the 1920s and the early 1940s, had to be preempted. This meant revising the features of the basic subassemblies that had been used in 14-ligne calibers from the Valjoux cal. 7730 to the cal. 7736. All of these traced their ancestry to the Venus cal. 188. Established in 1924, Venus was acquired by Ebauches SA in 1928, with Valjoux joining the ranks in 1944. Therefore, when Venus terminated independent operations circa 1967, Valjoux inherited the Venus cal. 188 from its sister company.

Venus cal. 188
Venus cal. 188

Each of the abovementioned hand-wound movements was an economy-class chronograph with a one-piece switching coulisse. Each relied on horizontal gear-coupling to connect the stopwatch mechanism with the movement per se. Valjoux now sacrificed this switching component on the altar of less costly engineering and cheaper production. The future would take direction from the past — specifically, the key to Valjoux’s new movement was to be a rocking pinion that Edouard Heuer, as part of his effort to develop a “perfected chronograph”, had invented and patented in 1887. His mechanism featured a mobile arbor with two pinions. The pinion on the dial-side engages with the movement’s fourth wheel. The opposite pinion responds to manual pressure on the start button by moving through a small arc and meshing with the chronograph’s center wheel, thus creating the connection that puts the chronograph in motion. Pressing the button a second time causes the rocking pinion to move away from the chronograph’s center wheel, thus halting the elapsed-time hands. Not only is this architecture simpler, it also reduces the overall mass, which can be beneficial when the watch suffers a severe impact.

Mobile pinion patented by Edouard Heuer
Mobile pinion patented by Edouard Heuer

Naturally, the economizing to which Valjoux subjected the cal. 7750 was not entirely without negative consequences. Even a layman can quickly spot the differences between a classical column-wheel movement and this mechanism, which has straightforward stamped components and simple wire springs. Comparing the Valjoux cal. 7750 with one of its contemporaries, Zenith’s El Primero, likewise speaks volumes. For example, cutting cost led to the use of a plastic ring for the bushing of the chronograph center wheel, as well as the inclusion of very simple blocking and jumper springs. Everything functioned impeccably, but there was nothing here that would send mechanical voyeurs into paroxysms of ecstasy.

Zenith El Primero
Zenith El Primero
ETA/Valjoux 7750
ETA/Valjoux 7750

A Working Proposition

Beauty and appealing aesthetics ranked low on the list of priorities, but the caliber’s developers took great pains to ensure that this new movement would function properly. Computers and software to design and engineer watch components were rare and exotic in the early 1970s. The only person at Valjoux who had a computer was the technical director, and he guarded it fiercely. This miraculous mechanical brain stood in Neuchâtel, where Edmond Capt regularly went after having accepted his new job. Though this computer was rudimentary by today’s standards, Capt could use it to digitize technical drawings and to simulate kinetic and functional sequences.

The 7750 was one of the earliest movements to be designed with the aid of a computer; today, movement design without one is inconceivable (Image: FHH)
The 7750 was one of the earliest movements to be designed with the aid of a computer; today, movement design without one is inconceivable (Image: FHH)

A dyed-in-the-wool son of the Vallée de Joux, Capt had studied watch engineering. “Combiers”, a term for the inhabitants of the valley, like Capt, zealously love their homeland, so he was eager to return after having completed his training and spending a year at Rolex. It was lucky for him that Valjoux SA, which had long delivered chronograph ébauches to Rolex for their Daytona timepiece, offered him a job in Les Bioux. Capt, an ambitious technician, eagerly accepted it because he welcomed the challenge of speedily developing an affordable self-winding chronograph that could be manufactured in large series. This task was comparable to squaring the proverbial circle, but that too didn’t deter him.

Capt worked entirely alone at first, but the existing base (Valjoux’s hand-wound cal. 7733) stubbornly resisted his attempts to add an automatic-winding subassembly to its rearward side. Kinetic energy had to be conveyed from the oscillating weight to the barrel, but the pathway for the necessary gear-train was obstructed by the chronograph’s indispensable components. Capt’s peers at Breitling, Büren, Heuer, Dubois-Dépraz, Seiko and Zenith had already suffered similar frustrations in the late 1960s. The conundrum seemed unsolvable unless a new and totally different approach could be invented.

To propel this project toward its goal, Valjoux took Gérald Gander on board in 1970. Gander had distinguished himself in a course that Edmond Capt had taught at the school of watchmaking in Vallée de Joux. Donald Rochat was chosen as the team’s third member. A technical draftswoman and a watchmaker completed the ambitious and industrious squad.

A Multilayered Synthesis of the Arts

Subassemblies were gradually created for a caliber that is deservedly celebrated today under the name “Valjoux 7750”. A side view of this opus, which is fully 7.9mm tall and accordingly cannot be described as slim, reveals that despite its integrated construction, the architecture is like a sandwich. A knowledgeable observer can distinguish three or even four strata: one layer is above the mainplate on the dial-side and two strata are in the rear beneath the plate, which bears the entire burden. The caliber’s diameter is 13 lignes, which is equivalent to 30mm. Approximately 250 components form the basic version of this synthesis of the horological arts.

Side profile of 7750
Side profile of 7750

The Mainplate

The back of the mainplate bears the gear train, the barrel, the escapement, and a balance beating at 4Hz (28,800vph). The first edition relied on Valjoux’s system to regulate the rate by altering the active length of the flat Nivarox balance spring, but the contemporary version uses the Etachron system common to ETA movements. The balance can be halted, which makes it easier to set the time with to-the-second precision. This caliber is an example of Lépine construction, so the continually running seconds hand at nine o’clock is diametrically opposite the crown. The mainspring stores sufficient energy to keep the watch running for approximately 45 hours, but the chronograph saps energy from the mainspring; so, the exact duration of the power reserve depends on how often and how long the stopwatch mechanism is activated.

In the conventional manner, the front side of the mainplate hosts the gear systems to power and set the hands, along with the manual-winding mechanism.

The Etachron regulation system, with its instantly recognizable oblong adjustment pins
The Etachron regulation system, with its instantly recognizable oblong adjustment pins
The Etachron regulation system, with its instantly recognizable oblong adjustment pins

Date and Day of the Week

The basic version of the cal. 7750 has semi-instantaneous digital date and day-of-the-week indicators that can be rapidly reset via the crown. The date plate can be removed from the front of the plate by removing three screws. This brings part of the underlying chronograph into view.

The basic version of the cal. 7750 has semi-instantaneous digital date and day-of-the-week indicators that can be rapidly reset via the crown

The Chronograph

Capt and his team positioned the chronograph hour-accumulating wheel (driven directly by the barrel) on the front. The rearward pivot of the staff on the counter’s hand turns inside a hole drilled into the plate. The designers chose not to put a jewel here because the pivot rotates only occasionally, and moves quite slowly when it does turn. A layman might overlook the lever that blocks the elapsed-hours counter when the stopwatch function is halted. Originally made of white plastic, this lever is surely not a sight for sore eyes, but neither is it a disadvantage from a technical viewpoint. Plastic serves the blocking lever’s purpose here and also puts less lateral pressure on the pivots of the chronograph hour-accumulating wheel than a harder metal lever would. This plastic component presses against the teeth of the hour-accumulating wheel, braking it. A slipping clutch on the arbor allows the brake to engage while the gear in contact with the barrel continues to turn. For aesthetic reasons and probably also in response to customers’ requests, a metal counterpart replaced the plastic lever in the mid 1990s, when ETA also increased the number of jewels from 17 to 25.

The chronograph hour wheel and its plastic blocking lever, indicated by a red arrow
The chronograph hour wheel and its plastic blocking lever, indicated by a red arrow
The chronograph hour wheel is set in an unjeweled hole and driven by a pinion on the barrel arbor, as indicated by the red arrow
The chronograph hour wheel is set in an unjeweled hole and driven by a pinion on the barrel arbor, as indicated by the red arrow

The chronograph’s switching mechanism is on the back, but it cannot be examined until the automatic-winding subassembly has been removed.

The stopwatch is operated via two push-pieces: the button at the two o’clock position starts and stops the chronograph; its companion at four o’clock returns the elapsed-time hands to zero. This facilitates additive stopping, that is, measuring several successive intervals. As is also true elsewhere throughout this caliber, the beholder cannot expect to encounter breathtaking beauty. Flat stamped components predominate. The chronograph’s three functions are controlled by the swing of a layered switching cam, which is comparatively inexpensive to manufacture. This component alternately creates and severs the connection between the movement and the chronograph, which can measure elapsed intervals to the nearest eighth of a second.

The chronograph switching cam
The chronograph switching cam

For reasons related to the caliber’s construction, the designers positioned the two elapsed-time counters (one for 30 minutes and the other for 12 hours) along a vertical axis. This created the typical cal. 7750 look, which was later imitated by other competitors. The zero-return mechanism is based on a concept patented by the watchmaker Henri Jacot-Guyot in 1941.

Chronograph running
Chronograph running
Chronograph stopped
Chronograph stopped

Automatic Winding

A bare minimum of components form the self-winding subassembly, which three screws affix at the top in the rear. Kinetic energy from the rotor, which is mounted on ball bearings, is transferred to the barrel via a ratchet wheel and a reduction gear. The rotor conveys energy in only one of its two directions of rotation. This doesn’t adversely affect its efficiency, but it does allow the oscillating mass and its outer heavy metal segment to sometimes whirl in their idling direction like a turbine — very speedily and with a noise that’s impossible to ignore.

On the Way to Hegemony

Success is the reward of the diligent, and this was first apparent in 1972, after the trials, errors and frustrations of previous years. More than once, a path that had been embarked upon turned out to be a cul-de-sac. After the first specimens began to tick, the next task was to gather experiences to ensure problem-free serial production, scheduled to commence in 1973. The watch brand Orfina numbered among the launching customers that were eagerly awaiting the new caliber. A new all-black chronograph, designed by Ferdinand A. Porsche, was in Orfina’s pipeline, but this model needed the Valjoux cal. 7750 before it could make its public debut.

Orfina chronograph by Porsche Design driven by the 7750 (Image: Christie’s)
Orfina chronograph by Porsche Design driven by the 7750 (Image: Christie’s)

Annual production quickly climbed to circa 100,000 units, but initially the cal. 7750 was anything but a bestseller. Sales were sluggish, so as early as 1975, it was threatened by the same fate that befell El Primero. Zenith had terminated its production due to insufficient demand and inadequate profitability; even the tools needed to manufacture the El Primero were earmarked for the recycling bin. Fortunately, Charles Vermot, a watchmaker in Le Locle, disobeyed his superiors’ orders; he gathered all the items that he deemed important and concealed them within Zenith’s capacious attic. A similar sequence of events transpired at Valjoux. When Edmond Capt’s stormy protests against the euthanizing of his brainchild fell on deaf ears, he likewise opted for insubordination: the godfather of the cal. 7750 painstakingly packed up all the essential items and stored them in a safe place. His next task, which lasted many long years, was to practise the saintly virtue of patience: not until 1983 and the renaissance of mechanical watches would the Valjoux cal. 7750 again spread its wings and soar into chronographic heights.

Epilogue

Capt’s insubordination in 1975 harmed neither him nor his career. He was hired in 1978 to serve as technical director at the Frédéric Piguet ébauche manufacturer, which joined the Swatch Group in 1992. In 1999, Capt took over the overall direction and management of Frédérique Piguet (later folded into Blancpain) and Nouvelle Lémania (now under the aegis of Breguet). The talented godfather of the cal. 7750 was later promoted to a top-tier managerial position in the Swatch Group.

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