ESA Caliber 9154

The ESA caliber 9154 is a vintage electronic “Dynotron” movement. This movement was in production starting around circa 1970.

In ESA’s own words:

“Electronic movement with sprung balance, sweep second, calendar mechanism sunk into the plate for showing the date through an aperture in the dial, balance-stop device. 28800 vibrations per hour.” -ESA Technical Communication 22a, 1970

ESA 1954 VS 1950:

The 1954 is an evolution of the 1950 movement which it is based upon. Unlike the tech sheets provided by modern movement producers, ESA was very through in providing documentation explaining the differences and improvements.

“Ebauches S. A. has made certain improvements to caliber ESA 9150 with a view to increasing its accuracy and reliability. “

Among the improvements are:

• Caliber ESA 9154 has a vibration count of 28 800 per hour.
• When removing the case, it is no longer necessary to detach the setting lever in order to extract the hand-setting stem. Take out the outer setting-lever screw. Pushed by the interrupter spring, the setting lever will shift, releasing the hand-setting stem
• The 1954 has a simpler date-indicator mechanism than the 1950.

More Useful Info:

• “The interrupter spring bridle when the stem must on no account touch the interrupter is in the “set” position. When the stem is pushed in, the interrupter spring will press against the interrupter bridle and will shift it slightly, thus insuring good contact.”
• Due to the high frequency and the shape of the balance used in the cal. 1954, it is difficult to check its amplitude. Nevertheless, the amplitude should be between the higher limit of 270 degrees in the dial up position and the lower limit of 200 degrees in the pendant down (crown down) position.
• “According to the type of case. Beware of the mechanical stresses due to the casing up process.”

Additional Resources:

• More electronic movements