S. Epson Caliber VS71 Watch Movement

Manufacturer	S. Epson (Seiko)
Caliber Number	VS71, VS71A
Movement Type	Quartz, solar-powered, chronograph
Lignes	12”’
Diameter	27mm
Height	4.4mm
Jewel Count	No jewels (0)
Frequency	32,768 Hz
Accuracy Rating	+/-20 seconds/month
Capacitor Part #	3023 34T aka 302334T (lithium, 1.55 V)
Power Reserve	6 months on a full charge
Hand Count	5
Hand Sizes	1.10mm (hrs) / .65mm (mins) / .21mm (chrono secs) / 2 x .21mm (subdials)
Functions	Central hours; central minutes; central chronograph seconds (1/5 sec); small running seconds at 6:00; 60 minutes chronograph counter at 12:00; date at 3:00
Chronograph Style	Bicompax (2 subdials)
Chronograph Layout	12-6
Hacking Seconds?	Yes
Other Features	Overcharge prevention, AC reset function, low battery indicator, quickset date
Country of Manufacture	Made in Japan
Known Models	Farr + Swit Solar Chrono, Farr + Swit Solar Chrono Vice, Farr + Swit Solar Chrono Vice 2.0 (Add your watch to the comments below…)

The S. Epson caliber VS71 is a solar-powered, bi-compax quartz chronograph movement. According to official technical documents from S. Epson, this caliber has been on the market since at least December 2017.

Solar-Powered Charging Time:

The VS71 is powered by a rechargeable secondary battery aka capacitor, which harnesses energy from light and stores it in the battery cell. The charging time depends on the type of light used to charge it.

The solar cell is under the dial (which has a transparency of at least 20%), so the light needs to reach the dial without obstruction. The chart below indicates the amount of time needed to charge the VS71 based on light type:

When charging, make sure the light is not too hot for the dial or it could cause warping and break the watch.

If the battery/capacitor does not have enough power stored, a low battery indicator (EOL) function will cause the seconds hand to jump or skip every two seconds. The watch will function this way for up to a week before running out of energy. Avoid letting your watch completely drain or it could cause charging problems later. Charge your watch as soon as possible.

Crown/Stem Removal:

To remove the crown and stem from your VS71 powered watch, look for the “Push” with an arrow pointing to a hole near the crown.

Pull the crown out one click to date-setting mode and the lever will appear. Gently press the lever/button with your tool while pulling the crown out.

Note: The detent lever is hidden unless the crown is in date-setting position.