S. Epson Caliber YN56

Manufacturer	S. Epson (Seiko)
Caliber Number	YN56 (aka YN56A)
Movement Type	Automatic, self-winding mechanical
Lignes	12.1”’
Diameter	27.4mm
Height	5.32mm
Jewels	22
Beat Rate	21,600 bph
Lift Angle	52 degrees (unconfirmed)
Power Reserve	40 hours
Hand Windable?	Yes
Anti-Shock System	Seiko Diashock
Hand Count	3
Hand Sizes	1.50mm / .90mm / .20mm
Functions	Central hours; central minutes; central sweeping seconds; day/date indicator at 3:00
Hacking Seconds?	Yes
Country of Manufacture	Made in Japan
Known Models	Vostok Europe Expedition North Pole-1, Aries Gold 9010 (Add your watch to the comments below…)

The S. Epson caliber YN56 (YN56A) is essentially an unbranded version of the Orient caliber F6922. It is a self-winding automatic movement with 22 jewels, also featuring hacking and hand-winding functionality. These movements are manufactured in Japan.

YN56, YN56A, YN56B, YN56C, etc…

The letter at the end of YN56 indicated the iteration of the movement. YN56 is the base caliber number and YN56A is the first version. As of this post, there is only a YN56A iteration, therefore, YN56 is the same as YN56A.

Accuracy:

Accuracy of the calibre YN56A is said to be within -25 seconds to +35 seconds per day. These ratings are based on the watch being at room temperature with the mainspring fully wound and the dial up position. Official documentation from Orient suggests that deviations from the accuracy claims should not be regarded within one day but within a one week period of results.

From the Orient manual:

“In order to maintain the watch’s accuracy, we recommend wearing the watch at least 8 hours a day.”

Power Reserve:

The YN56A has a power reserve of 40 or more hours. Winding the crown 30 times will wind the spring fully and achieve full power reserve.

Setting the Celendar:

To set the date on your S. Epson YN56 powered timepiece, pull the crown out one click to calendar setting position. Turn the crown counterclockwise to advance the date. Avoid setting the date between the hours of 8:00pm to 4:00am. Turn in the other direction to set the day of the week.

Additional Resources:

• Orient caliber F6922
• Orient Mako II user manual
• More Seiko movements