Miyota Caliber 0S80 Watch Movement

Manufacturer	Miyota (Citizen)
Caliber Number	0S80 (sometimes incorrectly typed as OS80)
Type	Quartz
Replaces Caliber	Unknown, please add in the comments below
Lignes	13.5”’
Diameter	30.8mm
Height	4.68mm
Jewels	0 (no jewels)
Frequency	32,768Hz
Battery Cell Number	SR927W (395/399)
Battery Life	~2 years
Quartz Type	Tuning fork type quartz crystal
Stem	065-453, tap 10 (alarm stem: 065-513)
Hand Sizes	1.20mm / .70mm / .17mm (small hands also .26mm)
Functions	Central hours; central minutes; central chronograph seconds; small running seconds and 1/20 chronograph seconds at 6:00; 60 mins chronograph counter at 12:00; 12 hour chrono counter at 9:00; date at 3:00; central alarm hand; alarm on/off indicator at 7:30
Country of Manufacture	Made in Japan
Known Models	(Add your watch to the comments below…)

The Miyota caliber 0S80 is a quartz chronograph watch movement with an alarm.

You might also see other listings incorrectly refer to this movement at OS8O, but is should be zero-S-8-zero not “O”.

Some of the topics covered in this caliber listing:

Alarm Function:

To set the alarm on the 0S80, pull the crown out one click to date setting mode. Turning the crown in one direction will change the date, and turning in the other direction will advance the alarm hand. One you get it to the time you want the alarm to chime, press the crown back in.

Note: When setting the date, do not make adjustments when the hands are between the hours of 9pm to 1am.

The alarm chimes when the hour hand is aligned with the alarm hand. The alarm will beep 15 seconds, every 3 minutes for 3 times or until it is turned off.

The alarm has an on/off indicator on the dial which is controlled by the crown on the side of the watch at 8:00. Unlike most alarm watches, it not just simply a pusher that operates the alarm, but an actual crown and stem.

Video: How to remove the alarm crown/stem (this video is in another language, but it is useful for learning how to remove the alarm crown).

Accuracy Rating:

Miyota claims the accuracy of this movement to be +/-20 seconds/month.

Recalibrating the chronograph hand to zero:

It is common for a quartz chronograph hand to be misaligned after a battery change. If your central chronograph second hand (or chronograph minute hand) is not resetting to 12:00 or “zero” position, you can try the following steps:

Pull the crown to position 2 (time setting mode)
Press button A (top button) to advance the chronograph hand forward until it is lined up with 12:00. If you long-press A, the hand will move forward faster.
Push button B (bottom button) to switch modes.
Push the crown back to position 0

Note: if you push the crown back in to position 0 while the chronograph hand is still advancing forward, then it will stop the chronograph hand and recognize it as zero position. In this case, you will have to start over again.