Miyota Caliber 6S21

Manufacturer	Miyota (Citizen)
Caliber Number	6S21
Type	Quartz, battery-powered
Replaces Caliber	Citizen 0510
Linges	15”’
Diameter	34.6mm
Height	4.9mm thick
Case Thickness	9.85mm minimum
Jewels	0
Frequency	32,768 Hz
Battery Cell Number	SR927W (395/399)
Battery Life	~3 years
Stem	065-A13, tap 10
Hand Count	5
Hand Sizes	1.20mm / .70mm / .26mm / .17mm
Functions	Central hours; central minutes; central chronograph seconds; small seconds subdial at 3:00; 60 minutes chrono counter at 9:00; date at 4:30 (could be different depending on the watch)
Country of Manufacture	Made in Japan
Known Models	Invicta Corduba (Add your watch to the comments below…)

The Miyota caliber 6S21 is a 0 jewel quartz chronograph watch movement made in Japan.

PICS COMING SOON – for now, there are images of the similar 6S20.

Miyota 6SXX Family:

The Miyota caliber 6S21 is part of the 6SXX family of quartz chronograph movements including the 6S10, 6S20, 6S30, and 6S11.

The 6S21 featured on this page is the closest to the 6S11 with the main difference being that the horizontal layout of the subdials at 3:00 and 6:00 on the 6S21 are positioned vertically on the 6S11 at 12:00 and 6:00.

Mechaquartz?

Although the 6S21 is not considered to be a mecaquartz movement, this caliber has features that are not often found on quartz chronograph watches. For example, the central chronograph hand has a quick reset via a heart cam reset system. The buttons are made to have a substantial clicking feel to them, similar to what it feels like to engage the chronograph on a mechanical timepiece. The central chronograph hand beats 4 times per second.

Accuracy:

Miyota states the accuracy of this movement to be +/-20 seconds per month in normal operating conditions.

Chronograph Hands Not Lining Up?

After a battery change, it’s common for the chronograph hand to not line up on the 12:00 mark. If this happens to your watch, perform the procedure below to reset your chronograph hands:

1. Pull the crown out to time setting position (two clicks)
2. Press the top pusher until the chronograph hand is lined up
3. Push the crown back in

Replacement Price:

At the time of this post, replacement prices for the 6S21 were found in the range of $22.95 to $29.95 USD.

Additional Resources:

• Official instruction manual (pdf)
• 6S21 technical drawings (pdf)