Introduction to the Seiko 6F22A

The Seiko 6F22A is a premium high-accuracy quartz movement developed in the late 1990s as part of Seiko’s 6F series, which includes some of the most refined quartz calibers ever produced by the brand. The 6F22A is notable for its twin quartz architecture, perpetual calendar function, and thermo-compensated timekeeping, delivering outstanding precision even by modern standards.

It was primarily used in high-end Seiko models, including Brightz and Credor, and targeted users who valued mechanical-level finishing with quartz-level accuracy.

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Technical Specifications

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Twin Quartz Architecture

The twin quartz system utilizes:

• One quartz oscillator for timekeeping

• Another for temperature sensing, allowing real-time thermal compensation

This approach greatly reduces drift caused by temperature fluctuations, ensuring ultra-precise performance.

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Key Features

• Perpetual calendar (adjusts automatically for month length and leap years)

• Independent calendar stepper motor allows instant date change at midnight

• Manual calendar correction possible, though rarely needed

• High-end movement finishing, uncommon for quartz calibers

• Smooth calendar transition, often changing the date in a snap

• Long battery life due to power-efficient electronics and stepper motors

• Built to last decades, not years

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Setting Instructions

Crown Positions

Calendar Correction

1. Pull crown to Position 1

2. Rotate clockwise to adjust date

3. Rotate counterclockwise to adjust month/year (leap year encoded)

4. Pull to Position 2 to adjust time; seconds hand stops

5. Push crown back to resume timekeeping

The calendar auto-adjusts through February 28/29 without user input until the year 2100.

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Battery Replacement

Battery Type

• SR920SW (Seiko 371)

• Voltage: 1.55V

• Expected lifespan: 5 years

Replacement Procedure

1. Open case back using correct tool

2. Remove old battery with non-metallic tweezers

3. Insert new SR920SW battery (ensure polarity)

4. No reset (AC) terminal is required — calendar and time resume once powered

5. Confirm operation of both motors (time and calendar)

A full battery change should always include a gasket check and water-resistance test if applicable.

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Construction and Design

The 6F22A features:

• 9 jewels, supporting high-load pivots and reducing wear

• Separate motors for timekeeping and calendar functions

• Metal plates and bridges, often beautifully finished

• Fine regulation trimmer for adjusting base frequency

• Low-profile design, allowing installation in dress watches

It reflects a mechanical mindset in a quartz chassis, built for long-term accuracy and reliability.

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Servicing and Maintenance

Although quartz, the 6F22A is serviceable and regulated like a mechanical movement.

Service Recommendations

• Battery change every 5 years

• Clean and inspect for corrosion at each service

• Circuit, motors, and gears can be tested individually

• Perpetual calendar functions should be verified using year-matching test dates

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Common Issues and Solutions

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Applications and Watch Models

The 6F22A was used in:

• Seiko Brightz Perpetual Calendar models

• Seiko Credor quartz dress watches

• Limited editions and high-end JDM-only quartz offerings

• Models with ultra-thin, finely finished cases

These watches were often marked “Perpetual Calendar” or “High Accuracy Quartz” on the dial.

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Conclusion

The Seiko 6F22A is one of the most refined quartz calibers Seiko has ever made. With:

• Perpetual calendar through 2100

• Twin quartz architecture for thermal compensation

• ±20 seconds/year precision

• Dual-motor engineering

• Mechanical-level build quality

…it offers true watchmaking excellence in a quartz format. For collectors and enthusiasts of high-end Seiko technology, the 6F22A represents the pinnacle of analog quartz precision and long-term reliability.

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