The Seiko 9923A is a high-precision quartz analog movement introduced in the late 1970s and used throughout the early 1980s. It belongs to Seiko’s prestigious twin quartz family, a category of movements that featured dual quartz oscillators for improved thermal compensation and remarkable long-term accuracy. The 9923A was often found in Seiko Superior Quartz models and high-end King Seiko dress watches.

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Technical Overview

• Caliber Number: 9923A

• Movement Type: Twin Quartz (analog)

• Display: Hour, Minute, Center Seconds, Date

• Calendar: Quickset date at 3 o’clock

• Jewels: 7 jewels

• Battery Type: SR927W (1.55V silver oxide)

• Battery Life: Approximately 3 years

• Accuracy: ±10 seconds per year

• Movement Dimensions:

  • Diameter: ~26.0 mm

  • Height: ~3.3 mm

• Hand Fitting Sizes:

  • Hour: 1.20 mm

  • Minute: 0.70 mm

  • Seconds: 0.20 mm

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Twin Quartz Technology

The standout feature of the 9923A is its temperature compensation system. It contains two quartz oscillators:

• One functions as the standard timekeeping oscillator.

• The second monitors ambient temperature fluctuations.

Using this dual-oscillator setup, the movement corrects for temperature-based drift in real time, resulting in extremely stable accuracy—even in varying environmental conditions.

This approach allowed Seiko to achieve annual accuracy rates that rivaled (and in some cases surpassed) early atomic timekeeping technologies.

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Crown and Setting Functions

• Position 0 (pushed in) – Normal operation

• Position 1 (first click) – Quickset date (rotate crown clockwise)

• Position 2 (second click) – Time setting with hacking seconds (the second hand stops)

Setting the time precisely is easy due to the hacking function, which is essential for watches with such high accuracy.

Important: Avoid setting the date between 9:00 PM and 4:00 AM to prevent damage to the calendar gear train.

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Battery Replacement and AC Reset

Battery replacement must be done carefully:

1. Open the case back with the appropriate tool.

2. Use plastic tweezers to remove the old SR927W battery.

3. Insert a fresh battery, checking for correct polarity.

4. Locate the AC (All Clear) contact near the battery well.

5. Short the AC contact with the battery’s negative side using metal tweezers for 2–3 seconds.

6. Confirm that the second hand begins ticking smoothly.

Failure to perform the AC reset can result in no display, erratic ticking, or failure to start.

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Servicing and Maintenance Notes

• Movement is dry-running with very limited lubrication points.

• Step motor and coil must be handled with care to avoid damage.

• Calendar parts may benefit from gentle cleaning and a small amount of synthetic watch grease.

• Due to the twin oscillator system, full calibration and servicing should be done by a Seiko-qualified technician familiar with high-accuracy quartz movements.

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Identification and Applications

The 9923A is stamped clearly on the main plate. Watches containing this movement are usually labeled "Twin Quartz", "Superior Quartz", or "King Seiko Quartz" on the dial. These timepieces often feature:

• Stainless steel or gold-plated cases

• Minimalist dials with a date window at 3 o’clock

• High-quality finishing, often with flat crystals and applied markers

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Conclusion

The Seiko 9923A is a landmark movement in quartz horology. With its twin quartz construction and exceptional ±10 seconds/year accuracy, it represents the pinnacle of Seiko’s late 20th-century innovation. For collectors, restorers, and horology enthusiasts, the 9923A stands as both a technical marvel and a reminder of Seiko’s ambition to challenge the boundaries of quartz precision.

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