The Seiko A031A is a vintage quartz analog movement from the early 1980s, designed for simplicity, thin construction, and accurate timekeeping. Part of Seiko’s A-series, the A031A was used in a wide range of entry-level and mid-range quartz watches, particularly slim dress models. This movement features a center seconds hand and a quickset date function, combining classic styling with low-maintenance operation.

Technical Specifications

• Caliber Number: A031A

• Movement Type: Quartz (step motor)

• Display: Hour, Minute, Center Seconds, Date

• Calendar: Quickset date (at 3 o’clock on most models)

• Jewels: 0 jewels

• Battery Type: SR920SW (1.55V silver oxide)

• Battery Life: Approximately 2 to 3 years

• Accuracy: ±15 seconds per month

• Movement Dimensions:

  • Diameter: ~26.0 mm

  • Height: ~3.1 mm

• Hand Fitting Sizes:

  • Hour: 1.20 mm

  • Minute: 0.70 mm

  • Second: 0.20 mm

Key Features

The Seiko A031A was designed with ease of use and reliability in mind. Its main features include:

• Time display: Traditional three-hand layout

• Date function: Quickset date allows for manual adjustment without cycling 24 hours

• Non-hacking seconds: The second hand continues to run when setting the time

• Low power consumption: Ideal for long battery life in compact cases

• No day-of-week complication: Simplifies the gear train and improves reliability

Crown Functions

• Position 0 (pushed in) – Normal operation

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

• Position 2 (pulled out) – Time setting (second hand does not stop)

Important: Do not change the date between 9:00 PM and 4:00 AM to avoid damaging the date-change mechanism.

Battery Replacement and Reset Procedure

1. Open the case back using the appropriate case knife or wrench.

2. Remove the used SR920SW battery using non-metallic tweezers.

3. Insert a fresh battery, ensuring proper polarity and contact with the terminals.

4. Locate the AC (All Clear) terminal on the movement plate.

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

6. Confirm the second hand begins moving normally.

The AC reset is essential to reinitialize the integrated circuit after battery installation.

Servicing and Maintenance

• Minimal lubrication is required. Most parts are designed to run dry.

• Clean the date wheel and quickset components periodically to prevent jamming.

• The coil and stator are fragile; avoid contact with metal tools or magnets.

• If the step motor or IC fails, replacing the entire movement is typically more cost-effective than repair.

This movement is widely regarded for its durability in daily-wear watches.

Identification and Use

The movement is marked “A031A” on the main plate, usually near the battery well. You’ll find this caliber in Seiko watches with reference numbers beginning with A031, 7123, or 7N variations from the 1980s and early 1990s. These watches typically feature slim cases, clean dial designs, and minimalistic styling aimed at office and formal wear.

Conclusion

The Seiko A031A is a classic, no-nonsense quartz movement designed for efficiency, ease of use, and longevity. Its quickset date function and accurate timekeeping made it a dependable choice for Seiko’s slim dress watches of the era. Today, it remains a respected and serviceable caliber among vintage watch enthusiasts and collectors.