The Seiko 8S23A is a precision quartz analog movement featuring a perpetual calendar mechanism, designed for elegant dress watches and executive timepieces. Manufactured in the late 1990s through the early 2000s, this movement showcases Seiko’s advanced quartz technology combined with calendar programming that automatically adjusts for months of varying lengths and leap years until the year 2100. It offers reliable accuracy with low maintenance, making it ideal for users seeking sophistication and convenience.

Technical Specifications

• Caliber Number: 8S23A

• Movement Type: Quartz (Analog)

• Display Features:

  • Hour, minute, and seconds hands

  • Date window (usually at 3 o’clock)

  • Some variants include day-of-week indication

• Calendar Function: Perpetual calendar, accurate through February 28, 2100

• Accuracy: ±20 seconds per month (temperature compensated)

• Battery Type: SR927W (1.55V silver oxide)

• Battery Life: Approximately 7 to 10 years

• Jewels: None (electronic movement)

• Crown Positions:

  • Position 0: Normal operation

  • Position 1: Date/day setting

  • Position 2: Time setting

Key Features

Perpetual Calendar

• Automatically adjusts for different month lengths (30 or 31 days).

• Accounts for leap years, including February 29th.

• Eliminates the need for manual date correction for nearly a century.

Accurate Timekeeping

• Thermo-compensated quartz oscillator ensures stable and precise timekeeping.

• Maintains accuracy within ±20 seconds per month.

Date and Day Display

• Date window located commonly at 3 o’clock for ease of reading.

• Some models include a day-of-week indicator, enhancing calendar functionality.

• Instant date change at midnight for smooth transitions.

Long Battery Life

• Efficient design provides 7 to 10 years of operation from a single SR927W battery.

Operating Instructions

Time Setting

1. Pull the crown to the second click (Position 2).

2. Rotate the crown to set the hour and minute hands.

3. Push the crown back to Position 0 to resume timekeeping.

Date and Day Adjustment

1. Pull the crown to the first click (Position 1).

2. Rotate clockwise to adjust the date.

3. For models with day display, rotate counterclockwise to set the day.

4. Avoid setting the date manually between 9 PM and 2 AM to prevent damage to the calendar mechanism.

Battery Replacement and Maintenance

• Use SR927W silver oxide battery for replacement.

• Replace battery every 7 to 10 years, or sooner if power weakens.

• No AC reset is typically necessary after battery change.

• Inspect and replace case gaskets during battery service to maintain water resistance.

Maintenance Recommendations

• No lubrication required for electronic movement.

• Avoid exposure to strong magnetic fields or shocks that could impair accuracy or hand alignment.

• Periodically test water resistance if the watch is designed for moisture protection.

• Clean case and crystal surfaces regularly for optimal appearance.

Watches Featuring the 8S23A

The 8S23A caliber is found in Seiko’s refined quartz collections, including:

• Executive and classic dress watches with perpetual calendar capabilities.

• Stainless steel, titanium, and gold-plated case variants.

• Sapphire or hardlex crystal watches emphasizing elegance and reliability.

Summary Table

Conclusion

The Seiko 8S23A is a reliable, elegant quartz movement offering accurate timekeeping combined with a perpetual calendar for hassle-free date management. Its long battery life and sophisticated programming make it well-suited for users who appreciate classic watch design with modern quartz technology. The 8S23A exemplifies Seiko’s commitment to precision, convenience, and style, delivering decades of dependable performance in a timeless package.