The Seiko 8C23A is a high-precision analog quartz movement introduced in the late 1990s to early 2000s, offering a refined blend of long-term reliability, low power consumption, and minimalist functionality. It is closely related to the 8C22A but is slightly simplified, eliminating the perpetual calendar and leap year tracking while maintaining robust accuracy and convenience features. Watches with the 8C23A are typically elegant dress models aimed at users who appreciate traditional styling with modern quartz precision.

Technical Specifications

• Caliber Number: 8C23A

• Movement Type: Quartz (Analog)

• Display Type: 3-hand analog display (Hours, Minutes, Seconds) + Calendar window

• Primary Features:

  • Hours, Minutes, Central Seconds

  • Date Display (Quickset via crown)

  • Month Indicator (Subdial or window depending on case design)

  • Instant Date Change at Midnight

• Time Format: 12-hour analog

• Battery Type: SR927W (1.55V silver oxide)

• Battery Life: Approximately 10 years

• Accuracy: ±20 seconds per month

• Jewels: Typically 0 (electromechanical)

• Power Consumption: Ultra-low

• Crown Positions:

  • Position 0: Normal running

  • Position 1: Quickset date

  • Position 2: Time setting

Functional Overview

The 8C23A is built for reliability and ease of use, focusing on analog simplicity with calendar utility. It lacks the leap year and perpetual calendar logic found in more complex calibers, but this also makes it less prone to logic errors or incorrect advancement during battery swaps.

Timekeeping

• Standard 3-hand time display

• Central seconds hand ticks once per second

• Quartz oscillator for accuracy and minimal drift

Calendar

• Quickset date function via crown (Position 1)

• Month display in either a small window or a rotating subdial (varies by case design)

• No leap year or perpetual calendar logic – user must manually adjust on months shorter than 31 days

• Instant date change at midnight for seamless transition

Setting Instructions

Setting the Time:

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

2. Turn the crown clockwise to adjust the time

3. Push the crown back in when done

Note: Always set the time forward to maintain correct gear alignment. Avoid setting between 9 PM and 2 AM to prevent damage to the date mechanism.

Setting the Date:

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

2. Turn the crown slowly until the correct date appears in the window

3. Push the crown back in to resume normal operation

Setting the Month (if applicable):

• Some 8C23A-based watches include a corrector button on the case side to adjust the month window

• Pressing it advances the month display by one

• If no corrector is present, month is mechanically linked to the date wheel in some models and must be manually adjusted at month-end

Battery Replacement & Post-Service Reset

The SR927W silver oxide battery provides long-lasting performance, often up to 10 years due to the ultra-low energy demand of the 8C23A.

Battery Change Notes:

• No AC reset is typically required

• After battery installation, time and date must be manually re-entered

• Always use non-metallic tweezers when handling the battery to avoid shorts

• Gaskets and seals should be inspected and replaced to maintain water resistance (if applicable)

Maintenance Recommendations

• No lubrication required – the movement is fully electronic with no high-friction parts

• Avoid magnetic exposure; it may cause temporary inaccuracy

• Handle the crown gently; over-tightening can cause stem misalignment

• Clean the case and crown area periodically to ensure smooth operation

• Ensure proper water resistance is maintained if labeled “Water Resistant”

Watch Models Using 8C23A

Seiko used the 8C23A in a range of conservative dress watches and classic analog calendar models, usually with:

• Stainless steel or gold-tone cases

• Leather or metal bracelets

• Thin profile (under 8 mm case thickness)

• Calendar windows positioned at 3 or 6 o'clock

• Subdial or arc-style month display near 6 or 12 o'clock (varies)

Typical reference numbers may include Seiko 8C23-00XX, 8C23-5000, and similar configurations.

These watches were marketed to those seeking timeless design and low-maintenance functionality.

Comparison to Related Calibers

The 8C23A is essentially a simplified version of the 8C22A, optimized for users who prefer manual date management with fewer complications.

Conclusion

The Seiko 8C23A is a reliable and efficient analog quartz movement that excels in simplicity, long battery life, and everyday usability. Its blend of classic styling, date and month features, and maintenance-free performance makes it ideal for owners seeking a timeless wristwatch with modern quartz dependability. While it may lack the complexity of perpetual calendar models, its longevity and accuracy make it a solid choice for anyone who values convenience and traditional aesthetics.