The Seiko 8621A is a dependable and precise quartz analog movement designed for everyday wristwatches that require accurate timekeeping paired with a practical date function. Produced primarily in the 1980s and 1990s, this caliber reflects Seiko’s expertise in crafting robust, low-maintenance quartz movements that deliver consistent performance. The 8621A is known for its reliability, long battery life, and straightforward operation, making it a popular choice in many Seiko watch models.

Technical Specifications

• Caliber Number: 8621A

• Movement Type: Quartz (Analog)

• Display:

  • Hour, minute, and seconds hands

  • Date window typically positioned at 3 o’clock

• Accuracy: Approximately ±20 seconds per month

• Battery Type: SR927W (1.55V silver oxide)

• Battery Life: Approximately 2 to 3 years

• Jewels: None (electronic quartz movement)

• Crown Positions:

  • Position 0: Normal operation

  • Position 1: Date adjustment

  • Position 2: Time adjustment

Key Features

Accurate Timekeeping

The 8621A utilizes a quartz oscillator to provide stable and precise timekeeping, with a typical accuracy of ±20 seconds per month, suitable for everyday use.

Date Function

Includes a date complication displayed in a window, usually at the 3 o’clock position, allowing for easy manual adjustment via the crown.

Efficient Power Consumption

Powered by an SR927W silver oxide battery, the movement offers efficient energy use and a battery life that typically lasts between two and three years.

Operating Instructions

Time Setting

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

2. Rotate the crown clockwise or counterclockwise to set the hour and minute hands to the correct time.

3. Push the crown back to Position 0 to resume normal operation.

Date Setting

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

2. Rotate the crown clockwise to advance the date.

3. Avoid adjusting the date between 9 PM and 2 AM to prevent damage to the date-change mechanism.

4. Push the crown back to Position 0 after setting.

Battery Replacement and Maintenance

• Use an SR927W silver oxide battery for replacement.

• Battery life typically ranges from 2 to 3 years depending on usage and environmental factors.

• Professional battery replacement is recommended to maintain water resistance and ensure correct handling.

• No reset procedure is usually needed after battery replacement, but time and date settings should be verified.

Maintenance Recommendations

• No mechanical lubrication is required due to its electronic quartz design.

• Avoid strong magnetic fields, shocks, and temperature extremes to preserve accuracy.

• Clean the watch regularly to maintain appearance and function.

• Water-resistant models should be pressure tested periodically.

Watches Featuring the 8621A

The 8621A movement has been installed in:

• Seiko quartz analog watches produced mainly in the 1980s and 1990s.

• Models focusing on reliable time and date display without additional complications.

• Watches designed for daily use with classic styling.

Summary Table

Conclusion

The Seiko 8621A quartz movement is a robust and accurate caliber that offers practical analog timekeeping combined with a convenient date function. Its long battery life, straightforward operation, and dependable performance make it a solid choice for everyday watches. The 8621A exemplifies Seiko’s dedication to producing quality quartz movements that combine precision, simplicity, and reliability.