Introduction to the Seiko 7320A

The Seiko 7320A is a vintage manual-winding mechanical movement from the late 1960s and early 1970s. Part of Seiko’s 73xx caliber family, it was primarily designed for smaller wristwatches, including many ladies’ models and unisex watches requiring a compact yet reliable mechanism.

This caliber is prized for its straightforward design, robust construction, and the inclusion of a practical date complication, making it a popular choice for collectors of vintage Seiko mechanical watches.

Technical Specifications

Key Features

• Manual winding: Requires regular winding via the crown to maintain operation.

• Date complication: Features a date window, advancing gradually near midnight.

• Non-quickset date: Date adjustment requires advancing the hour hand past midnight repeatedly.

• No hacking seconds: Seconds hand continues to run during time adjustment.

• Durable 17-jewel construction: Reduces friction and enhances longevity.

• Compact and slim design fits smaller cases elegantly.

Operation and Setting Instructions

Manual Winding

• Turn the crown clockwise until you feel resistance indicating a full wind.

• Do not force beyond this point to avoid damage.

Time Setting

• Pull the crown to the time-setting position.

• Rotate the hour and minute hands forward or backward to set the correct time.

• The seconds hand will continue to run during this adjustment.

Date Setting

• The date changes gradually at midnight.

• To set the date, rotate the hour hand repeatedly past midnight until the desired date appears.

• Avoid changing the date manually between 8 PM and 2 AM to prevent damage.

Construction and Durability

• Equipped with a lever escapement and operates at 18,000 bph for smooth hand motion.

• Contains 17 synthetic ruby jewels, minimizing wear and friction on key parts.

• The movement’s slim profile allows it to fit well in smaller watch cases.

• Offers approximately 40 hours of power reserve when fully wound.

Maintenance and Servicing

• Recommended servicing every 4 to 6 years to ensure optimal performance.

• Servicing involves cleaning, lubrication, timing adjustment, and calendar mechanism inspection.

• Replacement parts can often be sourced from vintage Seiko suppliers or donor movements.

• Proper maintenance helps prevent common issues such as skipping dates or inaccurate timekeeping.

Common Issues and Troubleshooting

Watches Featuring the 7320A

• Typically found in Seiko ladies’ watches and smaller unisex models from the late 1960s and early 1970s.

• Known for reliable timekeeping paired with a simple date complication.

• Popular among collectors who appreciate compact, durable mechanical movements.

Conclusion

The Seiko 7320A is a dependable manual-winding mechanical caliber that combines reliable timekeeping with a practical date function. Its compact size, durable construction, and classic mechanical design make it a favored movement for vintage Seiko enthusiasts and restorers, exemplifying the brand’s quality craftsmanship during its era.