The Seiko 7S35C is a robust and reliable automatic mechanical movement that is a direct evolution of the well-known 7S26 series. Designed for durability and long-term performance, the 7S35C is widely used in entry-level and mid-range Seiko watches, especially within the Seiko 5 lineup. This movement is favored for its increased power reserve, robust construction, and practical day-date complication.

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Technical Specifications

• Caliber Number: 7S35C

• Movement Type: Automatic mechanical (self-winding)

• Display:

  • Hours, minutes, and seconds hands

  • Day and date windows, typically positioned at 3 o’clock

• Frequency: 21,600 vibrations per hour (6 beats per second)

• Power Reserve: Approximately 41 hours when fully wound

• Jewels: 23 synthetic rubies

• Accuracy: Approximately ±25 seconds per day (varies with conditions and regulation)

• Hacking: No (seconds hand does not stop when setting time)

• Manual Winding: Not supported

• Crown Positions:

  • Position 0: Normal running

  • Position 1: Day/date quickset

  • Position 2: Time adjustment

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Key Features

Enhanced Power Reserve

Compared to its predecessor 7S26, the 7S35C boasts an improved power reserve of approximately 41 hours, allowing the watch to run longer without movement.

Automatic Winding

The movement winds automatically via wrist motion, storing energy in the mainspring. Lack of manual winding means consistent wearing is necessary to maintain power.

Day and Date Complications

Featuring practical day and date displays in a combined window at 3 o’clock. The day is often available in two languages (commonly English and Spanish), adjustable via the quickset crown function.

Increased Jewel Count

With 23 jewels, the 7S35C benefits from improved durability and reduced friction in moving parts, contributing to its longevity and smooth operation.

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Operating Instructions

Wearing and Powering

• The watch powers itself through wrist movement.

• Without manual winding, it requires regular wear or movement to remain operational.

• If the watch stops, shaking it gently or wearing it for several hours will wind the mainspring.

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.

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

4. Note: The seconds hand continues to move during time adjustment (non-hacking feature).

Day and Date Quickset

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

2. Rotate the crown clockwise to advance the date.

3. Rotate the crown counterclockwise to adjust the day.

4. Avoid setting day or date between approximately 9 PM and 4 AM to prevent damage to the date-change mechanism.

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Maintenance and Care

• Recommended servicing interval is every 4 to 5 years to maintain accuracy and mechanical integrity.

• Keep the watch away from strong magnetic fields and shocks to protect movement components.

• Clean the exterior regularly to maintain case and bracelet condition.

• Verify water resistance periodically, especially if the watch is exposed to moisture.

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Watches Featuring the 7S35C

The 7S35C movement powers:

• Various models in the Seiko 5 Sports and Seiko 5 Automatic collections.

• Timepieces designed for users seeking durable, affordable mechanical watches.

• Watches appreciated by both novices and collectors for mechanical authenticity and robust design.

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Summary Table

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Conclusion

The Seiko 7S35C is a well-regarded automatic movement that enhances the proven 7S26 design with a longer power reserve and additional jewels for improved durability. Its practical day-date complication, reliable performance, and robust construction make it an excellent choice for everyday mechanical watches. The 7S35C embodies Seiko’s philosophy of offering quality, affordable automatic calibers suited to a wide range of watch enthusiasts.

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