Seiko 5K25A Technical Guide

Introduction

The Seiko 5K25A is a quartz analog movement with day-date display, introduced in the early 2000s as part of Seiko’s reliable and accessible quartz lineup. This movement was developed to power everyday watches with practical features and dependable timekeeping. Positioned between the more basic 7N43 series and the slightly more refined 5G and 5H series, the 5K25A offers ease of maintenance, affordable production, and durable construction for both casual and dress watches.

It is commonly found in Seiko Quartz Day-Date models, especially those sold in Asia and Europe, and is a workhorse movement that continues to perform reliably even after decades of use.

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Technical Specifications

• Caliber: Seiko 5K25A

• Movement Type: Quartz analog

• Functions: Hour, minute, central seconds, day, date

• Jewels: 0

• Accuracy: ±20 seconds per month

• Battery Type: SR920SW (1.5V silver oxide)

• Battery Life: Approx. 3 years

• Hacking Seconds: No

• Quickset Day/Date: Yes

• Calendar Languages: English + another (usually Spanish or Kanji, depending on region)

• Movement Diameter: ~23.3 mm

• Movement Thickness: ~3.1 mm

• Integrated Circuit: CMOS-based with quartz oscillator

• Temperature Compensation: No

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Movement Features

Functional Design

The 5K25A is built with a simple and robust architecture that prioritizes efficiency and low production cost. Despite having no jewels, it is engineered to run reliably for years thanks to durable plastic and metal bushings. It powers three centrally mounted hands along with dual calendar wheels—a layout favored for legibility and practicality.

Day-Date Quickset Mechanism

• Crown Position 1 (pulled halfway):

  • Rotate clockwise to set the date

  • Rotate counterclockwise to set the day

• Crown Position 2 (pulled fully):

  • Time setting (hours and minutes)

  • Seconds hand does not hack

⚠️ Always avoid using the quickset function between 9 PM and 3 AM to prevent damage to the date-change gears.

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Watch Models Using the 5K25A

The 5K25A was used extensively in Seiko’s entry-level quartz watches, particularly from the early 2000s onward. These include:

• Seiko Quartz Day-Date stainless steel models

• Classic round and tonneau case watches

• Models with Arabic numerals, baton indices, or Roman numerals

• Two-tone watches for formal and casual wear

• Often labeled with "Quartz" and "Water Resistant" dials

While not positioned as luxury pieces, these watches are valued for their everyday reliability, convenient calendar functions, and low maintenance needs.

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Servicing and Maintenance

Battery Replacement

• Battery Type: SR920SW (1.5V)

• Ensure clean contact surfaces when installing the new battery.

• No reset is required unless the movement has stopped for an extended period.

Servicing Notes

• No jewels means there are no lubrication points—ideal for low-maintenance use.

• Movement is generally not designed for disassembly and repair, but full replacement is easy and affordable.

• Day/date disks and crown/stem components may be interchangeable with other basic Seiko calibers from the 5K, 7N, or 5Y series.

Replacement Parts

• Seiko 5K25A movements are readily available on the secondary market.

• Parts such as hands, calendar wheels, and stems are often compatible with similar Seiko quartz calibers.

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Summary Table

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Conclusion

The Seiko 5K25A is a no-frills, durable quartz movement made for long-term reliability in daily-wear watches. Its straightforward design, quickset calendar, and proven Seiko quality make it a solid choice for both watchmakers and collectors looking to restore or maintain affordable quartz models. While it may lack luxury features, the 5K25A excels in functionality, accessibility, and ease of service—hallmarks of Seiko’s commitment to dependable watchmaking.

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