The Seiko S800A is a multifunction analog-digital quartz movement designed for specialized tool watches that combine classic analog aesthetics with advanced digital functions. Positioned as a high-tier member of Seiko’s S-series hybrid movement family, the S800A supports complex operations like world time, chronograph, alarm, countdown timer, and a perpetual calendar, all while maintaining low power consumption and long-term reliability.

This movement is typically used in Seiko watches targeting global travelers, pilots, field operators, and digital watch enthusiasts seeking precision and flexibility in one sophisticated package.

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Overview

The S800A represents one of Seiko’s most feature-complete hybrid calibers, combining an analog display with an expanded multifunction LCD. It improves upon predecessors like the S701A and S610A by offering enhanced backlight functionality, faster digital refresh, and support for additional world time zones. The analog and digital systems are engineered to operate both independently and complementarily, offering unmatched flexibility for dual-time operations.

This movement is ideal for high-spec watches requiring robust timekeeping tools in any environment—be it daily urban use or extreme travel conditions.

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Key Features

• Analog Time Display: Hour and minute hands (central), with no analog seconds hand in most designs.

• Digital LCD Display: Multi-line readout for supporting functions.

• Chronograph (Stopwatch): Measures up to 100 minutes in 1/100-second increments.

• Countdown Timer: Programmable for task-specific timing.

• World Time / Dual Time: Digital tracking of a second time zone, with city code display.

• Daily Alarm: One or more programmable alarms (varies by implementation).

• Perpetual Calendar: Fully pre-programmed, typically through 2099.

• 12/24-Hour Time Format: Toggle between standard and military digital time display.

• Backlight: High-efficiency EL or LED lighting for nighttime visibility.

• Battery End-of-Life Indicator (EOL): Flashing display or dim backlight alerts user to low power.

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Technical Specifications

• Caliber: Seiko S800A

• Movement Type: Quartz (analog-digital hybrid)

• Battery Type: SR927W (1.55V silver oxide)

• Battery Life: Approx. 2–3 years (based on average backlight and alarm use)

• Accuracy: ±15 seconds/month

• Jewel Count: 0

• Module Size:

  • Diameter: Approx. 30 mm

  • Thickness: Approx. 6.3 mm

• Hand Hole Sizes:

  • Hour: 1.10 mm

  • Minute: 0.65 mm

Its size makes it compatible with medium to large watch cases in the 40–46 mm range.

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Operating Interface

The Seiko S800A typically uses a crown for analog control and four pushers to access digital functions.

Crown:

• Pull out to adjust analog hour and minute hands.

• Analog and digital times operate independently, making dual-time use convenient.

Button Layout (Standard Mapping):

• Button A (Top Left): Cycle through digital modes – Time, Chronograph, Timer, Alarm, World Time, Calendar.

• Button B (Top Right): Start/Stop in Chronograph, increase value in setting mode.

• Button C (Bottom Left): Reset (in stopwatch/timer), activate backlight.

• Button D (Bottom Right): Enter/exit setting mode, toggle 12/24-hour format, or access world city selection.

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Servicing & Maintenance

Battery Replacement:

• Use SR927W only for optimal voltage stability.

• After battery installation, perform an AC reset:

  • Locate the AC contact on the module and bridge it to the battery edge using tweezers or a probe.

• Confirm that the digital module reboots and test the backlight and alarm functions.

Hand Calibration:

• Set the analog hands via the crown.

• Analog and digital times must be synchronized manually if desired.

LCD Function Test:

• After reset, verify that all digital segments display properly.

• Faded or missing segments indicate LCD degradation—full movement replacement is typically required.

Gaskets and Water Resistance:

• Replace all gaskets upon case opening.

• Lubricate seals and perform a pressure test if the watch is water-resistant.

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Common Issues

• Blank or Frozen Digital Display: Usually caused by failure to perform AC reset after battery change.

• Non-Responsive Buttons: Often caused by moisture, dust, or worn pusher springs—clean and inspect.

• Analog/Digital Desynchronization: Set both time zones independently; no auto-sync.

• Backlight Failure: EL panel degradation or weak battery—replace battery or movement if necessary.

• Incorrect City/World Time Settings: Requires manual selection from city list via digital interface.

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Conclusion

The Seiko S800A is one of the most advanced and complete analog-digital movements in Seiko’s quartz lineup. With world time, stopwatch, calendar, dual time, and alarm functions—all packed into a durable and compact module—it offers everything today’s high-function watch enthusiast could need. Whether worn for adventure, travel, or technical use, the S800A provides seamless performance, intuitive controls, and Seiko’s trademark durability. It’s a movement built for those who expect their watches to do more than just tell the time.

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