The Seiko A718A is a slim-profile digital quartz LCD movement introduced by Seiko in the mid-1980s. Designed for sleek rectangular watches, the A718A balances essential digital functions—including timekeeping, calendar, and alarm—within a minimalist display layout ideal for formal or everyday use. It is part of Seiko’s A7xx series of reliable digital modules created for users who preferred clear, straightforward features without added complexity.

Technical Specifications

• Caliber Number: A718A

• Movement Type: Quartz (Digital LCD)

• Display Type: 7-segment Liquid Crystal Display

• Primary Functions:

  • 12-hour timekeeping (with PM indicator)

  • Day and Date Calendar

  • Daily Alarm

• Time Format: 12-hour (AM/PM)

• Backlight: Not integrated into module (some models have external lighting in case)

• Battery Type: SR1120W (1.55V silver oxide)

• Battery Life: ~2 years

• Accuracy: ±15 seconds per month

• Module Dimensions:

  • Width: ~24–26 mm

  • Height: ~21–23 mm

  • Thickness: ~3.5–4 mm (slim profile)

Display Layout

The A718A offers a single-line LCD display designed for clarity and elegance, particularly in compact dress watches.

• Top Indicators:

  • Day of the week (MO, TU, WE, etc.)

  • Alarm indicator (“AL”)

  • PM indicator for afternoon times

• Main Display Field:

  • HH:MM:SS in normal time mode

  • MM-DD (or DD-MM depending on regional version) in calendar mode

This layout is highly readable, emphasizing clean symmetry and simplicity.

Operating Modes

The module supports three basic operating modes:

1. Timekeeping Mode

• Standard 12-hour format with seconds

• PM indicator turns on after 12:00 noon

• This is the default mode after reset or start-up

2. Calendar Mode

• Displays current day of the week and numeric date

• No automatic correction for month-end or leap years—manual adjustment required

• Format: MM-DD or DD-MM based on regional model

3. Alarm Mode

• One daily alarm, settable by hour and minute

• ON/OFF toggle function

• A small “AL” icon appears when the alarm is active

• Audible signal through piezo buzzer

Hourly chime function is not standard on A718A watches.

Button Configuration

Watches equipped with the A718A usually feature three side pushers, designed to maintain the slim profile of the case.

• Button A (Top Left) – Mode selection (Time → Alarm → Calendar)

• Button B (Bottom Left) – Enter setting mode / select field

• Button C (Right Side) – Advance digits / toggle alarm ON/OFF

The layout is intuitive, designed for quick single-handed use.

Setting Instructions

Setting the Time:

1. Enter time mode using Button A

2. Press and hold Button B until digits flash

3. Use Button C to adjust the hour

4. Press Button B to switch to minute and second

5. Press Button A to confirm and exit

Setting the Alarm:

1. Press Button A to enter alarm mode

2. Press and hold Button B until hour flashes

3. Adjust hour using Button C

4. Press Button B to move to minutes, adjust again

5. Press Button A to confirm

6. Toggle alarm ON/OFF with a short press of Button B in alarm mode

Battery Replacement & AC Reset

An AC (All Clear) reset is required after inserting a new battery to initialize the circuit.

Steps:

1. Open the case back using a proper case knife or tool

2. Remove the old SR1120W battery using plastic tweezers

3. Insert a new battery with correct polarity

4. Locate the AC terminal marked on the PCB

5. Use metal tweezers to short the AC contact to the battery’s negative terminal (case or contact spring) for 1–2 seconds

6. The LCD will flash and reset to 12:00:00

Skipping the reset can leave the screen blank or unresponsive.

Maintenance Tips

• No lubrication needed – fully electronic

• Clean buzzer and button contacts periodically for optimal performance

• If buttons are unresponsive, internal contacts may require light cleaning with isopropyl alcohol

• LCD ghosting or missing segments often signals aging—typically resolved only by module replacement

• Most A718A-equipped watches are not water-resistant unless specifically marked

Watch Models Using A718A

The A718A was installed in a variety of slim Seiko dress watches from the mid-1980s. Typical model characteristics:

• Stainless steel or gold-plated rectangular cases

• Minimalist dials with clean bezels

• Matching integrated bracelets or leather straps

• Examples: A718-5000, A718-5019, etc.

These were often marketed as Seiko’s professional or "gentleman’s digital" watches, ideal for formal or business settings.

Conclusion

The Seiko A718A is a refined and reliable digital movement that reflects Seiko’s commitment to minimalism and everyday usability. Designed for slim-profile watches, it delivers essential digital functions without unnecessary complexity. Today, A718A-powered watches remain appreciated for their elegant simplicity and durable quartz performance—an enduring piece of Seiko’s digital watch heritage.