The Seiko A708A is a digital quartz LCD movement introduced in the mid-1980s, designed for compact and ultra-slim digital watches. As part of Seiko’s mission to innovate in size, functionality, and display technology, the A708A balances minimalist styling with core digital functions, including time, calendar, and a daily alarm. Though simpler than other A-series multifunction calibers, the A708A remains respected for its precision, slim profile, and ease of use.

Technical Specifications

• Caliber Number: A708A

• Movement Type: Quartz (Digital LCD)

• Display Format: 7-segment Liquid Crystal Display

• Time Format: 12-hour (with PM indicator)

• Functions:

  • Timekeeping (HH:MM:SS)

  • Day and Date Calendar

  • Daily Alarm

• Backlight: Not integrated in module (select cases may include a case-mounted light)

• 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: Ultra-thin design (~3.5–4 mm)

Display Overview

The A708A module is known for its clear, efficient layout on a single-line LCD:

• Main Display:

  • Time shown in HH:MM:SS format

  • PM indicator when in 12-hour mode

• Secondary Indicators:

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

  • “AL” icon (alarm set)

  • “CH” (hourly chime, if present)

Its display was engineered for clarity within a slim housing—often under 7 mm total watch case thickness.

Functional Modes

The Seiko A708A supports three core functions:

1. Timekeeping Mode

• Displays the current time in hours, minutes, and seconds

• 12-hour format only

• “PM” icon appears when time is after 12:00 noon

• Default mode on power-up

2. Calendar Mode

• Displays the day of the week and date (e.g., TU 12-24)

• No year or leap-year logic

• Requires manual correction for months under 31 days

3. Alarm Mode

• Single daily alarm

• Set by hour and minute

• Alarm ON/OFF toggle

• “AL” icon displays when the alarm is active

• Audible alert through internal piezo buzzer

Some models may include hourly chime functionality (with a small “CH” icon), toggled through the same button interface.

Button Layout (Typical)

Most A708A watches feature three side buttons, although four-button variants exist.

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

• Button B (Bottom Left) – Set/select digit or toggle alarm/chime

• Button C (Right Side) – Increase value or confirm setting

The interface is minimal by design, in keeping with the thin and stylish watch case.

Setting Instructions

To Set Time:

1. Enter time mode using Button A

2. Press and hold Button B to enter setting mode (hour digits flash)

3. Use Button C to advance value

4. Press Button B again to move to the next field (minute → second)

5. Press Button A to save and exit

To Set Alarm:

1. Enter alarm mode

2. Press and hold Button B to enter alarm set

3. Use Button C to adjust values

4. Press Button B to move between hour and minute

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

Battery Replacement and AC Reset

Performing an AC reset is required after battery installation.

AC Reset Steps:

1. Open the case back using an appropriate tool

2. Remove the used SR1120W battery with plastic tweezers

3. Insert a fresh battery with correct polarity

4. Locate the AC (All Clear) terminal—usually labeled on the PCB

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

6. LCD should flash briefly and reset to 12:00:00

If skipped, the display may remain blank or malfunction.

Maintenance Tips

• No lubrication required – fully electronic

• Piezo buzzer contacts may oxidize—clean if alarm becomes faint

• Clean button contacts if responsiveness declines

• LCD fade or segment loss is often a sign of module aging

• These watches were rarely water-resistant—avoid submersion unless otherwise marked

Watch Models and Applications

The A708A was used in Seiko’s ultra-thin digital watches of the 1980s, including:

• Slim stainless steel dress watches

• Gold-plated or black ion-plated rectangular cases

• Reference numbers such as A708-5000, A708-5029, etc.

• Often labeled “Quartz” or “Alarm Chronograph” on the dial

These models were marketed toward professionals and minimalists seeking sleek, reliable digital timepieces.

Conclusion

The Seiko A708A exemplifies Seiko’s dedication to combining style with function. With its ultra-slim profile, practical daily features, and sharp display layout, it served wearers who wanted performance without bulk. Today, it remains a stylish vintage digital movement for collectors and enthusiasts who appreciate Seiko’s pioneering work in compact quartz technology.