Seiko H556A – Technical Guide

The Seiko H556A is a quartz analog-digital (ana-digi) movement introduced in the 1980s, primarily used in models like the Seiko Sports 100 and Silverwave series. This movement is notable for its combination of analog timekeeping with a digital display, offering features such as a chronograph, alarm, and dual-time zone functionality.

Movement Overview

• Type: Quartz analog-digital (ana-digi)

• Production Era: 1980s

• Battery: SR920W / 370 (Silver oxide)

• Accuracy: ±10 seconds/month

• Day/Date: Yes

• GMT/World Time: Yes

• Chronograph: Yes

• Alarm: Yes

• Rate: 32,768 Hz

• Jewels: 3

• Dimensions: 23.6mm x 26.0mm

• Height: 2.9mm

• Development Division: Suwa (Nagano Prefecture, Japan)

Features

• Analog Time: Standard hour, minute, and central seconds hands.

• Digital Time: Displays hours, minutes, and seconds in a digital format.

• Local Time: A second digital time zone, indicated with "-L" on the display.

• Day/Date: Displays current day and date.

• Alarm: Programmable alarm function.

• Chronograph: Stopwatch function with start/stop and reset capabilities.

• Hourly Chime: Option to enable or disable hourly chime.

• 12/24 Hour Format: Switchable between 12-hour and 24-hour time formats.

• Backlight: Illuminates the digital display for low-light conditions.

Operating Instructions

Analog Time Setting:

1. Pull the crown to position 3 to stop the second hand.

2. Turn the crown to set the hour and minute hands.

3. Push the crown back to position 1 to resume timekeeping.

Digital Time Setting:

1. Press button B until the time is displayed.

2. Pull the crown to position 2.

3. Turn the crown to adjust the time:

   • Turn in direction X to increment time.

   • Turn in direction Y to decrement time.

4. Press button B to reset the seconds:

   • If seconds are less than 29, they reset to 00 without changing minutes.

   • If seconds are 29 or more, they reset to 00 and increment the minutes by one.

5. Push the crown back to position 1 when the time is correct.

Day and Date Setting:

1. Press button B until the day and date are displayed.

2. Pull the crown to position 2.

3. Turn the crown:

   • In direction Y to change the day.

   • In direction X to change the date.

4. Push the crown back to position 1 when the day and date are correct.

Local Digital Time Setting:

1. Press button B until the local time (indicated with "-L") is displayed.

2. Pull the crown to position 2.

3. Turn the crown to adjust the local time:

   • Turn in direction X to increment time.

   • Turn in direction Y to decrement time.

4. Push the crown back to position 1 when the local time is correct.

12/24 Hour Format Switch:

1. Press button B until the time is displayed.

2. Pull the crown to position 2, then back to position 1.

3. Repeat this action to toggle between 12-hour and 24-hour time formats.

Alarm Time Setting:

1. Press button B until the alarm time (AL) is displayed.

2. Pull the crown to position 2.

3. Turn the crown to adjust the alarm time:

   • Turn in direction X to increment time.

   • Turn in direction Y to decrement time.

4. Push the crown back to position 1 when the alarm time is correct.

Alarm and Hourly Chime Activation:

1. Press button B until the alarm time (AL) is displayed.

2. Pull the crown to position 2, then back to position 1.

3. Repeat this action to cycle through the following settings:

   • Off Off Off

   • On On Off

   • Blinking On On

Stopwatch Function:

1. Press button B until the stopwatch is displayed.

2. Press button A to start and stop timing.

3. Hold button A pressed for a second to reset the stopwatch.

4. The stopwatch continues running when changing to a different mode.

Backlight:

• Press button A to illuminate the digital display. Note: The backlight does not function in stopwatch mode.

Alarm Test:

• Press buttons A and B simultaneously to sound the alarm.

Maintenance and Troubleshooting

• Battery Replacement: When the watch stops or the digital display becomes dim, replace the battery with an SR920W or equivalent silver oxide battery.

• Water Resistance: Ensure the case back is properly sealed to maintain water resistance. Regularly check and replace gaskets as needed.

• Cleaning: Clean the watch case and strap with a soft cloth. Avoid using abrasive materials that may scratch the surface.

• Servicing: For complex issues or repairs, consult a professional watchmaker experienced with Seiko movements.