Casio G-Shock G7900A-4 Digital Sport Watch User Manual

Introduction

This manual provides detailed instructions for the operation and maintenance of your Casio G-Shock G7900A-4 Digital Sport Watch. Designed for durability and functionality, this timepiece offers advanced features including tide and moon data, world time, multiple alarms, and a stopwatch, all within a shock-resistant and water-resistant casing.

Front view of the Casio G-Shock G7900A-4 Digital Sport Watch, showcasing its red resin case and digital display with time, date, and tide/moon indicators.

Key Features

• Shock Resistant: Engineered to withstand impacts and vibrations.
• 200M Water Resistant: Suitable for professional marine activity and serious surface water sports.
• Tide Graph: Displays tide levels for specific dates and times.
• Moon Data: Shows moon age and phase graph.
• Low Temperature Resistant LCD: Operates reliably in temperatures down to -20°C (-4°F).
• Auto EL Backlight with Afterglow: Provides illumination for easy reading in low light conditions.
• Flash Alert: Flashes with buzzer for alarms, hourly time signal, and timer functions.
• World Time: Displays time for 29 time zones (48 cities).
• Multi-function Alarms: Four daily alarms and one snooze alarm.
• Countdown Timer: Measuring unit of 1 second, range up to 24 hours.
• Stopwatch: 1/100 second stopwatch with measuring capacity up to 999 hours.
• 12/24 Hour Formats: Selectable time display format.
• Auto Calendar: Pre-programmed until the year 2099.

Setup

Battery Information

The G7900A-4 watch uses one CR2025 lithium battery. The approximate battery life is 2 years under normal usage conditions. When the display becomes dim or the backlight function weakens, it may be time to replace the battery. Battery replacement should ideally be performed by a qualified technician to ensure water resistance integrity.

Initial Time Setting

1. In Timekeeping Mode, press and hold the ADJUST button until the city code starts to flash. This indicates the setting mode.
2. Use the SPLIT/RESET and START/STOP buttons to select your home city code.
3. Press the MODE button to cycle through the settings: DST (Daylight Saving Time), 12/24-hour format, seconds, hour, minute, year, month, and day.
4. Use the SPLIT/RESET and START/STOP buttons to adjust the flashing value.
5. After setting all desired values, press the ADJUST button to exit the setting mode.

Tide and Moon Data Setup

To ensure accurate tide and moon data, you must input your specific location's longitude, lunitidal interval, and UTC offset.

1. Enter the Tide/Moon Data Mode by pressing the MODE button until "TIDE" or "MOON" appears.
2. Press and hold the ADJUST button until the longitude setting starts to flash.
3. Use the SPLIT/RESET and START/STOP buttons to adjust the longitude.
4. Press MODE to move to the lunitidal interval setting. Adjust this value using the SPLIT/RESET and START/STOP buttons. Consult local tide charts or online resources for precise lunitidal interval data for your location.
5. Press MODE again to set the UTC offset if necessary.
6. Press ADJUST to save settings and exit.

Side view of the Casio G-Shock G7900A-4, showing the robust case design and button placement.

Operating the Watch

Button Functions

• ADJUST (Top Left): Used to enter and exit setting modes, and to confirm settings.
• MODE (Bottom Left): Cycles through the watch's various modes (Timekeeping, Tide/Moon Data, Stopwatch 1, Stopwatch 2, Countdown Timer, Alarm, World Time).
• SPLIT/RESET (Top Right): Used for adjusting values upwards in setting modes, and for split/reset functions in stopwatch mode.
• START/STOP (Bottom Right): Used for adjusting values downwards in setting modes, and for start/stop functions in stopwatch and timer modes.
• ILLUMINATOR (Front Center): Activates the EL backlight.

Modes Overview

Timekeeping Mode:

Displays the current time, date, and day of the week. This is the default mode.

Tide/Moon Data Mode:

Shows the current moon phase and tide graph based on your configured location data. The moon phase indicator shows the current phase as viewed from the Northern Hemisphere. The tide graph has six segments indicating tide level.

Stopwatch Mode (ST1 & ST2):

Two independent 1/100 second stopwatches. Measuring capacity is 999 hours, 59 minutes, 59.99 seconds. Features include elapsed time, split time, and 1st-2nd place times. ST1 also has a 5-second auto-start feature.

Countdown Timer Mode:

A countdown timer with a measuring unit of 1 second and a range of 24 hours. Features auto-repeat and a progress beeper.

Alarm Mode:

Set up to four independent multi-function alarms and one snooze alarm. An hourly time signal can also be activated.

World Time Mode:

View the current time in 29 time zones (48 cities). Daylight Saving Time (DST) can be toggled on or off for each city.

Illumination

Press the ILLUMINATOR button to activate the EL backlight. The watch also features an Auto EL Backlight, which can be enabled to automatically illuminate the display with a slight angle movement of the wrist. Flash Alert causes the display to flash in conjunction with alarm sounds or timer completion.

Maintenance

Water Resistance

The Casio G-Shock G7900A-4 is water resistant to 200 meters (660 feet). This makes it suitable for professional marine activity and serious surface water sports. It is not recommended for scuba diving. To maintain water resistance, ensure all buttons are not operated while the watch is submerged. Avoid exposing the watch to hot water, steam, or chemicals (like those found in soaps or shampoos), as these can degrade the seals over time.

Rear view of the Casio G-Shock G7900A-4, showing the stainless steel case back with "G-SHOCK RESIST" engraving.

General Care

• Clean the watch regularly with a soft, dry cloth. For stubborn dirt, use a mild soap solution and rinse thoroughly, then dry.
• Avoid exposing the watch to extreme temperatures, direct sunlight for prolonged periods, or strong magnetic fields.
• The resin band and bezel can be maintained using products designed for resin protection, such as Vinylex Quick Wipes, to prevent hardening or cracking over time.

Troubleshooting

Inaccurate Tide Graph Reading:

If your tide graph appears inaccurate after setting the lunitidal interval, try adding 7 hours to your calculated lunitidal interval value during setup. This adjustment has been noted to improve accuracy for some users.

World Time Discrepancies:

If certain World Time cities show an incorrect time, verify that the Daylight Saving Time (DST) setting is correctly configured for that specific city. Some regions may have unique DST rules or may not observe DST at all.

Dim Display or Weak Backlight:

This typically indicates a low battery. Replace the CR2025 battery. If the issue persists after battery replacement, consult a service center.

Specifications

A visual guide illustrating various watch case sizes for comparison.

Warranty and Support

For warranty information and customer support, please refer to the official Casio website or the warranty card included with your purchase. Casio provides support for its products, and details can typically be found in the documentation accompanying the watch or by contacting Casio customer service directly.

For additional resources and product information, visit the Casio Store on Amazon.