Casio 3551 Operation Guide

About This Manual

This manual provides information for operating the Casio 3551 digital watch. Button operations are indicated by letters (A, B, C, D) shown in illustrations. Each section covers operations for a specific mode, with further details in the "Reference" section.

Button Identification:

• Button A: Typically used for mode selection or confirmation.
• Button B: Typically used for illumination or starting/stopping operations.
• Button C: Typically used for selecting items or adjusting values.
• Button D: Typically used for mode selection or scrolling through data.

Display Elements:

• Graphic Area A: Shows hour, minute, and second of the Home City Time.
• Graphic Area B: Shows seconds or progress in Timer/Stopwatch modes.
• PM Indicator: Appears for times from noon to 11:59 PM in 12-hour format.

Procedure Lookup

A quick reference list of operational procedures:

• To toggle Timekeeping Mode time between DST and Standard Time: EN-18
• To turn on illumination: EN-21
• To view the time for another city code: EN-22
• To toggle a city code time between Standard Time and Daylight Saving Time: EN-23
• To change your Home Time city to the current World Time city: EN-24
• To set an alarm time: EN-26
• To test the alarm: EN-29
• To turn an alarm on and off: EN-30
• To turn the Hourly Time Signal on and off: EN-31
• To configure the countdown timer: EN-33
• To measure times with the stopwatch: EN-36
• To turn the button operation tone on and off: EN-39
• To turn off Auto Display: EN-42
• To turn on Auto Display: EN-42
• To use the countdown timer: EN-34
• To use the stopwatch: EN-35

Watch Features

The Casio 3551 offers several features:

• Multi Time: Access to current time and date in up to four different cities (Home City Time T-1, and Local Times T-2, T-3, T-4).
• World Time: Displays current time in 48 cities (31 time zones) worldwide.
• Alarm: Five alarms (daily or one-time) and an Hourly Time Signal.
• Timer: Countdown timer with a range of 1 second to 24 hours.
• Stopwatch: Measures elapsed time, split times, and two finishes, up to 23 hours, 59 minutes, 59.99 seconds.

More information is available at the CASIO website: https://s.casio.jp/mw/en/3551/

Selecting a Mode

Press button [C] to cycle through the different modes:

• Timekeeping Mode
• World Time Mode
• Alarm Mode
• Timer Mode
• Stopwatch Mode

In any mode (except when a setting screen is displayed), pressing button [B] illuminates the display.

Mode Transition Diagram:

• From Timekeeping Mode, press [C] to go to World Time Mode.
• From World Time Mode, press [C] to go to Alarm Mode.
• From Alarm Mode, press [C] to go to Timer Mode.
• From Timer Mode, press [C] to go to Stopwatch Mode.
• From Stopwatch Mode, press [C] to return to Timekeeping Mode.

Timekeeping

The Timekeeping Mode displays the current time and date. The Multi Time feature allows quick access to times in four cities (T-1 to T-4).

Display Layout:

• Top Area (Graphic Area A): Shows the current Home City Time (T-1) with hour, minute, and second.
• Bottom Area: Shows the day of the week, month, and day.
• PM Indicator: Appears to the left of the hour digits for times from noon to 11:59 PM in 12-hour format.

Switching Between Time Screens:

Pressing button [D] cycles through the time screens for T-1 (Home City), T-2 (Local Time), T-3 (Local Time), and T-4 (Local Time). Each city code is displayed for one second before the time.

Changing the Current Home City Time and Date Settings:

1. In the Timekeeping Mode, display the Home City Time (T-1) screen.
2. Hold down button [A] until the seconds start flashing, indicating the setting screen.
3. Press button [C] to move the flashing cursor to the setting you want to change (Seconds, DST, City Code, Hour, Minute, 12/24-Hour Format, Year, Month, Day).
4. Use buttons [D] (east/increase) and [B] (west/decrease) to change the flashing setting.
   • Seconds: Reset to 00 by pressing [D].
   • DST: Toggle between Daylight Saving Time (On) and Standard Time (Off) by pressing [D].
   • City Code: Change by pressing [D] (east) and [B] (west).
   • Hour/Minute: Change by pressing [D] (+) and [B] (-).
   • 12/24-Hour Format: Toggle by pressing [D].
   • Year: Change by pressing [D] (+) and [B] (-).
   • Month/Day: Change by pressing [D] (+) and [B] (-).
5. Press button [A] to exit the setting screen. The day of the week is automatically set based on the date.

Daylight Saving Time (DST):

DST advances the time by one hour. To toggle DST on/off for the Home City Time:

1. Display the Home City Time (T-1) screen.
2. Hold down button [A] until seconds flash.
3. Press button [C] until the DST setting screen is displayed.
4. Press button [D] to toggle between DST (On displayed) and Standard Time (Off displayed).
5. Press button [A] to exit. A DST indicator appears when DST is on.

12/24-Hour Format:

The selected format (12-hour with PM indicator or 24-hour) applies to all modes.

Changing the City Setting of a Local Time:

1. Display the Local Time (T-2, T-3, or T-4) whose city setting you want to change.
2. Hold down button [A] for at least two seconds until the current city code flashes.
3. Use buttons [D] (east) and [B] (west) to select the desired city code.
4. Press button [C] to display the DST setting screen.
5. Press button [C] to toggle between DST (On displayed) and Standard Time (Off displayed).
6. Press button [A] to exit.

Changing Your Home City Time:

You can set one of the Local Times (T-2, T-3, T-4) as your new Home City Time (T-1).

1. In the Timekeeping Mode, display the Local Time you want to make your Home City Time.
2. Press buttons [A] and [B] simultaneously. The selected Local Time becomes the new Home City Time.

Illumination:

An LED illuminates the display. Pressing button [B] turns on the illumination for 1.5 or 3 seconds (selectable in settings).

Illumination Precautions:

• Illumination may be hard to see in direct sunlight.
• Illumination turns off automatically when an alarm sounds.
• Frequent use of illumination reduces battery life.

World Time

World Time displays the current time in 48 cities across 31 time zones. All World Time Mode times are calculated based on the Home City Time using UTC offset values.

To View the Time for Another City Code:

1. Enter the World Time Mode by pressing [C].
2. Press button [D] (east) to scroll through the city codes. The current time and date for the selected city code are displayed.

To Toggle a City Code Time Between Standard Time and Daylight Saving Time:

1. In the World Time Mode, use button [D] to display the city code whose DST setting you want to change.
2. Hold down button [A] for at least two seconds to toggle between DST (DST indicator displayed) and Standard Time (DST indicator not displayed).

Note: The DST/Standard Time setting only affects the currently displayed city code. UTC city code does not support DST switching.

To Change Your Home Time City to the Current World Time City:

1. In the World Time Mode, use button [C] to display the city you want to make your new Home Time city.
2. Press buttons [A] and [B] simultaneously. The selected World Time city becomes the new Home Time city.

Alarm

The watch features five alarms, which can be set as daily alarms (sound every day) or one-time alarms (sound once). An Hourly Time Signal can also be enabled to beep twice every hour.

Alarm Operation: Alarms operate in coordination with the current Home City Time. The alarm tone sounds for 10 seconds or until any button is pressed.

To Set an Alarm Time:

1. Enter the Alarm Mode by pressing [C].
2. Use button [C] to scroll through the alarm numbers (1 through 5) until the desired alarm is displayed.
3. Hold down button [A] until the hour setting of the alarm time starts flashing. This also automatically turns on the One-time Alarm.
4. Press button [C] to move the flashing cursor to the setting you want to change (Hour, Minute, Alarm Type: One-time/Daily).
5. Use buttons [D] (+) and [B] (-) to change the flashing setting.
   • Hour/Minute: Change by pressing [D] (+) and [B] (-). Pay attention to the PM indicator for 12-hour format.
   • Alarm Type: Toggle between One-time Alarm (e.g., 1-On) and Daily Alarm (On) by pressing [D].
6. Press button [A] to exit the setting screen.

To Test the Alarm:

In the Alarm Mode, hold down button [C] to sound the alarm.

To Turn an Alarm On and Off:

1. In the Alarm Mode, use button [C] to select the alarm you want to turn on or off.
2. Press button [A] to cycle through the alarm status: Alarm Off, One-Time Alarm On, Daily Alarm On. The corresponding indicator (e.g., ALM) is displayed.

To Turn the Hourly Time Signal On and Off:

1. In the Alarm Mode, use button [C] to select the Hourly Time Signal.
2. Press button [A] to toggle it on or off. A signal on indicator is shown on the display in all modes when this function is on.

Timer

The countdown timer can be set from 1 second to 24 hours. An alarm sounds when the countdown reaches zero.

To Configure the Countdown Timer:

1. Enter the Timer Mode by pressing [C].
2. Hold down button [A] until the countdown start time begins flashing.
3. Press button [C] to move the flashing cursor to the setting you want to change (Hours, Minutes, Seconds).
4. Use buttons [D] (+) and [B] (-) to change the flashing value. To set a 24-hour countdown, set it to 0:00 00.
5. Press button [A] to exit the setting screen.

To Use the Countdown Timer:

• Press button [B] while in the Timer Mode to start the countdown.
• Press button [B] to pause the countdown. Press again to resume.
• To stop the countdown completely, pause it first by pressing [B], then press button [A]. This resets the countdown to its starting value.

When the countdown reaches zero, the alarm sounds for 10 seconds or until any button is pressed. The countdown time resets automatically.

Stopwatch

The stopwatch measures elapsed time, split times, and two finishes. The display range is up to 23 hours, 59 minutes, 59.99 seconds.

To Measure Times with the Stopwatch:

• Elapsed Time: Press [B] to start, press [B] to stop. Press [A] to clear.
• Split Time: Press [B] to start. Press [D] to record a split time (SPL displayed). Press [D] again to release the split and resume elapsed time. Press [B] to stop. Press [A] to clear.
• Two Finishes: Press [B] to start. Press [D] when the first runner finishes (displays first runner's time). Press [D] again to release the split and show the second runner's time. Press [B] to stop. Press [A] to clear.

The stopwatch continues to run and restarts from zero if it reaches its limit until stopped. Measurement continues even if you exit the Stopwatch Mode.

Reference

This section provides detailed and technical information, including precautions for watch features and functions.

Graphic Areas:

• Graphic Area A: In all modes, displays segments for the current Home City Time (hour, minute, second).
• Graphic Area B: In Timekeeping and World Time modes, displays seconds. In Timer and Stopwatch modes, displays progress in units of 1/10 second.

Button Operation Tone:

The button operation tone can be turned on or off. Even when off, alarms and signals still function. To toggle the tone on/off, hold down button [D] in any mode (except setting screens). The mute indicator ([MUTE]) appears when the tone is off.

Auto Return Features:

• If left idle in Alarm Mode for 2-3 minutes, the watch returns to Timekeeping Mode.
• If left on a screen with flashing digits for 2-3 minutes without operation, the watch exits the setting screen.

Specifications

Accuracy: ±30 seconds per month at normal temperature.

Timekeeping:

• Displays: Hour, minute, second, p.m. (P), month, day, day of the week.
• Time Format: 12-hour and 24-hour.
• Calendar System: Full Auto-calendar (2000-2099).
• Other: Multi Time (1 Home City, 3 Local Times), DST/Standard Time.

World Time:

• Cities: 48 cities (31 time zones) and UTC.
• Features: DST/Standard Time, Home Time City/World Time City swapping.

Alarms: 5 alarms (One-time or Daily), Hourly Time Signal.

Timer:

• Measuring Unit: 1/10 second.
• Input Range: 1 second to 24 hours.

Stopwatch:

• Measuring Unit: 1/100 second.
• Measuring Capacity: 23:59'59.99".
• Measuring Modes: Elapsed time, split time, two finishes.

Illumination: LED; selectable duration (1.5 or 3 seconds).

Other: Button operation tone on/off; Auto Display function.

Battery: One lithium battery (Type: CR1616). Estimated battery life is approximately 3 years with 10 seconds of alarm operation and 1.5 seconds of illumination per day.

Specifications are subject to change without notice.

City Code Table

The following table lists city codes, their UTC offsets, and GMT differentials. These values are based on data as of July 2022 and are determined by individual countries.