Casio 1680 User Manual

2. OPERATION CHART : QW-1680

• Press to change from mode to mode.

GENERAL GUIDE

• In the Timekeeping Mode, Temperature Data Recall Mode and Alarm Mode, press to illuminate the display for about two seconds. In the Countdown Alarm Mode and Stopwatch Mode,
press to illuminate the display for about two seconds.

Month-day display

Day of
week

Hour

PM

indicator

4.While any other setting (besides seconds) is selected (flashing), press to
increase it or to decrease it. While the 12/24-hour format setting is selected,
press to toggle it between 12 and 24.

• Except for the seconds or 12/24-hour setting, holding down a button changes the

setting at high speed.

5.After you set the time and date, press to return to the Timekeeping Mode.

• The day of the week is automatically set in accordance with the date.

• The date can be set within the range of January 1, 1995 to December 31, 2039.

• If you do not operate any button for a few minutes while a setting is flashing, the

flashing stops and the watch goes back to the Timekeeping Mode automatically.

Current Temperature Display

A built-in temperature sensor measures temperature and shows the measured value
on the display. The readout from the temperature sensor can also be switched
between Celsius (˚C) and Fahrenheit (˚F). The thermometer can be calibrated to
correct for errors.

Important

Temperature measurements are affected by your body temperature (while you are
wearing the watch), direct sunlight, and moisture. To achieve a more accurate
temperature measurement, remove the watch from your wrist, place it in a well
ventilated location out of direct sunlight, and wipe off all moisture from the case. It
takes approximately 20 to 30 minutes for the case of the watch to reach the actual
surrounding temperature.

Accurate temperature measurements cannot be achieved while you are wearing the
watch. The following graph illustrated affects of body temperature on actual
temperature.

Temperature

About Temperature Measurement

Temperature

The display shows “– – . – ˚C (or ˚F)” if a measured value falls outside the range of
–20˚C to 60˚C (–4˚F to 140˚F). The normal display will return as soon as the
temperature returns within the allowable range.

• Memory can hold up to 100 temperature data entries, which are managed on a first-

in, first-out basis. See “TEMPERATURE DATA RECALL MODE” of this manual for
details on how to recall memory data.

• The first data item is stored as data item 1, the second as data item 2, and so on up

to 100 data items.

• When a new data item is stored while there are already 100 data items (numbered 1

to 100) in memory, the new data item is “pushed” into memory from the top (on top of
item 100). This shifts all of the previous data items down one position (item 100
becomes item 99, 99 becomes 98, and so on), and item 1 is deleted.

Timekeeping Mode

Press

Current Temperature

Display

Press

TIMEKEEPING MODE

Month

Day

Seconds

Minutes

40˚C

30˚C

20˚C

10˚C

0˚C

Temperature measured when watch is worn on wrist

graph

You can select display of either the current date
(month and day) or temperature in the Timekeeping
Mode. Press to toggle between the date and
temperature display.

To set the time and date

1.While the current date (not the temperature) is
displayed in the Timekeeping Mode, hold down

until the seconds digits flash on the display.

2. Press to change the selection (flashing) in the
following sequence.

Seconds Hour Minutes

Day YearMonth

3.While the seconds setting is selected (flashing),
press to reset it to 00. If you press while the
seconds setting is in the range of 30 to 59, the
seconds are reset to 00 and 1 is added to the
minutes. If the seconds setting is in the range of
00 to 29, the minutes count is unchanged.

Approximate
Differences caused by

individual body
temperture or clothing

10˚C

20˚C 30˚C

40˚C

• A temperature measurement operation is

Current

temperature

performed whenever you switch from month-day
display to temperature display.

• Temperature measurements are performed and
the temperature value is updated every two
minutes while the current temperature is
displayed.

• Pressing while the current temperature is
displayed executes a temperature measurement
operation and stores the result in memory along
with the time of the measurement.

• At the top of each hour, the current temperature
is measured and stored in memory along with
the time of the measurement.

Countdown
Alarm Mode

12/24-Hour
Format

Temperature Data

Recall Mode

Switching between Celsius and Fahrenheit

1.Hold down while in the Current Temperature
Display and the current temperature digits flash.

2.Press to select either Celsius “˚C” or
Fahrenheit “˚F”.

3.After you select the Celsius or Fahrenheit, press

to return to the Temperature Display.

Alarm ModeStopwatch Mode

Flashes

• If you do not operate any button for a few minutes while a selection is flashing, the
flashing stops and the watch goes back to the Current Temperature Display
automatically.

Calibrating the Temperature Measurement

The temperature sensor of this watch is calibrated at the factory before shipment and
further adjustment is normally not required. If noticeable error is found in the
temperature readings produced by the watch, you can adjust it to correct the error.

Important

Incorrectly calibrating the temperature measurement of this watch can result in
incorrect readings. Carefully read the following before doing anything.

• Compare the readings produced by the watch with those of another reliable,
accurate thermometer.

• If calibration is required, remove the watch from your wrist and wait for 20 or 30
minutes to give the temperature of the watch time to stabilize.

• Perform the temperature calibration before procedure as quickly as possible to avoid
the temperature of the watch being affected by your body temperature.

• You can also perform temperature calibration underwater, if the water temperature is
stable.

To calibrate the temperature

Flashes

1.Hold down while in the Current Temperature
Display and the current temperature digits flash.

2.Each press of increase the displayed
temperature by 0.1˚C, and pressing the
decrease it by 0.1˚C.

• If you have selected Fahrenheit as your unit of
measurement, the above operations change the
reading by 0.2˚F.

• You can calibrate the temperature within a range
of –9.9˚C to +9.9˚C (–18.0˚F to +18.0˚F).

• Press and at the same time to reset the
temperature calibration to the factory setting.

3.After calibrating the temperature, press to
return to the Current Temperature Display.

• If you do not operate any button for a few minutes
while a selection is flashing, the flashing stops and
the watch goes back to the Current Temperature
Display automatically.

ABOUT THE BACKLIGHT

• Pressing (Timekeeping Mode, Temperature Data Recall Mode, Alarm Mode) or
(Countdown Alarm Mode, Stopwatch Mode) illuminates the display for about two
seconds.

• The backlight of the watch employs an electro-luminescent (EL) light, which loses
illuminating power after very long use.

• The illumination provided by the backlight may be hard to see when viewed under
direct sunlight.

• The watch will emit an audible sound whenever the display is illuminated. This is
caused by a transformer that vibrates when the EL panel lights up. It does not
indicate malfunction of the watch.

• The backlight automatically turns off whenever an alarm sounds.

COUNTDOWN ALARM MODE

The countdown alarm can be set within a range of 1

Seconds

1/10

second to 24 hours. When the countdown reaches

seconds

zero, an alarm sounds for 10 seconds or until you
press any button.

To set the countdown start time

1.Hold down while in the Countdown Alarm
Mode. The hour digits flash on the display 
because they are selected.

2.Press to change the selection in the following
sequence.

Hour SecondsMinutes

3.Press to increase the selected number or
to decrease it. Holding down either button 
changes the selection at high speed.

Mode
indicator

Hours

Minutes

• To set the starting value of the countdown time to 24 hours, set 0:00'00".

4.After you set the countdown start time, press to return to the Countdown Alarm
Mode.

• If you do not operate any button for a few minutes while a selection is flashing, the

flashing stops and the watch goes back to the Countdown Alarm Mode
automatically.

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To use the countdown alarm

1.Press while in the Countdown Alarm Mode to start the countdown alarm.

2.Press again to stop the countdown alarm.

•You can resume countdown alarm operation by pressing .

3.Stop the countdown alarm and then press to reset the countdown time to its
starting value.

•When the end of the countdown is reached and auto repeat timing is off, the alarm

sounds for 10 seconds or until you stop the alarm by pressing any button.
Countdown timing stops and the countdown time is automatically reset to its starting
value after the alarm stops.

To switch auto repeat timing on and off

1.Hold down while in the Countdown Alarm Mode. The hour digits flash on the
display because they are selected.

Auto repeat indicator

TEMPERATURE DATA RECALL MODE

Memory

number

Hours

Mode
indicator

Minutes

Temperature

Use this mode to recall temperature data that was
stored in memory. Memory can hold up to 100
temperature data entries, which are managed on a
first-in, first-out basis.

• When memory is full, the next measurement
causes the oldest entry to be deleted
automatically.

• Press to scroll forward through data, and to
scroll back. Recalling data starts with data item

100. You can then scroll back through the data
(99, 98, 97, and so on.)

• To delete all data in memory, hold down . You
cannot delete individual data items.

Press

OFF

2.Press to toggle auto repeat on and off.

3.Press to return to the Countdown Alarm Mode.
When the end of the countdown is reached while auto repeat is on, the alarm sounds,

•
but the countdown restarts from the beginning without stopping. You can stop the
countdown by pressing and manually reset to the start time by pressing .

•If you set a starting time of 10 seconds or less and have Auto Repeat turned on, the
countdown alarm tone (which normally sounds for 10 seconds) sounds for only one
second.

To turn the progress beeper on and off

Press while in the Countdown Alarm Mode to toggle the progress beeper on and
off.

•When the progress beeper is turned on, the watch beeps as the countdown time
passes the 10, 5, 4, 3, 2, and 1-minute marks, and the 50, 40, 30, 20, 10, 5, 4, 3, 2,
and 1-second marks.

Flashes

Press

Flashes

ON

OFF ON

STOPWATCH MODE

The stopwatch Mode lets you measure elapsed
time, split times, and two finishes. The range of the
stopwatch is 23 hours, 59 minutes, 59.99 seconds.
You can use the EL backlight at any time while the
stopwatch is operating.

Second runner
finishes.
Record time of
first runner.

About the Auto-Start function

With the Auto-Start function, the watch performs a
5-second countdown. When the countdown reaches
zero, stopwatch operation starts automatically.
During the final three seconds of the countdown, a
beeper sounds with each second.

To turn the Auto-Start function on and off

While the display is showing all zeros in the
Stopwatch Mode, press to toggle it on and off.

• 5 is shown in the upper display while Auto-Start is
turned on. 5 is not shown and the upper part of
the display shows all zeros when Auto-Start is
turned off.

Record time of
second runner.

Hours

1/100 seconds

Seconds

Minutes

Mode indicator

Elapsed time measurement

Start Stop Re-start Stop Clear

Split time measurement

Start Split Split release Stop Clear

Split time and 1st-2nd place times

Start
Split
Stop
Split release
Clear

•To stop the Auto-Start countdown and return to the all-zeros display, press .

•Pressing while the Auto-Start countdown is in progress immediately start the
stopwatch.

First runner
finishes.

ALARM MODE

Alarm on

Mode indicator

indicator

MinutesHours

Hourly time signal
on indicator

Alarm types

The types of alarm you get depends on the information you set.

• To set a daily alarm

Set the hour and minutes for the alarm time. Set “-” for the month and “--” for the day. This type
of setting causes the alarm to sound everyday at the time you set.

• To set a date alarm

Set the month, day, hour and minutes for the alarm time. This type of setting causes the alarm
to sound at the specific time, on the specific date you set.

• To set a 1-month alarm

Set the month, hour and minutes for the alarm time. Set “--” for the day. This type of setting
causes the alarm to sound every day at the time you set, only during the month you set.

• To set a monthly alarm

Set the day, hour and minutes for the alarm time. Set “-” for the month. This type of setting
causes the alarm to sound every month at the time you set, on the day you set.

To set the alarm time

1.Press while in the Alarm Mode to select Alarm 1 through Alarm 5.

Alarm 1

2.After you select an alarm, hold down until the hour digits start to flash on the
display. The hour digits flash because they are selected. At this time the Alarm is
automatically switched on.

3.Press to change the selection in the following sequence.

Hour DayMinutes

4.Press to increase the number or to decrease it. Holding down either button
changes the current number at high speed.

•The format (12-hour and 24-hour) of the alarm time matches the format you select

for normal timekeeping.

•When setting the alarm time using the 12-hour format, take care to set the time

correctly as morning or afternoon.

5.After you set the alarm time, press to return to the Alarm Mode.

•If you do not operate any button for a few minutes while a selection is flashing, the

flashing stops and the watch goes back to the Alarm Mode automatically.

To stop the alarm

•Press any button to stop the alarm after it starts to sound.

To switch an alarm and Hourly Time Signal on and off

1.In the Alarm Mode, press to select an alarm or the Hourly Time Signal.

2.When the alarm or Hourly Time Signal you want to is selected, press to switch it
on and off.

•The Alarm On indicator and Hourly Time Signal On indicator is shown on the display

when you change to another mode.

Alarm on indicator Hourly time signal on indicator

To test the alarm

Hold down while in the Alarm Mode to sound the alarm.

You can set five independent alarms with the hour,
minutes, month and day. Use the Alarm Mode to turn
the alarm and the Hourly Time Signal on and off.

• When an alarm is turned on, an alarm tone
sounds for 20 seconds when the preset time
reached.

• When the Hourly Time Signal is turned on, the
watch beeps every hour on the hour.

Alarm 2 Alarm 3

Hourly Time Signal

Alarm 4
Alarm 5

Month

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