Casio 2608, 2638, 2688 Reference, Daylight Saving Time (DST), Auto Return Features, Data and Setting Scrolling, Initial Screens, Radio-controlledAtomic Timekeeping Precautions

Operation Guide 2608 2638 2688

Daylight Saving Time (DST)

Daylight Saving Time (summer time) advances the time setting by one hour from Standard Time. Remember that not all countries or even local areas use Daylight Saving Time.

The time calibration signal transmitted from Fort Collins includes both Standard Time and DST data. When the Auto DST setting is turned on, the watch switches between Standard Time and DST (summer time) automatically in accordance with the received time signal.

•The default DST setting is Auto DST (AUTO) whenever you select HNL, ANC, LAX, DEN, CHI, or NYC as your Home City code.

•If you experience problems receiving the time calibration signal in your area, it is probably best to switch between Standard Time and Daylight Saving Time (summer time) manually.

To change the Daylight Saving Time (summer time) setting

1.In the Timekeeping Mode, hold down A until the city code starts to flash, which indicates the setting screen.

2.Press C and the DST setting screen appears.

3.Use Dto cycle through the DST settings in the sequence shown below.

Auto DST (AUTO)	DST off (OFF)	DST on (ON)
Auto DST (AUTO)	DST off (OFF)	DST on (ON)

4. When the setting you want is selected, press Atwice to exit the setting screen.

Reference

This section contains more detailed and technical information about watch operation. It also contains important precautions and notes about the various features and functions of this watch.

Auto Return Features

•If you leave the watch in the Time Recorder Mode or Alarm Mode for two or three minutes without performing any operation, it automatically returns to the Timekeeping Mode.

•If you leave a screen with flashing digits on the display for two or three minutes without performing any operation, the watch automatically saves anything you have input up to that point and exits the setting screen.

Data and Setting Scrolling

The B and Dbuttons are used in various modes and setting screens to scroll through data on the display. In most cases, holding down these buttons during a scroll operation scrolls through the data at high speed.

Initial Screens

When you enter the Alarm or World Time Mode, the data you were viewing when you last exited the mode appears first.

Radio-controlled Atomic Timekeeping Precautions

•	Strong electrostatic charge can result in the wrong time being set.
•	Even when the watch is within the reception range of the transmitter, signal
	reception is impossible if the signal is blocked by mountains or other geological
•	formations between the watch and signal source.
•	Signal reception is affected by weather, atmospheric conditions, and seasonal
•	changes.
•	The time calibration signal is bounced off the ionosphere. Because of this, such
	factors as changes in the reflectivity of the ionosphere, as well as movement of the
	ionosphere to higher altitudes due to seasonal atmospheric changes or the time of
	day may change the reception range of the signal and make reception temporarily
•	impossible.
•	Even if the time calibration signal is received properly, certain conditions can cause
	the time setting to be off by up to one second.

12-hour/24-hour Timekeeping Formats

The 12-hour/24-hour timekeeping format you select in the Timekeeping Mode is also applied in all other modes.

•With the 12-hour format, the P (PM) indicator appears on the display for times in the range of noon to 11:59 p.m. and the A (AM) indicator appears for times in the range of midnight to 11:59 a.m.

•With the 24-hour format, times are displayed in the range of 0:00 to 23:59, without any indicator.

Power Saving Function

When turned on, the Power Saving function automatically enters a sleep state whenever the watch is left in an area where it is dark for a certain period. The table below shows how watch functions are affected by the Power Saving function.

Elapsed Time		Display		Operation
in Dark
60 to 70 minutes	Blank, with Sleep indicator (S		/	All functions enabled, except
	SLEEP	) flashing		for the display

6 or 7 days	Blank, with Sleep indicator (S		/	Beeper tone, backlight, display,
	SLEEP	) not flashing		and auto receipt of the
				calibration signal are disabled.

•Wearing the watch inside the sleeve of clothing can cause it to enter the sleep state.

•The watch will not enter the sleep state between 6:00 AM and 10:59 PM. If the watch is already in the sleep state when 6:00 AM arrives, however, it will remain in the sleep state.

To recover from the sleep state

Perform any one of the following operations.

•Move the watch to a well-lit area. It can take up to two seconds for the display to turn on.

•Press any button.

•Angle the watch towards your face for reading.

To turn Power Saving on and off

		1. In the Timekeeping Mode, hold down A. This causes
		the city code to flash, which indicates the setting
ll		screen.
ll	l	2. Press Aagain.
l l ll
l	l	3. Press Cseven times until the Power Saving on/off
l l l		3. Press Cseven times until the Power Saving on/off
l l l
		screen appears.
		4. Press Dto toggle Power Saving on (ON) and off
Power saving on		(OFF).
Power saving on		5. After the setting is the way you want, press Ato exit
indicator		5. After the setting is the way you want, press Ato exit
indicator		the setting screen.
		the setting screen.

•The Power Saving on indicator is on the display in all modes while the Power Saving is turned on.

Backlight Precautions

•The electro-luminescent panel that provides illumination loses power after very long use.

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

•The watch may emit an audible sound whenever the display is illuminated. This is due to vibration of the EL panel used for illumination, and does not indicate malfunction.

•The backlight automatically turns off whenever an alarm sounds.

•Frequent use of the backlight shortens the battery operating time.

Auto light switch precautions

•Wearing the watch on the inside of your wrist as well as movement or vibration of your arm can cause the auto light switch to activate and illuminate the display. To avoid running down the battery, turn off the auto light switch whenever engaging in

activities that might cause frequent illumination of the display.

•	The current time setting in accordance with the time calibration signal takes priority
•	over any time settings you make.
•	The watch is designed to automatically update the date and day of the week for the
	period January 1, 2000 to December 31, 2099. Setting of the date by the time
•	calibration signal cannot be performed starting from January 1, 2100.
•	This watch can receive signals that differentiate between leap years and non-leap
•	years.
•	Though this watch is designed to receive both time data (hour, minutes, seconds)
	and date data (year, month, day), certain signal conditions can limit reception to time
•	data only.
•	Normally, the signal reception date shown by the Last Signal screen is the date data
	included in the received time calibration signal. When only time data is received,
	however, the Last Signal screen shows the date as kept in the Timekeeping Mode at
•	the time of signal reception.
•	If you are in an area where proper time calibration signal reception is impossible, the
•	watch keeps time within ± 15 seconds a month at normal temperature.
•	If you have problems with proper time calibration signal reception or if the time
	setting is wrong after signal reception, check your current city code, DST (summer
	time), and auto receive settings. The following are the initial factory defaults for
	these settings.

Setting	Initial Factory Default
City code	NYC	(New York)
DST (summer time)	DST	(Auto switching)
	AUTO
Auto receive		(Auto receive)
	ON

Timekeeping

•The day of the week is automatically displayed in accordance with the date (year, month, and day) settings.

•The year can be set in the range of 2000 to 2099.

•The watch’s built-in full automatic calendar makes allowances for different month lengths and leap years. Once you set the date, there should be no reason to change it except after you have the watch’s battery replaced or when battery power drops to Level 4.

•The current time for all city codes in the Timekeeping Mode and World Time Mode is calculated in accordance with the Greenwich Mean Time (GMT) differential for each city, based on the your Home City time setting.

•GMT differential is calculated by this watch based on UTC* data.

*The letters “UTC” stands for “Universal Time Coordinated,” which is the world-wide scientific standard of timekeeping. It is based upon carefully maintained atomic (cesium) clocks that keep accurate to within microseconds. Leap seconds are added or subtracted as necessary to keep UTC in sync with the Earth’s rotation. The reference point for UTC is Greenwich, England.

More than 15 degrees too high

•The backlight may not light if the face of the watch is more than 15 degrees above or below parallel. Make sure that the back of your hand is parallel to the ground.

•The backlight turns off in about one second, even if you keep the watch pointed towards your face.

•Static electricity or magnetic force can interfere with proper operation of the auto light switch. If the backlight does not light, try moving the watch back to the starting position (parallel with the ground) and then tilt it back toward you again. If this does not work, drop your arm all the way down so it hangs at your side, and then bring it back up again.

•Under certain conditions, the backlight may not light until about one second after you turn the face of the watch towards you. This does not necessarily indicate malfunction of the backlight.

•You may notice a very faint clicking sound coming from the watch when it is shaken back and forth. This sound is caused by mechanical operation of the auto light switch, and does not indicate a problem with the watch.