Citizen C900 Manual

	• Before using the watch, read this instruction manual
CAUTION	carefully for safe and correct use.
	• After reading this manual, keep it handy for future
	reference.

Safety Precautions (Instructions to be followed at all times)

This manual contains the following instructions that should be strictly followed at all times to prevent injury to yourself and other persons as well as damage to property. WInjuries and damage that might be caused by using the watch improperly or neglecting any of the instructions or precautions contained in this manual are

classified with the following symbols.

WARNING Can cause serious injury or death

CAUTION Can or will cause minor or moderate injury or damage

WImportant instructions that should be followed are classified with the following symbol.

Warning (caution) symbol followed by instructions that should be followed or precautions that should be observed.

Prohibition symbol followed by [do nots] (What you should not do)

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WARNING	English

Diving is inherently dangerous. When wearing this watch while diving, please make sure that you have a correct understanding of the handling of it as described in these instructions and observe the correct operating procedure at all times.

The water depth gauge of this watch is not certified for use as an officially sanctioned measuring instrument. It should only be used as a reference instrument for a rough indication of water depth.

•Although this watch is equipped with a water depth gauge and altimeter, do not attempt to measure altitude at elevated locations immediately after diving. Moving to elevated locations (such as mountain climbing or flying in an airplane) after diving without allowing a suitable rest period can cause the occurrence of decompression sickness (bends).

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•Diving while wearing this watch is limited to recreational diving only (nondecompression diving). Do not wear this watch during decompression diving, saturation diving or when diving at high altitudes. Although the watch can be worn in the water over a temperature range of +10°C to +40°C, water depth is not displayed correctly in water other than saltwater (specific gravity: 1.025).

•Sudden atmospheric changes and changes in water temperature may affect the display and performance of this watch. It is necessary to use the watch in combination with other instruments in such cases. The display of this watch should only be used for reference purposes as a rough indicator.

•Although the use of this watch is limited to recreational diving, even recreational diving can be dangerous. The user is strongly recommended to use this watch only as a supplementary instrument during diving after having first received the proper scuba diving training from a qualified instructor, acquiring the necessary experience and skills for safe diving, and completely mastering the handling and operation of this watch.

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CONTENTS
WARNING ...................................................................................................			3
1.	Features .................................................................................................		8
2.	Use of this Watch .................................................................................		10
	A. Use During Diving	B. Use of Altimeter and Barometer
3.	Digital Display ......................................................................................		18
4.	Names and Functions of Components		.............................................. 20
5.	Setting Analog Time ............................................................................		24
6.	Changing the Mode ..............................................................................		26
7.	Using the Time / Calendar Mode..........................................................		29
	A. Setting the Digital Time and Date		B. Temperature Measurement
	C. Display of Changes in Barometric Pressure
8.	Using the Alarm Mode .........................................................................		33
	A. Setting the Alarm Time
9.	Using the Chronograph Mode .............................................................		35
	A. Chronograph Measurement

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10.	Using the Log Memo Mode		................................................................		38	17.	Altimeter Applications ........................................................................		68
	A. Recalling Log Data	B. Deleting Log Data					A. Measuring Altitude when Mountain Climbing		B. Other Applications
	C. Explanation of Log Data Terms						C. Prominent Mountains and Lowlands Around the World (Reference)
11.	Using the Dive Alarm Mode		...............................................................		42	18.	Low Battery Warning Function ..........................................................		72
	A. Setting the Depth Alarm and Dive Time Alarm					19.	Other Functions ..................................................................................		73
12.	Using the Altitude Memo Mode .........................................................				46		A. Button Function Display	B. Rotating Bezel	C. Compass
	A. Recalling a Point Memo		B. Deleting a Point Memo				D. No Decompression Limits
13.	Using the Water Depth Measurement .....................................Mode				49	20.	Battery .................................................................................................		78
	A. Water Depth Measurement and Display			B. Measurement of Dive Time		21. Troubleshooting .................................................................................			80
	C. Measurement of Water Temperature					22.	Care for Long Term Use .....................................................................		82
	D. Warning Functions During Water Depth Measurement					23.	All-Reset ..............................................................................................		89
14.	Using the Surface Mode	.....................................................................			55	24.	Specifications .....................................................................................		90
15.	Altimeter Basic Features ....................................................................				57
16.	Using the Altitude Measurement ............................................Mode				59

A.Altitude Correction

B.Continuous Altitude Measurement and Fixed Duration Altitude Measurement

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1. Features

This watch is a combination watch equipped with a water depth gauge that measures water depth during diving, and an altimeter that measures altitude during mountain climbing and other high altitude activities.

<Water Depth Measurement Function>

•Begins measurement of water depth automatically simply by wearing on the wrist and entering the water.

•Measures water depth in 0.1 m units down to a maximum depth of 80 m.

•Automatically records diving data (log data) of the four most recent dives.

•Equipped with various warning functions necessary for ensuring safe diving.

<Altitude Measurement Function>

•Measures altitude in 5 m units over a range from -300 m to 6,300 m.

•Measures barometric pressure in 1 hPa (1 hectopascal = 1 millibar) units over a range from 452 hPa to 1050 hPa.

•Equipped with an altitude memo function that enables altitude, barometric pressure, time and other data to be stored in memory for a maximum of six measurement points.

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<Other Functions>

•Temperature measurement function that allows measurement of water temperature while diving and air temperature on land.

•Chronograph function (24 hour register) able to measure time in 1/100 second units.

•24-hour alarm function

All repairs performed on this watch, including battery replacement, are to be performed by a Citizen Service Center since special techniques and equipment are required for making final adjustments and checks after repairs (including battery replacement) have been completed. Please contact a Citizen Service Center when having your watch repaired or inspected.

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2. Use of this Watch

CAUTION

•When using this watch, please make sure that you have a thorough understanding of its handling and precautions relating to its use to ensure that it is used correctly. Please note that handling this watch in a manner not described in these instructions may cause it to function improperly.

WARNING

•The water depth measurement functions as well as the altitude and barometric pressure measurement functions of this watch are not certified for use as officially sanctioned measuring instruments. They should only used as auxiliary measurements.

•The measured values for water depth, altitude and barometric pressure displayed by this watch should only be used for reference purposes as rough indications of their respective values.

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A. Use During Diving

CAUTION: Please observe the following for safe diving.

•When using this watch during diving, always make sure to receive the necessary education and training and observe diving rules.

•Always make sure to use the “buddy system” *1 when diving.

•This watch is recommended to be used for recreational diving only to depths of no more than 20 m in consideration of safety.

•It is recommended that the battery be replaced promptly. The battery life of this watch is approximately 2 years after a new battery has been installed (although this varies considerably depending on the frequency of use of the water depth measurement function and other functions).

•Please make sure to allow for a suitable rest period after diving in accordance with rules for diving safety. Flying in an airplane or moving to high altitudes without allowing a suitable rest period after diving can cause decompression sickness (bends).

*1:The buddy system refers to diving in pairs so that each person can look out for the safety of the other.

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PROHIBITED: Prohibited Uses During Diving

Do not use this watch for diving under the following conditions:

• When the low battery warning function has been activated

• • • The second hand of the watch moves at two-second intervals when the battery level becomes low.

•When the watch stops or when an abnormality occurs (please be careful not to bump the watch on diving equipment, rocks or other hard objects).

•When the water depth measurement function is used outside the guaranteed temperature range or at high altitudes

• • • The temperature range over which the water depth measurement accuracy of this watch is guaranteed is +10°C to +40°C.

• • • Water depth cannot be measured at altitudes more than 4,000 m above sea level.

• When behavior or the situation is judged to be dangerous

• • • This watch is not made to be used as a preventive or emergency device for shipwrecks or other maritime accidents.

•When the watch is used in atmospheres containing helium gas (such as during saturated diving)

• • • Use of the watch under these conditions can cause failure or damage to the watch.

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CAUTION - Diving Precautions

<Before Diving>

•Check that the display of the watch is in a mode other than the altitude measurement mode or chronograph measurement mode.

•Check that “ER” or “CHEk” is not displayed on the digital display.

•Check that the crown is firmly pressed in and screwed in to the lock position.

•Check that the band is securely fastened to the watch body.

•Check that there are no cracks, chips or other abnormalities in the watch band or glass.

•Check that the rotating bezel rotates normally.

•Check that the time and date are set correctly.

•Check that the water depth alarm and dive time alarm are set correctly.

•Check that the second hand is moving properly.

*If the second hand is moving at two-second intervals, this indicates that the battery is nearly worn down. Please have the battery replaced at a Citizen Service Center.

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<During Diving>

•Avoid ascending too rapidly. Attempting to ascend at an excessively rapid rate can have detrimental effects on the body such as causing the bends. Observe a safe ascent rate at all times.

•Never attempt to operate the crown underwater. This can cause a malfunction due to impaired water resistance.

•Caution is required since the alarm may be difficult to hear due to breathing noise underwater.

<After Diving>

•Allow a suitable rest period after diving while referring to the surface mode (measurement of elapsed time after diving).

•Rinse off any sea water, mud or sand adhering to the watch with fresh water after confirming that the crown is screwed in and locked in position, and then wipe off any excess moisture with a dry cloth.

•Do not attempt to remove any debris or dirt trapped in the sensor by removing the sensor cover or poking with a sharp object. If debris should happen to enter the sensor, rinse with fresh water. When debris cannot be removed by rinsing, consult a Citizen Service Center.

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CAUTION - Diving at High Altitudes or in Fresh Water

•Do not use this watch when diving at high altitudes more than 4000 m above sea level since it is unable to measure water depth correctly under these conditions.

•When diving at high altitudes or in fresh water, only use the watch after receiving special safety training.

•Since this watch displays water depth by converting on the basis of sea water (specific gravity: 1.025), the water depth displayed when diving in fresh water is actually 2.5% deeper. For example, when the watch displays a water depth of 20 m in fresh water, the actual water depth is 20 x 1.025 = 20.5 m.

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B. Use of Altimeter and Barometer

CAUTION - Altitude and Barometric Pressure Measurement Functions

•The altitude displayed by this watch is approximate altitude as calculated by applying external barometric pressure as detected with a pressure sensor to the relationship between altitude and barometric pressure of an international standard atmospheric model. Consequently, even when altitude is measured at the same location, the displayed altitude varies if the barometric pressure changes. In order to measure altitude correctly, it is necessary to always correct altitude at a location where the correct altitude is clearly indicated. For further details, refer to Section 15 entitled, “Altimeter Basic Features”.

•Since barometric pressure displayed by this watch is the external barometric pressure detected by a pressure sensor at the location of the measurement, the displayed barometric pressure changes if altitude changes. In addition, it also differs from the barometric pressure indicated on weather maps (barometric pressure converted to that at 0 m above sea level). Use the barometric pressure measurement function of this watch as a general reference for monitoring changes in barometric pressure at the same location.

•Both the altitude and barometric pressure measurement functions of this watch are subject to the effects of temperature changes. Even in the case of

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the same barometric pressure, display values (for altitude and barometric pressure) may change if the temperature changes.

PROHIBITED - Prohibited Uses of Altitude and Barometric

Pressure Measurement Functions

Do not use the altitude or barometric pressure measurement function of this watch under the following conditions:

•When behavior or the situation is judged to be dangerous

•When there are sudden changes in barometric pressure and temperature due to changes in weather conditions

•When barometric pressure is being adjusted such as in an airplane or building

•When altitude changes greatly in a short time (such as when skydiving)

CAUTION - Pressure Sensor

•The pressure sensor used in this watch is a high-precision device. Never attempt to disassemble it or poke it with a sharp object.

•The altitude measurement function may not operate properly if air is not allowed to flow to the sensor. Be careful to prevent debris and dust from entering the sensor as much as possible. In case debris, dust or other dirt becomes trapped in the sensor, rinse the sensor with fresh water. If the debris cannot be removed by rinsing, please consult a Citizen Service Center.

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3. Digital Display

The digital display of this watch uses three major modes consisting of the “Standard Mode”, “Water Depth Measurement Mode” and “Altitude Measurement Mode”. There are several other modes (functions) contained in the “Standard Mode”, such as the time, calendar and alarm modes. Please refer to the respective sections describing the use of each mode for further details.

[Standard Mode]

•Time/Calendar [TME]

This mode is used to display and correct the time and date. Measurement of temperature and barometric pressure are also performed in this mode.

•Alarm [ALM]

This mode is used to switch the alarm on and off, and set the alarm time.

•Chronograph [CHR]

This mode is used to measure and display time with the chronograph function (measures up to 24hours).

•Log Memo [D.log]

This mode is used to recall and display the four most recent sets of diving data automatically stored in memory during water depth measurement.

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•Dive Alarm [D.AL]

This mode is used to display and set the depth alarm and dive time alarm.

•Altitude Memo [A.log]

This mode is used to recall and display the altitude memos of six points stored in memory in the altitude measurement mode.

•Surface Mode

This mode is used to automatically measure and display the elapsed time until 24 hours from completion of diving. (This mode only displays 24 hours of elapsed time after making a continuous dive to a depth of 1 m or more for at least 3 minutes.)

[Water Depth Measurement Mode]

This mode is used when diving. It is used to measure and display current water depth and dive time at 1 second intervals while diving.

[Altitude Measurement Mode]

This mode is used when mountain climbing and so forth. It is used to measure and display altitude and barometric pressure either at 1 second or 15 minute intervals. In addition, this mode is also used to correct altitude to measure altitude more accurately.

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4. Names and Functions of Components

Please read this section while referring to the watch illustration shown in the inside cover.

[Standard Mode]

	Name / Mode		Time / Calendar	Alarm	Chronograph	Log Memo	Dive Alarm	Altitude Memo	Surface
		Press once	Switches between seconds	Switches between	Starts and stops the	Recalls the memo	---	Recalls the memo	---
	Button (A)		and date / day display	on and off	chronograph
		Press for at least 2	Temperature / barometric	Alarm monitor	---	---	Dive alarm monitor	---	---
		seconds	pressure measurement
	Button (B)	Press once	---	---	Split time / reset	Switches display contents	---	Switches display contents	---
		Press for at least 2	To correction mode	To correction mode	---	---	To correction mode	---	---
		seconds
	Button (M)	Press once	To alarm mode	To chronograph mode	To log memo mode	To dive alarm mode	To altitude memo mode	To surface mode	To time/calendar mode
		Press for at least 2	To altitude measurement mode				To altitude measurement mode
		seconds
	1: Mode mark		TME	ALM	CHR	D.log	D.AL	A.log	---
	2: Digital display [1]		Hours, minutes	Hours, minutes	Hours, minutes	Log data	Depth alarm	Point data	Elapsed time
									(hours, minutes)
	3: Digital display [2]		Seconds / date, day	ON / OFF	Seconds,1 /100 seconds	Log data	Dive time alarm	Point data	SF.m
	20								21

[Water Depth Measurement Mode/Altitude Measurement Mode]

Name / Mode

Press once

Button (A)

Press for at least 2 seconds

Press once

Button (B)

Press for at least 2 seconds

Press once

Button (M)

Press for at least 2 seconds

1:Mode Mark

2:Digital display [1]

3:Digital display [2]

Water depth measurement mode (during measurement)

Recalls maximum water depth/ water temperature

Recalls maximum water depth/ water temperature

---

---

---

---

Displays on digital display [1]

Depth (m)

Dive time (minutes, seconds)

Altitude measurement mode (during measurement)

Starts/stops elapsed time

Stores memo of point data

Switches between altitude display/barometric pressure display

Measures temperature (when measuring altitude for a fixed period of time)

Switches the display (within the altitude measurement mode)

To [Standard Mode]

Displays on digital display [1]

Altitude (m)/barometric pressure (hPa)

Elapsed time (hours, minutes)

4 : Button (A) function display: Functions of button (A) are displayed with marks 5 : Button (B) function display: Functions of button (B) are displayed with marks 6 : Crown: Used to set analog time.

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7 : Analog time: Continuously displays the current time (hours, minutes, seconds) with the respective hands.

8 : Pressure sensor 1: Detects water pressure to measure and display water depth.

9 : Pressure sensor 2: Detects barometric pressure to measure and display altitude and barometric pressure.

10 : Water sensor: The watch automatically switches to the water depth measurement mode when this water sensor gets wet (except during display in the altitude measurement mode, during chronograph measurement and when correcting settings in any of the modes).

11 : Rotating bezel: Elapsed time can be measured by using this rotating bezel. 12 : Compass: A rough approximation of direction can be determined from the

position of the sun by using this compass (only applicable to models equipped with a compass).

VButton Symbols

The button symbols used in the explanatory illustrations of each section have the meanings indicated below.

(( )): Press the button for at least 2 seconds ( ): Press the button once.

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5. Setting Analog Time

Normal position

Time correction position

Crown

(1)After unscrewing the crown to loosen it, pull the crown out. The second hand stops when the crown is pulled out.

(2)Turn the crown to set the time.

(3)The second hand starts to move when the crown is returned to the normal position.

(4)Securely screw the crown in to lock in position.

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<Screw-Locking Crown>

•Unscrew the crown to loosen it before turning.

•Always make sure that the crown is screwed in and locked in position after turning.

•Do not press any of the buttons with the crown pulled out.

•Do not attempt to turn the crown when there are water droplets on the watch or when underwater. This can allow water to enter inside the watch and impair water resistance.

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6. Changing the Mode

•The mode changes in the following order each time button (M) is pressed: Time/calendar c alarm c chronograph c log memo c dive alarm c altitude memo c surface (after diving).

[Standard Mode]

(M)

Time/

Alarm

Chronograph

calendar

<TME>

(M)

<ALM>

(M)

<CHR>

Surface

(M)

(M)

*Only displayed for

24 hours after

diving.

Altitude

Dive alarm

Log memo

memo

(M)

(M)

<D.AL>

(M)

<D.log>

<A.log>

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•When the water sensor of this watch becomes wet in any of the modes of the standard mode (except during chronograph measurement), the mode automatically changes to the water depth measurement mode.

•When button (M) is pressed for at least 2 seconds in any of the modes of the standard mode (except during chronograph measurement), the mode changes to the altitude measurement mode (altitude correction display).

When water		[Water Depth Mea-
sensor gets wet
		surement Mode]
		(preliminary state)

*Please refer to the section 13 entitled, “Using the Water Depth Measurement Mode” for further details.

[Altitude Measure- ((M)) ment Mode] (alti-

tude correction display)

*Please refer to the section 16 entitled, “Using the Altitude Measurement Mode” for further details.

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*The surface mode only displays 24 hours of elapsed time after completion of a continuous dive of at least 3 minutes duration. In other cases, pressing button (M) when the watch is in the altitude memo mode switches the watch to the time/calendar mode.

*When none of the buttons are pressed for at least 3 minutes when the watch is in the alarm mode, reset state of the chronograph mode, log memo mode, dive alarm mode or altitude memo mode, the watch automatically returns to the time/calendar mode.

*The watch cannot be changed to the water depth measurement mode or altitude measurement mode when the low battery warning function has been activated.

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7. Using the Time / Calendar Mode

This mode is used to display the current time and date.

•The watch alternates between displaying “hours, minutes and seconds” and “hours, minutes, date and day” each time button (A) is pressed during the normal display.

•Temperature and barometric pressure are displayed for 3 minutes when button (A) is pressed for at least 2 seconds during the normal display.

		((A))	Barometric
(B)	(A)		pressure
Seconds	Hours /
	minutes
(M)	TME	(A)	TME
	(A)		Temperature

Date / day

TME

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