Citizen C900 User Manual
• Before using the watch, read this instruction manual
carefully for safe and correct use.
CAUTION
• 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)
2
WARNING
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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English
• 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.
4 5
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
17. Altimeter Applications ........................................................................ 68
A. Measuring Altitude when Mountain Climbing B. Other Applications
C. Prominent Mountains and Lowlands Around the World (Reference)
18. Low Battery Warning Function .......................................................... 72
19. Other Functions .................................................................................. 73
A. Button Function Display B. Rotating Bezel C. Compass
D. No Decompression Limits
20. Battery ................................................................................................. 78
21. Troubleshooting ................................................................................. 80
22. Care for Long Term Use ..................................................................... 82
23. All-Reset .............................................................................................. 89
24. Specifications ..................................................................................... 90
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10. Using the Log Memo Mode ................................................................ 38
A. Recalling Log Data B. Deleting Log Data
C. Explanation of Log Data Terms
11. Using the Dive Alarm Mode ............................................................... 42
A. Setting the Depth Alarm and Dive Time Alarm
12. Using the Altitude Memo Mode ......................................................... 46
A. Recalling a Point Memo B. Deleting a Point Memo
13. Using the Water Depth Measurement Mode ..................................... 49
A. Water Depth Measurement and Display B. Measurement of Dive Time
C. Measurement of Water Temperature
D. Warning Functions During Water Depth Measurement
14. Using the Surface Mode ..................................................................... 55
15. Altimeter Basic Features .................................................................... 57
16. Using the Altitude Measurement Mode ............................................ 59
A. Altitude Correction
B. Continuous Altitude Measurement and Fixed Duration Altitude Measurement
6
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.
<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.
8 9
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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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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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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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 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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<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 remov-
ing 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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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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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
16
• 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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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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21
4. Names and Functions of Components
Please read this section while referring to the watch illustration shown in the
inside cover.
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Name / Mode Time / Calendar
Switches between seconds
and date / day display
Temperature / barometric
pressure measurement
---
To correction mode
To alarm mode
To altitude measurement mode
TME
Hours, minutes
Seconds / date, day
Alarm
Switches between
on and off
Alarm monitor
---
To correction mode
To chronograph mode
ALM
Hours, minutes
ON / OFF
Chronograph
Starts and stops the
chronograph
---
Split time / reset
---
To log memo mode
CHR
Hours, minutes
Seconds,1 / 100 seconds
Press once
Button (A)
Button (B)
Button (M)
Press for at least 2
seconds
Press once
Press for at least 2
seconds
Press once
Press for at least 2
seconds
1: Mode mark
2: Digital display [1]
3: Digital display [2]
Log Memo Dive Alarm Altitude Memo Surface
Recalls the memo
---
Recalls the memo
---
---
Dive alarm monitor
--- ---
Switches display contents
---
Switches display contents
---
---
To correction mode
--- ---
To dive alarm mode To altitude memo mode To surface mode To time/calendar mode
To altitude measurement mode
D.log D.AL A.log
---
Log data Depth alarm Point data
Elapsed time
(hours, minutes)
Log data Dive time alarm Point data SF.m
[Standard Mode]
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).
V
Button 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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[Water Depth Measurement Mode/Altitude Measurement Mode]
22
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.
Name / Mode
Water depth measurement mode
(during measurement)
Altitude measurement mode
(during measurement)
Press once
Recalls maximum water depth/
water temperature
Starts/stops elapsed time
Press for at
least 2 seconds
Button (A)
Button (B)
Button (M)
Recalls maximum water depth/
water temperature
Stores memo of point data
Press once
---
Switches between altitude
display/barometric pressure display
Press for at
least 2 seconds
---
Measures temperature (when measuring
altitude for a fixed period of time)
Press once
---
Switches the display (within the altitude
measurement mode)
Press for at
least 2 seconds
---
To [Standard Mode]
1: Mode Mark Displays on digital display [1] Displays on digital display [1]
2: Digital display [1] Depth (m)
Altitude (m)/barometric pressure (hPa)
3: Digital display [2] Dive time (minutes, seconds) Elapsed time (hours, minutes)
<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.
25
5. Setting Analog Time
(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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Normal position
Time correction position
Crown
• 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).
27
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).
26
(M) (M)
(M)(M)
(M)(M)
(M)
(M)
* Please refer to the
section 13 entitled,
“Using the Water
Depth Measurement
Mode” for further
details.
When water
sensor gets wet
((M))
[Water Depth Measurement Mode]
(preliminary state)
[Altitude Measurement Mode] (altitude correction
display)
* Please refer to the
section 16 entitled,
“Using the Altitude
Measurement Mode”
for further details.
[Standard Mode]
Surface
*Only displayed for
24 hours after
diving.
Time/
calendar
<TME>
Alarm
<ALM>
Chronograph
<CHR>
Altitude
memo
<A.log>
Dive alarm
<D.AL>
Log memo
<D.log>
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.
29
* 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.
28
Seconds
Hours /
minutes
Date / day
Barometric
pressure
Temperature
TME
TME
TME
(A)
(B)
(M)
(A)
((A))
(A)
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