Citizen Nighthawk BJ7000-52E User manual

CONTENTS
A. BEFORE USING .......................................................................................2
B. SETTING THE TIME AND DATE .............................................................3
C. USING AS A DUAL TIME WATCH ...........................................................6
D. FUNCTIONS OF SOLAR POWERED WATCH ........................................8
Insufficient Charge Warning Function......................................................10
Quick Start Function.................................................................................10
Time Setting Warning Function ...............................................................11
Overcharge Prevention Function ............................................................11
E. CARE AND HANDLING DURING CHARGING ......................................12
F. REPLACING THE SECONDARY BATTERY..........................................13
G. TIME REQUIRED FOR CHARGING ......................................................14
H. USING THE SLIDE RULE .......................................................................16
l. PRECAUTIONS ......................................................................................28
J. SPECIFICATIONS ...................................................................................34
1
English

B. SETTING THE TIME AND DATE
*If the crown is of the screw- type, set the time and calendar after first loosening
the screw. Retighten the screw after the time and calendar have been set.
A. BEFORE USING
This watch is powered not by an ordinary battery, but by converting photo
energy to electrical energy.
Before using, expose to light and make sure the watch is sufficiently
charged.
See "G. TIME REQUIRED FOR CHARGING" for charging time reference.
A secondary battery is used in this watch to store electrical energy. This
secondary battery is a clean energy battery which doesn't use any toxic
substances such as mercury. Once fully charged, the watch will continue
to run for about 6 months without further charging.
To use this watch comfortably, make sure that the watch is always recharged
before it stops.
There is no concern for overcharging this watch. (Overcharge Prevention
Function is included)
We recommend that you recharge the watch everyday.
2 3
Minute hand
Date
Date and Hour hand
correction position
Local time
hours hand
Time (24hour,
minute,second)
correction position
Crown
Second hand Solar cell 24 hour hand
Normal position

4
WWSetting the Date
(1) Pull the crown out to the date correction position.
(2) Turn the crown to the left (counter-clockwise direction) and set the date.
(3) Securely return the crown to the normal position.
* Since the date is linked to movement of the hour hand, the date changes
when the hour hand approaches 12:00 midnight. Please note this
operation when using as a dual time watch.
* Do not attempt to correct the calendar when the hour hand is between the
hours of 9:00 PM and 1:00 AM. Setting the calendar during this time may
result in the date not changing on the following day.
5
WWSetting the Time
(1) Pull the crown out to the time correction position. (The second hand stops
when the crown is pulled out.)
(2) Turn the crown to set the 24 hour hand and minute hand to the current
time. At this time, the movement of the hour hand is linked with the
movement of the 24 hour hand.
(3) Push the crown back in to the normal position. (The second hand begins
to move when the crown is pushed in.)
(4) Pull the crown out to the date correction position. (1st click position)
(5) Turn the crown to the right (clockwise direction) and set the hour hand to the
current time. Pay attention to AM and PM since the location of the hour hand
where the date changes is approximately 12:00 midnight.
(6) Securely return the crown to the normal position.
Reading the Time Based on a 24-Hour Clock
Read the time on the inside (1:00 to 12:00) with the short hand of the 24 hour
hand, and the time on the outside (13:00 to 24:00) with the long hand.

WWCorrecting the Local Time Hours
(1) Pull the crown out to the local time correction position. (1st click position)
(2) Turn the crown to the right (clockwise direction) and set the hour hand to the
desired time. The hour hand can be corrected in +1 hour increments in the
clockwise direction. Set the time while paying attention to AM and PM.
(3) Securely return the crown to the normal position.
* The hour hand cannot be corrected in the counter-clockwise direction. The
date changes when the crown is turned to the left (counter-clockwise). In
addition, since the calendar is linked with the operation of the hour hand, it
may be necessary to correct the calendar after correcting the hour hand
depending on the time to which the hour hand was set.
7
C. USING AS A DUAL TIME WATCH
This watch allows the hour hand only to be corrected independently without
stopping the watch. It can be used as a dual time watch by setting the 24 hour
hand and hour hand to different times. After correcting the time, the hour hand
is used to indicate the "local time hours".
6
Hour (local time hour) hand
Minute hand
Crown
Normal position
24 hour hand
Local time
correction position

If the charge becomes insufficient, a warning function will operate and the
display changes, as below.
8
D. FUNCTIONS OF SOLAR POWERED WATCH
9
If insufficiently
charged and
time is set
If insufficient charge continues
Hitch movement
Stop
The watch will begin to operate
soon after it is exposed to light due
to Quick Start Function
Time setting
warning display
If insufficiently
charged
If sufficiently charged and time is set
Normal time
display
Insufficient charge
warning display
One second
interval movement
Two second
interval movement
If sufficiently
charged

WWInsufficient Charge Warning Function
The second hand changes to a two second
interval movement to indicate insufficient
recharging.
Even in such a case, the watch keeps correct
time, but about 3 days after the two second
interval movement begins, the watch will stop.
After exposing the watch to light, recharging takes
place and the watch returns to one second
interval movement.
WWQuick Start Function
The watch will stop if it is completely discharged.
It will begin to operate soon after it is exposed to light.
(However, the time to start may vary according to the brightness of the light.)
WWTime Setting Warning Function
If the watch stops, subsequent exposure to light
allows the Quick Start Function to start again, and
the second hand moves with a hitch to
indicate that the time incorrect.
In this case, quickly recharge the watch and reset
the time.
Otherwise, the hitch movement will continue.
WWOvercharge Prevention Function
You can recharge without worry.
Once the secondary battery is fully recharged, the overcharging prevention
feature comes into operation and prevents over-recharging.
10 11
Two second interval
movement Hitch movement
2sec.
2sec.
2sec.
2sec.

E. CARE AND HANDLING DURING CHARGING
WWNotes on use
Take care to charge your watch during use.
Please note that if you wear long sleeves, the watch can easily become
insufficiently charged because it is hidden and not exposed to light.
• When you take the watch off, place it in as bright a place as possible, and it
will always continue to run properly.
WWNotes On recharging
• Avoid recharging at high temperatures (over about 60°C/140°F), otherwise the
watch will be damaged during recharging.
(eg) Charging the watch near a light source that easily becomes hot, such as
an incandescent lamp or a halogen lamp.
Charging in a place that easily becomes hot, such as a dashboard.
When you charge the watch with an incandescent lamp, halogen lamp or other
light source that generates heat, take a distance about 50cm (20in.) from the
light source to prevent extremely high temperature.
F. REPLACING THE SECONDARY BATTERY
Unlike ordinary batteries, the secondary battery used in this watch doesn't
have to be periodically replaced due to repeated charging and discharging.
CAUTION
Never use another battery different from the secondary battery used in this
watch.
The watch structure is so designed that a different kind of battery other than that
specified cannot be used to operate it. In case a different kind of battery such as
a silver battery is used by some chance, there is a danger that it will be
overcharged to burst, causing damage to the watch and even to the human
body.
12 13

G. TIME REQUIRED FOR CHARGING
Time required for recharging may vary according to the design (color of the dial,
etc.) and operating environment. The following table will serve you as rough
reference.
* The recharging time is the time when the watch is continuously exposed to
radiation.
Full recharging time ... The time for fully recharge from stopped.
(Empty to full)
One day usage .......... The time required for the watch to run for one day with
one second interval movement
14 15
Illuminance
(lux)
500
1000
3000
10000
100000
Environment
inside an ordinary
office
Time required
22 hours
11 hours
3 hours
30 minutes
1 hour
14 minutes
One day
usage
1 hour
30 minutes
45 minutes
15 minutes
5 minutes
2 minutes
Empty to full
320 hours
158 hours
53 hours
17 hours
6 hours
60-70cm (24-28in.) under
a fluorescent light (30W)
20cm (8in.) under a
fluorescent light (30W)
Exterior, cloudy
Exterior, summer,
sunny
From the stop state
to the one second
movement

1716
H. USING THE SLIDE RULE
Flying distance and other navigation
calculations as well as general
calculations can be performed using
the slide rule located around the
outside of the dial. This slide rule is
not able to display decimal places for
calculation results, and should only
be used as a general reference as an
alternative to more accurate
calculations. Turning the crown at
the 8:00 position allows the slide rule
around the dial (Outside Scale) to be
rotated.
A. Navigation Calculator
1. Calculation of time required
Question: How long does it take an airplane flying at 180 knots to fly a
distance of 450 nautical miles?
Solution: Set the 18 mark on the outside scale to the SPEED INDEX (Y). At
this time, the point on the inside scale that is aligned with 45 on the
outside scale indicates (2:30), and the answer is 2 hours and 30
minutes.
Inside scale
Outside
scale
Crown for turning the outer scale

2. Speed (Ground Speed) Calculation
Question: What is the speed (ground speed) of an airplane when it takes 1
hour and 20 minutes to fly a distance of 240 nautical miles?
Solution: Align the 24 on the outside scale with 1:20 (80) on the inside scale.
At this time, 18 is aligned with the SPEED INDEX (Y) on the inside
scale, and the answer is 180 Kt.
18 19
3. Flying distance calculation
Question: What is the flying distance traveled in 40 minutes at a speed of 210
knots?
Solution: Align the 21 on the outside scale with the SPEED INDEX (Y) of the
inside scale. The 40 of the inside scale is now pointing to 14, and
the answer is 140 nautical miles.