Casio 5251(OC) Operation Manual Download Page 2

Operation Guide 5251 (OC)

E-15

How Power Saving works

The watch will enter the sleep state if it is left in a dark location for about one week.

In the sleep state:

 

x

 All hands stop at 12 o’clock.

 

 Auto Receive is disabled.

 

 Internal timekeeping continues to operate normally.

 

 The watch will not enter a sleep state between 6:00 AM and 9:59 PM. If the watch is already in a sleep 

 

x

state when 6:00 AM arrives, however, it will remain in the sleep state.

To recover from the sleep state

Move the watch to a well-lit area, press the 

A

 button, or pull out the crown to the fi rst click.

 It can take up to eight minutes for the watch to resume normal operation after recovering from the sleep 

 

x

state. Do not perform any button operations during that time.

E-14

Charging Times

Exposure Level (Brightness)

Daily Operation 

*1

Level Change *2

Level 4

Level 3

Level 2

Level 1

Outdoor sunlight (50,000 lux)

8 minutes

2 hours

25 hours

Window sunlight (10,000 lux)

30 minutes

4 hours

93 hours

Window sunlight on cloudy day (5,000 lux)

48 minutes

6 hours

151 hours

Indoor fl uorescent lighting (500 lux)

8 hours

59 hours

– – –

1  Approximate exposure each day to generate power for normal daily operation.

 

*

2  Approximate exposure to take power up one level.

 

*

 The above times are for reference only. Actual times depend on lighting conditions.

 

x

 For details about the operating time and daily operating conditions, see the “Power Supply” section of 

 

x

the Specifi cations (page E-36).

Power Saving

A Power Saving feature causes the watch to enter a sleep state automatically whenever it is left for a 
certain period in an area where it is dark.

E-13

To use the charging guide

 Pull the crown out to the fi rst click. The 

1. 

x

 

Second Hand

 will move to the currently selected location 

setting. Next, push the crown back in.

 For about one second, the 

 

x

x

 

Second Hand

 will perform movement that indicates whether the watch’s 

battery requires charging. 

Charge is very low. 
Leave the watch in bright 
light for long time until 
charged.

Battery is charged.

Charge is low. 
Consider leaving the watch in 
light for charging.

Charge is low. 
Leave the watch in light for charging.

 The current charging requirement is indicated whenever you push the crown back in from the fi rst 

 

x

click.
 Failure to expose the watch to light when charging is required will cause the charge to be reduced 

 

x

even further.
 The charging guide is based on a calculated value (not the actual battery charge). Because of this, 

 

x

the battery charge may go low even if the charging guide indicates that immediate charging is not 
required. If this happens, expose the watch to light as soon as possible to charge the battery.

E-12

 When power drops to Level 4, all functions will be disabled but the watch will continue to keep time 

 

x

internally for about one week. If you recharge the battery suffi ciently during this period, the analog 
hands will move automatically to the correct setting and regular timekeeping will resume. After one 
week, all settings (including timekeeping) will be cleared. Recharging the battery will reset all settings 
to their initial factory defaults.

Charging Guide

The charging guide causes the 

x

 

Second Hand

 to perform movement that gives you a rough idea of 

whether the watch needs to be exposed to light in order to charge the battery.

E-11

Important!

 Keep the watch in an area normally exposed to bright light when storing it for long periods. This helps 

 

x

to ensure that power does not run down.
 Storing the watch for long periods in an area where there is no light or wearing it in such a way that it is 

 

x

blocked from exposure to light can cause power to run down. Make sure that the watch is exposed to 
bright light whenever possible.

Power Levels

You can get an idea of the watch’s power level by observing the movement of 
the 

x

 

Second Hand

 in the regular timekeeping.

Level

Hand Movement

Charge

1

Normal.

Battery is charged.

2

x

x

 

Second Hand

 moves in the following 

pattern.

1 second 

 1 second 

 2 seconds

Battery is starting to go low.

3

x

 

Second Hand

 moves at two-second 

intervals.

v

 

Day Indicator

 changes to 

1

 (home 

position).

Battery is low.

4

x

 

Second Hand

 stopped.

z

 

Hour Hand

 and 

c

 

Minute Hand

 

stopped at 12 o’clock.

Battery is very low.

+

B

>

@

Movement indicates the 
current charge level.

E-10

Charging the Watch

The face of the watch is a solar panel that generates power from light. The generated power charges a 
built-in rechargeable battery, which powers watch operations. The watch charges whenever it is exposed 
to light.

Charging Guide

Whenever you are not wearing 
the watch, be sure to leave it in 
a location where it is exposed 
to light.

 Best charging performance 

 

x

is achieved by exposing 
the watch to light that is as 
strong as possible.

When wearing the watch, 
makes sure that its face is 
not blocked from light by the 
sleeve of your clothing.

 The watch may enter a sleep 

 

x

state (page E-14) if its face is 
blocked by your sleeve even 
only partially.

Warning!
Leaving the watch in bright light for charging can cause it to become quite hot. Take care when 
handling the watch to avoid burn injury. The watch can become particularly hot when exposed to 
the following conditions for long periods.

 On the dashboard of a car parked in direct sunlight

 

x

 Too close to an incandescent lamp

 

x

 Under direct sunlight

 

x

E-9

E-29  Adjusting the Home Positions

E-32 Troubleshooting

E-36 Specifi cations

E-8

Contents

E-2 

About this manual

E-3 

About the face

E-4 Crown 

Operations

E-6 

Things to check before using the watch

E-10  Charging the Watch

E-13 

To use the charging guide

E-15 

To recover from the sleep state

E-16  Radio Controlled Atomic Timekeeping

E-18 

To get ready for a receive operation

E-20 

To perform manual receive

E-21 

To check the result of the latest receive operation

E-22 Confi guring Time and Date Settings

E-23 

To check the current location setting

E-23 

To change the location setting

E-24 

To set the time manually

E-26 

To set the date manually

Summary of Contents for 5251(OC)

Page 1: ...ge E 24 and when performing x home position adjustment page E 29 E 4 Crown Operations The crown can be pulled out to one of two click positions Never apply undue force when pulling out the crown Important When pulling out the crown avoid using undue force which creates the risk of personal injury to your x fingers and fingernails and of watch malfunction First click For selecting the location settin...

Page 2: ... move automatically to the correct setting and regular timekeeping will resume After one week all settings including timekeeping will be cleared Recharging the battery will reset all settings to their initial factory defaults Charging Guide The charging guide causes the x Second Hand to perform movement that gives you a rough idea of whether the watch needs to be exposed to light in order to charg...

Page 3: ...en try again See To get ready for a receive operation page E 18 E 19 Signal reception may be difficult or even impossible under the conditions described below x Inside or among buildings Inside a vehicle Near household appliances office equipment or a mobile phone Near a construction site airport or other sources of electrical noise Near high tension power lines Among or behind mountains What you sh...

Page 4: ...n x 15 minutes 00 seconds Perform steps 7 8 9 and 10 of this procedure B E 28 After the tens digit setting is the way you want press 8 A The x x Second Hand will move to the ones digit of the current year setting Rotate the crown to move the 9 x Second Hand to the year ones digit setting you want Note If you want to continue on to the time setting press x A and then perform the procedure starting ...

Page 5: ...Cause Remedy Page Your location setting is wrong Check your location setting and correct it if necessary E 22 There is not enough power for signal reception Expose the watch to light to charge it E 10 E 33 Hand movement is stopped The watch may have been exposed to magnetism which will cause the hands to stop at their current positions Pull the crown out to the first click or press a button to res...

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