Casio 5088 Operation Manual Download Page 1

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Operation Guide 5088

MA0910-EA

Congratulations upon your selection of this CASIO watch.

This watch does not have a city code that corresponds to the UTC offset of –3.5 
hours. Because of this, the radio-controlled atomic timekeeping function will not 
display the correct time for Newfoundland, Canada.

Note that CASIO COMPUTER CO., LTD. assumes no responsibility for any 
damage or loss suffered by you or any third party arising through the use of this 
product or its malfunction.

About This Manual

Button operations are indicated using the letters 

A

 

through 

D

 shown in the illustration.

Hand Functions

 Hour Hand

 Second Hand

 Minute Hand

 Upper Left Dial Hand

 Lower Left Dial Hands

 Right Dial Hand: 

 Indicates the current mode.

 Day

This User’s Guide uses numbers shown above to identify 
watch hands and indicators.

Things to check before using the watch

1.  Hold down 

C

 for about two seconds to enter the Timekeeping Mode, and 

then observe the movement of the 

x

 

Second Hand

.

Is the 

x

 

Second Hand

 moving smoothly in one-second intervals?

Is the 

x

 

Second Hand

 moving at 

two-second intervals or is it stopped 
completely? 

Go to step 2.

The watch is charged suffi ciently. 
For details about charging, see 
“Charging the Watch”.

Power is low. Charge the watch by placing 
it in a location where it is exposed to light. 
For details, see “Charging the Watch”.

NO

YES

YES

NEXT

2. Check the Home City and the daylight saving time (DST) setting.

Use the procedure under “To confi gure Home City settings” to confi gure your Home 
City and daylight saving time settings.

Important!

Proper time calibration signal reception and World Time settings depend on correct 
Home City, time, and date settings in the Timekeeping Mode. Make sure you 
confi gure these settings correctly.

3. Set the current time.

 

 

To set the time using a time calibration signal

See “To get ready for a receive operation”.
 

 

To set the time manually

See “Confi guring Current Time and Date Settings Manually”.

The watch is now ready for use.

 For details about the watch’s radio controlled timekeeping feature, see “Radio 

 

Controlled Atomic Timekeeping”.

Charging the Watch

The face of the watch is a solar cell 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 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 state 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

 

Too close to an incandescent lamp

 

Under direct sunlight

 

Important!

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

 

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

B

+

@

*

6

>

5

Power Levels

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

x

 

Second Hand

 in the 

Timekeeping Mode.

 If the 

 

x

 

Second Hand

 is moving normally in one-second 

intervals, power is at Level 1.
 If the 

 

x

 

Second Hand

 is moving at two-second intervals, 

power is at Level 2, which is quite low. Expose the watch 
to light as soon as possible so it can charge.

Level Hand Movement

Function Status

1

Normal.

All functions enabled

2

x

 

Second Hand

 moving at two-second 

intervals.

m

 

Day

 changes to 

1

 (home position).

Beeper and time calibration signal 
reception disabled

3

x

 

Second Hand

 stopped.

 z

 

Hour Hand

 and 

c

 

Minute Hand

 stopped 

at 12 o’clock.

All functions disabled

 When power drops to Level 3, all functions will be disabled but the watch will 

 

continue to keep time 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.

Power Recovery Mode

The watch is designed to go into a power recovery mode that stops hand operation 
temporarily whenever power suddenly drops below a certain level due to overuse 
of the alarm tone over a short period. Note that all operations are disabled while the 
watch is in the power recovery mode.
The hands will move to the correct positions and the watch will resume normal 
operation after power recovers (in about 15 minutes). Putting the watch in a location 
where it is exposed to light will help power to recover sooner.

Charging Times

Exposure Level (Brightness)

Daily 

Operation 

*1

Level Change *2

Level 3

Level 2

Level 1

Outdoor sunlight (50,000 lux)

8 minutes

2 hours

24 hours

Window sunlight (10,000 lux)

30 minutes

6 hours

90 hours

Window sunlight on cloudy day 
(5,000 lux)

48 minutes

8 hours

– – –

Indoor fl uorescent lighting (500 lux)

8 hours

92 hours

– – –

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

 

*

2  Approximate exposure to take power up one level.

 

*

 The above exposure times all are for reference only. Actual exposure times depend 

 

on lighting conditions.
 For details about the operating time and daily operating conditions, see the “Power 

 

Supply” section of the Specifi cations.

Power Saving

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

 There actually are two sleep state levels: “second hand sleep” and “function sleep”.

 

Elapsed Time in Dark

Operation

60 to 70 minutes (second hand 
sleep)

x

 

Second Hand

 only is stopped at 12 o’clock, all other 

functions are enabled.

6 or 7 days (function sleep)

 All functions, including analog timekeeping, disabled

 

 Internal timekeeping maintained.

 

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

 

is already in a sleep state when 6:00 AM arrives, however, it will remain in the sleep 
state.
 The watch will not enter a sleep state while it is in the Stopwatch Mode.

 

To recover from the sleep state

Move the watch to a well-lit area or press any button.

Radio Controlled Atomic Timekeeping

This watch receives a time calibration signal and updates its time setting accordingly. 
However, when using the watch outside of areas covered by time calibration signals, 
you will have to adjust the settings manually as required. See “Confi guring Current 
Time and Date Settings Manually” for more information.

This section explains how the watch updates its time settings when the city code 
selected as the Home City is in Japan, North America, Europe, or China, and is one 
that supports time calibration signal reception.

If your Home City Code setting 
is this:

The watch can receive the signal from the 
transmitter located here:

LON, PAR, ATH

Anthorn (England), Mainfl ingen (Germany)

HKG

Shangqiu City (China)

TYO

Fukushima (Japan), Fukuoka/Saga (Japan)

HNL, ANC, LAX, DEN, CHI, NYC

Fort Collins, Colorado (United States)

Important!

 The areas covered by 

 

HNL

 and 

ANC

 are quite far from the calibration signal 

transmitters, so certain conditions may cause reception problems.
 When 

 

HNL

 or 

HKG

 is selected as the Home City, only the time and date are 

adjusted according to the time calibration signal. You need to switch manually 
between standard time and daylight saving time (DST) if required. See “To toggle 
the Home City time between standard time and daylight saving time” for information 
about how to do this.

B

+

5

@

Moving at two-second 
intervals.

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