My Casio module #2735 is 12 hours off. when I set it, it is off 12 hours when it reached the 12: o'clock hour.

Deron, Check the attached links,manual,instruction and guides, Good luck .
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Casio 91W User Guide Quick guide to set the time and use all the functions
How do you turn off hourly beep on casio 91w
Casio F91W Module No 593 Watch

If your watch is 1 hour out it could be showing daylight saving time (DST).

If this is the case, then press the mode button until you reach DST and then use the one at 2 or 4 O'clock to turn it off or on as required.

click on mode or setting option.then you will see the default time.edit it..try to change it using select or any mode available.there you can see 24hr clock and 12 hr clock.select which one you want.if it is in 12 hr then the time will be displaying like eg:7:00am or 7:00pm it means that it is in twelve hours.if it is showing 7:00 or 19:00 it means it is in 24hr clock.

The crown has 3 positions.

Normal screwed down.
First pull out position.
Second pull out position.

Setting the Time:
Pull out the crown to position 3.
Rotate the crown to set the exact time.
Ensure that you are in the daytime12 hour segment by allowing the hands to pass 12 o'clock and notice if the date moved on or not.
If the date changed, then you will need to advance at least 2 hours before moving on to set the date.
If you do not need to change the date, return the crown to position 1.


Setting the Date:
DO NOT DO THIS IF THE WATCH IS BETWEEN 8pm & 2am
Pull crown to position 2.
Rotate the crown clockwise to set to the correct date.
Return the crown to position 1.


Setting the Alarm [12 hour]
Pull the crown to position 2.
Rotate the crown anti clockwise to move the alarm hand to the desired time.
Return the crown to position 1.
To activate the alarm, press the 8 o'clock button. You will hear 2 beeps.
To deactivate the alarm, press the 8 o'clock button. You will hear 1 beep.
NB If the alarm is not cancelled while it sounds the first time, it will repeat again in 2 minutes time. The alarm sound last for 15 seconds. If the alarm time coincides with 1 beep of the countdown, the alarm function will be cancelled.


Battery EOL [End Of Life]
The Swiss ISA 8270 movement uses a 395 cell and will signify a low power state by advancing the small seconds hand 4 steps every 4 seconds.


Setting the Countdown
You can specify a countdown of between 1 and 10 minutes.
Press the 4 o'clock button to enter setting mode. You will hear 1 beep.
Press the 4 o'clock button to move the central timing hand successively to the desired countdown time.
Wait 3 seconds for the watch to automatically exit the setting mode.
You can change the duration of the countdown [except in the last minute] at any time.
e.g. If the countdown is set to 10minutes, and you now want to change the countdown to 9 minutes, press the 4 o'clock button. The hours/seconds counter sub-dial will perform one complete turn and then stop at 60, before continuing.


Activating the Countdown:
Press the 2 o'clock button to start the countdown. You will hear 2 beeps.
The hours/seconds counter sub-dial will perform one complete turn and then stop at 60, before continuing.
When the countdown begins, the hour/seconds counter sub-dial indicates the seconds with 1 step every 2 seconds, and the central timing hand indicates the minutes with 1 step being 2.4 seconds.


Countdown tone:
There are 2 beeps every minute.
in the last minute:
50 seconds=1 beep.
40 seconds=1 beep.
30 seconds=2 beeps.
20 seconds=2 beeps.
10 seconds and less=1 beep every second with zero being 1 second long beep. Timer function automatically starts.


Timer:
After countdown has finished the timer starts automatically.
The central timing hand indicates the minutes with 1 step every 12 seconds. The hour/minutes counter sub-dial indicates the hours up to a maximum of 96.
Press the 4 o'clock button to see the timer seconds [display lasts up to a minute].
Press the 4 o'clock button to see the timer hours.
The timer has a maximum time of 96 hours [4 days] after which the hour/seconds sub-dial counter will stay at 0 and the central timing hand will stay at 12.


Start/Stop Timer:
Press the 2 o'clock button to stop the timer. You will hear 1 beep.
Press the 2 o'clock button to resume the timer. You will hear 2 beeps.


Setting the Countdown & Timer:
Countdown reset:
Press the 2 o'clock button to stop the countdown. You will hear 1 beep.
Press the 4 o'clock button to reset.


Setting the Timer:
Press the 2 o'clock button to stop the timer. The hour/seconds counter sub-dial will show the elapsed hours and the central timing hand the elapsed minutes.
Press the 4 o'clock button to view the seconds elapsed on the hour/seconds counter sub-dial.
Press the 4 o'clock button to reset.


Resetting the Hands:
If the hands do not zero correctly, which might occur after a battery change or a violent shock, you can make adjustments by doing the following settings as long as the countdown is not in operation.
To correct the hour/seconds counter sub-dial, pull the crown out to position 2 and wait 1 second.
Press either the 2 or 4 o'clock button; the central timing hand will turn and stop [not necessarily at 12].
Press the 2 o'clock button to increment the hours/seconds counter sub-dial hand to position it at 60.
To correct the central timing hand, press the 4 o'clock button to increment the hand to the 12 position.
Return the crown to position 1.



If the battery had been replaced, the central timing hand defaults to the 10 minute position. If the battery had not been replaced, the central timing hand will return to the previously set position.

Hi Harry,

Your Module number is 2271.
1. To set the time, press and hold button A (left top) until Seconds digits start to flash.
2. Press button D (lower left) to move flashing in the following sequence to change other setting:
Seconds >> Hour >> Minutes >> 12/24 Hour Format >> Year >> Month >> Day >> (Then back to Seconds)
3. While a setting is flashing, use E (+) (bottom right) and B (-) (top right) to change it.
Note: When in the 12/24 Hour Mode, use E and B to toggle between 12-Hour and 24-Hour Mode.
4. Press buton A to exit setting screen.
Your time should now be set.

You may also download a manual for watch/Module number:
http://pathfinder.casio.com/resource/manuals/module_2271.pdf

This should give you all the info you need to operate all the functions of your watch. Thanks.

Regards, Bill

Actually, the watch has 3 buttons -- "Light" being the 3rd one. Press Mode until a number in the time mode begins flashing. Then press the Light button to get it to the hour indicator. Use the 12-24 Hr button to set it to the current hour. Then press the Light button again to get it to the minutes section. Again, use the 12-24 Hr. Button to set it to the next minute coming up in the current time. Then push the Light button again. This will bring up the seconds indicator. At the precise time the minute you set before begins, hit the 12-24 Hr. button, and the indicator goes back to zero and begins ticing away. Then hit the Mode button again until the watch is in the current time mode. Hope this helps. I use Internet time to set a precise time.

1. Press the Bottom Left side button until you reach time keeping mode.
2. Press the Bottom Left side button 6 times to reach hand setting mode.
   
3. Hold down the Top Left side button until the digital time starts to flash.
4. Press the Bottom Right side button to advance the analog time by 20 seconds; Holding the button down will advance the time faster. Pressing both of the Right side buttons will lock the time into advancing quickly without holding buttons down; this will continue until you press a button or the clock advances 12 hours.
5. Press the Top Left side button to exit the settings screen.
6. Press the Bottom Left side button to return to timekeeping mode.
   

Here is the link to your watch manual download:

http://www2.casio.co.jp/manual_pdf/wat/en/pdf_search.php?MODULE=2600&submit.x=60&submit.y=11

Save it on your PC and follow instructions how to set an hourly alarm.
Don't forget to rate, please.

Hi Try www.casio.com you will need your 4 figure model number to locate manual.

Use this page to download a copy of CASIO watch manuals in PDF format. To download a PDF file, enter the four-digit (or three-digit) module number marked on the back cover of your watch.

http://world.casio.com/wat/download/en/manual/

You will need a pdf reader on your pc, you will find all instructions in there.

If you don't have a pdf reader you can get one from
http://www.foxitsoftware.com/pdf/rd_intro.php