Sharp OZ-640 - Manual (Page 62)

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turned off, ie. no audible alarm will sound, until you use the
above procedure to turn them on again by re-selecting ALARM
SOUND ON. However, each alarm will still be displayed when
it reaches its set time, even when the unit is turned off. This
means the alarm sounds are disabled, but not the alarms
themselves.
The Clock application menu
Sets the time and date
Sets the local city
Sets the world city
Turns all DST settings on
or off