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User manual page B43... http://support.polar.fi/...oduct/S625X?openForm
1. In the Time of day display scroll up or down until OPTIONS is displayed.
2. Press OK to enter the Options mode. EXERCISE SET is displayed.
3. Scroll up or down until MONITOR SET is displayed.
4. Press OK to start the monitor settings. Sound is displayed.
Turning activity/button sound on/off
If you start from the Time of day display, repeat steps 1-4.
5. Press OK to start setting the sound. On/OFF starts to flash.
6. Scroll up or down to set sound On or Off. Press OK.
Activity/button sound consists of the button sound and in the Measuring and Recording modes the following activity sounds: start, stop and lap
recording, phase start, interval phase end and recovery calculation end sounds. It does not consist of target zone alarms, watch alarm or fitnesstest alarm. If that's not it,, you might try asking your question at the S625X group at Yahoo Groups or
http://www.polar.fi/...g/polar/contact.html