Acer TravelMate P643-V Service Manual page 185

 Drag the slider to 50. Confirm that the volume is not muted.
 Click Mixer to verify that other audio applications are set to 50 and not muted.
6. Navigate to Start  Control Panel  Hardware and Sound  Sound. Confirm that
Speakers are selected as the default audio device (green check mark).
NOTE: NOTE:
If Speakers do not show, right-click on the Playback tab and select Show Disabled
Devices (clear by default).
7. Select Speakers and click Configure to start Speaker Setup. Follow the on-screen
prompts to configure the speakers.
8. Remove any recently installed hardware or software.
9. Restore system and file settings from a known good date using System Restore.
10. If the issue is remains, repeat step 9, selecting an earlier time and date.
11. Reinstall the Operating System.
12. If the issue is still not resolved, refer to the
Troubleshooting
Online Support Information on page 8-3.
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