Ubuntu 7.10/Issues/Second Headphone Jack Does Not Work
From DellLinuxWiki
Description: Second headphone jack does not work.
Systems Affected: Inspiron 1420n, 1525n, XPS M1330n
Impact: Connecting headphones to this jack does not send audio to headphones. Sound comes out through system's internal speakers.
Fix:
1. Open the GNOME volume control tool:
$ gnome-volume-control
Select Edit -> Preferences and verify the following tracks are visible: Surround, Front and Line In as Output. Click Close when done.
2. In the Switches tab, place a checkmark by Line In as Output by clicking on the square next to it. This unmutes the second headphone jack.
3. In the Playback tab, you can control the volume or mute the laptop speakers with Front. You can control the volume (or mute) the headphones volume with Surround.