Sony PCG-NV170 - Manual (Page 84)

To connect external speakers
1. Make sure that your speakers are designed for computer use.
2. Turn down the volume of the speakers.
3. Locate the Headphone jack on the left panel of the computer.
4. Plug one end of the speaker cable (not supplied) into the Headphone jack.
Connecting External Speakers to the Headphone Jack
See the manual that came with your speakers for more information on its installation and use.
Page 84