How to shut down the S/PDIF output in my sound card?

I realized that there is a red light coming out of my earphone jack. It's something like this:

I looked in the folder that Toshiba created for installing drivers , then I found out that they had installed this driver for my sound card: Realtek HD Audio Driver v6.0.1.5689_withMaxxAudio_Compal(20080908)

I'm guessing that the sound card supports Optical Audio Output. I also found out that when I mute the speakers, the light goes away. But when I unmute it, it comes back.

I don't really mind having it but it drains my battery. So, is there a Ubuntu version for my sound card driver?

3 Answers

Open a terminal with Ctrl-Alt-T keyboard shortcut and type: alsamixer

Use the arrow keys to move around and when over S/PDIF press M to mute, this will turn the light OFF. Hit the escape key to leave or just close the terminal.

Okay, so I followed Tenplus1's answer and it seemed to work. But it got restored after reboots. So I did some research and found a way.

1. Open Terminal by Ctrl + Alt + T
2. Type in sudo alsamixer
3. Use the arrow keys to move around and when over S/PDIF press M to mute, this will turn the light OFF.
4. Hit the Escape key - DO NOT CLOSE TERMINAL
5. Type sudo alsactl store - This will make it persist across reboots
6. Close Terminal

It did not work in my case but I found a "trick" that does the job, so maybe it will be useful for someone. Just type this in terminal:

echo "1" > /sys/module/snd_hda_intel/parameters/power_save 

If it works, add it to your start-up scripts.