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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?

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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.

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Thanks for the quick answer! It worked! – Shifat Taushif Sep 21 '12 at 15:34
both are doing same thing. – Anwar Shah Sep 22 '12 at 11:30
Wait... Your method disables it temporarily. What I mean is that when I reboot my computer, the light come backs on. Is there any way to disable it permanently? – Shifat Taushif Sep 23 '12 at 14:58
up vote 2 down vote accepted

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
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