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I don't know if this problem happened when I installed Ubuntu before.

Recently I noticed that when I boot Ubuntu, the Digital Audio Output light automatically switches on. Digital Audio Output light on means "Something wrong in the headphone port". Although my headphone is working in Ubuntu.

I've heard that the headphone contains some magical "switch" that will fix the light problem. So I poked the headphone port with chopsticks, pens, paper clips, even my finger, and the Digital Audio Output light still stays on.

I don't have this problem in OSX.

How do I switch the light off?

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It's not a warning light - it's the optical digital output, which also uses the headphone port. Still, it would be good if it wasn't on when you're not using it! – Jeremy Kerr Jun 27 '12 at 1:17
I thought it was! To me, everything that is bright and red is a warning sign. Anaways, do you know how to fix it? – Emerson Hsieh Jun 27 '12 at 1:24
up vote 3 down vote accepted

This is the digital audio output (optical SPDIF), not a warning light. You should be able to turn it off with:

amixer set IEC958 off
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  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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