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Interference on sound and monitor when I plug my laptop in to charge.

  1. Apr 22, 2008 #1
    I use my laptop as desktop, run a monitor on it and speakers etc.... anyways when I plug it in it causes interference in the monitor and sound. Anyone know what causes this?? And how to remedy the problem.
  2. jcsd
  3. Apr 22, 2008 #2
    The interference is probably coming from the higher voltage power wire... EMI. Make sure that the wire for the power supply doesn't run parallel with either the audio or monitor cable and try to separate them as much as possible. For the audio cable you can purchase a ferrite toroid to get rid of some of the interference in case you have trouble keeping them separated.

    http://www.mag-inc.com/ferrites/ferrite_toroids.asp [Broken]

    You'll loop the speaker wire around the toroid like so... more loops for greater interference...

    http://www.arrl.org/news/features/2001/09/14/2/toroids-2-lrg.jpg [Broken]

    The best place to get them is from old junk PC power supplies... can't beat them for free! That's where i've gotten mine at least.
    Last edited by a moderator: May 3, 2017
  4. Apr 22, 2008 #3

    Hmm, are there any modifications that I can make to the power supply EMI? Its mostly the interference it causes in my monitor that bothers me.

    Wasnt the interference problem a factor when they decided to use this type of power system?
    Last edited by a moderator: May 3, 2017
  5. Apr 22, 2008 #4
    EMI stands for electromagnetic interference. The most typical problem i've run into like that is when people install an amp in a car and they make the mistake of running the power wire along the same side as the audio signal wire. When they're routed that close together like that, they end up making the rear speaker emit an audible hum that increases in frequency with the engine RPMs... pretty annoying.

    An option for the monitor cable would be to get a roll of EMI shielding tape and wrap the monitor cable with it. It sounds like the monitor output is very close to the power plug which is unusual... for the reasons your experiencing.

    What model is your laptop?
  6. Apr 22, 2008 #5
    Its a gateway M-6750. The wire was a little but its not now and still giving the same problem. I was reading that I have a Switch Mode Power Supply, and that it might be letting some ac slip by or something? Yah I read about the EMI too i was thinking about maybe getting and EMI filter. But honestly haha I have no idea what it is. I moved my power adapter as far away from the monitor as i could but that didnt fix the problem.
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