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  • Static Noise

    I recently purchased an Fm modulator to go with my new head unit that doesn't have an aux input. When the computer is on i hear the music but there is a very loud staticy sound with it. Its not the fm modulator because i've plugged a walkman in instead of the computer and the sound is crystal clear. Also, when i've tried connecting to computer to a power cord from inside the house the noise is gone and it sounds fine. I've grounded everything to the same point and tried to attach the power inverter to the battery, acc wire and cigg lighter but the same thing happens. any suggestions?

  • #2
    where is the modulator located in the car? likewise for the computer? what were the test conditions?.... i.e. was the car running, where was the modulator when you were testing it?

    moron question for me.... the fm modulator outputs a radio frequency right?

    i have some ideas, but tell me more about the set up...

    ~mike
    Single Member of the "1000 Post and No MP3 Car" Club
    PROJECT ON INDEFINATE HOLD... BOUGHT A HOUSE
    2000 Cavalier Z24 [###-------] Only 30% Done ... Still

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    • #3
      I've grounded everything to the same point and tried to attach the power inverter to the battery, acc wire and cigg lighter but the same thing happens.
      I'd have to say it is the inverter causing the noise, look for a noise filter (try radio shack if you aren't sure where to find one).

      It could be something else as well, but that should fix your problem anyway... anyone else have other suggestions, or think this is worng?
      Josh Karger
      By reading this post you agree to overlook all grammatical, spelling, and typographical errors! ;)

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      • #4
        the modulator is located right behind the headunit and the computer is located in the trunk. i have an audio cable running up there. i tested it with the engine on and off with the same results.

        i've also tried a power noise filter from radio shack but it didn't do anything.

        thanks

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        • #5
          well, getting the same results with engine on and off you ruled out EMI from the ignition system.
          but, where are your power wires run? do they come down the same side as the audio cables. if so, you are going to get interference from those power cables. you will need to run the power and audio cables on different sides of the car.

          another test to run....
          disconnect the inverter, run an extension cord to the cpu. see what happens. if you still get the static, then probably isnt the inverter.

          hmmmmmm.....

          what kind of sound card are you running?
          are you just using the stereo miniplugs?
          how high is the volume set on the computer sound settings?

          ~mike
          Single Member of the "1000 Post and No MP3 Car" Club
          PROJECT ON INDEFINATE HOLD... BOUGHT A HOUSE
          2000 Cavalier Z24 [###-------] Only 30% Done ... Still

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          • #6
            i seperated my cables so that the power cables run down the left side of the car and the audio cables down the right side. i have a creatice pci 512 soundcard. the volume on the computer is about half way up. i've tried running an extension cord from inside the house and the sound stops. any other suggestions>

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            • #7
              if the noise stopped with the invertor disconnected, then the problem is the inverter.

              ground the inverter to the trunk panel/frame of the car. that is where all the grounds should be going. all you have to do is pull up the carpet a little and find a screw that is secured to the metal pan of the trunk. make sure that the metal is bare and ground the inverter to the trunk metal. if you want to, you can put some silcone or liquid electrical tape over the connection when you are done securing it, so that it doesnt corrode.

              other than that.... move the inverter away from the audio cables. more extreme, build a metal case for the inverter.

              would a ferrite core on the begining and end of the audio cabling reduce the noise? hmmmm

              i would check the grounding first....

              anyone else with ideas?

              ~mike
              Single Member of the "1000 Post and No MP3 Car" Club
              PROJECT ON INDEFINATE HOLD... BOUGHT A HOUSE
              2000 Cavalier Z24 [###-------] Only 30% Done ... Still

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              • #8
                Try running a wire from the Power Supply case to a ground on the cars frame. (Just wrap it around a fan grill or duct tape it to the side of the ps's case) Worked for me like a dream!
                http://www.jeepmp3.com/
                CarPC Stolen. Starting over.
                Ne1 recognize the avatar?

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