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B Why doesn't this mp3 player work in the car?

  1. Jun 29, 2016 #1

    ProfuselyQuarky

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    My father has this old mp3 player that he really likes to use. He uses it in the car often but the only problem is that, sometimes, the interference is so bad you can't hear anything. This only happens in car. What's more is that this only happens in the car when the driver's door is closed. When the door is open, everything goes back to normal and you can hear whatever is being played just fine. This only works with the front door. When the driver's window is open, it doesn't work, either. I have no idea what could possibly cause this. It definitely has nothing to do with the player itself or our location. Other devices that can be used to listen to the radio (e.g. iPod, etc.) works just fine. What's up?
     
    Last edited: Jun 29, 2016
  2. jcsd
  3. Jun 29, 2016 #2
    My first instinct would be to say "Faraday Cage", but then that doesn't explain why the iPod works.
     
  4. Jun 29, 2016 #3
    That is quite the mystery....
    Does the player even have any sending or receiving electronics?
    Maybe the interference happens on different frequencies than the ones used in radio or by the iPod.
     
  5. Jun 29, 2016 #4

    billy_joule

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    Is it connected via an aux cord or FM transmitter? Sounds like it's the door switch circuit. Leave the door open and push the door switch, it'll be somewhere on the door frame.
     
  6. Jun 29, 2016 #5
    Ok don't throw me stones here, but isn't an MP3 player used for listening to MP3 files located in a memory card (or maybe a CD/DVD). What does an MP3 player got to do with listening to Digital or Analog FM radio???
     
  7. Jun 30, 2016 #6
    Ok maybe the Mp3 player has integrated digital/analog FM radio.

    If it is digital FM radio then there might be an explanation for this. When we close the door the SNR (signal to noise ratio) of the received signal drops. There must be something wrong in the receiving/decoding circuit of the Mp3 player so that it requires a higher SNR in order to decode properly the signal. If the SNR is lower than a critical value then in digital FM radio you ll hear nothing.
     
  8. Jun 30, 2016 #7

    CWatters

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    Is he powering the MP3 player from it's own batteries or from an adaptor plugged into the car?

    Is he using some sort of adaptor that allows the MP3 player to play over the speakers in the car? Some use FM radio for this.
     
  9. Jun 30, 2016 #8

    ProfuselyQuarky

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    I haven't heard of that before. I'll look into it.
    I'm not sure what you mean. Could you elaborate? Sorry.
    FM transmitter.
    *throws stone at Delta2* Yeah, he uses it for books mostly but the radio in the old car is busted so that's where the mp3 player comes in handy.
    That's a nice/interesting explanation :smile: Is there a way I could fix it or at the very least experiment to see if this is the cause? My father doesn't care about the player itself but I'd like to delve a bit deeper and figure it out once and for all.
    The mp3 player can be charged either by plugging it into an outlet or PC. I've never seen it plugged into the car with an adaptor, but I'm close to positive that it can be done. We can plug in a phone into the other car to play stuff over the speakers, so I can take the plug and see if the mp3 player can do the same, if that'll be of any interest.
     
  10. Jun 30, 2016 #9

    CWatters

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    Hi, I wasn't really suggesting you try this. I was asking if he was doing this already because it might explain the problem. If he's not doing either then the cause must be elsewhere.
     
  11. Jun 30, 2016 #10

    CWatters

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    Is he using headphones?
     
  12. Jun 30, 2016 #11

    ProfuselyQuarky

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    Alright, then.
    Yes...well, not headphones. They're earbuds, but same thing, right?
     
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