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Thread: Dedicated circuit for GPS - ground issue

  1. #1
    Danger: Keep Back 500 Ft FredRydr's Avatar
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    Dedicated circuit for GPS - ground issue

    I have my Zumo 550 connected to the dedicated GPS circuit on my F800GS. However, when my Zumo's audio is plugged in to my Starcom1 Advance, it creates alternator noise in my communications system. From what I've read, there is a "ground loop" problem, requiring me to take care that the two devices are properly grounded. Furthermore, there is a small spark when I touch the audio plug to the Zumo when I insert it.

    I love the convenience of the automatic delayed shut-off of the canbus power. Is there a method to improve the ground through the dedicated circuit? In the alternative, is it possible to use the ground (-) from the battery and the power (+) from the dedicated GPS circuit for the Zumo, and not use the ground through the dedicated circuit?

    Thanks much.

    Fred

    P.S. I have the identical set-up on my R1200R using the dedicated ciruit on that, and I move the Zumo and Starcom1 from one bike to the other, but no ignition noise issues on the Roadster!

  2. #2
    PRAY BEFORE RIDING roadcrave's Avatar
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    Just run a ts/15 from tourtech, 5amp fused from you battery all your assesaries up to 5amps, the bmw plug r/wht strip then powers your tc/15 coil...matthew

  3. #3
    Danger: Keep Back 500 Ft FredRydr's Avatar
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    Quote Originally Posted by matthewfelton View Post
    Just run a ts/15 from tourtech, 5amp fused from you battery all your assesaries up to 5amps, the bmw plug r/wht strip then powers your tc/15 coil...matthew
    Matthew,

    I was unable to find part Nos. ts/15 or tc/15 in the Tourtech catalogue or website. I don't know electrical lingo, so can you be more specific? Thanks so much!

    Fred

  4. #4
    PRAY BEFORE RIDING roadcrave's Avatar
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    Part Number (044-0450) Tps15, acc go straight to battery thru relay contacts, w/ 5 terminals to utilize for 5 accesories....Matthew

  5. #5
    Back in the Saddle mcmxcivrs's Avatar
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    I had the same issue with my Autocom and Zumo. The solution was to use a ground loop isolating cable to connect the two. No more noise.
    Ed Miller, Calgary, AB
    2008 K1200GT, 2009 F800GS
    I can't wait to retire and have a fixed income. The one I have now is always broke.

  6. #6
    K Bikes Complex by Choice cjack's Avatar
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    Quote Originally Posted by MCMXCIVRS View Post
    I had the same issue with my Autocom and Zumo. The solution was to use a ground loop isolating cable to connect the two. No more noise.
    This is what you want. This device passes the audio without having the grounds connected together. The issue is that the ground wiring has the noise on it and it gets added to the audio if you use it directly for the audio return path.
    BMWMotorcycles, fun when they're running...
    My other bike is a BMW.
    Jack Hawley MOA and RA #224, KE9UW ("Chuck")

  7. #7
    Danger: Keep Back 500 Ft FredRydr's Avatar
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    Quote Originally Posted by cjack View Post
    This is what you want. This device passes the audio without having the grounds connected together. The issue is that the ground wiring has the noise on it and it gets added to the audio if you use it directly for the audio return path.
    The Starcom1 has a aluminum box, but how does one ground it to a plastic Zumo?

    Fred

  8. #8
    Back in the Saddle mcmxcivrs's Avatar
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    The ground loop isolator works something like a transformer to connect the two devices without actually creating a hard connection. In this way, the ground loop noise is not carried through, only the audio signal is trasmitted.
    Ed Miller, Calgary, AB
    2008 K1200GT, 2009 F800GS
    I can't wait to retire and have a fixed income. The one I have now is always broke.

  9. #9
    K Bikes Complex by Choice cjack's Avatar
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    Quote Originally Posted by FredRydr View Post
    The Starcom1 has a aluminum box, but how does one ground it to a plastic Zumo?

    Fred
    This has nothing to do with the box metal or otherwise. This has to do with the power ground and the audio ground circuits inside the boxes.
    BMWMotorcycles, fun when they're running...
    My other bike is a BMW.
    Jack Hawley MOA and RA #224, KE9UW ("Chuck")

  10. #10
    Danger: Keep Back 500 Ft FredRydr's Avatar
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    Quote Originally Posted by MCMXCIVRS View Post
    I had the same issue with my Autocom and Zumo. The solution was to use a ground loop isolating cable to connect the two. No more noise.
    I believe I have one of these already. The lead or cable that plugs into the upper socket on the left side of the Zumo cradle has that small square plastic box in it. After tests with eliminating variables, Starcom suspects this cable is defective and is sending a replacement from England.

    That sure is counterintuitive, because the noise stops not when I remove this cable, but rather, when I remove the audio cable in the lower socket (even when the Zumo is turned off)! Also, when I use the same cables (and everything else except for the Zumo cradle) on the R1200R, there is no noise.

    Fred
    Last edited by FredRydr; 04-24-2009 at 11:05 AM. Reason: added more info

  11. #11
    Danger: Keep Back 500 Ft FredRydr's Avatar
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    Problem resolved. I now have BOTH cables between the Zumo 550 and the Starcom1 module isolated cables. Starcom sells the improved isolated audio cable as part No. MUS-04. I think some of you knew this, but I went the long way 'round with Starcom to reach the same conclusion.

    I'm happy.

    Fred

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