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!

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

matthewfelton said:

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

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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

Part Number (044-0450) Tps15, acc go straight to battery thru relay contacts, w/ 5 terminals to utilize for 5 accesories....Matthew

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.

MCMXCIVRS said:

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.

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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.

cjack said:

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.

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The Starcom1 has a aluminum box, but how does one ground it to a plastic Zumo?

Fred

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.

FredRydr said:

The Starcom1 has a aluminum box, but how does one ground it to a plastic Zumo?

Fred

Click to expand...

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.

MCMXCIVRS said:

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.

Click to expand...

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

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