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Reducing or eliminating RF / EMI noise

Discussion in 'XJ Technical Chat' started by sybe, Sep 15, 2019.

  1. sybe

    sybe Active Member

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    I have recently upgraded my coils to Dyna 3 and since the install, I have been getting increased RF noise that is causing the Motogadget mbutton to glitch out. Some of the glitches are random horn beeps and turn signal activation. The instructions for the mbutton now says that it needs to go into the handle bars for proper shielding. Prior to the coil upgrade i didn't have any problems. The other change i should mention is that i swapped out the stock headlight bucket. The new bucket is a thinner metal and might be allowing more noise through.

    To help solve the issue i was thinking of wrapping the mbuttion in a few layers of copper tape. Before i try this i wanted to see if any one had any advice? Also would the copper tape need to be grounded? Would lining the inside of the new headlight bucket with copper tape work better?
     
  2. Polock

    Polock Well-Known Member

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    there's spiral wrapped plug wires for that. the old school way was to twist the input signal wires in pairs. look into Ferrite RFI Suppression Chokes
     
  3. Rooster53

    Rooster53 Well-Known Member Premium Member

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    My best guess would be the EMI is likely being picked up on the green communication (config) wire, the only wire that goes from the M-button to the M-unit and is likely running very close to the coils. You can try the suppression wires, resistive plugs, moving the green wire as far from the coils as possible, and even the ferrite beads as a possible fix, but I would suggest just converting that green wire to a single conductor shielded cable particularly in the area near the coils. The best bet would be to have as much of that comm wire shielded as possible, and then tie the shielded braid to ground on one end only.
     
  4. Ryengoth

    Ryengoth Active Member

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  5. Polock

    Polock Well-Known Member

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    for that kind of money there should be some customer support from the Motogadget people
     
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  6. sybe

    sybe Active Member

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    its $50. i think they added the line saying it must be in the handle bars from all the complaints.

    I think the noise is affecting the button itself causing it to trigger. Another site where they posted a reply from Motogadget about emi/rf issues and they said its mostly from the spark plug caps and to use resistor caps. I used the dyno coil kit from up top so i need to double check the wires.

    Thanks for that. I will try it out.


    too bad they don't sell wire harness tape or wraps that is already insulated.
     
  7. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    A $50 button should come fully shielded. My $30 DVD player has more RF shielding by the sound of it.
     
  8. Rooster53

    Rooster53 Well-Known Member Premium Member

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    Well they do sell single conductor shielded wire if you need it but I kind of like what Ryengoth posted as you wouldn't need a splice. I would still be inclined to think the issue is from the comm wire (green) and shielding that would solve the problem. If I were doing it I would want to pick the smallest shield possible just for aesthetic issues. You would likely need a piece of solid wire that you could tack the green wire to and pull it back through the shielded braid but first solder a wire to the end of the shield with an eyelet terminal at the m-unit end to attach to ground. It could be scoped out to troubleshoot, but I know that is not likely a tool that many have. The induced EMI pulses can be easily seen using the oscilloscope.

    You may have seen this already but he mentions they have only had one case (a maybe) on EMI interference - starts at time 5:16

     
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  9. Ryengoth

    Ryengoth Active Member

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    Ground the shield on one end only to the frame. If you ground both then a ground loop could make it worse.
     
  10. Polock

    Polock Well-Known Member

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    drill some holes in the frame and pull the wire thru the frame
     
  11. sybe

    sybe Active Member

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    I got new suppression spark plug wires coming in. Going to try the new wires then the metal braided sleeve if it doesnt help.
     

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