Servo - audio interference

I have a good quality, screened stereo lead running directly from the audio out socket of my Zumo cradle, under the tank terminating in a socket at the front of the seat. When I plug my ultimate ear monitors in I pick up a high pitched whine from the servo.

It's not engine speed related but does change in volume when I apply the brakes.

If I run the lead over the tank through the baglux tank harness there is no noise.

Is there an easy way of shielding this lead or a better way to route it?

The sound is not passed through an intercom of any sort, straight from the mount to the UE monitors.

Zumo 550, 1150GSA, twin spark with servo & ABS.

Any help much appreciated.

Are you certain that the screening on the lead is terminated correctly at both ends ? Is it soldered or crimped ? Sounds like a screening/lead problem- you might find that an in-line suppressor or similar would help, but no idea what sort -sorry. If the audio out on the Zumo is a "mini jack", then these are notorious for giving a bad connection - I'd just check the lead thoroughly on a meter.
Does the noise get worse when you apply your brakes ( ie servo), or is it a constant noise, regardless of brakes ?

Thanks for the initial diagnosis.....

Roger Chatterton said:

Are you certain that the screening on the lead is terminated correctly at both ends ? Is it soldered or crimped ?

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It was a good quality manufactured lead. Not sure whether terminations inside are crimped or soldered. I take it one must be better than the other.

Roger Chatterton said:

If the audio out on the Zumo is a "mini jack", then these are notorious for giving a bad connection

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Audio out is via a 3.5mm stereo socket/jack. The lead has gold plated jacks.

Roger Chatterton said:

Does the noise get worse when you apply your brakes ( ie servo), or is it a constant noise, regardless of brakes ?

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The noise is constantly there but increases when I apply the brakes. It does not seem to be engine speed related.

Personally I would always favour a soldered joint over a crimp, but doesn't therefore mean it's better !
If noise is constant, even with no servo in use, I'd say it might not be directly related to the servo/s ?

Sorry I can't be of more direct help -have you tried a different lead ?
Are you hearing audio as well as the high pitch noise ?
Is the audio feed from the Zumo clean if you use it off the bike ?
Try checking lead for continuity on a voltmeter...
Dumb questions maybe, but it will really boil down to a process of elimination, as in all this sort of annoying troubleshooting....
I know you can buy little "polo-mint" shaped noise supressors , and you wind your cable around them a couple of times ( I think they are a carbon ring or something), and they are supposed to eliminate noises -bit like a car radio really -you are probably picking up radiated noise from some electrical interference -motors (sevos), HID ballasts ? etc.... But then you knew that

Roger Chatterton said:

I know you can buy little "polo-mint" shaped noise supressors , and you wind your cable around them a couple of times ( I think they are a carbon ring or something)

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Them'll be ferrite rings - worth a go as a cheap experiment - Maplin sell them in many shapes and sizes.

That's what I meant -having a hard day today -software -installs !!!