Support Team Shaun_E Posted August 9, 2006 Support Team Share Posted August 9, 2006 We have recently started to get a whining noise in the headsets of our Autocom. The noise is engine speed related and of course it is intermittent. I have the Autocom mounted in the boot and the wires for the phone and music player run along the tunnel and come out near the handbrake. The headset leads come out over the boot top chassis rail under the tonneau. Moving the phone lead around appears to affect (sometimes eliminating) the noise. I have checked the wires for damage and they are OK. The only change to the setup recently is that we have replaced one of the headsets. What else should I check and is there a simple way of eliminating the noise? Yellow SL #32 Link to comment Share on other sites More sharing options...
rgrigsby Posted August 9, 2006 Share Posted August 9, 2006 I've had this and it was when the audio lead was not plugged in and managed to touch some bare metal, other than that I guess it's got to be an earthing/broken wire somewhere. Does it happen when you only have a single headset plugged in? (ie unplug the new headset to check that isn't the cause) Rob G www.SpeedySeven.com Link to comment Share on other sites More sharing options...
Support Team Shaun_E Posted August 9, 2006 Author Support Team Share Posted August 9, 2006 Could be the audio lead - I'll check that. I thought we did try with only the new headset unplugged but will double check. Cheers. Yellow SL #32 Link to comment Share on other sites More sharing options...
simonbell Posted August 9, 2006 Share Posted August 9, 2006 Check all the connections are dry and tight, and if the audio lead is plugged into autocom but not connected to mp3 player or whatever it will act as an aerial and introduce interference. Simon Bell - Caterham 7 Duratec R I`ve seen the future.....and it`s powered by duratec Check out the website here Link to comment Share on other sites More sharing options...
Support Team Shaun_E Posted August 9, 2006 Author Support Team Share Posted August 9, 2006 OK - will check everything thoroughly tonight. I have had problems in the past when the connections got wet or oily (don't ask ). Thanks. Yellow SL #32 Link to comment Share on other sites More sharing options...
Myles Posted August 9, 2006 Share Posted August 9, 2006 I have this on and off. I can confirm that it seems to be guaranteed if your phone/audio cable touches something metallic. Also had it with the usual culprit of a poor earth. Doesn't bother me too much as I never listen to music - just the speedcam/satnav. Project Scope-Creep is live... Alcester Racing 7's Equipe - 🙆🏻™ Alcester-Racing-Sevens.com Link to comment Share on other sites More sharing options...
Nigel Riches Posted August 10, 2006 Share Posted August 10, 2006 Have you checked the alternator suppressor, or the ignition capacitor if you run old fashioned points (probably not) as you say the noise is engine speed related, I take it you mean the pitch varies with engine speed. 1982. 5 speed, clamshells. B.R.G / Ali. The True Colours. Link to comment Share on other sites More sharing options...
Myles Posted August 10, 2006 Share Posted August 10, 2006 Pitch of mine varies with engine speed. Haven't the foggiest how to locate or test the 'alternator suppressor'... Project Scope-Creep is live... Alcester Racing 7's Equipe - 🙆🏻™ Alcester-Racing-Sevens.com Link to comment Share on other sites More sharing options...
Support Team Shaun_E Posted August 10, 2006 Author Support Team Share Posted August 10, 2006 Yes it is the pitch that varies with engine speed. I had wondered about "suppression" as this type of radio interference was typical on old cars with points (my mini and Mk2 Escort spring to mind) - an ignition capacitor was required. In this day of electronic engine management, I assumed that was no longer required. My alternator is a reconditioned unit and has been banged around a bit recently (have had to remove it a couple of times) so perhaps that is the cause. Didn't get to do much on this last night - too busy fitting an aero screen . Yellow SL #32 Link to comment Share on other sites More sharing options...
Richard H Posted August 10, 2006 Share Posted August 10, 2006 Morning All, If the pitch varies with engine speed and is heard as a whine then it is most likely alternator noise, the suppression will probably be a capacitor which is (electrically) bonded to electrical ground (ie the alternator frame, it's mounts, the engine block and finally the chassis) having a really good earth path is very important to the suppression capacitor working well BTW the chassis being the return path for all of this noisy stuff is why Myles has noted that touching any of the audio cables onto chassis metalwork is a sure fire way of introducing noise into the intercom Must get back to the day job, currently trying to keep interference out of a headset on a helicopter 😬 Cheers, Richard..................... Richard...................... Photos here Link to comment Share on other sites More sharing options...
Area Representative Golf Juliet Tango Posted August 10, 2006 Area Representative Share Posted August 10, 2006 The noise is engine speed related and of course it is intermittent. Is it Jill? GJT Crossflow 524 my secret Link to comment Share on other sites More sharing options...
Support Team Shaun_E Posted August 10, 2006 Author Support Team Share Posted August 10, 2006 GJT - have you got a death wish 🤔 😬 Good job we haven't been to Penn for a while and won't be going this month either. Yellow SL #32 Link to comment Share on other sites More sharing options...
Area Representative Golf Juliet Tango Posted August 10, 2006 Area Representative Share Posted August 10, 2006 Yup we have missed you both! GJT Crossflow 524 my secret Link to comment Share on other sites More sharing options...
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