AirTalk.org Aviation discussions newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Electric whine in the light circuit - Help          AirTalk.org Forum Index -> Owning Airplanes View previous topic :: View next topic   Author Message Victor J. Osborne, Jr. Guest Posted: Tue Jul 29, 2003 10:01 pm    Post subject: Electric whine in the light circuit - Help I flew my (new to me) '87 A36 Bonanza at night for the first time recently and discovered a whine when the panel lights where turned on. The flood light switch / circuit doesn't do it and the rheostat for the panel light dimmer changes the frequency. Where do I start with the troubleshooting? I know any component has to be replaced by an approved shop but I can read a meter. Could it be as simple as a lose ground? -- TIA, {|;-) Victor J. (Jim) Osborne, Jr. [email]VOsborne2shoes (AT) charter (DOT) net[/email] take off my shoes to reply Back to top nobody@nowhere.moc Guest Posted: Tue Jul 29, 2003 10:36 pm    Post subject: Re: Electric whine in the light circuit - Help On Tue, 29 Jul 2003 18:01:01 -0400, "Victor J. Osborne, Jr." <VOsborne2 (AT) charter (DOT) net> wrote: Quote: I flew my (new to me) '87 A36 Bonanza at night for the first time recently and discovered a whine when the panel lights where turned on. The flood light switch / circuit doesn't do it and the rheostat for the panel light dimmer changes the frequency. Where do I start with the troubleshooting? I know any component has to be replaced by an approved shop but I can read a meter. Could it be as simple as a lose ground? I'll bet that the Bo uses a Pulse Width Modulator (PWM) style of lamp dimmer. If the chopping frequency (or harmonics thereof) are between 30 and 10000 Hz, it might be getting into the low level audio. You have to ask yourself why? Has it always done this? Did some idiot avionics tech install an intercom/stereo entertainment system and screw up the audio grounds by grounding the jacks? Do you hear alternator whine or strobe squeal in the audio? Ask the previous owner when it started doing it... MikeM Skylane '1mm PAcer '00z Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         AirTalk.org Forum Index -> Owning Airplanes All times are GMT Page 1 of 1   Jump to: Select a forum Aviation----------------alt.aviationAviation safety EnhancementPlanes, gliders and flying in AustraliaAviation et pilotage (Français)rec.aviationAviation (Aerobatics)Hot air, gas balloons and airshipsHang-gliding, paragliding, foot-launched flightAircraft Design & BuildingInstrument Flight RulesAviation (Classifieds)Military AircraftNaval AviationAviation (Miscellaneous Topics)Owning AirplanesAviators (General Discussions)Aviation related productsAircraft RestorationHelicopters and rotary wing aircraftsFlight SimulationSailplanesAviation (Students)Light aircraftFlying related activities in the UK Airports----------------alt.airportsEdinburgh Airport Glasgow Airport Humberside Airport Luton Airport Aberdeen Airport Glasgow Prestwick Airport  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.