Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!cornell!uw-beaver!tektronix!orca!tekecs!titus!morganh From: morganh@titus.gwd.tek.com (morganh) Newsgroups: sci.electronics Subject: Re: need help to reduce a monitor's squeal Message-ID: <10409@tekecs.TEK.COM> Date: 28 Sep 88 15:43:52 GMT References: <716@pedsga.UUCP> Sender: nobody@tekecs.TEK.COM Reply-To: morganh@titus.UUCP () Organization: Tektronix, Inc., Wilsonville, OR Lines: 31 In article <716@pedsga.UUCP> jeffj@pedsga.UUCP writes: >I have a question worthy of the net's collective wisdom. >My hearing extends into the high frequency end (>15kHz). > >I can hear several terminals and televisions 'squeal'. >I understand that this is the flyback transformer at the scan frequency. > >Is there anything I can do to attentuate the squeal? >... :-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-) Have I got a solution for you! It includes (1) John Deere model MC Crawler Tractor sans muffler (the old two-cylinder "poppin johnny"), several older chainsaws in which the exhaust baffles have been eaten through, and .44 magum and .375 magnum handguns. Mix well with a lack of ear protection and sheer stupidity over a number of years. I am a glowing example of the efficacy of this treatment. I haven't been bothered by outside high frequency sounds in years. My ears begin rolling off at about 4500 Hz (of course the tinnitus keeps my desire for high frequency sound satisfied with CONTINOUS mixed squeals..) :-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-) Seriously, however, when I could hear such things (working on old TV sets), it was almost always connected to some sort of corona discharge around the flyback. You might check with a local supplier for what we used to call "Corona Dope" -- it used to solve the problem for me. To diagnose, try operating the monitor in a pitch black room with the back off. Morgan