Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!cornell!uw-beaver!tektronix!midas!jeffw
From: jeffw@midas.TEK.COM (Jeff Winslow)
Newsgroups: sci.electronics
Subject: Re: need help to reduce a monitor's squeal
Message-ID: <3459@midas.TEK.COM>
Date: 28 Sep 88 16:32:46 GMT
References: <716@pedsga.UUCP>
Reply-To: jeffw@midas.UUCP (Jeff Winslow)
Organization: Tektronix, Inc., Beaverton, OR.
Lines: 22

In article <716@pedsga.UUCP> jeffj@pedsga.UUCP writes:

>I can hear several terminals and televisions 'squeal'.
>I understand that this is the flyback transformer at the scan frequency.

True. Sometimes, however, you're hearing instability in the switching power
supply often used in these units. This happens more often than you might
think, even with supposedly "perfected" and "professional" designs. These
noises are almost always pitched lower and are (to me) much more irritating
that the scan frequency.

>Is there anything I can do to attentuate the squeal?

When my terminal squeals, I drop its back end on the desk from about 1/2" up.
Most of the time it quits, so I suspect the transformer mounting is a bit, ah,
flexible.

Funny thing - I just tried it out and it caused the noise to *start*. I had
to drop the front from about an inch up - twice - to get it to stop. Isn't
this fascinating? :-)

						Jeff Winslow