Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!ames!vsi1!ubvax!ardent!sleat
From: sleat@ardent.UUCP (Michael Sleator)
Newsgroups: sci.electronics
Subject: Re: need help to reduce a monitor's squeal
Summary: not always the flyback
Message-ID: <620@ardent.UUCP>
Date: 6 Oct 88 01:19:13 GMT
References: <716@pedsga.UUCP> <3459@midas.TEK.COM>
Reply-To: sleat@ardent.UUCP (Michael Sleator)
Organization: Ardent Computer
Lines: 19

Several people have suggested mechanically damping the flyback transformer
to reduce the squeal.  Good advice, I believe, but if it's an open frame
construction I'd caution you to be careful of the wires leading from the
windings to the terminals.  They tend to be fragile.  Also, don't
use just any old goop, because there are some fairly high voltages even
on the primary side.

I've run into one case where mechanical damping didn't help at all because
the sound was coming from elsewhere.  It turned out that the retrace
capacitor was acting as a very effective transducer.  The solution in this
case was to switch to a different style of capacitor.  Both were epoxy-
dipped mylar types, but one must have been more loosely wound.  This was
a manufacturing situation, and all of one vendor's caps seemed to exhibit
the same behavior, so we just switched vendors.  (I think that the good
ones were Sprague "Orange Drops", but I don't remember for sure.)

Michael Sleator
Ardent Computer
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