🚀 go-pugleaf

In article <9012040056.AA14472@polar.bowdoin.edu> poulin@POLAR.BOWDOIN.EDU (Jeff Poulin) writes:

   Ok, must be the fan, I thought.  However, some of the squeaks last about a
   second in duration and occur every 2-3 seconds.  The pitch is (a guess)
   10,000 - 15,000 Hz (very high, but audible).  The sound is a pretty clean
   tone (it wouldn't show a lot of junk on an oscilliscope). 

What you are hearing is very likely the flyback transformer in the
monitor.  Sometimes the laminations in the core are loose, and vibrate
at the horizontal scan rate (about 15Khz).  High-frequency sounds are
very directional, and so whether you hear it or not may be related to
where you put your head.

Another possible source of high-frequency sound is the power supply,
especially if it's a switcher.  In this case, it might be load-
dependent.  Does the sound vary with what you're doing on the computer?
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