poulin@POLAR.BOWDOIN.EDU (Jeff Poulin) (12/04/90)
Many thanks to Johnathan Chandross, Jeff French, and Earl Sharp who responded directly to my squeaks inquiry. I, too, thought it was the drives, but it isn't. I unplugged the power supply to to my C drive (seagate 138R) and the squeaks persisted. Then I unplugged the power to my D drive (seagate 277R-1) and all I heard was the quiet hum of the fan -- and the squeaks! 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). It doesn't seem reasonable to me this could be caused by a fan that rotates at maybe 600-900 rpm (another guess). Besides, the sound doesn't seem to come from the cooling fan end of the computer. There must be movement for sound, it's simple physics. If it's not the drives or the fan, the only thing else I can think of is the PC speaker. Unfortunately by the time I thought of this, the sound drifted away (as it sometimes does). I unplugged the speaker and haven't heard the squeaks for about an hour now (uncommonly long). So, suppose it is the speaker. I would assume its making the sounds because of unwanted voltage in the speaker wire. This, I would gather, is caused by something not being grounded properly. If this is the case, does anyone know where I could go from here. I really don't want a mute computer. Suggestions are still quite welcome! -- Jeff Poulin poulin@polar.bowdoin.edu jpoulin@bowdoin.bitnet P.S. For those of you who think the sound is all in my head, I checked that too. When I leave the room, the sound goes away :-)
steve@Advansoft.COM (Steve Savitzky) (12/07/90)
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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\__ steve@arc.UUCP _________________________________________________________jcm@MSR.EPM.ORNL.GOV (James A. Mullens) (12/08/90)
This subject reminds me of something that happened to me years ago. I am 99% certain this is not related to the original poster's problem, but I have always been curious about it. Maybe someone can shed some light on it. Many moons ago I was writing some assembly language code for the 8087 on an original-model Big Blue PC. At one point I made a programming mistake which resulted in (something like) continuous divides by 0.0. When I ran this faulty program I heard a continuous high-pitched squeal. I couldn't decide if it came from the monitor or the computer itself. My guess was the monitor, but as someone else has pointed out, these sounds are very directional. This was a very reproducible phenomenon. The squeal only happened when I ran the faulty program and never occurred after then program was fixed. Any comments? jim mullens oak ridge national labs jcm@msr.epm.ornl.gov -or- mullens@jamsun.ic.ornl.gov