Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!usc!apple!arc!arc!steve From: steve@Advansoft.COM (Steve Savitzky) Newsgroups: comp.sys.misc Subject: Re: Any more squeak ideas? Message-ID: Date: 6 Dec 90 21:46:18 GMT References: <9012040056.AA14472@polar.bowdoin.edu> Sender: @advansoft.com Organization: Advansoft Research Corp, Santa Clara, CA Lines: 16 In-Reply-To: poulin@POLAR.BOWDOIN.EDU's message of 4 Dec 90 00:56:02 GMT 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? -- \ --Steve Savitzky-- \ ADVANsoft Research Corp \ REAL hackers use an AXE! \ \ steve@advansoft.COM \ 4301 Great America Pkwy \ #include \ \ arc!steve@apple.COM \ Santa Clara, CA 95954 \ 408-727-3357 \ \__ steve@arc.UUCP _________________________________________________________