Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!seismo!cmcl2!phri!roy From: roy@phri.UUCP (Roy Smith) Newsgroups: comp.sys.mac Subject: Re: Burnt Mac+ Message-ID: <2542@phri.UUCP> Date: Wed, 17-Dec-86 12:54:25 EST Article-I.D.: phri.2542 Posted: Wed Dec 17 12:54:25 1986 Date-Received: Thu, 18-Dec-86 21:46:38 EST References: <16644@ucbvax.BERKELEY.EDU> Reply-To: roy@phri.UUCP (Roy Smith) Organization: Public Health Research Inst. (NY, NY) Lines: 25 In <16644@ucbvax.BERKELEY.EDU> dlee@miro.Berkeley.EDU (David Lee) tells of some problems he had with a Mac-plus. He turned it on, got strange video for 10-15 seconds, then the machine started to smoke. When he brought it in to be fixed, it worked fine, has has worked ever since. One possibility is some sort of momentary short in the high-voltage section. If you had some dust or something in the wrong place which allowed the HV supply to arc, you might either produce enough EMI or drag the power suply down enough to flake out the video. If the dust burned away all by itself, that would account for the machine working fine later. This is just conjecture, however. Note that on high tension transmission lines, similar effects can be seen. Most high-power circuit breakers are designed to automatically reset themselves after a short time, in the expectation that whatever caused the short (fallen branch, out-of-control automobile, small animal, etc) has either burned up or fallen out of the way. A typical reclosing program might include attempts after 1/15th (4 cycles), 1, and 15 seconds, after which the breaker locks out, requiring manual intervention to reset. -- Roy Smith, {allegra,cmcl2,philabs}!phri!roy System Administrator, Public Health Research Institute 455 First Avenue, New York, NY 10016 "you can't spell deoxyribonucleic without unix!"