Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site peora.UUCP Path: utzoo!watmath!clyde!cbosgd!ihnp4!pesnta!peora!jer From: jer@peora.UUCP (J. Eric Roskos) Newsgroups: net.micro.mac Subject: What part fails in power supply? (a repeat) Message-ID: <1899@peora.UUCP> Date: Thu, 9-Jan-86 11:39:09 EST Article-I.D.: peora.1899 Posted: Thu Jan 9 11:39:09 1986 Date-Received: Fri, 10-Jan-86 05:35:52 EST Organization: Concurrent Computer Corporation, Orlando, Fl Lines: 30 I asked this question in here awhile back, but haven't gotten an answer yet; I'm hoping by now someone may have found out the answer... It's now fairly well known that some subset of the Macintoshes experience a power supply failure if left turned on for an extended period of time. The symptom of this failure is that a transformer on the analog board becomes shorted and overheats. However, this isn't necessarily the actual problem; it could be that some other part, e.g., a capacitor or transistor, has a manufacturing defect or was not used according to the part's rated specifications, and that this part fails. For example, the failure might cause the oscillator in the switching power supply to stop running, causing a DC current to run through the transformer for an extended period, causing it to overheat. So, my question once again is, what part is failing? If it is some small part, it could probably be replaced with a part with a better rating, thus avoiding the failure. I would rather replace a 30 cent capacitor or $2.00 transistor, than have to replace the whole board, now that my machine is out of warranty. If you know what part is failing, or even just have a rumor about what part is failing, please mail to me, and I will summarize... Thanks... -- UUCP: Ofc: jer@peora.UUCP Home: jer@jerpc.CCC.UUCP CCC DNS: peora, pesnta US Mail: MS 795; CONCURRENT Computer Corp. SDC; (A Perkin-Elmer Company) 2486 Sand Lake Road, Orlando, FL 32809-7642 "Oh, is he your friend? Ask him his name!"