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From: kevin@ucrmath.UCR.EDU (kevin lund)
Newsgroups: comp.sys.mac,comp.sys.mac.hardware
Subject: Got them mean old power supply blues
Message-ID: <2995@ucrmath.UCR.EDU>
Date: 9 Dec 89 23:42:48 GMT
Reply-To: kevin@ucrmath.UCR.EDU ()
Distribution: na
Organization: University of California, Riverside
Lines: 18


  I have a really ancient mac (originally 128K) and, over the years, the
analog board has required no more than an occasional resolderning.  Until
now...
  The symptoms are:  no video (not so much as a measly dot in the middle),
sound is corrupted (a buzz instead of a bong when it comes on, and when
reset...so I guess it's supplying power ok), and not much else (won't boot).
There is a big fat transistor (Q3 I believe; it's at the top and has a big
heat sink on it) which gets extremely hot and, with the power off, has no
appreciable resistance though any pairs of it's legs (bad sign if I don't
miss by guess).
  So, does anybody have any idea what the problem is?  I could always
try replacing the transistor but maybe it was wrecked by something
else...is all else fails, where can I get a new board, cheap?

  thanks

      kevin           kevin@ucrmath.ucr.edu