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From: gordon@cs.washington.edu (Gordon Davisson)
Newsgroups: comp.sys.mac.hardware,comp.sys.mac
Subject: Re: dead power sweep board
Message-ID: <10253@june.cs.washington.edu>
Date: 30 Dec 89 04:36:35 GMT
References: <20495@kuhub.cc.ukans.edu>
Reply-To: gordon@june.cs.washington.edu (Gordon Davisson)
Organization: University of Washington, Computer Science, Seattle
Lines: 22

In article <20495@kuhub.cc.ukans.edu> CRABTREE@kuhub.cc.ukans.edu writes:
>Hi.  My Mac Plus has a fried transistor on the power board.  Everything else
>on the board checks out except one transistor next to the large heat sink
>toward the top of the board.  Do any of you technical types have the specs
>for the transistors, etc on the board?  If I could buy a $2 part instead of
>the extreme penalty that Apple charges for a board, my life would be much
>better.  If anyone has any info that might help, I would appreciate it if
>they would forward it to me, or at least clue me as to how I could find it.

I assume you're talking about the one labeled Q3?  If so, it's a
standard BU406 bipolar power transistor, and you should be able to find
them at any reasonably serious electronic supply store (i.e. not Radio
Shack).

By the way, the most common cause of Q3 failure seems to be shorts in
the flyback.  Have you checked to make sure your flyback's 2 windings
are still isolated?

--
Gordon Davisson
Westwind Computing	(206) 632-8141
4518 University Way NE, Suite 313, Seattle WA 98105