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From: gordon@milton.acs.washington.edu (Gordon Davisson)
Newsgroups: comp.sys.mac.hardware
Subject: Re: Are these flyback transformer symptoms?
Keywords: flyback, transformer
Message-ID: <3997@milton.acs.washington.edu>
Date: 7 Jun 90 08:25:33 GMT
References: <173ldg@yoda.byu.edu>
Reply-To: gordon@milton.u.washington.edu (Gordon Davisson)
Organization: University of Washington, Seattle
Lines: 22

In article <173ldg@yoda.byu.edu> ldg@yoda.byu.edu (Lyle D. Gunderson) writes:
>Our venerable Mac Plus has lost its video. All that is left is a faint
>vertical line up the center of the screen. When my Mac 128k needed a new
>"analog board" I seem to remember the same thing happening. In both cases
>the final failure was preceded by intermittent  flashes on the screen.
>
>I have a few sources for flyback transformers, but it would be nice to know
>if I have correctly identified the problem before I buy the part.

It's a little hard to tell from the description (it's a thin line, like
a millimeter or less thick, right?), but it sounds like what happens
when one of the solder joints on the yoke connector (the 4-pin connector
near the top front of the analog board) cracks.  It's almost always the
top pin that goes, but theoretically the second from the top could also
cause this.  Other possibilities include bad connections on C1, L2, L3,
or the flyback, or failure of any of these components.  Try resoldering
these before you invest in any replacement parts.

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