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From: omh@cs.brown.edu (Owen M. Hartnett)
Newsgroups: comp.sys.mac.hardware
Subject: Re: flaky mac+ monitor
Message-ID: <60826@brunix.UUCP>
Date: 7 Jan 91 03:52:50 GMT
References: <009421BA.480FB640@uclapp.physics.ucla.edu> <1991Jan6.220909.10319@nuchat.sccsi.com>
Sender: news@brunix.UUCP
Reply-To: omh@cs.brown.edu (Owen M. Hartnett)
Organization: Brown University Department of Computer Science
Lines: 48

In article <1991Jan6.220909.10319@nuchat.sccsi.com> brentb@nuchat.sccsi.com (Brent Burton) writes:
>
>Well, your power supply has bit the dust.  I just had mine replaced two
>weeks ago for the second time.  I have appleCare now thru March, so if
>anything goes bad on my system, it gets fixed for 'free'.  This past
>power supply didn't cost me any $$.
>
>Now that I have had AppleCare I wouldn't do this, but you need to see
>Larry Pina's book, "Macintosh Repair and Upgrade Secrets."  He details
>how to fix the power supply.  99% of the problems are the result of a
>bad flyback transformer.  These transformers are cheap (<$20?) compared
>to a new power supply (~$320).  If you aren't technical, get it replaced,
>get AppleCare, and suck up the loss.  I'm praying my mouse and disk drive
>die before March so I can get those replaced, too.  
>
I don't recall seeing the quote of 99% problems related to the flyback
transformer.  In fact, from talking to Larry, I sincerely doubt that
he would make such a statement.  While failures of the original OEM flyback
were high, the newer OEM flyback is much more robust and is the same one
that you buy as part of the upgrade.

>My mac plus had the same problems:  screen jitters, deformed display (mine
>was 1/4" taller on the left than the right), and blackouts.  Mine also
>made real high squealing noises.  These are all indications of a bad PS
>according to Larry Pina and my past experience.

You're right about the bad power supply, but it was probably cold solder
joints at J4 rather than the flyback.  When the flyback goes, you've
probably lost all video.  Cold solder joints, however, will cause the
screen jitters and intermittent blackouts.

I just wanted to clear this up because from the above post, it seems like
Larry's book is recommending replacement of the flyback as a general
panacea, when in fact this isn't so.

Also, when you're on Applecare, the replacement power supply, although new,
will have the same marginal OEM parts that came with your original board,
but if you install an upgrade kit such as that one offered by SoftSolutions,
you're installing better than original equipment parts making your upgraded
board better than the OEM, which means it will last a lot longer.

-Owen


Owen Hartnett				omh@cs.brown.edu.CSNET
Brown University Computer Science	omh@cs.brown.edu
					uunet!brunix!omh
"Don't wait up for me tonight because I won't be home for a month."