Path: utzoo!attcan!uunet!seismo!sundc!pitstop!sun!hanami!landman
From: landman%hanami@Sun.COM (Howard A. Landman)
Newsgroups: comp.sys.mac
Subject: Re: My Mac is coming down with something
Message-ID: <58201@sun.uucp>
Date: 28 Jun 88 10:25:43 GMT
References: <1531@randvax.UUCP>
Sender: news@sun.uucp
Reply-To: landman@sun.UUCP (Howard A. Landman)
Organization: Sun Microsystems, Mountain View
Lines: 28

In article <1531@randvax.UUCP> florman@randvax.UUCP (Bruce Florman) writes:
>    Over the last couple of days the screen my faithful old Mac Plus 
>has started to jump and flicker rather badly.  I recall from other 
>people's horror stories that the Mac has a failure mode where the 
>screen goes black with a narrow white stripe running up the middle 
>:-(skunk mode).  Can anyone tell me what part is going bad, and 
>whether or not there is any advantage in getting it fixed before it 
>goes out altogether?

I had similar symptoms last week, although the brightness was also way down,
so you could only see the stripe with it turned up all they way.  It turned
out to be that capacitor C1 on the analog board was blown.  This is a 3.9uF,
+-20%, 25V, (bipolar?) electrolytic capacitor.  I had trouble finding a
replacement, so I bought four 1.0uF 250V metallized film capacitors from
Radio Shack and soldered them in parallel to make 4.0uF.  Cost of parts was
about $3.81 including tax.

If C1 *is* blown, it may not be obvious from casual inspection.  All I saw
was that the board was a little brown there (indicating overheating?), and
the top of the can was *slightly* bulging.  After removing C1, I could see
cracks in its base around the leads.

I have been told that you can get similar symptoms from cracked solder joints
on the analog board or the CRT yoke, but mine looked OK.

	Howard A. Landman
	landman@hanami.sun.com
	UUCP: sun!hanami!landman