[vcf-midatlantic] MAC with squashed screen

william degnan billdegnan at gmail.com
Thu Apr 28 08:38:31 EDT 2016


Yes, usually it's fine, but as preventative maintenance I wanted to fix
this and my Lisa display too.  Maybe next workshop we could focus on early
Mac/Lisa displays or something
b

On Thu, Apr 28, 2016 at 8:36 AM, Ian Primus via vcf-midatlantic <
vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:

> Just reread the description of the fault on your site - I'd gotten the
> impression it was always squashed like that the first time I looked at
> it. If it's intermittent (i.e., you can hit it and it pops back), it's
> probably just a bad solder joint. Resolder Q1 and Q2, and nearby
> components, as well as the yoke connector. If it starts out bad and
> gets better as it heats up, or starts good and gets worse as it heats
> up, and hitting it doesn't affect it, then, it's definitely one of
> those caps.
>
> -Ian
>
> On Thu, Apr 28, 2016 at 8:12 AM, william degnan via vcf-midatlantic
> <vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:
> > thanks.
> > b
> >
> > On Thu, Apr 28, 2016 at 8:09 AM, Ian Primus via vcf-midatlantic <
> > vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:
> >
> >> Kind of covered - in my class on CRT monitor repair, I mentioned
> >> vertical problems like this, and in my old Mac class, I went over some
> >> of the basics there, but, didn't specifically get to this as it
> >> relates to Macs. It's hard to cram that much information into a one
> >> hour class - I had to move rather quickly.
> >>
> >> The 128 uses a pair of discrete transistors for it's vertical driver.
> >> One of the caps in that circuit has failed/is failing. I'm guessing
> >> it's C6. Failing that, it's either C5 or C11. While you're in there,
> >> be sure to resolder the yoke connector, it's a very common point for
> >> cold solder joints (will cause total loss of deflection)
> >>
> >> -Ian
> >>
> >> On Thu, Apr 28, 2016 at 7:57 AM, william degnan via vcf-midatlantic
> >> <vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:
> >> > I am thinking about working to repair the display on my '84 MAC,
> >> > occasionally the horizontal is "squashed" although for now it
> recovers.
> >> > Was this covered in any VCF E classes this or last year?
> >> >
> >> > http://vintagecomputer.net/browse_thread.cfm?id=95
> >> >
> >> > I assume there are a few places on the web that describe MAC repairs
> like
> >> > these, but any comments as to what to target are welcome and will
> save me
> >> > some time.
> >> >
> >> > b
> >> >
> >> > --
> >> > @ BillDeg:
> >> > Web: vintagecomputer.net
> >> > Twitter: @billdeg <https://twitter.com/billdeg>
> >> > Youtube: @billdeg <https://www.youtube.com/user/billdeg>
> >> > Unauthorized Bio <http://www.vintagecomputer.net/readme.cfm>
> >>
> >
> >
> >
> > --
> > @ BillDeg:
> > Web: vintagecomputer.net
> > Twitter: @billdeg <https://twitter.com/billdeg>
> > Youtube: @billdeg <https://www.youtube.com/user/billdeg>
> > Unauthorized Bio <http://www.vintagecomputer.net/readme.cfm>
>



-- 
@ BillDeg:
Web: vintagecomputer.net
Twitter: @billdeg <https://twitter.com/billdeg>
Youtube: @billdeg <https://www.youtube.com/user/billdeg>
Unauthorized Bio <http://www.vintagecomputer.net/readme.cfm>



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