[comp.sys.mac.hardware] More mac+ video problems

zing@hpdmd48.boi.hp.com (Blair Elzinga) (01/29/91)

Besides the 'too hot' power supply and video woes I've heard about in
this notes group, my mac+ recently developed a similar, but definately
different problem:

After a couple of weeks of a jittery screen, I turned it on one day to find
that the only video output I got was a single vertical line in the middle of
the screen.

Has anyone had that happen to them?  What did you do?

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|     Blair Elzinga                                            |
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|                                                              |
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|     Hewlett-Packard                                          |
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wnn@ornl.gov (Wolfgang N. Naegeli) (01/31/91)

In article <15590010@hpdmd48.boi.hp.com> zing@hpdmd48.boi.hp.com (Blair 
Elzinga) writes:
> After a couple of weeks of a jittery screen, I turned it on one day to 
find
> that the only video output I got was a single vertical line in the 
middle of
> the screen.

I had exactly the same problem. I resoldered the width coil (L1), the yoke 
plug (J1), and the lin coil (L2). This fixed the problem. There was no 
visible deterioration of the solder points, but such things are often hard 
to see.  The 3.9uf capacitor at C1 can also cause these symptoms if it 
goes bad. Replace it with one reated for at least 25 volt.

To avoid future trouble, I installed a power supply upgrade kit (which 
includes a 100 v version of C1 and a heavy-duty flyback transformer, plus 
several other parts to replace marginal components that often cause 
trouble) from MicroMat Computer Systems ($50). Their number is 
800-829-6227 and they have a free HyperCard catlog stack. 

**************************************************************
Wolfgang N. Naegeli
President, MacClique--East Tennessee Macintosh Users Group
Internet: wnn@ornl.gov     Bitnet: wnn@ornlstc
Phone: 615-574-6143        Fax: 615-574-6141 (MacFax)
QuickMail (QM-QM): Wolfgang Naegeli @ 615-574-4510
Snail: Oak Ridge National Laboratory, Oak Ridge, TN 37831-6206
**************************************************************