10 Apr
2008
10 Apr
'08
1:57 p.m.
At 12:00 -0500 4/10/08, David Griffith wrote:
I've just brought up a Mac SE/30 with fresh disks
and noticed that the
monitor occasionally gets wavy or shudders. How should I proceed in
fixing this?
I had a long, long series of problems with my Mac Plus. They
got pretty much cured when I took loose the power cable connecting
the Analog/video board to the digital board, cleaned the pins (sanded
lightly and wiped with ethanol), and put some silicone oil spray on
to inhibit corrosion. I had previously done this at the digital board
end, but the resistance (ohms to tens of ohms, and variable,
responding to temperature and vibration) was at the analog board end.
I finally discovered I could diagnose these by using an ohmmeter
between the solder pads on the back sides of the boards at either end
of the cable.
I don't know how many differences there are between SE/30 and
Plus, but some, for sure. Be very careful disconnecting at the analog
board end of the cable - pull too hard, and your hand can smack into
the thin end of the CRT, letting the vacuum out. I have a .pdf of the
Apple Service Manual for the SE/30, which I'll be happy to forward
(off-list, obviously).
On the Plus, there are also a set of variable resistors on
the analog board setting various parameters (width, height, etc.) of
the video. Those might also be corroded. Running them back and forth
and then back to the original settings might clear that, or some
contact cleaner (which is probably a better treatment for the
connectors than what I list above) might be a good idea.
Finally, capacitors on the analog board might be going bad.
An ESR meter could give you some indications there.
Additional clues from somebody with an SE/30 would be very valuable!
At 12:00 -0500 4/10/08, Ian Primus wrote:
But I have a
book at home, forget the name, but it's a Macintosh
repair guide that has a lot of good info to help
pinpoint failed parts. It has a purple cover. Anyone
remember this book? This is going to drive me nuts all
day. :)
The "Dead Mac Scrolls"? "Macintosh Repair and Upgrade
Secrets"? Google for Larry Pina, I think he's the most-recognized
author in this area.
At 12:00 -0500 4/10/08, David Griffith wrote:
It happens perhaps once every ten seconds. The
disturbance is something
like a ripple or wave that crawls up the side of the screen.
Oh. Probably my advice above is good in general but not
specific to this problem. I think the Pina books may well address it
though. If Jeff W. is listening, he can probably verify that.
--
- Mark, 210-379-4635
-----------------------------------------------------------------------
Large Asteroids headed toward planets
inhabited by beings that don't have
technology adequate to stop them:
Think of it as Evolution in Fast-Forward.
10 Apr
10 Apr
3:17 p.m.
On Thursday 10 April 2008 13:57, Mark Tapley wrote:
On the Plus, there are also a set of variable
resistors on
the analog board setting various parameters (width, height, etc.) of
the video. Those might also be corroded. Running them back and forth
and then back to the original settings might clear that, or some
contact cleaner (which is probably a better treatment for the
connectors than what I list above) might be a good idea.
I'd tend to avoid tweaking those if at all possible, unless you have a pretty
good indication that it's the problem...
Finally, capacitors on the analog board might be
going bad.
An ESR meter could give you some indications there.
I think that's pretty likely. I had one monitor that I was given a number of
years back, EGA when I'd been running mono before that (g), and it was
_very_ wavy, so changing the cap out between that and a scrapper nearby with
a similar chassis fixed it.
And speaking of older monitors, I mentioned this in here once before, but
this guy is offering me a *pile* of older monitors -- mono, cga, ega, but
nothing newer. I'm holding off on going and getting them because I don't
really have a place to put them at this point in time, no storage available,
and he said in recent correspondence that I'd need a truck or a van to be
able to haul them all away. I've got past correspondence from a few of you
folks, but anybody else who's interested, drop me a line offlist, and
let's talk. I'd sure rather get 'em to somebody who can use them than scrap
them out.
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
13 Apr
13 Apr
5:29 a.m.
On Thu, 2008-04-10 at 12:57 -0500, Mark Tapley wrote:
I had a long, long series of problems with my Mac
Plus. They
got pretty much cured when I took loose the power cable connecting
the Analog/video board to the digital board, cleaned the pins (sanded
lightly and wiped with ethanol), and put some silicone oil spray on
to inhibit corrosion. I had previously done this at the digital board
end, but the resistance (ohms to tens of ohms, and variable,
responding to temperature and vibration) was at the analog board end.
I finally discovered I could diagnose these by using an ohmmeter
between the solder pads on the back sides of the boards at either end
of the cable.
Anywhere you get tinned connectors that are even a little bit exposed to
the outside environment (near a ventilation grille), you get problems.
Or at least, that's been my experience.
The problems caused by the capacitive keyboards on Ensoniq ESQ- and
VFX-family synths nearly sunk the company (maybe they did, at that).
All this because of a little multiplug between the two halves of the
keyboard PCB, positioned right under the key bed where moisture would
get at it. Nearly all of these have had the plugs removed and the
connection hardwired.
Gordon
6016
days inactive
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2 comments
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gordonjcp＠gjcp.net -
mtapley＠swri.edu -
rtellason＠verizon.net