Re: Sams PhotoFacts for the IIgs Monitor

[a2aviator@gmail.com]

After some digging..

I found tabloid sheets with AutoCAD printed, hand entered via
examination and reverse engineering, schematics.

They're pretty basic, straight up drawing, component for component.

Once upon a time I was interested in making the Macintosh 12" RGB work
with the IIgs because of it's similar form factor and CRT type, and it
is basically the same monitor except the horizontal scan rate is 24.5
KHz instead of 16Hz, "halfway" between VGA and analog RGB. So I
thought that I could just modify portions of the 12" RGB main logic
board and produce another monitor, being as those 12" LC monitors were
pretty plentiful at the time.

What I ultimately ended up doing was just swapping CRTs from the Mac
monitors into the IIgs monitors.

If you wish to swap CRTs, understand that it is basically a TV set,
and all those things you heard about that voltage inside there
possibly killing you, are true.

But.. if you swap the CRT, DO NOT remove the yokes. You may need to
change the connector on the yoke to match pinout on the IIgs RGB, I
can't recall exactly anymore, it's color for color the same, the
positioning of the wires and if it's two connectors or one complete
one may vary, and does actually across the IIgs RGB monitor production
runs. They were not all completely the same inside. But they were
interchangeable.

No worries if you put the connector on 'wrong', you'll just get a
mirrored/reversed/flipped/upsidedown picture or something along those
lines.

(which brings an old prank to mind.. bored in a motel room? Got too
much time on your hands, while at the 'Six? ;-) ... open up the TV and
re-arrange the yoke wires... flip the TV picture around, so that it
looks normal except all the text will read backwards, like you're
looking in the rearview mirror at the front of the bus behind you. )

Warning. Working with CRTs is considered dangerous and can ruin your
day. If you are unfamiliar with this type of work and the precautions
needed, please refer to someone that is.

Additionally, another tip on the IIgs RGB, and many other monitors
that have the same problem;

Got a IIgs RGB that turns on and goes straight to a deep, loud, neon
red, alien like green or blasting blue?  It's a simple fix.

On the neck PCB, you will see three identical components that look
similar to tantalum capacitors, a blob looking item with colored dots
for the value, in looking at the schematic, I think they are what I
have labeled as Q6R1, Q6B1 and Q6G1, A673. If this goes bad, IE, it
opens up, you get the full effects of that color.

you can verify the problem by yanking/swapping red for green, etc, or
just removing the one that corresponds to the color you see and you'll
see the other two color components being generated on the monitor.

Lastly, back in the day, one trick with CRTs was to use a CRT
Rejuvenator on the thing, this was pretty much a waste of time. The
CRTs used in the IIgs monitor were pretty much immune to these
machines and if it did work, your symptoms came back in several
months. The IIgs RGB monitor had a really short life compared to other
monitors, they just didn't last long at all, and interestingly, we all
used them and didn't notice because everyones monitor it seemed was
looking the same. ;-)

Basically they would loose brightness and focus ability, take as long
as a half hour to warm up to a usable picture, and that caused people
just to leave them on.. which.. made them go even faster.

I'll figure out some good settings to scan this thing so that I don't
end up with a 600 meg file, though that it's readable.

Sorry, but I have no idea where the .dfx files went, it was an old 386
that had my PCB files, JEDEC, ROMs, etc - and for whatever reason the
AutoCAD stuff never got transferred off it during the years of
migration. So it's scan or nothing, and these drawings should really
have been printed on a E sheet but I have them on tabloid in landscape
orientation. The quality is good, so that won't be a real issue I
hope. Not double sided, so no echos will come through..

http://www.starkelectronic.com/bk490.htm