Re: Using a Mac monitor on a GS?

[spec@vax2.concordia.ca (Mitchell Spector)]

In article pelagic@no.spam (Pelagic) writes...

>I have a "Macintosh 12" RGB Display" with a 15-pin "D"
>shell connector; when I plug this into a GS I get a blurry
>picture that seems out of synch.

    That is exactly the problem, the horizontal scanning
frequency is going to be out of synch on an Apple IIgs.
The Macintosh RGB monitor works at VGA frequency -- 30 kHz
or higher, and it cannot do anything lower. The Apple IIgs
outputs its video at an NTSC rate which is 15.75 kHz.

>Am I barking up the wrong (apple) tree? Or can I open the case
>and start tweaking with the controls? (The monitor is someonewhat
>blurry even on a Mac and I'm not sure if that's fixable;

    If you open the back, there will be two knob controls on the
flyback transformer marked "Focus" and "Screen". You can get a
TV-alignment tool kit from Radio Shack for about $1, which has
a plastic rod for safely making the adjustment. 'Focus' will fix
the blurriness problem, 'Screen' will up the master brightness
if your screen is unusually dark.

    Note that it is EXTREMELY DANGEROUS with all the high voltage
and other hazzards in there though, so if you decide to do it I
advise you to read up on safety tips and take precautions. I've
done adjustments to several of my Apple and non-Apple monitors,
though only when absolutely necessary because of the risk. It's
one area of hardware I don't like to open and play with. ;-)

>I just need an idea if it's worth trying to get it going on the GS.)

    Well you could purchase a Second Sight video card, then add to
that an SVGA->Macintosh adapter -- though other than that, there
isn't much you can do. Your better off with the official AppleColor
RGB monitor (A2M6014) which looks virtually identical, except the
power light is a slash shape ("/") rather than a dash ("-").

    You can use any analog RGB monitor that supports an NTSC
scanning frequency (e.g. Amiga or Atari ST monitors) but you
will of course need a custom made cable.

Mitchell Spector
spec@vax2.concordia.ca