15 Apr
2013
15 Apr
'13
8:58 a.m.
Another method to interface classic computer to a standard VGA monitor
would be to use an Extron 202xi converter ( Other models may work, I used
this model). You can still find these old boxes out there for $30- 80.
This model can handle ECL inputs, which was why I chose it for my
application. My application was to connect a standard VGA monitor to a SUN
3/140 that had a dying ECL monochrome CRT 1152x900 Horiz=61.8KHz Vert
66Hz ( model M19P114) attached to it .You have to make a custom cable
between the computer and the Extron input ( Because the Exton DB9 inputs
are weirdly configured), the manual for the 202xi box is at the Extron
website. When making my cable from the Sun to the Extron, I had to keep it
very short ...6 inch...because the ECL had a problem with long cables. The
results were amazing, very nice output from my SUN on the VGA monitor ( HP
L1925). The Exron has 5 BNC outputs RGBVH, so I also had to buy a 5BNC to
VGA cable, Amazon , about $10.
Hutch
On Mon, Apr 15, 2013 at 8:43 AM, Matthew Stock <stock at csgeeks.org> wrote:
On Mon, Apr 15, 2013 at 7:56 AM, Kevin Parker
<trash80 at internode.on.net
--
e-?
wrote:
Hi Matt - while I really liked watching what you
did and watching it fire
up
I'm interested in the RGB to VGA converter you used as I have quite a few
legacy machines but a shortage of old monitors but no shortage of VGA
screens.
Kevin,
The CoCo uses a fairly simple signal that's similar to CGA in many
respects. The main issue I had was the fact that it uses separate H and V
sync signals instead of a composite sync. The board I purchased and that
you see in the video is similar to this (
http://www.ebay.com/itm/RGB-CGA-EGA-YUV-to-VGA-Arcade-HD-Video-Converter-Bo…
).
While it supports separate sync signals, it won't capture at 15kHz.
So I found a schematic at
http://www.epanorama.net/circuits/vga2rgbs.htmlon how to build a
simple composite sync, fed that into the converter board,
and it worked like a champ. That little board isn't visible in the video,
but I home etched it. Both conversion boards run off of a small 5v
switching wall wart.
Total cost was about $30 and a little time and soldering.
Hope that helps.
-Matt