Yet another nifty project idea: RGB using Cat-5e

["A.J." <naijireja@yahoo.com>]

Hi all,

For those interested, I have discovered that it is possible to connect
an Apple IIGS to an RGB color monitor using a standard Category 5e
network cable. This is accomplished by assembling a pair of male D-Sub
15 to RJ-45 modular adapter kits with the correct pinouts.

I have wired each of the D-Sub 15 modular adapters as follows:

Signal.................D-Sub 15 Pin....RJ-45 Adapter Pin...Cat-5e Color
Red Composite Video.....2..............1 (blue)............white/orange
Red Video Ground........1..............2 (orange)..........orange
Green Composite Video...5..............3 (black)...........white/green
Blue Video Ground......13..............4 (red).............blue
Blue Composite Video....9..............5 (green)...........white/blue
Green Video Ground......6..............6 (yellow)..........green
Composite Sync..........3..............7 (brown)...........white/brown
Unknown................10..............8 (white)...........brown

The above pinout ensures that each color signal and its corresponding
ground are paired together in the same twisted pair. Just for fun, I
tried to make each pair color correspond to its video signal color.
Since a Category 5e cable does not include red wires, I settled for
orange.

When using the above pinout, the shield ground is not connected.

I'm not sure what Pin 10 is used for, but since it is present in my
Apple IIGS monitor cable, I will connect it to RJ-45 Pin 8.

I have tested this kit using a 3-foot Cat-5e cable without any
noticable loss of signal.  I'm not sure how well Cat-5e cable carries
analog video over long distances.

The only problem that I had with this kit was that the adapter didn't
correctly fit into the back of the Apple IIGS.  Apparently, the plastic
on the case takes away from the available "real estate" of the
connector, and the adapter sticks out a bit making the connection a
little bit difficult.  I managed to secure one of the screws and things
seem to work fine.

--A.J.