Graphics Cable For VT241

[bobaboba]

I have a VT241 (VS240 with the colour VR241 monitor) and I need to make up a graphics cable for it. Looks like just 3x75 ohm from the monitor connector to bnc on the terminal.
The VS240 J8 monitor connector also has a few 'extra' pins which I'm not sure about:

12 - monochrome out (I guess I can ignore this)
13 - monitor present ???
14 - keyboard tx ???
15 - keyboard rx ???

Anyone know what pins 13-15 are for and do I need to do anything with them?
I guess I can study the schematics but easier if someone knows offhand . There's nowhere on the VR241 that I can see to output a 'monitor present' signal.
Thanks

 

[bobaboba]

Made up a cable and tried things out.
A partial answer is that unless pin 13 is shorted to ground the terminal reports error 9 - monitor error.
Sadly although the terminal fired up OK and ran for about 30 minutes it then stopped responding. Now it brings the screen up OK but hangs before displaying the 'WAIT' message. Ah well - one for the winter I think.