[ChrisW6ATV]

If it has a DB25 connector for the RGB input, it may use this pinout:

Pin Signal Descr
---------------------------------------------------------------
1 IBM Select High: IBM mode (RGBI)
Low: 3 Bit TTL (RGB)

2 Audio Select High: Audio input from pin 13
Low: Audio input from LINE A/B/VTR jacks

3 HSync/CSync Horizontal or Composite Sync, Negative Pol.

4 Blue Input Video Inputs: Positive Pol.

5 Green Input (Sync on green optional in analog mode)

6 Red Input

7 NC

8 NC

9 Analog/Digital High: Analog mode
Low: Digital mode

10 RGB/Normal High: RGB input selected
Low: LINE A/B/VTR input selected

11 VSync Vertical Sync, Negative Pol.

12 Blanking High: Video input from RGB input only
Low: LINE A/B/VTR signal is superimposed over
signal from RGB input

13 Audio Input -5 dB / 100% mod.

14 NC

15-24 Ground

25 intensity Positive Pol.

Oops, the columns are garbled in the post though my original is correct, but you should still be able to see what each pin is for.