Dougm

I'm upgrading (slowly) my cctv system. It is a Witness 2K comprising of 4 cameras connected to B/W monitor via a 6 pin mini din. I initially wish to take just the video signal to a new dvr. Each camera has audio in and out as well as power (12V I think) and video. Does anyone know the pin wiring for this make / type of cctv system. I wish to keep the cameras, for now. And keep them powered from the monitor, befor obviously upgrading them. Then the monitor.