Gotta northhurst cctv kit i put in a few years back but the monitor keeps failing and has been repaired many times now are the camera's interchangable with other systems they seem to have a 5 pin din type plug which appears identical to a computer ps2 mouse plug fitted it for a mate so trying to see if i can replace it with a separate switcher and monitor any idea's guys?

I'm pretty sure the camera's will be compatible, but I'm not familiar with the system.

When you cut the PS2 plugs off the end and figure out which cores are for power/video, then you can just reconnect them with the appropriate connectors (BNC, etc)

Only problem is, without a wiring diagram of the camera you'll need a bit of luck to find out what cable's what, without blowing the camera!

I've converted a system like that a few years ago. Can't remember what cables did what but there were upto 5 in one kit i modified, video, mic, speaker, power, common ground etc. What I do remember is that the colours were non standard, ie. RED wasn't =12v, YELLOW wasn't =video etc.

I did it by trial and error in the end and didn't blow the offending camera.

Try measuring the output of the sockets for +12v common with the plug chassis. Introduce a test video signal down the remaining pins, won't do any harm that way.