3 way cctv cable with power

[gb]

I want to shorten a CCTV camera cable (3 way with power)but was confused when I discovered an unexpected blue wire inside the sheath. I need some help with the pairings for the reconnection, please.

I assume the yellow (Video) and white (Audio) share a common return but have no idea whether the plasticised metallic inner sheath serves this function. I also assumed that the red and blue were the positive and negative for the power, but despite trying every combination I can think of, I can't get the camera to work. I only hope I haven't buggered the camera by applying current incorrectly !!

Anyone?

Thanks

[Toby]

Are you cutting an end off and trying to reconnect from there?

If so, you should be able to use a multimeter, or a simple battery and a lamp to see what cables are connected to the original connector.

If you are chipping a bit of cable out the middle, then you should be able to just connect up like for like, including the screen.

Does the camera have some kind of motion detection, and end it a SCART connection? if so, this extra wire may be for switching the TV over to the relevant SCART input when it detects something.

A picture might help here!