mtc1670

How to test Video inputs without a camera? VCR? Connectors?

Aquired a Palco DVR DX7000 (8ch.) system with no cameras. I have some 12 VDC cameras with video BNC outputs with 1 Vpp. When I hook them up it displays a gray bar accross the screen and jumps around up and down, and the connectors get a little warm. In addition when the BNC is connected to the unit under power it gives a little arc. Can anyone help me?