Hi there, I have a computer with 2 hahua HD-SDI video cards, I have 6 HD-SDI cctv cameras to go with it. I was using a usb dvr card with 6 analogue cameras, I disconnected all cameras, connected my new HD-SDI cameras in to the Dahua dvr cards directly on the back of the computer all work great. When I connected the HD-SDI cameras to the existing wiring the cameras are showing as no signal. There is power to the camera, I have checked the existing wiring with a multi meter all is good, could someone tell me what I am doing wrong. I went to Maplins and bought a 10 amp power supply as I thought that would help, I bought a new 20 metre lead to see if that would work and it doesnt. I plugged all the cameras back directly in to the computer and all the cameras work fine with the new power supply. Thanks in advance for any help I am given, Regards Steven in the UK.