I have a camera not displaying video, is there anything I can check to determine if a service technician needs to visit?

If a camera is not displaying the video on your live feed more than likely there is hardware issue. The first thing you should check is the beige color metal power supply box that is mounted on the wall by your DVR. The power cord should be firmly connected on the left side. If this does not power the camera back on then you should check the connections. There are BNC twist connections at the camera and at the back of the DVR where the camera lines connect to the DVR. Ensure that these are tight as they can come loose over time. There may be splice points in the wire depending on the length of the run but they may be hard to access. There are BNC connections at these points as well and the problem could be there. Once all of these areas have been inspected, if the camera is still not working, it may be time for a service technician to visit and further troubleshoot the issue. There could be a voltage issue or even worse, a bad camera.