Symptom: Ground loops
Ground loops are indicated by seeing 60 Hz noise on the video.
1.Check for resistance between the grounds of the keyboard and the system. Ideally, there should be zero ohms.
2.Remove the coaxial BNC connector and check for voltage between the BNC shield of the controller and the BNC shield of the system. No voltage should be detected.
It is recommended that a Pelco GIT100 ground isolation transformer be installed to eliminate the above problems.
Symptom: No video or poor video
1.Check the system power and video BNC connections.
2.Check all coaxial BNC connectors from the camera to the monitor.
3.Make sure the controller is set for the correct
4.Check for normal load termination of 75 ohms. When looping through VCRs or multiplexers, make sure the signal is terminated at the end device. Some termination symptoms and problems are listed below.
Symptom | Problem |
Extremely bright video | No termination or high resistance |
Over contrast or contrast level of monitor needs to | Double termination (37.5 ohms) |
be increased to maximum for a good video image |
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Symptom: Unable to view activity through glass
When the camera is pointed to a window, it cannot pick up any activity behind the glass. This is a limitation of thermal imaging technology.
53 |
