(What’s wrong with this picture?)
Problem: Bright spot smears on monitor.
Cameras are designed to view light reflected from the scene being viewed. When you have a bright light
source in the picture, it may produce a bright white spot on the monitor and a vertical line through it.
This is a problem especially at night.
Solution: Reposition camera to avoid bright light sources in the scene.
Problem: Bright background, dark foreground
A bright area in the picture causes the iris to close or the imager to reduce gain. This causes the unlit
area to appear darker.
Solution: Use a camera with backlight compensation or reposition camera to avoid bright background
and/or illuminate foreground to even lighting of scene.
Problem: Picture rolls when switcher changes
Line locked cameras get synchronization from the AC power supply they use. If camera power supplies
are out of phase during switching, you will notice a rolling between frames from one camera to another.
This can be confusing to the person monitoring the system. It can also create problems for your time
Solution: Power cameras from the same phase on your electrical panel or use cameras that have a phase
Problem: Picture is snowy or snowy bars roll on screen.
The coax cable is picking up electrical, magnetic, or radio interference. This is very prevalent when
using inexpensive cable.
Solution: Re-route cables away from problem area Keep all low voltage
and coax cabling away from existing mains and data cable routes and use
only good quality cable for example RG59BU. Also video signals may be
using cat5 cable via (BALUNS) this will eliminate most line bourne
Problem: No picture at the monitor.
An open or short in the cable is the most common cause. Breaks in the center conductors are caused by
excessive pulling or bending, shorts are usually caused by improper connector installation.
Solution: Disconnect the cable at both ends and check with a meter.
1) From center pin to outer connector should read open. If it reads shorted, reinstall the connector. If it
still reads shorted, read cable directly. If this fails and cable still reads shorted, replace cable.
2) Short one end (pin to outer), meter from other end, it should read shorted. If it reads open, check the
cable directly. If the cable reads open, replace the cable.
supply loss is also a common cause of picture failure, especially if
its a low voltage camera. Check power supply fuses and system mains
Problem: Monitor has “ghosts”
When a video signal is not properly terminated it reflects back on itself, resulting in secondary images
called “ghosts.” Unless you pass the signal onto another video product, the signal needs to be terminated.
Solution: Make sure “Hi-Z/75 ohm” switch is in “75ohm” position unless looping video signal on to
Problem: Picture tears horizontally or snowy bars roll
The system is suffering from a ground loop(s).
A ground loop is caused when camera and monitor are
powered from sources using different grounds with different ground potentials. If a path for current flow
(other than the coax) exists, ground loops are possible. A difference of a few millivolts can cause a
ground loop. Ground loops are not predictable and may appear or disappear after the system is installed.
Solution: Install a ground loop corrector or power all cameras from the same source as the monitor.