Sierra Video Pro XL Series 8 - Manual (Page 66)

SIERRA VIDEO
60
Video Signal
Problem Remedy
No video at the
output device,
regardless of input
selected.  Confirm that your sources and destination device are powered on and
connected properly. Video signals connected to the input of the switcher
should be of an identical signal format as the output of your source. Video
signals at the output of your switcher should be of an identical signal form
required by your video monitor or recorder.
 Confirm that any other switchers in the signal path have the proper input
and/or output selected.
 Use a Video Tester to test the video path leading to/from your Matrix Switcher.
 Replace the video crosspoint module with one that is known to be functional.
Video level is too
high or too dim.  Verify that the video line is terminated with a precision 75 ohm impedance,
otherwise it results in a video level that is too high or too low when looping is
performed and the termination is not within 1% of 75 ohms.
 Confirm that the connecting cables are of high quality, properly built and
terminated with 75 ohms. Check level controls located on your source input
device or output monitor or recorder.
 Replace the video crosspoint module with one that is known to be functional.
Problem Remedy
Noise bars are "rolling"
up or down in the output
image
or:
Low Frequency hum in
the audio output of the
audio
Hum bars (ground loop) are caused by a difference in the ground potential
of any two or more devices connected to your signal path. Passing that
voltage difference through any available interconnection, including your
video cables, creates hum bars in the picture and/or hum in the audio.
WARNING!
Do not disconnect the ground from any piece of video equipment in your
signal path!
Check the following to remove hum bars:
 Confirm that all interconnected equipment is connected to the same phase
of power, if possible.
 Remove equipment connected to that phase that may introduce noise,
such as motors, generators, etc.
 Disconnect all interconnect cables and reconnect them one at a time until
the ground loop reappears. Disconnect the cable, or insert an isolation
transformer in the signal path.