B&K Precision 1249B - Manual - Manual (Page 28)

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APPLICATIONS
NTSC COLOR BARS
Versatility
The NTSC color bars pattern is the basic pattern used for
most testing, troubleshooting and adjustments in video
equipment. It is one of the most valuable and versatile
color patterns ever devised. The NTSC color bars pattern is
very effective for adjusting any type of consumer or
industrial color video equipment for maximum
performance. For troubleshooting and servicing, analysis of
the NTSC color bars pattern or its waveform usually
localize a color related problem to a specific few circuits.
Color Television Receivers
The NTSC color bars pattern provides a standard
reference for color adjustments and troubleshooting in
television receivers. The pattern contains bars of the three
primary colors: red, blue, and green. These are good
reference for checking 3.58MHz phase problems. The grey,
yellow, cyan, and magenta help define problems wherein the
mix of colors is not in the correct proportions. The
COLOR OFF switch removes the chroma component
entirely and is very helpful in defining problems as either
chroma or luminance related.
Video Recorders
The NTSC color bars pattern is virtually a necessity for
video recorder servicing. This includes video cassette
recorders and video disc players.
Most manufacturers specify an NTSC color bar input signal
in their literature. Adjustment procedures are usually based
upon an NTSC color bar input, and the waveforms shown at
various points on the schematic diagram are those obtained
with an NTSC color bar input. Some manufacturers provide
"field" and "factory" procedures in their literature. However,
the "field" procedures merely eliminate all adjustments that
require an NTSC color bars pattern which severely restricts
the amount of servicing that can be performed. With an
NTSC generator you can perform the "factory" procedures.
The NTSC color bars pattern is essential for chroma and
luminance alignment and is also preferred for general
troubleshooting.
Overall VCR Performance
An overall performance test of a VCR may be conducted
by recording the NTSC color bars pattern then playing it
back on a video monitor. There should be no noticeable
difference between the video played back from the VCR and
an NTSC color bars pattern applied directly to the monitor.
Luminance and Chroma Balance
In a VCR, the luminance and chroma signals are
separated during the recording process and recombined
during the playback process. If luminance and chroma
signals are not maintained at the proper proportions when
separated, color distortion will probably occur, particularly
in the vividness of colors or color saturation. Waveforms