B&K Precision 1249B - Manual - Manual (Page 25)

25
OPERATING INSTRUCTIONS (CONT.)
Only LINE switch engaged:
A single vertical and horizontal line intersecting at the center of
the screen.
LINE and 7 X 11 switches engaged:
7 horizontal lines and I I vertical lines.
Only DOT switch engaged:
A single dot at the center of the screen.
DOT and 7 X 11 switches engaged:
7 horizontal rows by I I vertical columns of dots.
3. Convergence patterns use interlaced scan when the RGB
TTL/LOW switch is released. This causes a slight jitter
effect in the appearance of the pattern. Progressive scan may
be selected by engaging the RGB TTI/LOW switch for a
jitter-free pattern. Most people prefer to use progressive
scan for convergence patterns, but some newer TV sets will
not accept the signal unless interlaced scan is used.
All convergence patterns are monochrome. On most sets the
entire 7 X 11 pattern (when 7 X 11 switch is engaged) will not be
visible due to overscan: it is desirable to display a pattern of at
least 7 horizontal and 10 vertical lines or dots.
BLACK RASTER PATTERN
1.
Perform the "INITIAL SET-UP" procedure.
2. Press the RAST switch. The COLOR OFF switch should
have no effect on the display regardless of whether it is
engaged or disengaged.
3. The screen should not be completely black (black raster or
black-burst).
4.5 MHz SUBCARRIER USE
To check for audio isolation, the 4.5MHz can be switched on
when the NTSC color bars pattern is selected. In a well designed
properly adjusted receiver, the sound trap should prevent the 4.5Hz
subcarrier from affecting the picture quality. In receivers where
the audio is not completely removed
from the video component
of the signal, a "herring bone" pattern will appear on the screen.
To check the audio circuitry, the 4.5MHz switch should be
engaged when any pattern is selected. The 4.5MHz subcarrier is
modulated by an audio tone (approximately lKHz) that can be used
to troubleshoot the audio circuitry in video equipment.
RGB OUTPUT
Independent red, green, and blue (RGB) outputs are available
for testing and adjusting color monitors that use separate red,
green, and blue inputs rather than a composite video input. Such
color monitors are often used with computers having color graphic
display capability, etc.
The Model 1249B will provide compatible test signals for most
RGB monitors using standard 525 line, 15.750KHz horizontal