Fluke PM5414V - Handbuch (Seite 25)

PM 5414 V OPERATING INSTRUCTIONS 3 - 1 1
3.5.8 Applications of the Test Patterns
The generator provides many different test patterns or combined test patterns for checking and align­
ment of monochrome and color television sets, VLPs, and VCRs. Colored and B/W patterns are
available. The following description and suggestions show the user how the test patterns can be
applied to full advantage.
1. Circle on a black background is suited for checking the overall linearity and geometry.
The circle can be added to all available patterns. The white circle changes automatically to black
when used with the white pattern and is useful for checking reflections.
2 . Center cross / Border lines
This pattern is ideal to center TV monitors and TV screens. Furthermore, it is applied to check
the deflection linearity and for pin-cushion correction.
3. White pattern 100 % with color burst is designed for the whitesetting and check of the color
purity. It is also useful for adjustment of the maximum beam current of the picture tube. For
videocassette recorders, the luminance writing current is checked by means of this pattern.
4. Dot pattern mainly for static convergence. The screen should contain pure white dots. The
presence of colored dots is an indication that one or more of the electron beams is passing the
wrong hole in the shadow mask.
5. Crosshatch / Center indication with 17 vertical and 12 horizontal lines (13 lines for NTSC) is
used for checking and realigning dynamic and corner convergence. When pin-cushion correc­
tion is needed E/W and N/S adjustments have to be made.
It is important that this pattern is generated without interlacing: finally evaluating the adjustment
is more convenient with a stable test pattern. If the test is required with interlacing a further
pattern, for example circle or center cross, it must be added.
Checkerboard pattern of six times eight rows of squares provides a visual standard for basic
picture tube alignments, for example: centring, focus, horizontal and vertical deflection and
linearity. Bandwidth can be checked by observing the vertical transitions; transitions from black
to white should be sharp. Furthermore, this pattern indicates main hum interference in the
synchronization. Furthermore no picture interference (Moiré) should occur.
7. Greyscale
A full screen linear staircase signal with eight equal steps from black to white is used to locate
faulty linearity of the video amplifier or greyscale setting.
A color receiver should show no color in any of the eight bars. Color here means that the guns
of the picture tube are incorrectly adjusted. This part of the pattern is also used when checking
the contrast controls.