6-3-4 Luminance Uniformity Check
Luminance is considered uniform only if the ratio
of lowest to highest brightness areas on the screen
is not less than 7:10.
CONDITIONS
Scanning frequency: 53.6 kHz/85Hz (800 x 600)
Display image: White flat field
Brightness: Cut off point at 2.4 ft-L
Contrast: Maximum
PROCEDURE
Measure luminance at nine points on the display
screen (see figure below).
6-3-5 Focus Adjustment
CONDITIONS
Scanning frequency: 53.6 kHz/85Hz (800 x 600)
Display image: “H” character pattern
Brightness: Cut off point
Contrast: Maximum
PROCEDURE
1. Adjust the Focus VR on the FBT to display the
sharpest image possible.
2. Use Locktite to seal the Focus VR in position.
6-3-6 Color Purity Adjustment
Color purity is the absence of undesired color.
Conspicuous mislanding (unexpected color in a
uniform field) within the display area shall not be
visible at a distance of 50 cm from the CRT
surface.
CONDITIONS
Orientation: Monitor facing east
Scanning frequency: 53.6 kHz/85Hz
Display image: White flat field
Luminance: Cut off point at the center
of the display area
Note: Color purity adjustments should only be
attempted by qualified personnel.
PROCEDURE
For trained and experienced service technicians
only.
Use the following procedure to correct minor
color purity problems:
1. Make sure the display is not affected by
external magnetic fields.
2. Very carefully break the glue seal between the
2-pole purity convergence magnets (PCM), the
band and the spacer (see Figure 6-12).
3. Make sure the spacing between the PCM
assembly and the CRT stem is 29 mm ± 1 mm.
4. Display a green pattern over the entire display
area.
5. Adjust the purity magnet rings on the PCM
assembly to display a pure green pattern.
(Optimum setting: x = 0.295 ± 0.015,
y = 0.594 ± 0.015)
6. Repeat steps 4 and 5 using a red pattern and
then again, using a blue pattern.
Table 6-3. Color Purity Tolerances
(For 9300K color adjustment: x = 0.283 ± 0.02, y = 0.298 ± 0.02)
7. When you have the PCMs properly adjusted,
carefully glue them together to prevent their
movement during shipping.
6 Alignment and Adjustments
CKF5607L 6-7
Red: x = 0.625 ± 0.015 y = 0.340 ± 0.015
Green: x = 0.280 ± 0.015 y = 0.595 ± 0.015
Blue: x = 0.150 ± 0.015 y = 0.063 ± 0.015
Figure 6-10. Luminance Uniformity Check Locations
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