5 Alignment and Adjustments
5-3-4 Luminance Uniformity CheckCONDITIONS
Orientation:Monitor facing east
Luminance is considered uniform only if the ratio
of lowest to highest brightness areas on the screenScanning frequency:68 kHz/85 Hz (17�)
is not less than 7.5:10.54 kHz/85 Hz (15�)
Display image:White flat field
CONDITIONSLuminance:Cut off point at the center
Scanning frequency:68 kHz/85 Hz (17�)of the display area
54 kHz/85 Hz (15�)Note: Color purity adjustments should only be
(1024 x 768)attempted by qualified personnel.
Display image:White flat field
Brightness:Cut off point at 24 ft-LPROCEDURE
Contrast:MaximumFor trained and experienced service technicians
PROCEDUREonly.
Use the following procedure to correct minor
Measure luminance at nine points on the displaycolor purity problems:
screen (see figure below).
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 Figures 5-12).
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 displayFigure 5-10. Luminance Uniformity Check Locations
area.
5-3-5 Focus Adjustment5. Adjust the purity magnet rings on the PCM
assembly to display a pure green pattern.
CONDITIONS
(Optimum setting: x = 0.295 ? 0.015,
Scanning frequency:68 kHz/85 Hz (17�)y = 0.594 ? 0.015)
54 kHz/85 Hz (15�)6. Repeat steps 4 and 5 using a red pattern and
(1024 x 768)then again, using a blue pattern.
Display image:OH� character pattern
Brightness:Cut off pointTable 5-3. Color Purity Tolerances
Contrast:Maximum
Red:x = 0.640 ? 0.015y = 0.323 ? 0.015
PROCEDUREGreen:x = 0.295 ? 0.015y = 0.594 ? 0.015
1. Adjust the Focus VR on the FBT to display the
sharpest image possible.Blue:x = 0.142 ? 0.015y = 0.066 ? 0.015
2. Use Locktite to seal the Focus VR in position.
(For 9300K color adjustment: x = 0.283 ? 0.02, y = 0.298 ? 0.02)
5-3-6 Color Purity Adjustment7. When you have the PCMs properly adjusted,
carefully glue them together to prevent their
Color purity is the absence of undesired color.movement during shipping.
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.
5-8CKB5237L/7227L |
ACEC
