Samsung CF21M Service Manual page 72

4 Alignment and Adjustments
4-3-4 (c) WHITE BALANCE ADJUSTMENT
CONDITIONS
Scanning frequency:
Display image:
Brightness:
Contrast:
1. Click on the << or >> boxes next to R_GAIN
and B_GAIN to make the video white.
(For 5000K color adjustment:
x = 0.346 ± 0.02, y = 0.359 ± 0.02.)
2. Refer to the procedure for 9300K, section
4-3-2 (c) steps 2 and 3.
Without ABL
With ABL
Luminance Table (6000K) 4-5
4-3-4 (d) WHITE BALANCE ADJUSTMENT VERIFICATION
Refer to the procedure for 9300K, section 4-3-2 (d).
4-3-5 Luminance Uniformity Check
Luminance is considered uniform only if the ratio
of lowest to highest brightness areas on the screen
is not less than 7.5:10.
CONDITIONS
Scanning frequency:
Display image:
Display size
Brightness:
Contrast:
PROCEDURE
Measure luminance at nine points on the display
screen (see figure below).
Figure 4-10 Luminance Uniformity Check Locations
4-3-6 Focus Adjustment
CONDITIONS
Scanning frequency:
Display image:
Brightness:
Contrast:
4-6
91 kHz / 85 Hz
Full white pattern
Cut-off
Maximum
21"
32ft-L
28ft-L
91 kHz / 85 Hz
(1024 x 768)
White flat field
312 (H) x 234 (V)
Cut off point
Maximum
91 kHz / 85 Hz
"H" character pattern
Cut off point
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.
4-3-7 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:
Scanning frequency:
Display image:
Luminance:
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.
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 4-6. Color Purity Tolerances
Red: x = 0.620 ± 0.015
Green: x = 0.289 ± 0.015
Blue: x = 0.153 ± 0.015
(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.
Monitor facing east
68 kHz/85 Hz
White flat field
Cut off point at the center
of the display area
y = 0.334 ± 0.015
y = 0.595 ± 0.015
y = 0.072 ± 0.015
CF21M*