Samsung CF21M, Service Manual

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4-3-4 (c) WHITE BALANCE ADJUSTMENT
CONDITIONS
Scanning frequency: 91 kHz / 85 Hz
Display image: Full white pattern
Brightness: Cut-off
Contrast: Maximum
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.
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: 91 kHz / 85 Hz
(1024 x 768)
Display image: White flat field
Display size 312 (H) x 234 (V)
Brightness: Cut off point
Contrast: Maximum
PROCEDURE
Measure luminance at nine points on the display
screen (see figure below).
4-3-6 Focus Adjustment
CONDITIONS
Scanning frequency: 91 kHz / 85 Hz
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.
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: Monitor facing east
Scanning frequency: 68 kHz/85 Hz
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.
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
(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.
4 Alignment and Adjustments
4-6 CF21M*
Red: x = 0.620 ± 0.015 y = 0.334 ± 0.015
Green: x = 0.289 ± 0.015 y = 0.595 ± 0.015
Blue: x = 0.153 ± 0.015 y = 0.072 ± 0.015
Figure 4-10 Luminance Uniformity Check Locations
21”
Without ABL
32ft-L
With ABL
28ft-L