Samsung SyncMaster CSH7839L Service Manual page 23

6-3-4 (d) WHITE BALANCE ADJUSTMENT VERIFICATION
Refer to the procedure for 9300K, section 6-4-2 (d).
6-3-5 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 6-10 Luminance Uniformity Check Locations
6-3-6 Focus Adjustment
CONDITIONS
Scanning frequency:
Display image:
Brightness:
Contrast:
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.
6-3-7 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.
CSH7839L/CSH9839L
68 kHz/85 Hz
(1024 x 768)
White flat field
352 (H) x 264 (V) - 19"
306 (H) x 230 (V) - 17"
Cut off point
Maximum
68 kHz/85 Hz
"H" character pattern
Cut off point
Maximum
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 (see Figure 6-11 and
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
Red: x = 0.640 ± 0.015
Green: x = 0.295 ± 0.015
Blue: x = 0.142 ± 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.
6 Alignment and Adjustments
Monitor facing east
68 kHz/85 Hz
White flat field
Cut off point at the center
of the display area
y = 0.323 ± 0.015
y = 0.594 ± 0.015
y = 0.066 ± 0.015
6-7