Sharp LC-20AV1U Service Manual page 22

The following adjustment normally are not attempted
in the field. Only when replacing the LCD Panel then
adjust as a preparation.
5. White Balance Adjustment
Purpose: To mix red, green and blue beams correctly
for pure white.
Symptom of Misadjustment: White becomes bluish
or reddish.
Method 1
Vary the "RCUTOFF", "BCUTOFF", "RGAIN" and
"BGAIN" settings of the adjustment process below.
Adjustment Process
RCUTOFF 0
GCUTOFF 0
BCUTOFF 0
R-GAIN 0
G-GAIN 0
B-GAIN 0
1. Receive the black signal (white 40%).
Adjust the "RCUTOFF" and "BCUTOFF" settings to
have the black color temperature as specified.
2. Receive the white 80% signal.
Adjust two of the "R-GAIN", "G-GAIN" and "B-GAIN"
settings in the decreasing direction to be visible
white.
Note: Make sure at least one of the "R-GAIN", "G-
GAIN" and "B-GAIN" settings is "0".
3. Check to see if the black and white color tempera-
tures are as specified. If not, repeat the above steps
1 and 2.
Red cut - off adjustment
Green cut - off adjustment
Blue cut - off adjustment
White balance
White balance
White balance
Method 2
Test point Adj. Point
CH
Screen
buttons
M. EQ.
Pattern Generator,
Color analyzer
L = 50 cm
INPUT: WHITE 80%
Note: Use remote control unit
1. Operate the unit for more than 20 minutes.
2. Input the White Purity (APL 80%).
3. Set the color analyzer to the CHROMA mode and
bring the optical receptor to the center on the LCD-
Panel surface after zero point calibration as shown
above.
Note: The optical receptor must be set perpendicu-
larly to the LCD Panel surface.
4. Enter the Service mode. Press "VOL p" button on
the remote control unit and select "C/D" mode.
5. When "x" value and "y" value are not within specifi-
cation, adjust "DB" or "DR". Refer to "1. Initial Set-
ting."
6. Input the White Purity (APL 40%).
7. Press "VOL p" button on the remote control unit and
select "C/D" mode.
8. When "x" value and "y" value are not within specifi-
cation, adjust "COB" or "COR". Refer to "1. Initial
Setting."
9. Also VIDEO 2 mode.
5-3
Mode Input
White Purity
VIDEO 1
(APL 80%
VIDEO 2
and 40%)
Spec.
APL x (0.282 to 0.302)
80% y (0.297 to 0.317)
APL x (0.276 to 0.296)
40% y (0.289 to 0.309)
Figure
It carries out in a darkroom.
Perpendicularity
Color Analyzer
Fig. 2
L0370EA