Sharp LC-20S2U-S Service Manual page 14

LC-20S2U-S
2. Adjusting procedure
(1) Getting initialized
1) Set pins (81) and (82) of the IC2001 microprocessor to GND. Turn on the power.
2) Make sure the model number is A622. * Note: The model number cannot be selected.
3) Select the screen size (13/15/20 inches).
Select the inch size according to the 20" model.
(2) +B adjustment
1) Receive the standard color bar signal.
2) Rotate R3710 (semi-fixed variable resistor) to adjust the voltage at pin (4) of P3701 on the sub PWB to
5.00V±0.02V.
Note: Be sure to adjust this PWB in pairs with the main PWB.
Adjust to the 5.00V level as exactly as possible because this level is used as reference for all the other supply
voltages.
(3) Common bias adjustment
1) Adjust the "COM BIAS" setting on adjustment process page 2 so that the contrast goes to maximum (black most
accentuated). (For this adjustment, receive a B/W broadcast channel.)
(4) White balance (cut-off and gain) adjustment
1) Receive the black signal (white 40%).
Adjust the "RCUTOFF" and "BCUTOFF" settings on adjustment process page 3 to have the black color
temperature as specified.
Adjustment Process Page 3
RCUTOFF
GCUTOFF
BCUTOFF
R-GAIN
G-GAIN
B-GAIN
D2 RCUTOFF
D2 GCUTOFF
D2 BCUTOFF
D2 R-GAIN
D2 G-GAIN
D2 B-GAIN
2) Receive the white 80% signal.
Adjust two of the "R-GAIN", "G-GAIN" and "B-GAIN" settings in the decreasing direction to have the white color
temperature as specified.
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 temperatures are as specified. If not, repeat the above steps 1) and
2).
4) 480P mode white balance adjustment
Set the "D2 GCUTOFF" setting to -7. Check to see if the black and white color temperatures are as specified.
If not, repeat the steps 1) thru 3). Adjust also the "D2 R/G/B CUTOFF" and "D2 R/G/B-GAIN" settings.
Red cut - off adjustment
0
Green cut - off adjustment
0
Blue cut - off adjustment
0
White balance
0
White balance
0
White balance
0
Red cut - off adjustment (D2:480P)
0
Green cut - off adjustment (D2:480P)
0
Blue cut - off adjustment (D2:480P)
0
White balance (D2:480P)
0
White balance (D2:480P)
0
White balance (D2:480P)
0
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