Sharp 28JW-74H Service Manual page 10

28JW-74H
• When the volume down button is pressed the top and bottom scanning decreases and
the centre scanning increases.
• Press the stand-by button on the remote control to store.
Vertical Shift
Adjust the Vertical Shift so that the picture is centred.
The effect of this adjustment is shown in figure 13.
• When the volume up button is pressed, the picture moves down.
• When the volume down button is pressed, the picture moves up.
• Press the stand-by button on the remote control to store.
Colour Adjustments
The following adjustments should only be carried out when the CRT or IC850 are replaced.
G2 (screen), R-G-B Cut Off and Gain Adjustments
1. Follow the procedure below to set the G2
1.1 Tune the set to the output of a signal generator (monoscope pattern).
1.2 In the user menu, set contrast to 80/100 and brightness to 40/100 (TV normalized).
1.3 Select FULL MODE.
1.4 Enter the Service Mode.
1.5 Select RED GAIN in Service Mode.
1.6 Adjust SCREEN VR so that the OSD value (indicated on Figure 14) reaches 50h ± 8h.
2. Follow the procedure below to set the Cut Off.
2.1 Adjust G2.
2.2 Tune a white pattern.
2.3 Adjust colour to minimum.
2.4 Position colorimeter in the centre of screen.
2.5 Adjust brightness and contrast to obtain a luminance of ≈ 3 NITS.
2.6 Operate in Service Mode and select location RED CUT OFF, GREEN CUT OFF and BLUE CUT OFF, to obtain
colour coordinates:
To increase press volume-up button and to decrease press volume down button.
RED CUT OFF
GREEN CUT OFF
BLUE CUT OFF
3. Follow the procedure below to set the GAIN.
3.1 Using brightness and contrast buttons, select a luminance of ≈100 NITS.
3.2 Operate in Service Mode and select location RED GAIN, GREEN GAIN and BLUE GAIN, to obtain colour
coordinates:
To increase press volume-up button and to decrease press volume down button.
XX XX XX XX
XX 50 XX XX
RED GAIN
Figure 14
X=0.290 ± 0.015
alter «X» coordinate.
alter «Y» coordinate.
alter «X» and «Y» coordinate.
X=0.290 ± 0.015 Y=0.284 ± 0.015
Adjust value
to 50h ± 8h
XX
Y=0.284 ± 0.015
10
Figure 13