Sharp 20CT-250 Service Manual page 8

CRT CUT-OFF, SUB-CONTRAST, WHITE BALANCE AND SUB
BRIGHTNES ADJUSTMENT
No. Adjusting point Adjusting procedure/conditions
1 CRT cut-off 1. Receive the Monoscope Pattern signal.
adjustment: 2. Set to the P-NORM mode.
I 2 C bus control 3. Turn on the service switch and select the "Cut-
adjustment off/background" mode.
4. Set the screen control to 0/10 position.
5. Press the "9" key on the remote controller to reach
the horizontal centering mode.
6. Turn the screen control clockwise until the hori-
zontal raster of the first glimmering colour be-
comes slightly visible.
7. Adjust the cut-off data of the other two colours
until the horizontal raster becomes whitish.
8. Turn off the screen control (counterclockwise) until
the horizontal raster disappears.
Note: Before starting this adjustment, warm
up the unit for 30 minutes or longer at
a beam current of over 700 µA.
9. Press the "9" key on the remote controller to call
the NORMAL mode.
Sub contrast, 1. Receive the Monoscope Pattern signal.
2
white balance, 2. Set to the P-NORM mode.
& sub bright- 3. Connect the DC miliammeter between TP602 (-)
and TP603 (+).
ness Service
» Full Scale: 3.0mA range
mode adjust-
ment: 4. Make sure the beam current be 1,100µA.
I 2 C Bus Con- 5. Adjust the "G-DRIVE" and "B-DRIVE" data to have
trol Adjust- a colour temperature of 12,300°K (white).
6. Adjust the contrast and brightness control to have
ment
a beam current of 200µA.
If the colour temperature is not at 12,300°K, go back
to step1 above.
7. Receive the Crosshatch Pattern signal.
8. Adjust the "SUB BRI" bus data, so that the block
1st to 3rd inside the window area will
disappear.(black)
Waveform and others
* First of all, make sure that the
R/G/B cut-off data are all initial
values.
Note:
R CUT OFF UP "1" KEY
DOWN "4" KEY
G CUT OFF UP "2" KEY
DOWN "5" KEY
B CUT OFF UP "3" KEY
DOWN "6" KEY
The data can be turned up and
down with the above keys.
* 12,300°K X : 0.273
Y : 0.276
(with colour temperature meter
CA-100 (MINOLTA).)
Note:
G-DRIVE UP "7" KEY
DOWN "-/--" KEY
B-DRIVE UP "8" KEY
DOWN "0" KEY
The data can be turned up and
down with the above keys.
1 2 3 4 5
Make sure all the 1st, 2nd
and 3rd black portions are at
the same black level.
8-1
No. Adjusting point Adjusting procedure/conditions
3 Maximum 1. Receive the Monoscope Pattern signal.
beam current 2. Set to the P-NORM mode.
(check item) 3. Connect the DC ammeter between TP602 and
TP603.
» Ammeter's full-scale
» Ammeter's positive (+) lead : TP603
» Ammeter's negative (-) lead : TP602
4. Make sure the beam current is 1,100 ±100 µA.
Note: Before starting this adjustment, warm
up the unit for 30 minutes or longer at
a beam current of over 700 µA.
HORIZONTAL AND VERTICAL CIRCUIT ADJUSTMENT
No. Adjusting point Adjusting procedure/conditions
1 V-AMP 50 1. Adjust the overscan to 9% typical.
V-LINEARITY - 1. Adjust to get the best linearity.
50 Hz
V-S CORREC- 1. Adjust the proper condition.
TION - 50 Hz
V-SHIFT 50 (V- 1. Align the screen center with the CRT's geometri-
CENTER) cal center (E-5).
H-SHIFT (50) 1. Align the screen center with the CRT's geometri-
(H-CENTER) cal center (E-5).
Note: For the V-AMP 60, V-LINEARITY 60, V-S
CORRECTION 60, V-SHIFT 60 and H-
SHIFT 60 adjustments, their corrected
data are automatically entered when the
corresponding 50 Hz mode adjustments
are made.
2 Focus adjust- 1. Receive the Monoscope Pattern signal.
ment 2. Set to the P-NORM mode.
3. Adjust the focus control so that the screen be in
best focusing.
Waveform and others
: 3 mA range
Waveform and others
The selected channels in paren-
theses have the following signals.
(E-2): crosshatch pattern (50 Hz)
signal
(E-5): monoscope pattern (50 Hz)
signal
8-2