Service Adjustments (Electronic Control); Sub-Contrast; Tint/Color Adjustment; Sub-Brightness - Panasonic CT-20R6E Service Manual

Service Adjustments (Electronic Controls)
Note: Is recommended to allow at 30 min. warm
up at highest bright (using white screen) before
perform any picture adjustment.

Sub-Contrast

Service DAC (B3)
This adjustment is factory set. Do not adjust unless
repairs are made to associated circuit, the CRT Board
or when the CRT is replaced.
Preparation:
1. Apply a color bar signal pattern with 87.5%
modulation, 70% saturated color bar with a 100
IRE white and 7.5 black.
Note:
The pattern used in this procedure is an EIA
color bar pattern with 87.5% modulation with 100 IRE
white and 7.5 black. Correlate the information in this
procedure to the pattern used if another signal is used.
2. Preset the following controls:
• Brightness . . . . . . . .Center.
• Picture . . . . . . . . . . . Max.
• Sharpness . . . . . . . . Center.
• Gamma, S5 . . . . . . . 15
• ACL OFF CA . . . . . . 00
• Cut Off G C1 . . . . . . 00
3. Connect the scope probe between TP35 (C-Board)
and cold ground ( ).
Procedure:
1. In the Service Mode, select DAC Sub-Contrast
Adjustment (B3) and adjust for 2.5Vp-p ±0.1V from
white level to black level on video waveform (see
video waveforms detail, Fig. 24).
White
Yellow
Cyan
2.5V ±0.1V
p-p
1V ±0.5V
p-p
Figure 24. TP35 waveform
2. Following adjustments, set Service Registers to
original values (Preparation step 2).
3. Turn the set Off. Remove all connections from
chassis.
Green
Magenta
Red
Blue
Black
SYNC
TIP

Sub-Brightness

Service DAC (B2)
Due the characteristics of this chassis, Sub-Brightness
adjustment is no required. To obtain a good brightness
level in the picture, set the Service Register to the
default level: 127.
Perform "Final Sub-brightness adjustment" only if
prefer different level of brightness in the picture.

Tint/Color Adjustment

Service DACs (B1) (B0)
Preparation:
1. Apply a rainbow color bar signal.
2. Preset the following controls:
• Brightness . . . . . . . . Min.
• Color . . . . . . . . . . . .Center.
• Tint. . . . . . . . . . . . . .Center.
• Picture . . . . . . . . . . .Max.
• Sharpness . . . . . . . . Min.
• Gamma S5 . . . . . . . 15
• ACL OFF CA . . . . . .00
3. Connect the oscilloscope probe between TP37
(C-Board) and cold GND (
:
Procedure
1. In the Service Mode, select DAC B1, Sub-Tint
Adjustment. Adjust until the waveform measured is
as the one shown in Fig. 25.
A to B = 1 Unit
A to B = 1 unit
A to C = 1 Unit
B to C = 2 units
Figure 25. TP37 waveform
2. Connect the oscilloscope to TP35 (C-Board).
3. Select DAC Sub-Color Adjustment (B0) and adjust
for peak to peak amplitude to be 0.8Vp-p ±0.05V
as shown in Fig.26.
1 2 3 4 5 6
Figure 26. TTP35 waveform
4. Following adjustments, set Service Registers to
original values (Preparation step 2).
5. Turn off the set. Remove all connections from
chassis.
- 27 -
).
A
B
C
1 2 3 10
4 5 6 7 8 9
0 .8 V p-p±0 .0 5 V
7 8 9 10