Service Adjustments; (Electronic Control); Sub-Brightness; Sub-Contrast - Panasonic CT-27D10B Service Manual

Service Adjustments (Electronic Controls)

Sub-Brightness

Serviceman DAC Adjustment (B2)
Adjustment of this control is important for setting proper
operation of customer brightness and picture controls.
This adjustment must be made after Sub-Contrast or
Color Temperature adjustments are made. Do not
adjust SCREEN after the Sub-Brightness is set.
Preparation:
Apply a color bar signal wit 100 IRE white and 7.5
IRE black. (Switch Color to "OFF" on the signal
generator.) Operate the Receiver for a minimum of
10 minutes prior to performing this adjustment.
Procedure:
In the Serviceman Mode for making electronic
adjustments, select the DAC adjustment (B2) and
adjust until the black starts to look gray. Then
decrease the level to the point where gray turns
to black.
Note: You may set the accurate value following the
Preparation steps and the Procedure step No.
2 of the Sub-Contrast adjustment described
below.

Sub-Contrast

Serviceman DAC Adjustment (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.
• Color . . . . . . . . . . . . Min.
• Picture . . . . . . . . . . Max.
• Sharpness . . . . . . . Center.
3. Connect the oscilloscope to TP47R. Set the scope
time base to 20µs (horizontal).
4. Connect a jumper from TPD2 to ground (
White
Yellow
Cyan
2.0V ±0.1V
p-p
1.5V - 1.9V
p-p
Figure 19. TP47G waveform
)..
Green
Magenta
Red
Blue
Black
SYNC
TIP
Procedure:
1. In the Serviceman Mode, select DAC Sub-
Brightness Adjustment (B2) and adjust for 1.5-
1.9Vp-p between blanking and 7.5 IRE level. (See
video waveforms detail, Fig. 19)
2. In the Serviceman
adjustments, select DAC Sub-Contrast Adjustment
(B3) and adjust for 2.0Vp-p ±0.1V white level to
black level on video waveform (see video
waveforms detail, Fig. 19).
3. Remove the jumper (Preparation step 4).

Tint/Color Adjustment

Serviceman DAC Adjustment (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.
3. Connect the oscilloscope to TP47B (A-Board).
4. Connect a jumper from TPD2 to GND (
5. Change the value of DAC S3 from 1 to 0.
Procedure:
1. In the Serviceman Mode for making electronic
adjustments, select DAC Sub-Tint Adjustment
(B1). Adjust until the waveform measured is as the
one shown in Fig. 20.
TP47B (A-Board)
A to B = 1 unit
B to C = 2 units
Figure 20. TP47B waveform
2. Connect the oscilloscope to TP47G (A-Board).
3. Select DAC Sub-Color Adjustment (B0) and adjust
for peak to peak amplitude to be 0.65Vp-p ±0.05V
for 27" models as shown in Fig. 21.
TP47G (A-Board)
1 2 3 4 5 6
Figure 21. TP47G waveform
4. Remove the jumpers (Preparation steps 4 & 5).
- 24 -
Mode for electronic
).
A
B
C
1 2 3 10
4 5 6 7 8 9
0.65Vp-p±0.05V
7 8 9 10