Panasonic CT-1388YD, Service Manual

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Service adjustments (electronic controls)
Note: It is recommended to allow a 30 min. warm
up at highest bright (using white screen) before
perform any picture adjustment.
Sub-Contrast
Service DAC (B03)
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,
S05 . . . . . . 15
• ACL OFF C0A . . . . . 00
• Cut Off G C01 . . . . . 00
3. Connect the scope probe between TP35 (C-Board)
and cold ground (
).
Procedure:
1.
In the service mode, select DAC Sub-Contrast
adjustment
(B03) and adjust to obtain
2.3Vp-p ±0.1V for 13” models and 2.5Vp-p ±0.1V
for 20” and 27” models from white level to black
level on video waveform (see video waveforms
detail, see Fig. 23).
2. Following adjustments, set service registers to
original values (preparation step 2).
3. Turn the set off and remove all connections from
chassis.
Sub-Brightness
Service DAC (B02)
Due to 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 (B01) (B00)
Preparation:
1.
Apply a rainbow color bar signal.
2. Preset the following controls:
• Brightness . . . . . . . .Min.
• Color . . . . . . . . . . . .Center.
• Tint. . . . . . . . . . . . . .Center.
• Picture . . . . . . . . . . .Max.
• Sharpness . . . . . . . .Min.
• Gamma S05 . . . . . .15
• ACL OFF C0A . . . . .00
3. Connect the oscilloscope probe between TP37
(C-Board) and cold GND (
).
Procedure
:
1. In the service mode, select DAC B01, Sub-Tint
adjustment. Adjust until the waveform measured is
as below (see Fig. 24).
2. Connect the oscilloscope to TP35 (C-Board).
3. Select DAC sub-color adjustment (B00) and adjust
for peak to peak amplitude to be 0.7Vp-p ±0.05V
for 13” and 0.8Vp-p ±0.05V for 20” and 27” as
shown in see Fig. 25.
4. Following adjustments, set service registers to
original values (preparation step 2).
5. Turn off the set and remove all connections from
chassis.
Figure 24. TP35 waveform
2.3V
p-p
±0.1V (13”)
White
Yellow
Cyan
Green
Magenta
Red
Blue
Black
SYNC
TIP
7.5 IRE
2.5V
p-p
±0.1V (20” and 27”)
A to B = 1 unit
A
C
1 2 3 10
4 5 6 7 8 9
B
B to C = 2 units
Figure 25. TP37 waveform
A to B = 1 Unit
A to C = 1 Unit
1 2 3 4 5 6
7 8 9 10
Figure 26. TP35 waveform
0.7Vp-p±0.05V for
0.8Vp-p±0.05V for
20” & 27”
13”