14- Crt Cut Off Calibration - Panasonic TC-20KL04A Service Manual

ADJUSTMENTS
ITEM / PREPARATION
11- WHITE QUALITY CALIBRATION
PREPARATION:
1. Adjust the HELMHOLTZ device to local magnetic field. Ho-
-4
rizontal: 0 ± 0.003 x 10 T
2. Receive a white purity pattern.
3. Adjust CONTRAST and BRIGHT controls to maximum.
4. Previously adjust the CONVERGENCE.
5. Fully degauss the CRT by using an external degaussing
coil.
12- CONVERGENCE CALIBRATION
1. Adjust the HELMHOLTZ device to local magnetic field.
2. Receive a crosshatch pattern.
3. Adjust IMAGE menu to DINÂMIC NORMAL and the DAC
BRIGHT control for the crosshatch pattern to be gray.
4. Remove the DY wedges and slightly tilt the deflection
yoke to the vertically and horizontally to obtain the good
overall convergence.
5. If purity error is found, repeat "Color Purity" adjustment
4 poles magnets (G-3)
6 poles magnets (R-G-B)
13- CRT CUT OFF CALIBRATION
1. Supply a WINDOWS signal.
2. Position DACs with the data below:
BRT —> 50H
S-BRT —> 31H
RGB CONTRAST —> [A]
SUB-CONTRAST —> 21H
R,G,B DRIVE —> 31H
R,G CUT —> 31H
20KL [A] = 7DAC
29KL [A] = 11DAC
PROCEDURE
CALIBRATION:
1. Adjust the magnetic field in 0.4x10-4T (400 mG), and check
the white quality with the CRT turned to EAST and to WEST.
2. Receive a red pattern, adjust the COLOR control to
maximum and confirm the purity adjustment.
3. If purity error is found at the CRT corners, apply magnetic
tapes to correct it, fully degauss the CRT again and repeat
the steps 1 and 2. Don't use this magnetic tapes on the
internal side of the yoke.
4. Receive a white purity pattern, adjust the COLOR control
to minimum and confirm the purity adjustment.
CALIBRATION
Static convergence calibration
l) Assure that the magnets are positioned according to
illustration 1.
ll) Adjust the 4 poles magnets to align the R and B
CENTRAL DOTS and adjust the 6 poles magnets to
align both DOTS with G.
lll) After adjustment above, assure that the magnets are
sealed, through the application of white glue.
Note:
The electron beams are moved rotationally when the
static convergence magnets are rotated.
The reduction of rotational beams differ depending of
the two magnets angle. Therefore, it is necessary to
repeat the magnets calibrations sometimes, until
obtaining a good alignment.
CALIBRATION:
1. Press "5" (AKB OFF) and confirm that OSD becomes
blue.
2. Connect the oscilloscope in TPL5 and adjust BRT to
obtain 130V as in the Fig. 1 below.
3. Adjust the SCREEN to obtain a horizontal fine line in the
screen center.
Y = 1.0 +1.0 -0.5
4. Press "5" (AKB ON) and confirm that OSD becomes
white.
- 15 -
TC-20KL04A / TC-20KL04P / TC-29KL04A / TC-29KL04P
Fig. 1