Philips 20MC4206/37, Service Manual

Page: 26 / 79

1-6-6 T8201EA
11. Cut-off Adjustment
Purpose: To adjust the beam current of R, G, B, and
screen voltage.
Symptom of Misadjustment: White color may be
reddish, greenish or bluish.
Note: Screen Control FBT --- Main CBA
FBT= Fly Back Transformer
Use service remote control unit
1. Degauss the CRT and allow the unit to operate for
20 minutes before starting the alignment.
2. Input the Black Raster Signal from RF Input.
3. Enter the Service mode. (See page 1-6-1.)
4. Press "VOL
p
" button on the service remote
control unit to enter "C/D" mode. Then press "1."
The display will momentarily show "CUT OFF R"
(R= Red.) Now there should be a horizontal line
across the center of the picture tube. If needed,
gradually turn the screen control on the flyback
clockwise until the horizontal line appears. Adjust
the Red Cut off by pressing the "CH.
o
/
p
"
buttons. Proceed to Step 5 when the Red Cut off
adjustment is done.
5. Press the "2" button. The display will momentarily
show "CUT OFF G" (G=Green.) Adjust the Green
Cut off by pressing the "CH.
o
/
p
" buttons.
Proceed to step 6 when the Green Cut off
adjustment is done.
6. Press the "3" button. The display will momentarily
show "CUT OFF B" (B=Blue.) Adjust the Blue cut
off by pressing the "CH.
o
/
p
" buttons. When
done with steps 4, 5 and 6 the horizontal line
should be pure white. If not, then attempt the Cut
off adjustment again.
The following 2 adjustments normally are not
attempted in the field. They should be done
only when replacing the CRT then adjust as a
preparation.
12. Purity Adjustment
Purpose: To obtain pure color.
Symptom of Misadjustment: If Color Purity Adjust-
ment is incorrect, large areas of color may not be
properly displayed.
* This becomes RED COLOR if the 7KEY is pressed
while in service mode.
1. Set the unit facing east.
2. Operate the unit for over 30 minutes before adjust-
ing.
3. Fully degauss the unit using an external degauss-
ing coil.
4. Set the unit to the AUX mode which is located
before CH2, then input a red raster from video in.
5. Loosen the screw on the Deflection Yoke Clamper
and pull the Deflection Yoke back away from the
screen. (See Fig. 7.)
6. Loosen the Ring Lock and adjust the Purity Mag-
nets so that a red field is obtained at the center of
the screen. Tighten Ring Lock. (See Fig. 6,7.)
7. Slowly push the Deflection Yoke toward the bell of
the CRT and set it where a uniform red field is
obtained.
8. Tighten the clamp screw on the Deflection Yoke.
Test Point Adj. Point Mode Input
---
Screen-Control
CH.
o
/
p
buttons
RF
Black Ras-
ter
Tape M. EQ. Spec.
---
Pattern
Generator
See Reference
Notes below.
Figure
PATTERN GENERATOR
Fig. 5
RF INPUT
Test point Adj. Point Mode Input
---
Deflection Yoke
Purity Magnet
--- *Red Color
Tape M. EQ. Spec.
--- Pattern Generator See below.
Figure
BLUE
GREEN
RED
Fig. 6