Philips MAGNAVOX 20MC4304 Service Manual page 212

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.
16. Purity Adjustment
Purpose: To obtain pure color.
Symptom of Misadjustment: If Color Purity
Adjustment is incorrect, large areas of color may not
be properly displayed.
Test Point Adj. Point
Deflection Yoke
---
Purity Magnet
Tape M. EQ.
--- Pattern Generator
GREEN
* This becomes RED COLOR if the [7] button is
pressed while in service mode.
1. Set the unit facing east.
2. Operate the unit for over 30 minutes before
adjusting.
3. Fully degauss the unit using an external
degaussing 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. 9.)
6. Loosen the Ring Lock and adjust the Purity
Magnets so that a red field is obtained at the
center of the screen. Tighten Ring Lock. (See Fig.
8, 9.)
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.
Mode Input
--- *Red Color
Spec.
See below
Figure
RED BLUE
Fig. 8
17. Convergence Adjustment
Purpose: To obtain proper convergence of red, green
and blue beams.
Symptom of Misadjustment: If Convergence
Adjustment is incorrect, the edge of white letters may
have color edges.
Test Point Adj. Point
C.P. Magnet (RB)
--- C.P. Magnet (RB-G)
Deflection Yoke
Tape
--- Pattern Generator
CRT
DY WEDGE
DEFLECTION YOKE
C.P. MAGNET (RB)
R
B
C.B. MAGNET (RB-G)
RB
G
1. Set the unit to the AUX mode which is located
before CH2 then input a dot or crosshatch pattern.
2. Loosen the Ring Lock and align red with blue dots
or crosshatch at the center of the screen by
rotating (RB) C.P. Magnets. (See Fig. 10.)
3. Align red / blue with green dots at the center of the
screen by rotating (RB-G) C.P. Magnet.
(See Fig. 11.)
4. Fix the C.P. Magnets by tightening the Ring Lock.
5. Remove the DY Wedges and slightly tilt the
Deflection Yoke horizontally and vertically to
obtain the best overall convergence.
6. Fix the Deflection Yoke by carefully inserting the
DY Wedges between CRT and Deflection Yoke.
1-7-9
Mode
Dot Pattern
---
Crosshatch
M. EQ. Spec.
See below
Figure
RB RB-G
COIL PURITY
SCREW
RING LOCK
SCREW
C.P. MAGNET CLAMPER
C.P. MAGNET
COIL CLAMPER
G
RB
Input
or
Fig. 9
R
G
B
Fig. 10
G
Fig. 11
T1102EA