5-8
L3820EA
19. 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.
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. Loosen the screw on the Deflection Yoke Clamper
and pull the Deflection Yoke back away from the
screen. (See Fig. 6)
5. 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.
5,6)
6. Slowly push the Deflection Yoke toward bell of
CRT and set it where a uniform red field is
obtained.
7. Tighten the clamp screw on the Deflection Yoke.
20. VRS Adjustment
1. Connect Oscilloscope and get the cross hatch
pattern.
2. Adjust the two magnets for VRS adjustment like
the below figure so that the cross hatch pattern
becomes flat.
21. 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.
1. 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. 7)
2. Align red / blue with green dots at the center of the
screen by rotating (RB-G) C.P. Magnet. (See Fig.
8)
3. Paintlock the C.P. Magnets after adjustment.
Test Point
Adj. Point
Mode
Input
---
Deflection Yoke
Purity Magnet
---
Red Color
Tape
M. EQ.
Spec.
---
Pattern
Generator
See below
Figure
Fig. 5
GREEN
RED
BLUE
Test Point
Adj. Point
Mode
Input
---
C.P. Magnet (RB)
C.P. Magnet (RB-G)
Deflection Yoke
---
Dot Pattern
or
Crosshatch
Tape
M. EQ.
Spec.
---
Pattern Generator
See below
Figure
Fig. 6
Fig. 7
Fig. 8
DY WEDGE
DEFLECTION YOKE
C.P. MAGNET
RING LOCK
SCREW
SCREW
RB-G
RB
PURITY
CRT
COIL
COIL CLAMPER
C.P. MAGNET CLAMPER
B
G
R
R
G
B
C.P. MAGNET (RB)
RB
G
RB
G
C.B. MAGNET (RB-G)
