Purity And Convergence Procedures - Panasonic CT-20SX10B Service Manual

Purity and Convergence Procedure
Adjustment is necessary only if the CRT or the
deflection yoke is replaced or if the setting was
disturbed. The complete procedure consists of:
1. Vertical Raster Shift Adjustment.
2. Initial static convergence.
3. Setting the purity.
4. Final static convergence.
When the CRT or the Yoke is Replaced
Place the yoke on the CRT neck (do not tighten
the clamp).
Position purity/convergence assembly as shown and
tighten clamp snugly. Remove the hot-melt glue seal
on assembly and position like tabs of purity device
together at 12 o'clock to reduce its magnetic field
effect.
Place the vertical raster shift tabs at 3 o'clock (90
the purity and convergence tabs, see Fig. 10 and
Fig. 11 )
R&B Convergence Rings
R&B&G Convergence Rings
G3
Purity Rings
Figure 10.
Positioning of Purity/Convergence
Assembly
R&B&G Convergence Rings
R&B Convergence Rings
Vertical Raster
Purity Rings
Figure 11.
Positioning of Purity/Convergence
Assembly
Turn the Receiver ON. Operate the Receiver for 60
minutes using the first Purity Check field (white screen)
to stabilize the CRT.
Fully degauss the Receiver by using an external
degaussing coil.
Slide the deflection yoke back and forth on the neck of
the CRT until it produces a near white, uniform raster.
o
from
Vertical Raster Shift Ring
Over G3/G4 Gap
G4
o
90
Shift Rings
Vertical Raster Shift Adjustment
Apply a green pattern with a horizontal line, adjust the
Deflection Yoke so that has no tilt, then secure it.
Adjust center line of the pattern with the mechanical
center of the CRT, this center is determined by two
marks at the side edges of the screen. To adjust the
line, once the vertical raster shift tabs are place at 3
o'clock to reduce its magnetic field effect (see Fig. 10
and Fig. 11) open the tabs the same angle from the
center, until the center line of the pattern becomes a
straight line, centered with the marks of the CRT. (see
Fig. 12)
Center line
from pattern
Mechanical
Center Marks
Figure 12.
Vertical Raster Shift Adjustment
Initial Center Static Convergence
Connect a dot/cross hatch generator to the Receiver
and tune in a signal. Observe misconvergence at
center of the screen only.
Adjust the R&B pole magnets; by separating tabs and
rotating to converge blue with red.
Adjust the R&B and R&B&G pole magnets: by
separating tabs and rotating to converge blue and red
(magenta) with green.
Note: Precise convergence
not important.
Purity Adjustment
When the Receiver is in the Serviceman Mode for
making electronic adjustments, press the Recall button
on the Remote Control to enter Purity Check. (See the
Service Adjustments
procedure).
Operate the Receiver for 60 minutes using the first
Purity Check field (white screen) to stabilize the CRT.
Fully degauss the Receiver by using an external
degaussing coil.
Press the Recall button on the Remote Control again
until the Purity Check (green screen) appears.
Loosen the deflection yoke clamp screw and move the
deflection yoke back as close to the purity magnet
as possible.
- 15 -
Open the
same angle
from center
Vertical Raster Shift tabs
at this point
Electronic Controls
is