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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.
Initial static convergence.
2.
Setting the purity.
3.
Final static convergence.
When the CRT or the Yoke is Replaced
Place the yoke on the CRT neck (do not tighten
the clamp).
For a 2-piece assembly (Fig. 7):
Position purity/convergence assembly as shown and
tighten clamp snugly. Cut the hot-melt glue seal on
assembly and place like tabs of purity device together
at 12 o’clock to reduce its magnetic field effect.
Manually degauss the CRT.
Turn the Receiver ON and slide the deflection yoke
back and forth on the neck of the CRT. Stop at the
position that produces a near white, uniform raster.
For a 1-piece assembly (Fig. 8):
Place like tabs of purity devices together at 12 O’clock
to reduce any magnetic field effect. Manually degauss
the set.
Connect a Black/White pattern generator and tune the
receiver to the signal. Slide the deflection yoke & purity
ring assembly back and forth on the CRT neck. Stop at
a position that produces a near white signal.
Initial Center Static Convergence
Connect a dot/crosshatch generator to the Receiver
and tune in signal. Observe misconvergence at center
of the screen only.
Adjust the 4 pole magnet (center rings); separate tabs
and rotate to converge blue with red.
Adjust the 6 pole magnet (rear rings): separate tabs
and rotate to converge blue and red (magenta)
with green.
Note: Precise convergence at this point is
not important.
Purity Adjustment
When the Receiver is in the Servicemen Mode for
making electronic adjustments, press the Recall button
on the Remote Control to enter Purity Check. (See
Service Adjustments Electronic Controls.)
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.
For a 2-piece assembly (Fig. 7):
Loosen the deflection yoke clamp screw and move the
deflection yoke back as close to the purity magnet
as possible.
Adjust the front rings to set the vertical green raster
precisely at the center of the screen (Fig. 9).
Slowly move the deflection yoke forward until the best
overall green screen is displayed.
For a 1-piece assembly (Fig. 8):
Slowly move the deflection yoke and purity rings
assembly toward the CRT board and adjust the purity
magnet rings to set vertical green raster at center of
screen (see Fig. 9).
Gradually move the deflection yoke & purity rings
forward and adjust for best overall green screen.
Continue from here for either assemblies:
Tighten the deflection yoke clamp screw.
Press the Recall button on the Remote Control again
until the purity check (blue screen) and (red screen)
appear and observe that good purity is obtained on
each respective field.
Press the Recall button on the Remote Control again
until Purity check (white screen) appears. Observe the
screen for uniform white. If purity has not been
achieved, repeat the above procedure.
Final Convergence Procedure
(Fig. 10 through Fig. 12):
Note: Vertical size and focus adjustments must be
completed prior to performing the convergence
adjustment. Connect a dot pattern generator to the
Receiver. The Brightness level should not be higher
than necessary to obtain a clear pattern.
Converge the red and the blue dots at the center of the
screen by rotating the 4 pole (R with B) Static
Convergence Magnets.
Align The converged red/blue dots with the green dots
at the center of the screen by rotating the 6 pole (R/B
with G) Static Convergence Magnets. Melt wax with
soldering iron to reseal the magnets.
G3
G4
Purity Rings Centered
Over G3/G4 Gap
Figure 7.
Positioning of Purity/Convergence Assembly
(2-piece assembly)
Figure 8.
Positioning of Purity/Convergence
Assembly (1-piece assembly)
NOTES:
1. CRT warm up with white screen
(three guns activated) is needed
to stabilize the shadow mask
expansion.
2. Initial center static convergence
(roughly centers three gun
beams) is required in order to
perform purity adjustment.
Figure 9.
Green Raster Adjustment
Green Raster
