Hitachi 27GX01B-501 Service Manual page 16

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.
For a 2-piece assembly (see Fig. 4):
Loosen the deflection yoke clamp screw and move the
deflection yoke back as close to the purity magnet
as possible.
Adjust the Purity rings to set the vertical green raster
precisely at the center of the screen (see Fig. 9).
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
beams) is required in order to
perform purity adjustment.
Figure 9. Green Raster Adjustment
Slowly move the deflection yoke forward until the best
overall green screen is displayed.
For a 1-piece assembly (see Fig. 7):
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.
at this point
Electronic Controls
gun
Green Raster
Final Convergence Procedure
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 R&B pole Static Convergence
Magnets.
is
Align The converged red/blue dots with the green dots
at the center of the screen by rotating the R&B&G pole
Static Convergence Magnets. Melt wax with soldering
iron to reseal the magnets.
Slightly tilt vertically and horizontally (do not rotate) the
deflection yoke to obtain a good overall convergence.
If convergence is not reached at the edges, insert
permalloy (see following section) from the DY corners
to achieve proper convergence. Recheck for purity and
readjust if necessary.
After vertical adjustment of the yoke, insert wedge at 11
o'clock position,
tilt adjustment.
Secure the deflection yoke by inserting two side
wedges at 3 and 7 o'clock positions.
Apply adhesive between tab (thin portion) of wedge
and CRT and place tape over the tab to secure to
the CRT.
Permalloy Convergence Corrector Strip
(Part No. 0FMK014ZZ)
This strip is used in some sets to match the yoke and
CRT for optimum convergence. If the yoke or CRT is
replaced, the strip may not be required.
First converge the set without the strip and observe
the corners.
If correction is needed:
1. Place strip between CRT and yoke, in quadrant
needing correction. Slowly move it around for
desired results.
2. Press adhesive tightly to the CRT and secure
with tape.
- 16 -
(see Fig. 10
then make the horizontal