Zenith C27C35T Series, Service Manual

Page: 29 / 63

CM152
3-3
XC - SERVICING
SERVICING (continued)
PRELIMINARY SETUP
1.Allow the receiver to warm up for 15 to 20 minutes.
2.Degauss the CRT.
3.Connect a crosshatch generator to the receiver and
“rough in” the static (center) convergence. Follow
the Convergence Procedure.
4.Adjust for best focus.
PURITY ADJUSTMENT
1.Purity tab positioning. Set the 2 pole purity tabs
together in the 3 or 9 o’clock positions and the 4-
and 6-pole purity tabs together in the 12 or 6 o’clock
positions.
2.Move yoke to the maximum forward funnel position.
3.Next, switch the crosshatch generator to a red field.
4.Pull the yoke toward the rear of the CRT neck, keeping
it centered, until a red raster is displayed.
5.If the red raster is not displayed as a pure red field,
adjust the 2-pole purity tabs until a pure field is
obtained.
6.Check for proper yoke tilt setting.
CONVERGENCE ADJUSTMENT
1.Release locking assembly.
2.Connect crosshatch generator to the receiver and
adjust static (center) convergence as follows:
a. Adjust the 4-pole static control by moving the
two tabs separately to converge the red and blue
lines horizontally. Move the two tabs together
around the neck of the CRT (in a 45° arc) from the
top-dead-center position to converge the red and
blue lines vertically.
b. After the 4-pole control has been adjusted to
superimpose the red and blue lines on top of one
another. Use the 6-pole static adjustment to place
the converged red and blue lines over the green
line. Move the two tabs together around the neck
of the CRT (in a 30° arc) from the top-dead-center
position to move the lines vertically. Adjusting the
two tabs separately will move the converged beam
to the left or right. Using a crosshatch generator
capable of producing individual fields, adjust the
generator to produce a red field. Use the purity
tabs to center a red stripe.
PURITY & CONVERGENCE SETUP PROCEDURE
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