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SERVICING
PURITY & CONVERGENCE
SET-UP PROCEDURE
FOR COTY CRTs
PRELIMINARY
SET-UP
1. Allow the receiver to warm up for 15 to 20 minutes.
2. Degauss the receiver.
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. Switch the crosshatch generator to a red field.
4. Pull the yoke toward the rear of the CRT neck until the
centered pure 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.
PURITY &CONVERGENCE
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 generator to
produce a red field. Use the purity tabs to
center a red stripe.
CRT Ring Location Purity
Adjust Tabs Beam Movement
for Convergence
Ring
Pairs
Rotation direction
Movement
of Red
of both tabs
and Blue beams
6 Pole
Opposite
43
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8
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