CM151
3-4
CA - SERVICING
SERVICE ADJUSTMENTS (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-pole and 6-pole purity
tabs together in the 12 or 6 o’clock positions.
2. Move yoke to the maximum forward funnel position.
3. Now 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
Yoke's Glass Cloth Tape
Wedges' Adhesive Tape (3)
Rubber Wedges (3)
Deflection Yoke
Purity & Convergence
Magnet Assembly Unit
6 Pole
Purity Magnet
4 Pole
Ring
Pairs
6 Pole
Convergence
R&B over G
Convergence
R over B
4 Pole
Rotation direction
of Both Tabs
Opposite
Opposite
Same
Same
Movement of Red
and Blue Beams
B
B
B
R
R
B
B
R
R
B
R
R
OR
OR
OR
B
B
R
R
OR
CRT Ring Location Purity
Adjust Tabs Beam Movement
for Convergence