Service manual

SERVICING
3828VD0171F 3-5 DIGITAL CL - SERVICING
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
BR
R
B
R
R
OR
OR
OR
B
B
R
R
OR
CRT Rin
g
Location Purit
y
A
d
j
ust Tabs Beam Movement
for Convergence
PURITY & CONVERGENCE SETUP PROCEDURE
PRELIMINARY SETUP
1. Allow the receiver to warm up for 15 to 20 minutes.
2. Degauss the CRT.
3. Connect a cross hatch generator to the receiver and
“rough in” the static (center) convergence. Follow
the Convergence Procedure.
4. Adjust for the 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, keep
ing it centered, until a red raster is displayed.
5. If the red raster is not displayed as a pure red field,
adjusts 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 to
gether around the neck of the CRT (in a 45º
arc) from the top-dead-center position to con
verge the red and blue lines vertically.
b. After the 4-pole control has been adjusted to su
perimpose 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 30º arc) from
the top-dead-center posotion 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 pro
ducing individual fields, adjust the generator
to produce a red field. Use the purity tabs to
center a red stripe.