Toshiba 27a50 Service Manual page 7

CONVERGENCE ADJUSTMENTS
NOTE: Before attempting any convergence adjustments,
the receiver should be operated for at least fifteen
minutes.
CENTER CONVERGENCE ADJUSTMENT
1. Display built-in cross-dot pattern using the TEST SIG-
NAL SELECTION function.
2. Adjust the BRIGHTNESS and CONTRAST Controls
for well defined pattern.
3. Loosen the tightening ring and adjust two tabs of the
4-Pole Magnets to change the angle between them
(See figure 4.) and superimpose red and blue vertical
lines in the center area of the picture screen.
(See figure 3.)
4. Turn the both tabs at the same time keeping the con-
stant angle to superimpose red and blue horizontal
lines at the centre of the screen. (See figure 3.)
5. Adjust two tabs of 6-Pole Magnets to superimpose red/
blue line with green one. Adjusting the angle affects
the vertical lines and rotating both magnets affects the
horizontal lines.
6. Repeat adjustments 3, 4, 5 keeping in mind red, green
and blue movement, because 4-Pole Magnets and 6-
Pole magnets interact and make dot movement com-
plex.
7. After completing the "CENTER CONVERGENCE AD-
JUSTMENT", tighten the tightening ring to fix the mag-
nets.
BLU RED
BLU RED/BLUE
RED
4-POLE MAGNETS
MOVEMENT
Center Convergence by Convergence Magnets
Figure 3.
Xv COIL ADJUSTMENT
Adjust the Xv coil (on the deflection yoke) to correct
misconvergence at both sides on screen.
Use a hexagonal tip stick (plastic) to adjust the core of
coil.
Clockwise Adjustment Counterclockwise Adjustment
Clockwise Adjustment Counterclockwise Adjustment
R B
B R
X v Cross Pattern View
X Cross Pattern View
V
RED/BLUE GRN
GRN
6-POLE MAGNETS
MOVEMENT
B R
R B
– 7 –
6-POLE
MAGNETS
PURITY
MAGNETS
PURITY/CONVERGENCE
MAGNETS
ADJUST THE ANGLE
(VERTICAL LINES)
FIXED
ROTATE TWO TABS
AT THE SAME TIME
(HORIZONTAL LINES)
ADJUSTMENT OF MAGNETS
Figure 4.
SCREEN-CORNER CONVERGENCE
When the misconvergence is still evident on corners even
though the above adjustment is done, use the ferrite sheet
(Part No. 23993622) to correct misconvergence.
1. Put ferrite sheets into the space under the yoke.
Decide such position that misconvergence becomes
minimum, watching picture screen. (See figure below.)
2. Remove cover paper of ferrite sheet to stick it in the
place on the tube. Put adhesive tapes on ferrite sheets
to fix.
Ferrite
Sheets
A
For correcting misconvergence
on the position A
4-POLE
MAGNETS
Ferrite
Sheets