Purity Adjustment; Convergence Adjustment - Sharp 21YF30 Service Manual

PURITY ADJUSTMENT

No. Adjustment point Adjustment procedure/conditions
1 PURITY ADJ. 1. Receive the GREEN-ONLY signal. Adjust the
beam current to ~700 µ
2. Degauss the CRT enough with the degausing coil.
Note: Follow the Job Instruction Sheet to adjust
the magnetic field.
Vertical Bv: +0.010 mT (0.10 gauss)
Horizontal Bh: +0.040 mT (0.40 gauss)
3. Maintain the purity magnet at the zero magnetic
field and keep the static convergence roughly
adjusted.
4. Observe the points a, b as shown in Fig. 1-1
through the microscope. Adjust the landings to A
rank requirement.
5. Orient the raster rotation to 0 eastward.
6. Tighten up the deflection coil screws.
» Tightening torque: 108 N ± 20 N (11 kgf ± 2 kgf)
7. Make sure the CRT corners landing meet the A
rank requirements. If not, stick the magnet sheet
to correct it.
Note: This adjustment must be done after warm-
ing up the unit for 30 minutes or longer with
a beam current over 700 µA.
Note: Set the service mode by JA304 & JA307
(short) then press factory process R/C RGB
key to change to RGB mono colour mode.
* For the following colours press R/C RGB(Hex 7E)
key to change.
GREEN BLUE
ONLY ONLY
Signal-colour
screen cleared
Waveform and others
a
Fig. 1-1
30mm 30mm
A
B
Fig. 1-2
Rank "A"
(on the right of CRT)
A
RED
ONLY
B
Fig. 1-3
Rank "A"
(on the left of CRT)
* Press R/C RGB key for 1 sec-
ond in NORMAL MODE, the
colour will change to RGB
mono colour mode.
8-1

CONVERGENCE ADJUSTMENT

No. Adjustment point Adjustment procedure/conditions
1 1. Receive the "Crosshatch Pattern" signal.
CONVERGENCE
2. Using the remote controller, call NORMAL mode.
ADJ.
( To be done
b
Static convergence
after the purity
1. Turn the 4-pole magnet to a proper opening an-
adjustment.)
gle in order to superpose the blue and red col-
ours.
2. Turn the 6-pole magnet to a proper opening an-
gle in order to superpose the green colour over
the blue and red colours.
Dynamic convergence
1. Adjust the convergence on the fringes of the
screen in the following steps.
a) Fig. a: Drive the wedge at point "a" and swing
the deflection coil upward.
b) Fig. b: Drive the wedge at point "b" and "c" and
swing the deflection coil downward.
c) Fig. c: Drive the "c" wedge deeper and swing
A = B
the deflection coil rightward.
d) Fig. d: Drive the "b" wedge deeper and swing
the deflection coil leftward.
2. Fix all the wedges on the CRT and apply glass
tape over them.
3. Apply lacquer to the deflection yoke lock screw,
magnet unit (purity, 4-pole, 6-pole magnets) and
magnet unit lock screw.
Finally received the Red-only and Blue-only sig-
nals to make sure there is no other colours on the
screen.
A = B
Purity magnet
Waveform and others
B
G
R
R
G
B
4-pole magnet
6-pole magnet
About
CRT neck
100Deg
Lacquer
Wedge
"b"
Lacquer 20mm
8-2
BGR
B
G
R
Fig. a
RGB
R
G
B
Fig. b
RGB
Fig. c
BGR
Fig. d
Wedge "a"
About
100Deg
Wedge
"c"