Sharp 29WF200, Service Manual

Page: 9 / 68

9
9-1
9-2
29WF200
29WF500
PURITY
ADJUSTMENT
No.
Adjusting point
Adjusting condition/procedure
W
aveform or others
PURITY
ADJ.
1
.
Select the green monocolour screen with re- mote controller
, and set the beam current of
1.7mA with the contrast control.
2
.
Degauss the CR
T
enough with the degausing coil.
For the adjustable magnetic field NOTE:
Horizontal = 0 V
ertical = 0.1
Adjustable magnetic field is shown in P8-1.
3.
The purity magnet must be previously set at the zero magnetic field, and the convergence must be adjusted to be rough. W
ith P-MG, adjust it to the center - rank
A.
4
.
Observe the points a, b as shown in Fig. 4-1 through the microscope. Move DY
fore and aft to set the landing at the
point. (rank
A)
5
.
If the a/b balance is poor
, compensate it to the
center "Rank AB".
6.
Aline it to zero, keeping the raster rotation in the east direction.
7.
T
ighten the deflection coil fastening screws.
»
T
ightening torque: 108
±
20 N (1
1
±
2 kgf)
8
.
Checking the CR
T
corner area, bond the mag-
netic sheet to set the landing at Rank
A
for com-
pensation. Note:
Apply the adjustment after aging with the beam current 1700
±
50
µ
A or more
for 30 minutes or more.
Note:
Select the service mode, and press the monocolour key of R/C for process,and the monocolour screen (green) will be selected.
1
a
b
A B A
90mm
90mm
B
A = B A = B
Rank "A"
(on the right of CRT)
Rank "A"
(on the left of CRT)
Fig. 4-1
Fig. 4-2
Fig. 4-3
*
Continuosly press the mono- colour key 1 second or more, and the monocolour mode will be selected without the service mode.
*
Even with
TEXT
key or "R/G/
Cy" key
, it can be directly
switched to each monocolour screen.
Monocolour
screen release
Monocolour
GREEN
screen
Monocolour
BLUE
screen
Monocolour
RED
screen
*
Adjustment for uniformity is mentioned in another content. Please refer to the following page.
*
Every push of the monocolour key
, changes the
screen as follows.
PURITY
ADJUSTMENT
(Continued)
No.
Adjusting point
Adjusting condition/procedure
W
aveform or others
Uniformity adjustment (T
o
perform after the purity and convergence adjustment.)
2
Before adjustment begin, Horizontal magnetic field = 0G V
ertical magnetic field = Each destination's adjust-
ment magnetic field. Make sure degauss it. (North direction Red uniformity) 1
.
Horizontal mf = Set to monocolour screen Red and adjust to + 0.25G.
2
.
Pay attention to the edge of CR
T
, if the landing is
poor
, adjust by attaching the compensation mag-
net at the back of the CR
T
. (Refer to Fig.5)
(South direction Red uniformity) 1
.
Horizontal mf = Set to monocolour screen Red and adjust to - 0.25G.
2
.
Pay attention to the edge of CR
T
, if the landing is
poor
, adjust by attaching the compensation mag-
net at the back of the CR
T
.
(The same method is applied for adjustment of monocolour screen Blue for blue uniformity
, and
changing both the magnetic field for North and South direction.) *
During the pasting of compensation magnet, use the crosshatch pattern. Make sure there is no blur or bend lines occur
.
If the blur or bend are serious, adjust the location of compensation magnet to make it better
.
(CR
T
surface)
(CR
T
back)
Miss landing
Compensation magnet
Fig. 5