Sharp CX48K4, Service Manual

8

8-1

8-2

CX48K4

RGB

BGR

R
G
B

R
G
B

B
G
R

B
G
R

RGB

BGR

Lacquer

Wedge "a"

Wedge
"b"

Wedge
"c"

About
100

°

About
100

°

4-pole magnet

6-pole magnet

CRT neck

Lacquer

Purity magnet

20mm

CONVERGENCE ADJUSTMENT

NO. Adjustment part

Adjusting procedure and conditions

Waveform and others

1

CONVERGENCE
ADJ.
(To be done
after the purity
adjustment.)

1. Receive the "Crosshatch Pattern" signal.
2. Using the remote controller, call NORMAL

mode.

Static convergence
1. Turn the 4-pole magnet to a proper opening

angle in order to superpose the blue and red
colours.

2. Turn the 6-pole magnet to a proper opening

angle 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. 5-1: Drive the wedge at point "a" and

swing the deflection coil upward.

b) Fig. 5-2: Drive the wedge at points "b"

and "c" and swing the deflection coil
downward.

c) Fig. 5-3: Drive the "c" wedge deeper and

swing the deflection coil rightward.

d) Fig. 5-4: 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
signals to make sure there is no other colours
on the screen.

Fig. 5-2

Fig. 5-1

Fig. 5-3

Fig. 5-4

Fig. 5-5

Fig. 5-6

1. Call "SUB-BRI" in service mode. (Receive

Crosshatch pattern with 5 black level windows)

2. Adjust the "SUB BRIGHT" bus data in order

that the line 1, 2 and 3 have the same darkness
wherelse line 4 is slightly brighter than line 1,
2 and 3 and finally line 5 will be the brighter
than line 4.

1. Switch TV to VIDEO mode, BLUE BACK OFF

with NO VIDEO signal.

2. Press R/C to set Picture Normal condition.
3. Connect the oscilloscope to Red OUT from

IC801.(TP852)

Range

: 1 V/Div (DC)

Sweep

: 5 msec/Div

4. Adjust SCREEN VR, so that the tip of signal

reach 3.0 +0.1 Vdc.

CRT CUT-OFF, BACKGROUND AND SUB-CONTRAST ADJUSTMENT

NO. Adjustment part

Adjusting procedure and conditions

Waveform and others

1

2

SUB-
BRIGHTNESS
ADJUSMENT
(I

2

C BUS

CONTROL)

1, 2 and 3 are in same black level.

CRT CUTOFF
ADJUSTMENT
(I

2

C BUS

CONTROL)

Fig. 6

3

WHITE
BALANCE
SERVICE
MODE ADJ.
(I

2

C BUS

CONTROL)

1. Receive the "WHITE" Pattern with BURST

signal.

2. Press R/C to set Picture NORMAL condition.
3. Connect the DC miliammeter between the

TP602 (-) and TP603 (+).

4. Check Beam current should be around 1,100 µA.
5. Set it to service mode and adjust the " WPG"

(White Point-G), "WPB" (White Point-B) data
to have a colour temperature of 12,300°K
(white). * Note .

6. Receive "White" pattern, with BURST Signal, and

set Brightness Y by generator, to ** 10 cd/m

2

(Minolta CA-100) by reducing Luminate Y signal.

7. Adjust "CUT-R" & "CUT-G" to get 12,300°K. Then

go back normal mode (High Bright)** to check
colour temperature. If out of range, back to (1).

Note: This adjustment must be  done after

warming up the unit for 30 minutes
or longer with a beam current over
700µA.

* Adjust DRI-GC/GW, DR-BC/BW as following

data, after finishing DRI-GS and DRI-BS:

DRI-GC=DRI-GW="DRI-GS"-7: DRI-BW="DRI-BS"-7:
DRI-RC=25: DRI-BC=DRI-BS: DRI-RW=32

** Low=10cd/m

2

: High=120cd/m

2

* 12,300

°

K

X : 0.272
Y : 0.275

(MINOLTA COLOUR ANALYZER
CA-100)
*Note: Above Data can be UP/

DOWN by Volume key.

4

Maximum
beam check

1. Receive the "Monoscope Pattern" signal.
2. Press R/C to set Picture NORMAL condition.
3. Connect the DC miliammeter between TP603

(+) and TP602 (–).
(Full Scale: 3 mA Range)

4. Beam current must be within 1,100 ±100 µA.

1 V

3.0Vdc

0

1 2 3 4 5

Fig. 7