Sharp 21GT-22, Service Manual

Page: 8 / 40

8-1
8-2
8
21GT-22
1
.
Call " SUB-BRI" in service mode. (Receive Cross- hatch pattern with 5 black level windows)
2
.
Adjust the " SUB BRIGHT " bus data in order that the line 1and 2 have the same darkness wherelse line 3 is one step (data) brighter than line 2. Finally data minus 1 to make line 1, 2, and 3 are in same level (darkness).
Remark 1
.
Before CRT cutoff adjustment, SUB-BRIGHT
, DRI-
RS/R
W
/RC, DRI-GS/GW/GC, DRI-BS/BW/BC,
CUT
-R and CUT
-G must be INITIAL
DA
T
A
.
2. CRT Cutoff adjustment must be done inside a dark
room.
1
.
Switch
TV to VIDEO mode,BLUE BACK OFF
, with
NO VIDEO signal.
2.
Press R/C to set Picture Normal condition.
3
.
First, of
f the screen by adjust screen variable resistor
.
*4. Next, checking
AKB circuit function by slowly increase
screen variable resistor until colour raster suddenly on and of
f (AKB start function).
5.
Then continue adjust until retrace line appear
.
6. Finally
, slowly decrease the screen variable resistor
until screen retrace line cut of
f (Not Raster)
Note :
Must confirm the
AKB function in set before continue
the next adjustment.
CRT CUT-OFF, BACKGROUND AND SUB-CONTRAST ADJUSTMENT
N
O
.
Adjustment
part
Adjusting procedure and conditions
W
aveform
and
others
1 2
SUB- BRIGHTNESS ADJUSTMENT (I
2
C BUS
CONTROL)
Line 3 is one step (data) brighter than line 2
CRT CUT
OFF
ADJUSTMENT (I
2
C BUS
CONTROL)
3
WHITE BALANCE SER
VICE
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
TP602 (-)
TP603 (+).
4.
Check Beam current should be around 1
100
µ
A.
5
.
Set it to service mode and adjust the DRI-GS, & DRI- BS data to have a colour temperature of 12300
°
K (
white ). * Note .
6.
Receive "WHITE" pattern, WITH BURST signal, and set BRIGHTNESS
Y
by generator
, to **10 cd/m2
(MINOL
T
A
CA-100) by reducing LUMINA
TE
Y
sig-
nal.
7
.
Adjust "CUT
-R" & "CUT
-G" to get desired colour tem-
perature #.
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 warm-
ing up the unit for 30 minutes or longer with a beam current over 700
µ
A.
*
Adjust DRI-GC/GW
, DRI-BC/BW as following DA
T
A
,
after finishing DRI-BS and DRI-GS DA
T
A
ADJUST
-
MENT
.
DRI-R
W = 32 (FIXED), DRI-RS = 32 (FIXED)
DRI-BC = "DRI-BS" (For 12300
°
K Condition)
# 12300
°
K
X
: 0.272
Y : 0.275
(MINOL
T
A
COLOUR
ANAL
YZER CA-
100) *Note:
Above Data can be UP/DOWN
by V
olume key
.
LOW
HIGH
21"
10cd/m2
120cd/m2
4
Max. beam check
1.
Receive the "Monoscope Pattern" signal.
2.
Press R/C to set Picture NORMAL condition.
3.
Connect the DC miliammeter between TP603 (+) & TP602 (–). (Full Scale: 3 mA Range)
4.
Beam current must be within
1100
±
100
µ
A.
1 2 3 4 5
t
3.2Vdc 0
*Alternative Procedure (1) Step (1), (2), (3) and (4) are same
as beside procedure.
(2)
Then continue adjust until retrace
line appear and make sure the col- our appear whether red, green or biue.
(3) Connect the oscilloscope to related
test points as below which is based on colour appear at (2)
RED =
TP47R,
GREEN =TP47G, BLUE =
TP47B
(4)
Then adjust Screen VR until the tip
of signal reach 3.2Vdc.
1 2 3 4 5
1
2
* 12300
°
K DRI-GW="DRI-GS"-7
DRI-BW="DRI-BS"-7 DRI-GC="DRI-GS"-7 DRI-RC=25
HORIZONTAL AND VERTICAL DEFLECTION LOOP ADJUSTMENT
N
O
.
Adjustment
part
Adjusting procedure and conditions
W
aveform
and
others
1 2 3 4 5 6
V
-SLOPE (I
2
C
BUS CON- TROL) V
-SHIFT
-50
(I
2
C BUS
CONTROL) V
-AMP50
(I
2
C BUS
CONTROL) H-SHIFT (50) (H-CENTER) S-CORREC- TION (I
2
C BUS
CONTROL) SUB- SHARPNESS
1.
Receive Monoscope Pattern Signal.
2.
Call the "V
-LIN" mode.
3.
Increase or decrease "V
-LIN" by V
olume key
till the horizontal line in the center of monoscope is just at the position where the blanking starts.
1.
Call the "V
-CENT" mode.
2. Increase or decrease "V
-CENT" by V
olume key
till the picture is centered.
1.
Call the "V
-AMP" mode.
2
.
Increase or decrease "V -
AMP" by V
olume
key to set overscan of 9.5% typical. Adjustment Spec 9.5% range +1% -0%.
1.
Call the "H-CENT" mode.
2
.
Increase or decrease "H-CENT" by V
olume key
to center the picture horizontal.
1. SET
DA
T
A
T
O
20
* Check the E-5 CH Monoscope Pattern then re-
adjust V
-Slope, V
-Shift and V
-Amp to makesure
adjustment is in acceptable Ring-Shaped.
1. SET
DA
T
A
T
O
20
PAL CHROMA ADJUSTMENT
N
O
.
Adjustment
part
Adjusting procedure and conditions
W
aveform
and
others
1
SUB COLOUR (I
2
C BUS
CONTROL)
1.
Receive the "P
AL
Color Bar" signal.
2.
Press R/C to set Picture Normal condition.
3.
Connect the oscilloscope to Red cathode(D882 Chathode) for 21" (Normal Neck).
»
Range
: 20 V/div
. (AC)
(Using
10:1
probe)
»
Sweep time
:
10
µ
sec/div
.
4
.
Using the R/C call "SUB COL" in SERVICE mode.
Adjust SUB COLOUR bus data, so that
the 75% White & Red portions of P
A
L
Color
Bar be at the same level shown as
Fig. 1-1
.
5
.
Add another 6 steps up into the value of SUB- COL obtained in 4.
6.
Clear the SER
VICE Mode.
1
Focus
1.
Receive the "Monoscope Pattern" signal.
2.
Press R/C to set Picture NORMAL condition.
3.
Adjust the focus control to get the best focus- ing.
Fig. 1-1
Cy
G
B
W
Y
100%W
75%
Mg
R