Samsung CT721APX/XAX User manual

COLOR TELEVISION RECEIVER
Chassis : K56B
Model: CT721APX/XAX
COLOR TELEVISION RECEIVER CONTENTS
Precautions
Reference Information
Specifications and IC Data
Alignment and Adjustments
Troubleshooting
Exploded Views and Parts List
Electrical Parts List
Block Diagrams
Schematic Diagrams
1.
2.
3.
4.
5.
6.
7.
8.
9.

ELECTRONICS
©Samsung Electronics Co., Ltd. APR.2000
Printed in Korea
3K56B-7201

Alignment and Adjustments
Samsung Electronics 4-1
4. Alignment and Adjustments
4-1 Preadjustment
1. Alignment should be done only when
absolutely necessary.
2. Use only the specified test equipment
3. Correct impedance matching is essential.
4. Insertion markers from the marker generator
must not be allowed to distort the response.
Excessive signal from a sweep generator can
cause overload.
5. Connect the receiver only to an AC source
with voltage and frequency only as specified
on the back-cover nameplate.
6. Do not attempt to connect or disconnect any
wires while the receiver is ON. Make sure the
power cord is disconnected before replacing
any parts.
7. An isolation transformer must be used to help
protect against shock hazard.
4-2 Dynamic Focus Adjustment
1. A dynamic focus adjustment should be done
after replacing the CRT PCB, FBT or CRT.
2. Input a crosshatch pattern.
3. Enter Ò STANDARD Ò in video mode.
4. Turn the static focus VR fully clockwise
(maximum).
5. Turn the dynamic focus VR fully
counterclockwise (maximum).
6. Slowly turn the static focus VR
counterclockwise. Adjust until the
vertical line in the middle of the screen
has maximum clarity.
7. Slowly turn the dynamic focus VR (clockwise)
and adjust the 3rd horizontal line for
maximum clarity.
8. Repeat 4-7, if necessary.
STATIC FOCUS VR
DYNAMIC FOCUS VR
H
V
SCREEN
<FBT FOCUS PACK>

Alignment and Adjustments
4-2 Samsung Electronics
4-3 Sub-Contrast Adjustment
1. In power stand-by, set up the receiver by pressing the
MUTE ® 1 ® 8 ® 2 ® POWER ON buttons.
2. Input a crosshatch pattern using
Channel UP/DOWN.
3. Select ÒSCT Ò using the volume UP/DOWN buttons.
4. Adjust white horizontal line (1H) for using MENU or MUTE.
5. Press the ADD button.
4-4 Screen Adjustment
1. Input a Òlion-headÓ pattern.
2. Select ÒStandardÓ from the menu.
3. Check the Screen voltage at the CRT Drive PCB. Use a multimeter (1000:1 probe).
4. Set the Screen Voltage (on FBT) to 780 volts.
4-5 Sub-Brightness Adjustment
1. In power stand-by, set up the receiver by pressing
MUTE ® 1 ® 8 ® 2 ® POWER ON buttons.
2. Select ÒSBT Ò using Channel UP /DOWN.
3. Choose ÒSBT Ò with volume UP/DOWN.
4. Adjust MENU or MUTE until the 6th step on the right side of the screen disappears.
5. Press the ADD button.
4-6 I2C Adjustment
1. After replacing IC902 EEPROM, power ON the receiver
for 4 to 5 minutes after plugging in the EEPROM.
2. Set DATA LEVEL to 32. Note: M30 TOT adjustment is not done on this chassis.
3. After replacing IC902 EEPROM, input standard data for all items before adjusting GEOMETRIC,
WHITE BALANCE, B-CONTRAST, PIP CONTRAST, and SUB-BRIGHTNESS.

Alignment and Adjustments
Samsung Electronics 4-3
4-7 CUT-OFF Adjustment
■ Equipment: Multimeter and Scope
■ Input Signal: No Video Signal
1. Power on the TV set.
2. Enter the Video Mode by pressing the TV/VIDEO button on the remote control.(No Video Signal)
3. Adjust the FBT Screen VR (T444 : FTZ-29A012) using a multimeter or scope so that the DC voltage
of RK,GK, BK (CRT PCB) becomes 180V.
Note : If any variance is caused by the value of DCR (using a multimeter), recheck with the
adjusted screen.
4-8 White Balance Adjustment
■ Equipment : Color-Analyzer (CA-100)
■ Input Signal : Pattern signal (Toshiba pattern)
1. Select STANDARD from the menu.
2. Input an 100% White pattern.
3. In power stand-by, turn on the TV set by pressing the remote control buttons in the
following sequence: Mute ® 1 ® 8 ® 2 ® Power
4. Warm up the TV set at least for 30 minutes.
5. Input a Toshiba pattern signal.
6. Enter the picture mode in the Factory Mode.
-Adjust SCT so that Y (luminance) becomes 50 ft ±3.
-Use GA,BA to adjust High-Light (X : 262, Y : 264).
-Adjust SBT so that Y (luminance) becomes 1.6 ft ±5.
-Use GC,BC to adjust Low-Light (X : 250, Y : 250).
7. Adjust CA-100 so that the final adjustment value can be fixed.
8. Use the Channel Up/Down (▲/▼) buttons to move the cursor on the adjustment modes.
9. Use the Volume +/- buttons to change the adjustment value.
4-8-1 White Balance Coordinate
x y
H/L 262 264 ±3 50FL - CT-29A5PX
- CT-29A6PX
ALL model
L/L 250 250 ±5 1.45FL
luminanceerror model option
BYTE 1 : 60
BYTE 2 : 02

Alignment and Adjustments
4-4 Samsung Electronics
4-9 F.S. (Fail Safe) Circuit Check
1. Turn on the TV.
2. Select the ÒSTANDARDÓ video mode.
3. Short R and X terminals of R257,R255. Then, check both picture and sound disappear.
Note : Even if the shorted terminals are removed, both picture and sound do not appear
This proves the F.S. circuit is working normally.
4. Turn off the TV and reset it after about 30 seconds. (At this time, check that both picture and
sound are normal.)
4-10 Focus Adjustment
■ Adjustment Signal : lion head pattern or crosshatch pattern
1. Select the ÓSTANDARDÓ video mode.
2. Turn the static focus VR fully clockwise (maximum).
3. Slowly turn the static focus VR counterclockwise.
Adjust until the vertical line in the middle of the screen has maximum clarity.
4. After all adjustments are completed, check ÓOSGÓ.
Repeat adjustments 1~3, if necessary.
Note : If the single focus adjustment is done on center basis, that is out of specification.
4-11 E2PROM (IC902) Replacement
1. When IC902 is replaced, all adjustment data revert to the initial values.
So, all adjustment values when servicing should be readjusted.
2. After IC902 is replaced, connect the AC power supply cord.
3. Turn the power switch ON.
4. In stand-by, warm up the TV for at least 10 seconds.
5. Power on the TV.

Alignment and Adjustments
Samsung Electronics 4-5
4-12 MICOM
4-12-1 Description
The MICOM used for this K56B Chassis is made by ZILOG (USA).
But Samsung have ordered and installed appropriate soft programs in it.
4-12-2 Precaution
1. In power stand-by, apply power supply to only MICOM and E2PROM.
Apply power supply to the TV set
Turn ON/OFF the
TIMER LED
Picture Switch On or
Remocon Power Switch ON
TV Power On?
Micom OK Check Q904 and CNM01
(Power Board)
Check the circumference of the MICOM
1. Check the micom applies power supply to
IC901 pins 22,39.
2. Check the MICOM applies power supply to
IC902 pin 8.
3. Check the MICOM keeps IC901 pins 17, 19,
30, 31, 35, 47 ,48, 49,50 HIGH.
4. Check the MICOM oscillates to IC901 Pins
36,37.
5. Check IC901 pin 28 has the HSYNC PULSE.
6. Check IC901 pin 29 has the VSYNC PULSE.
No
No

Alignment and Adjustments
4-6 Samsung Electronics
4-13 Factory Adjustment
4-13-1 Factory/Service Mode
1. To enter the Service Mode, press the remote control buttons in the
following sequence :
■ Power OFF (about 10 seconds later) ® MUTE ® 1 ® 8 ® 2
■ Power ON ®Display ® Factory
2. After the Factory Adjustment Mode is entered, the initial screen
is as shown in the figure below.
3. Use the Channel Up/Down (▲/▼) buttons to move the cursor
on the adjustment parameters.
Note :
1. When CRT, EEPROM, FBT, or MICOM is replaced, the adjustment
values should be controlled.
2. After the Factory Adjustment is completed, be sure to reset the
TV set.
11 CH NO.
SERVICE MODE
GEOMETRIC
PICTURE
SOUND (FIXED)
PIP (FIXED)
OPTION (BYTE 1 : 60, BYTE 2 : 02)
READ Not Used
RESET

Alignment and Adjustments
Samsung Electronics 4-7
4-13-2(A) GEOMETRIC ADJUSTMENT VALUE
4-13-2 Geometric Adjustment Mode
11
GEOMETRIC
VS 63.
VA 63.
VCP 3.
VLN 15.
VSC 15.
HS 15.
HPC 15.
HA 63.
HPP 15.
HAA 15.
HAB 15.
HUC 15.
HLC 15.
VAS 40.
VSR 33.
VUV 15.
VLV 15.
VJS 0.
VZS 0.
VRP 3.
VBS 3.
HBS 1.
HLB 15.
HRB 15. 16 : 9 mode
FIXED mode
NO OSD RANGE CT-29A6PX CT-29A5PX FUNCTION IC
1 VS 0~6 17 17 ADJUSTS VERTICAL PICTURE POSITION
2 VA 0 ~ 1 26 26 ADJUSTS VERTICAL PICTURE SIZE
3 VCP 0 ~ 1 1 SETS VERTICAL HIGH VOLTAGE VARIANCE CORRECTION
4 VLN 0 ~ 1 10 10 ADJUSTS VERTICAL LINEARITY
5 VSC 0 ~ 1 10 10 ADJUSTS VERTICAL S-CORRECTION
6 HS 0 ~ 1 6 6 ADJUSTS HORIZONTAL PICTURE POSITION
7 HPC 0 ~ 6 32 32 ADJUSTS THE GAIN OF HORIZONTAL PARABOLA WAVE
8 HA 0 ~ 6 33 33 ADJUSTS HORIZONTAL PICTURE SIZE
9 HPP 0 ~ 1 8 8 ADJUSTS HORIZONTAL TILT
10 HAA 0 ~ 1 8 8 ADJUSTS THE SLOPE CORRECTION OF VERTICAL LINE
11 HAB 0 ~ 1 7 7 ADJUSTS THE BOW CORRECTION OF VERTICAL LINE
12 HUC 0 ~ 1 7 7 HORIZONTAL DISTORTION CORRECTION OF TOP
13 HLC 0 ~ 1 6 6 HORIZONTAL DISTORTION CORRECTION OF BOTTOM
14 VAS 0 ~ 6 40 40 ADJUSTS THE VERTICAL PICTURE SIZE OF 16:9 SCREEN
15 VSR 0 ~ 6 33 33 ADJUSTS THE SCROLL OF 16:9 SCREEN
16 VUV 0 ~ 1 0 0 ADJUSTS THE LINEARITY OF THE TOP 16:9 SCREEN
17 VLV 0 ~ 1 0 0 ADJUSTS THE LINEARITY OF THE BOTTOM 16:9 SCREEN
18 VJS 0 ~ 1 0 0 ADJUSTS THE JUMP OF 16:9 SCREEN
19 VZS 0 ~ 1 0 0 ADJUSTS THE ZOOM OF 16:9 SCREEN
20 VRP 0 ~ 1 3 3 ADJUSTS THE REFERENCE PULSE TIME OF 16:9 SCREEN
21 VBS 0 ~ 1 3 3 ADJUSTS THE VERTICAL BLANK WIDTH OF 16:9 SCREEN
22 HBS 0 ~ 1 1 1 H BLK WIDTH ADJUSTMENT ON/OFF 16:9 SCREEN
23 HLB 0 ~ 1 15 15 ADJUSTS THE LEFT BLANK WIDTH OF 16:9 SCREEN
24 HRB 0 ~ 1 15 15 ADJUSTS THE RIGHT BLANK WIDTH OF 16:9 SCREEN
(FIXED)
(FIXED)
(ADJUSTMENT
MODE)
(ADJUSTMENT
MODE)

Alignment and Adjustments
4-8 Samsung Electronics
11
PICTURE
DCT 1.
DPI 1.
AS 1.
DCL 1.
ABL 1.
POV 3.
SFO 3.
TA 15.
SCT 15.
SBT 15.
SCR 15.
STT 15.
GA 63.
BA 63.
GC 15.
BC 15.
GAM 3.
AGC 1.
TOT 1.
SSP 63.
AM 1.
FH 0.
CF 0.
SC 32.
LWC 63.
COR 63. SINEMAX mode
(No Function)
4-13-3 Picture Adjustment Mode
4-13-3 (A) PICTURE ADJUSTMENT VALUE
NO OSD RANGE CT-29A6PX CT-29A5PX FUNCTION IC
1 DCT 0~1 1 1 Y DC TRANSMISSION RATE SWITCHING SWITCH
2 DPI 0~1 1 1 Y BLACK EXPANSION ON/OFF SWITCH
3 LMT 0~1 1 1 Y DC TRANSMISSION RATE LIMET
4 DCL 0~1 1 1 DYNAMIC COLOR ON/OFF SWITCH
5 ABL 0~1 1 1 ABL MODE SWITCHING SWITCH
6 POV 0~3 1 1 PRE/OVER RATE SWITCHING SWITCH
7 YDL 0~15 3 3 Y TIMEING DELAY CONTROL
8 SFO 0~3 1 1 SHARP FO SWITCHING SWITCH
9 TA 0~15 11 11 CHROMA TRAP FO ADJUST
10 SCT 0~15 10 10 CONTRAST GAIN CONTROL
11 SBT 0~63 25 25 BRIGHTNESS CONTROL
12 SCR 0~15 10 10 COLOR GAIN CONTROL
13 STT 0~15 4 4 TINT GAIN CONTROL
14 GA 0~63 35 35 G OUTPUT GAIN ADJUST
15 BA 0~63 30 30 B OUTPUT GAIN ADJUST
16 GC 0~15 7 7 G OUTPUT CUTOFF ADJUST
17 BC 0~15 6 6 B OUTPUT CUTOFF ADJUST
18 GAM 0~3 2 2 GAMMA CONTROL
19 AFC 0~3 1 1 AFC LOOP GAIN CONTROL
20 TOT 0~1 0 0 CHROMA TOT BAND SWITCHING SWITCH
21 SSP 0~63 60 60 SHARPNESS ADJUST
22 SF0 0~1 1 1 INPUT LEVEL SWITCHING SWITCH
23 COR 0~63 25 25 HORIZONTAL FREQUENCY INPUT SELECT SWITCH
24 VM2 0~1 0 0 CONTINUOUS TOOTH PATH FILTER SELECT SWITCH
25 STC 0~63 45 45 STEPNESS ADJUST
26 LWC 0~63 50 50 LINE WIDTH ADJUST SWITCH
(FIXED)
CXA2095S
(ADJUSTMENT
MODE)
(FIXED)
(ADJUSTMENT
MODE)
(FIXED)
TDA9177
NO FUNCTION
(FIXED)