Samsung txj2766 service manual

COLOR TELEVISION RECEIVER
Chassis : K51A Model: TXJ2060 TXJ2754
TXJ2066 TXJ2766 TXJ2067 TXJ2767 TXJ2554 TXJ2768 TXJ2566 TXJ2879 TXJ2567
COLOR TELEVISION RECEIVER CONTENTS
Precautions
Alignment and Adjustments
Troubleshooting
Exploded Views and Parts List
Electric Parts List
Block Diagrams
Schematic Diagrams
1.
2.
3.
4.
5.
6.
7.
8.
ELECTRONICS
©
Samsung Electronics Co., Ltd. APR.1999 Printed in Korea
3K51A-2001
1. Precautions
1-1 Safety Precautions
1. Be sure that all of the built-in protective devices are replaced. Restore any missing protective shields.
2. When reinstalling the chassis and its assemblies, be sure to restore all protective devices, including: nonmetallic control knobs and compartment covers.
3. Make sure that there are no cabinet openings through which peopleÑparticularly childrenÑmight insert fingers and contact dangerous voltages. Such openings include the spacing between the picture tube and the cabinet mask, excessively wide cabinet
ventilation slots, and improperly fitted back
covers.
If the measured resistance is less than 1.0 megohm or greater than 5.2 megohms, an abnormality exists that must be corrected before the unit is returned to the customer.
4. Leakage Current Hot Check (Figure 1-1): Warning: Do not use an isolation transformer during this test. Use a leakage­current tester or a metering system that complies with American National Standards Institute (ANIS C101.1, Leakage Current for Appliances), and Underwriters Laboratories (UL Publication UL1410, 59.7).
5. With the unit completely reassembled, plug the AC line cord directly into the power outlet. With the unitÕs AC switch first in the ON position and then OFF, measure the current between a known earth ground (metal water pipe, conduit, etc.) and all exposed metal parts, including: antennas, handle brackets, metal cabinets, screwheads and control shafts. The current measured should not exceed 0.5 milliamp. Reverse the power­plug prongs in the AC outlet and repeat the test.
Fig. 1-1 AC Leakage Test
6. Antenna Cold Check: With the unitÕs AC plug disconnected from the AC source, connect an electrical jumper across the two AC prongs. Connect one lead of the ohmmeter to an AC prong. Connect the other lead to the coaxial connector.
7. X-ray Limits: The picture tube is especially designed to prohibit X-ray emissions. To ensure continued X-ray protection, replace the picture tube only with one that is the same type as the original. Carefully reinstall the picture tube shields and mounting hardware; these also provide X-ray protection.
8. High Voltage Limits: High voltage must be measured each time servicing is done on the B+, horizontal deflection or high voltage circuits. Correct operation of the X-ray protection circuits must be reconfirmed whenever they are serviced.
(X-ray protection circuits also may be called
Òhorizontal disableÓ or Òhold-downÓ.)
Heed the high voltage limits. These include the XÐray Protection Specifications Label, and the Product Safety and X-ray Warning Note on the service data schematic.
Precautions
Samsung Electronics 1-1
LEAKAGE CURRENT
TESTER
DEVICE UNDER
TEST
TEST ALL
EXPOSED METAL
SURFACES
2-WIRE CORD
ALSO TEST WITH
PLUG REVERSED
(USING AC ADAPTER
PLUG AS REQUIRED)
EARTH
GROUND
(READING SHOULD
NOT BE ABOVE
0.5mA)
Follow these safety, servicing and ESD precautions to prevent damage and protect against potential hazards such as electrical shock and X-rays.
1-1 Safety Precautions (Continued)
9. High voltage is maintained within specified limits by close-tolerance, safety-related components and adjustments. If the high voltage exceeds the specified limits, check each of the special components.
10. Design Alteration Warning: Never alter or add to the mechanical or electrical design of this unit. Example: Do not add auxiliary audio or video connectors. Such alterations might create a safety hazard. Also, any design changes or additions will void the manufacturerÕs warranty.
11. Hot Chassis Warning: Some TV receiver chassis are electrically connected directly to one conductor of the AC power cord. If an isolation transformer is not used, these units may be safely serviced only if the AC power plug is inserted so that the chassis is connected to the ground side of the AC source.
To confirm that the AC power plug is inserted correctly, do the following: Using an AC voltmeter, measure the voltage between the chassis and a known earth ground. If the reading is greater than 1.0V, remove the AC power plug, reverse its polarity and reinsert. Re-measure the voltage between the chassis and ground.
12. Some TV chassis are designed to operate with 85 volts AC between chassis and ground, regardless of the AC plug polarity. These units can be safely serviced only if an isolation transformer inserted between the receiver and the power source.
13. Some TV chassis have a secondary ground system in addition to the main chassis ground. This secondary ground system is not isolated from the AC power line. The two ground systems are electrically separated by insulating material that must not be defeated or altered.
14. Components, parts and wiring that appear to have overheated or that are otherwise damaged should be replaced with parts that meet the original specifications. Always determine the cause of damage or overheating, and correct any potential hazards.
15. Observe the original lead dress, especially near the following areas: Antenna wiring, sharp edges, and especially the AC and high voltage power supplies. Always inspect for pinched, out-of-place, or frayed wiring. Do not change the spacing between components and the printed circuit board. Check the AC power cord for damage. Make sure that leads and components do not touch thermally hot parts.
16. Picture Tube Implosion Warning: The picture tube in this receiver employs Òintegral implosionÓ protection. To ensure continued implosion protection, make sure that the replacement picture tube is the same as the original.
17. Do not remove, install or handle the picture tube without first putting on shatterproof goggles equipped with side shields. Never handle the picture tube by its neck. Some Òin-lineÓ picture tubes are equipped with a permanently attached deflection yoke; do not try to remove such Òpermanently attachedÓ yokes from the picture tube.
18. Product Safety Notice: Some electrical and mechanical parts have special safety-related characteristics which might not be obvious from visual inspection. These safety features and the protection they give might be lost if the replacement component differs from the originalÑeven if the replacement is rated for higher voltage, wattage, etc.
Components that are critical for safety are indicated in the circuit diagram by shading, ( ) or ( ).
Use replacement components that have the same ratings, especially for flame resistance and dielectric strength specifications. A replacement part that does not have the same safety characteristics as the original might create shock, fire or other hazards.
Precautions
1-2 Samsung Electronics
!
1-2 Servicing Precautions
1. Servicing precautions are printed on the cabinet. Follow them.
2. Always unplug the unitÕs AC power cord from the AC power source before attempting to: (a) Remove or reinstall any component or assembly, (b) Disconnect an electrical plug or connector, (c) Connect a test component in parallel with an electrolytic capacitor.
3. Some components are raised above the printed circuit board for safety. An insulation tube or tape is sometimes used. The internal wiring is sometimes clamped to prevent contact with thermally hot components. Reinstall all such elements to their original position.
4. After servicing, always check that the screws, components and wiring have been correctly reinstalled. Make sure that the portion around the serviced part has not been damaged.
5. Check the insulation between the blades of the AC plug and accessible conductive parts (examples: metal panels, input terminals and earphone jacks).
6. Insulation Checking Procedure: Disconnect the power cord from the AC source and turn the power switch ON. Connect an insulation resistance meter (500V) to the blades of the AC plug.
The insulation resistance between each blade of the AC plug and accessible conductive parts (see above) should be greater than 1 megohm.
7. Never defeat any of the B+ voltage interlocks. Do not apply AC power to the unit (or any of its assemblies) unless all solid-state heat sinks are correctly installed.
8. Always connect a test instrumentÕs ground lead to the instrument chassis ground before connecting the positive lead; always remove the instrumentÕs ground lead last.
Precautions
Samsung Electronics 1-3
Warning 1 : First read the “Safety Precautions” section of this manual. If some unforeseen circumstance creates
a conflict between the servicing and safety precautions, always follow the safety precautions.
Warning 2 : An electrolytic capacitor installed with the wrong polarity might explode.
1-3 Precautions for Electrostatically Sensitive Devices (ESDs)
1. Some semiconductor (Òsolid stateÓ) devices are easily damaged by static electricity. Such components are called Electrostatically Sensitive Devices (ESDs); examples include integrated circuits and some field-effect transistors. The following techniques will reduce the occurrence of component damage caused by static electricity.
2. Immediately before handling any semicon ductor components or assemblies, drain the electrostatic charge from your body by touching a known earth ground. Alternatively, wear a discharging wrist-strap device. (Be sure to remove it prior to applying powerÑ this is an electric shock precaution.)
3. After removing an ESD-equipped assembly, place it on a conductive surface such as aluminum foil to prevent accumulation of electrostatic charge.
4. Do not use freon-propelled chemicals. These can generate electrical charges that damage ESDs.
5. Use only a grounded-tip soldering iron when soldering or unsoldering ESDs.
6. Use only an anti-static solder removal device. Many solder removal devices are not rated as Òanti-staticÓ; these can accumulate sufficient electrical charge to damage ESDs.
7. Do not remove a replacement ESD from its protective package until you are ready to install it. Most replacement ESDs are packaged with leads that are electrically shorted together by conductive foam, aluminum foil or other conductive materials.
8. Immediately before removing the protective material from the leads of a replacement ESD, touch the protective material to the chassis or circuit assembly into which the device will be installed.
9. Minimize body motions when handling unpackaged replacement ESDs. Motions such as brushing clothes together, or lifting a foot from a carpeted floor can generate enough static electricity to damage an ESD.
Precautions
1-4 Samsung Electronics
Specifications and IC Data
Samsung Electronics 2-1
2. Specifications and IC Data
2-1 Specifications
MODEL
VOLTAGE POWER CONSUMPTION POWER FREQUENCY CHANNELS RECEIVED
CN-565BWZ CN-566BWZ
CN-25D4WZ CN-663AWZ
CN-29D4WZ CN-7202WZ CN-765DWZ
AC 100-240V (Argentina: AC 220V)
85 WATTS 110 WATTS 120 WATTS
50/60 Hz (Argentina: 50 Hz)
VHF: 2~13, UHF: 14~69, CATV: 1,14~125
MODEL
VOLTAGE POWER CONSUMPTION POWER FREQUENCY CHANNELS RECEIVED
AC100-240V (Mexico: AC127V±10%)
CT-5072BWZ
CT-5072BPZ
85 WATTS
50/60Hz (Mexico: 60Hz)
VHF; 2~13, UHF; 14~69, CATV; 1,14~125
CT-565BZ / 566BWZ
CT-567BWZ / 568BPZ
CT-225BZ / 228BWZ
CT-22B6PZ
CT-25D4WZ
110 WATTS
CT-29D4WZ
120 WATTS
CT-765DWZ CT-766DWZ
CT-30D6PZ CT-30A9PZ
120 WATTS
AC120V
TXJ2048/2060 TXJ2066/2067
TXJ2754/2766 TXJ2767/2768
TXJ2879
85 WATTS
60Hz
VHF; 2~13, UHF; 14~69, CATV; 1,14~125
120 WATTS 130 WATTS
TXJ2554/2566
TXJ2567
110 WATTS
MODEL
VOLTAGE POWER CONSUMPTION POWER FREQUENCY CHANNELS RECEIVED
Specifications and IC Data
2-2 Samsung Electronics
2-2 IC Line Up
Table 2 - 1 IC Line - Up
Loc No
SF101
SF102
IC201
IC202
IC301
IC603
IC701
IC801
IC802
IC901
IC902
ICD01
Specification
M3951M
M9260M
TDA8377
TDA8373
TDA8375
LA7510
LA7845
TDA7056B
TDA7266S
TDA7449
KA3S1265R
KA7630
SZM368ET
XL24C08P
CXA2104S
Remarks
CT566BV/CT567BW/CT568BW/CT766DW
CT633BW/CT683BW
CN565BW/CN25D4W/CN663A/CN765DW
1.5W x 2 (MONO)
3W x 2 (MONO)
STEREO MODEL
CT633BW/CT683BW/CT766DW
CT566BV/CT566BW/CT567BW/CT568BW
STEREO MODEL ONLY
Description
SAW FILTER (VIF)
SAW FILTER (SIF)
ONECHIP TV PROCESSOR
ONECHIP TV PROCESSOR
ONECHIP TV PROCESSOR
AUDIO IF AMP/4.5M DETECT
VERTICAL AMP IC
SOUND AMP IC
VOLUME CONTROL IC
POWER IC
MULTI REGULATOR IC
MICOM
EEPROM
MTS IC
No
1
2
3
4
5
6
7
8
9
10
11
12
Specifications and IC Data
Samsung Electronics 2-3
2-3 Semiconductor Base Diagrams
ELECTROLYTIC­CONDENSER
IC
DIODE
XLS24C08P (PIN 8) TDA8377 (PIN 56)
IC
TRANSISTOR TRANSISTOR
LA7845
KA7812 KA7809
IN
G
out
C2331-Y KSR1010
TRANSISTOR
TRANSISTOR
KSC2073 KSA940 2SD1887 2SD1880 KSD5072 KSD5703
B
C
E
E B C
KSC815Y KSA539-Y
M3951M M9260M
SAW-FILTER
1
E C B
Fig. 2-1 Semiconductor Base Diagrams
Specifications and IC Data
2-4 Samsung Electronics
2-4 One Chip TV-processor
Fig. 2-2 SDIL56
CVBS : Composite Video Blanking Signal
26 27 28
17 18 19 20 21
22 23 24 25
1
2 3 4 5 6 7 8 9
10 11 12
13 14 15 16
56 55 54 53 52 51
50 49 48 47 46 45 44 43 42 41 40
39 38 37 36 35 34 33 32
31 30 29
SOUND IF INPUT
EXT AUDIO INPUT
VCO REF FILTER
VCO REF FILTER
PLL LOOP FILTER
IF VIDEO OUTPUT
BUSINPUT : SCL
BUSINPUT : SDA
BANDGAP DECOUPLING
CHROMA INPUT
Y/CVBS INPUT
MAIN POSITIVE SUPPLY
INT CVBS INPUT
GROUND
AUDIO OUT
DECOUPLING FILTER TUNING
EXT CVBS INPUT
BLACK CURRENT INP
BLUE OUTPUT
GREEN OUTPUT
RED OUTPUT
V-GUARD INP/BEAM CUR LIMITER
RED INPUT
GREEN INPUT
BLUE INPUT
PIP/OSD RGB INSERTION SWITCH INP
LUMINANCE INPUT
LUMINANCE OUTPUT
DECOUPLING SOUND DEMODULATOR AUDIO DEEMPHASSIS/MPX OUT TUNER AGC OUTPUT
AGC DECOUPLING CAPACITOR REREFERENCE CURRENT INPUT VERT, SAWTOOTH CAPACITOR
EHT/OVERVOLTAGE PROTECTION INP (X-RAY PROTECTION)
IF INPUT
IF INPUT
VERT. DRIVE NEG VERT. DRIVE POS EAST-WEST DRIVE
GROUND
PHI1 FILTER PHI2 FILTER / FLASH PROT SAND CASTLE OUTPUT/FLYBACK INP HOR. OUTPUT
POSITIVE SUPPLY
LOOP FILTER BURST PHASE DET
X-TAL (PAL-N (4.43)/PAL-M (3.58)) X-TAL (3.58)
SECAM REF OUTPUT
(R-Y) INPUT (B-Y) INPUT (R-Y) OUTPUT
(B-Y) OUTPUT
CVBS OUTPUT
BLACK PEAK HOLD CAPACITOR
SDIL56
Alignment and Adjustments
Samsung Electronics 3-1
3. Alignment and Adjustments
3-1 Preadjustment
1. Since there are no VRs in the K51A chassis, all adjustments after parts replacement must be done in the Service Mode.
2. The Factory Mode adjustments are necessary when either the EEPROM (IC902) or the CRT is replaced.
3. Do not tamper with the Ò AdjustmentÓ screen of the Factory Mode menu. This screen is intended only for factory use.
4. WHEN EEPROM (IC902) IS REPLACED
(1) When IC902 is replaced, all adjustment data
revert to their initial values. It is necessary to re-program this data.
(2) After IC902 is replaced, warm up the TV for
10 seconds.
Make the following adjustments AFTER setting up purity and convergence:
White Balance Sub-Brightness Vertical Center Vertical Size Horizontal Size (No use in 21Ó and 25Ó
models)
3-2 Factory (“SERVICE”) Mode
1. The set must be in Factory (ÒServiceÓ) Mode. Selection sequence: STAND-BY ® MUTE ® 1 ®8 ® 2 ® POWER ON
2. The Ò FACTORY MODEÓ message will be displayed. The Factory Mode has four components : Adjustment, MPX, PIP, Option Byte and Factory Reset.
3. Access the Adjustment Mode by pressing the ÒVOLUMEÓ keys ( , ) The adjustment parameters are listed in the accompanying table.
Select them by pressing the CHANNEL keys (▲,▼).
4. After completing the Factory Mode adjustments, turn the power switch OFF.
AGC 15 VCO 62 SBT 7 SCT 11 SCR 8 STT 8 RG 32 GG 32 BG 32 SCO 20 VSL 26
VS 32 VA 27 HS 46 EWA 52 EWP 31 EWC 32 EWT 31 MAT off PLA 6
*FACTORY*
¯
Press VOL
Press CH
Press VOL or
SBT 3
POWER OFF
Adjustment Mpx Pattern Option Reset
AGC 15 VCO 62 SBT 7 SCT 11 SCR 8 STT 8 RG 32 GG 32 BG 32 SCO 20 VSL 26
¯
¯
¯
VS 32 VA 27 HS 46 EWA 52 EWP 31 EWC 32 EWT 31 MAT off PLA 6
VSLN 30 VSN 32 VAN 32 HSN 45 EWAN 45 EWPN 33 EWCN 32 EWTN 38
*SERVICE*
¯
Press VOL
Press CH
Press VOL or
SBT 3
POWER OFF
Adjustment MTS PIP Option Reset
AGC 15 VCO 62 SBT 7 SCT 11 SCR 8 STT 8 RG 32 GG 32 BG 32 SCO 20 PLA 5
¯
¯
¯
VSLP 30 VSP 32 VAP 32 HSP 39 EWAP 46 EWPP 33 EWCP 32 EWPT 38
VSLN 30 VSN 32 VAN 32 HSN 45 EWAN 45 EWPN 33 EWCN 32 EWTN 38
AGC 15 VCO 62 SBT 7 SCT 11 SCR 8 STT 8 RG 32 GG 32 BG 32 SCO 20 PLA 5
VSLP 30 VSP 32 VAP 32 HSP 39 EWAP 46 EWPP 33 EWCP 32 EWPT 38
3-2-1 Adjustment
1. Selection sequence : STAND-BY ® MUTE ® 1 ® 8 ® 2 ® POWER ON
2. Example : Sub-bright Adjustment
Alignment and Adjustments
3-2 Samsung Electronics
SZM368ET1 (R4027)
SZM368ET2 (R4127)
Alignment and Adjustments
Samsung Electronics 3-3
MEMORY SPECIFICATION
765DWZ
8
63
2 7 0
7 32 32 32 14 25 26 34 46 51 24 32 32
5
OFF
87 00 13 46 32
275 295
35
275 295
1.4
2.4V
Table 3 - 1 Memory Specification
FUNCTION
A D J U S T
M
E N T
OP
M
P X
MODE
(OSD)
AGC VCO
SBT SCT
SCR
STT
RG GG BG
SCO
VSL
VS VA
HS EWA EWP EWC EWT
PLA SEP
29D4WZ
8
63
2 7 0
4 32 32 32 14 26 32 29 48 33 34 32 32
0
OFF
95 00 13 46 32
275 295
40
275 295
1.4
2.4V
225BZ
8
63
2 7 0
4 20 20 20 14 24 32 36 46 47
4 32 32
6
OFF
82 00
OFF OFF OFF 275 295
45
275 295
1.4
2.4V
25D4WZ
8
63
2 7 0
4 32 32 32 14 23 32 27 41 32 36 32 32
0
OFF
85 00 13 46 32
268 275
40
277 283
1.4
2.4V
565BZ
8
63
2 7 0
4 20 20 20 14 24 32 36 46 47
4 32 32
6
OFF
82 00
OFF OFF OFF 275 295
45
275 295
1.4
2.4V
566BWZ
8
63
2 7 0
4 20 20 20 14 24 32 36 46 47
4 32 32
6
OFF
87 00 13 46 32
275 295
45
275 295
1.4
2.4V
228BWX
8
63
2 7 0
4 20 20 20 14 24 32 36 46 47
4 32 32
6
OFF
87 00 13 46 32
268 275
45
277 283
1.4
2.4V
RANGE
63
127
15 13 13 13 63 63 63 63 63 63 63 63 63 63 63 63 10 31 FF FF 15 63 63
x y
Y ± 5
x y
Y ± 0.2
28B2
8
63
2 7 0
4 32 32 32 20 28 20 38 44 42 45 32 32
5
OFF
8F 03 13 46 32
275 295
33
275 295
1.4
2.4V
No
1 2 3 4 5 6 7 8
9 10 11 12 13 14 15 16 17 18 19 20
BYTE 0 BYTE 1
ATT
SPECTRAL
WIDEBAND
HIGH - LIGHT
LOW - LIGHT
WHITE
BALANCE
ADJUSTMENT
MEASURING PULS ADJUSTMENT VOLTAGE
VIDEO MUTE AUDIO MUTE
NO ATS
NO V - CHIP
NO VIDEO MUTE
NO AUDIO MUTE
ATS
V-CHIP
USA
PAL M/N
Alignment and Adjustments
3-4 Samsung Electronics
3-2-2 Option Table
NOTE : The Option Adjustment must be done in the Service Mode.
3-2-2 (A) OPTION BYTE 00
Table 3-2 Option Byte 00
NAME
V-SYNC
AUTO ON
PIP
CATV
S-VIDEO
TONE
CRT
MPX
NOT USED
NOT USED NO PIP FUNCTION AIR/STD/HRC/IRC
NOT USED
NO TONE CONTROL
4 : 3 CRT
NOT USED
USED ( NO V-SYNC, POWER OFF)
USED
PIP FUNCTION
AIR/STD/HRC/AFN
USED
TONE CONTROL
12.8 : 9 CRT USED
REMARK
ARMY : 1
3-2-2 (B) OPTION BYTE 01
BYTE : 00
D7 D6 D5 D4 D3 D2 D1 D0
FUNCTION
01
Table 3-3 Option Byte 01
NAME
AREA
LANGUAGE
NO VIDEO MUTE
NO AUDIO MUTE
ATS
V-CHIP
REMARK
SYSTEM/LANGUAGE
PAL
PAL
NT NT
BYTE : 01
D7 D6
D5
D4
D3 D2 D1 D0
FUNCTION
01
00 : ENGLISH
01 : SPANISH (SEDA)
02 : PORTUGUESE
11 : NOT USED
Alignment and Adjustments
Samsung Electronics 3-5
3-2-4 Factory Reset
When Ò Factory ResetÓ is selected, the User-Control data reverts to the initial values. The User-Control data is available at MENU (picture, sound and the other functions).
Note : When Ò Factory ResetÓ is selected, the Factory Mode Data does not change.
Selection sequence : Stand-By ® MUTE ® 1 ® 8 ® 2 ® POWER ON
* FACTORY *
Press VOL
Execute
Press CH
¯
¯
¯
Adjustment Mpx Pattern Option Reset
Adjustment Mpx Pattern Option Reset
* SERVICE *
Press VOL
Execute
Press CH
¯
¯
¯
Adjustment MTS PIP Option Reset
Adjustment MTS PIP Option Reset
3-3 Other Adjustments
3-3-1 General
1. Usually, a color TV needs only slight touch-up adjustment upon installation. Check the basic characteristics such as height, horizontal and vertical sync and focus.
2. Observe the picture for good black and white details. There should be no objectionable color shading. If color shading is present, perform the purity and convergence adjustments described below.
3. Use the specified test equipment or its equivalent.
4. Correct impedance matching is essential.
5. Avoid overload. Excessive signal from a sweep generator might overload the front-end of the TV. When inserting signal markers, do not allow the marker generator to distort test results.
6. Connect the TV only to an AC power source with voltage and frequency as specified on the backcover nameplate.
7. Do not attempt to connect or disconnect any wires while the TV is turned on. Make sure that the power cord is disconnected before replacing any parts.
8. To protect against shock hazard, use an isolation transformer.
SZM368ET1 (R4027)
SZM368ET2 (R4127)
Alignment and Adjustments
3-6 Samsung Electronics
3-3-2 Automatic Degaussing
A degaussing coil is mounted around the picture tube, so external degaussing after moving the TV should be unnecessary. However, the receiver must be properly degaussed upon installation.
The degaussing coil operates for about 1 second after the power is switched ON. If the set has been moved or turned in a different direction, disconnect its AC power for at least 10 Minutes.
If the chassis or parts of the cabinet become magnetized, poor color purity will result. If this happens, use an external degaussing coil. Slowly move the degaussing coil around the faceplate of the picture tube and the sides and front of the receiver. Slowly withdraw the coil to a distance of about 6 feet before removing power.
3-3-3 High Voltage Check
CAUTION : There is no high voltage adjustment on this chassis. The B+ power supply must be set to either +135V or +125V (for 20Ó screen). Conditions : Full color bar input and normal picture level.
1. Connect a digital voltmeter to the second anode of the picture tube.
2. Turn on the TV. Set the Brightness and Contrast controls to minimum (zero beam current).
3. The high voltage must not exceed 29.5KV.
4. Adjust the Brightness and Contrast controls to both extremes. Ensure that the high voltage does not exceed 29.5KV under any conditions.
3-3-4 FOCUS Adjustment
1. Input a black and white signal.
2. Adjust the tuning control for the clearest picture.
3. Adjust the FOCUS control for well defined scanning lines in the center area of the screen.
3-3-5 B+Line Check
There are 3 power modes :
1. ÒAÓ : When AC power supply is connected ; Ò Stand-ByÓ mode.
2. ÒBÓ : When Ò Set Power-ONÓ button is pressed.
3. ÒCÓ : Driven by FBT.
Each voltage is marked on its lead-in wire. ( )
3-3-6 F/S (Fail Safe) Circuit Check
1. The failsafe circuit check is the final step after servicing.
2. Turn the power switch on and adjust the screen for ÒNormalÓ.
3. Temporarily short Pin R and Pin X on the chassis (RX05, RX04). Sound and picture will disappear.
4. The TV should remain in this state. This shows that the failsafe circuit is working properly.
5. To restore picture and sound, temporarily turn off the AC power supply. After about 30 seconds, switch power ON.
21”±1
27.5KV
25”
29.5KV
29”
29.5KV
29”± 1
29.5KV
SIZE MAX
H-VOLTAGE
Alignment and Adjustments
Samsung Electronics 3-7
3-3-7 Color Purity Adjustment
1. Warm up the receiver. Operate it for 20 minutes, with the Brightness control set to maximum.
2. Fully degauss the receiver. Use an external degaussing coil.
3. Roughly adjust convergence by rotating the Convergence Magnet.
4. Input a black and white signal.
5. Loosen the Deflection Yoke clamp screw, and move the Deflection Yoke as close to the purity magnet as possible.
6. Loosen the Purity Magnet clamp. Adjust the purity magnet so that the vertical green raster is precisely at the center of the screen. Then tighten the clamp.
7. Slowly move the Deflection Yoke forward, and adjust it for the best overall green screen.
8. Tighten the Deflection Yoke clamp screw.
Fig. 3-1 Tube Assembly
RUBBER WEDGES
30
30
LOCATION
DEFLECTION YOKE
30
RUBBER WEDGE
ADHESIVE
RUBBER WEDGES KIT
RUBBER WEDGES
PURITY AND CONVERGENCE MAGNET ASS'Y
CRT
DEFLECTION YOKE
TAPE
CLOTH
GRASS
(1-3/16")
31 mm
Fig. 3-2 Purity and Convergence Magnets
2 POLE PURITY
YOKE CLAMP SCREW
6 POLE
CONVERGENCE 4 POLE CONVERGENCE
ADJUST THE ANGLE (VERTICAL LINES)
FIXED
ROTATE TWO TABS AT THE SAME TIME
(HORIZONTAL LINES)
Alignment and Adjustments
3-8 Samsung Electronics
3-3-8 Center Convergence Adjustment
Note: Before attempting any convergence adjustment, make sure that the receiver has been powered ON for at least twenty minutes.
1. Input a crosshatch pattern from a color bar generator.
2. Adjust the Brightness and Contrast controls for a well defined pattern.
3. Adjust the two tabs of the 5-pole magnets. Change the angle between the tabs, and superimpose red and blue vertical lines in the center area of the picture screen.
4. Next, turn both tabs at the same time. Keep the angle between the tabs constant, and superimpose the red and blue horizontal lines at the center of the screen.
5. Adjust the two tabs of the 6-pole magnets. Superimpose the red/blue lines on the green. Adjusting the angle affects the horizontal lines.
6. Repeat adjustments 3, 4 and 5. The dot movement is complex because the 4-pole and 6-pole magnets interact.
Fig. 3-3 Center Convergence Adjustment
RED
BLUE
BLUE
RED
4-Pole Magnet Movement
GREEN
RED/BLUE
RED/BLUE
GREEN
6-Pole Magnet Movement
3-3-9 AGC Adjustment
1. Input a COLOR-BAR pattern. (CH2)
2. Set the RF input signal to 70 dBmV.
3. Use Generator for PM5518 & PM5418.
4. Set AGC (in the Factory Mode) so that the DC level of IC TDA8377 Pin 53 is 3.0±0.05V.
3-3-10 AFT (VCO Adjustment)
1. Input an AGC adjustment signal.
2. Select Factory Mode VCO and press the MUTE key one time.
3. GEOMATRIX adjustments
VS EWA VA EWP VSL EWC HS EWT
Alignment and Adjustments
Samsung Electronics 3-9
3-3-11 White Balance Adjustment
3-3-11 (A) SCREEN ADJUSTMENTS
1. Input a TOSHIBA pattern.
2. Check R506 ÒGÓ pin on the CRT PCB with an oscilloscope.
3. Enter the Horizontal Line Mode.
4. Adjust the Screen Control on the FBT so that the waveform of the 21st line is DC 2.0 (±0.5)V.
3-3-11 (B) HIGH-LIGHT ADJUSTMENT
1. NOTE : If a color analyzer is not available, then approximate the following color adjustments Òby eyeÓ.
2. Input a TOSHIBA pattern.
3. Set high-light to 290/300 (X,Y) with a color analyzer.
4. Set low-light to 1.4F/L.
5. Adjust RG, BG and set GG to step 32.
3-3-11 (C) SUB-CONTRAST ADJUSTMENT
1. Set SCT so that the brightness level in high­light is 40 F/L (for a 29Ó SCREEN).
3-3-11 (D) SUB-BRIGHTNESS ADJUSTMENT
1. Input a TOSHIBA pattern.
2. Set SBT so that the brightness level in low­light is 1.4 F/L.
3-3-11 (E) SUB-COLOR ADJUSTMENT
Set ÒSCRÓ in the Service Mode to step 0.
3-3-11 (F) SUB-TINT ADJUSTMENT
Set ÒSTTÓ in the Service Mode to step 4.
3-3-11 (G) VERTICAL SIZE ADJUSTMENT
1. Input a lion head pattern.
2. Set VS to 32 in the Factory Mode.
3. Set VA so that the top margin is 4.0. Adjust SL so that the bottom margin is 4.0. If the top and bottom margins are different, adjust VA so that their sum is 8.0.
3-3-11 (H) HORIZONTAL SHIFT ADJUSTMENT
1. Input a lion head pattern.
2. Adjust ÒHSÓ in the Service Mode so that the left and right margins of the lion head pattern
are 5.0 ± 0.5 : CT633BW/CT683BW, 6.3 ± 0.5 :
CT566BV/CT566BW/CT568BW/CT765DW/ CT766DW/CT762B/CT25D4/CT29D4.
SIZE
DC
29”
2.4
26”
2.4
22”
2.4
HEIGHT
LIGHT
30”
33 ± 5
29”
37 ± 5
26”
45 ± 5
22”
45 ± 5
<TOSHIBA PATTERN>
High-Light
Low-Light
For the power system of K51A chassis, all output voltages remain the same during stand-by. So, to reduce power consumption, it is necessary to cut the leakage current flowing through FBT B+(130V) and tuner port VT(33V)
during stand-by (Picture OFF).
The power consumption reduction circuit cuts leakage current. A P-channel MOSFET is used as a switching element. The operating principles are as follows:
1. In stand-by, the voltage of the power control port (micom IC) becomes low (0V). During power ON, however, it becomes high (over 4V).
2. The voltage between S-G (Q801 P-channel MOSFET) should be over 3.5V, so that the S-D current (Q801) can keep flowing.
3. When the voltage of the power control port becomes low, the current flowing through Q903 (R812) is cut.
4. When the voltages across R803 become less than 3.5V, the S-D current (Q801) is cut.
5. DZ809 is required for protecting the G-port (Q801).
3-3-13 Precautions when servicing
1. Q801 can sustain a continuous flow of 11ADC. If Q801 is destroyed, the S-D is shorted. But, the TV functions normally and only the power consumption during stand-by increases (2.5W® 6W).
2. No Picture ON : Q903 is open or DZ809 is shorted. At this time, check both Q903 and DZ809. If the power-consumption reduction circuit does not work normally after checking both Q903 and DZ809, then short the S-D ports of Q801.
Alignment and Adjustments
3-10 Samsung Electronics
3-3-12 Power Consumption Reduction Circuit during Stand-by (Option)
OmA
R801
FBT B
+
OmA TUNER 33V
OmA
Q903
130 RECTIFIED
DZ809
Q801
SFP9640
R812
R910 10K
POWER CONTROL
4. Troubleshooting
4-1 No Raster and No Sound
Troubleshooting
Samsung Electronics 4-1
Measure the B
+
Voltage at the Cathode
of D812 (D811)
No Raster and No Sound
Normal
Less than 50V
More than 130V
Check/Replace
IC801 Q801
Check the horiz
output signal at TR
collector.
Measure the B+
voltage at the cathode
of D812*
No Voltage
More than 130V
Normal
Normal
Check/Replace F801
Abnormal
Check/Replace AVR Circuit, Horiz Output
Circuit and B+
Voltage Line.
Check +12.5 Line
Check/Replace FS
circuit
Check/Replace
AVR circuit
(ADJ Pin of STR)
Check/Replace the AVR circuit.
Open
Check/Replace
1) D801
2) Short the Degaussing Coil
3) C801
Check/Replace
the power switch
Normal
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