Samsung TXH2048 Service Manual

COLOR TELEVISION RECEIVER
Chassis : KCT57A Model: TXH2048 TXH2740
TXH2545 TXH2755 TXH2555 TXH2756 TXH2556 TXH2869
TXH2879
COLOR TELEVISION RECEIVER CONTENTS
Precautions
Alignment and Adjustment
Troubleshooting
Exploded View and Parts List
Electric Parts List
Block Diagram
PCB Layout Diagram
Wiring Diagram
Schematic Diagrams
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
ELECTRONICS
Samsung Electronics Co., Ltd.JUL.1998
©
Printed in Korea
3KCT57A-6804
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
Warning1: 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.
Warning2: An electrolytic capacitor installed with the wrong polarity might explode.
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
1-3 Precautions for Electrostatically Sensitive Devices (ESDs)
Specifications and IC Data
Samsung Electronics 2-1
2. Specifications and IC Data
2-1 Specifications
Model
Television System : Channels :
Intermediate Frequencies :
Sound System Picture Tube : Power Requirements : Antenna Input Impedance : Speaker Impedance : Protection :
TXH2048 TXH2545/2555/2556 TXH2740/2755/2756 TXH2869/2879
NTSC-M VHF : CH 2 ~ CH 13
UHF : CH 14 ~ CH 69 CATV : CH 1, CH 14 ~ CH 125
Picture IF Carrier : 45.75 MHz Sound IF Carrier : 41.25 MHz Color Sub Carrier : 42.17 MHz
MTS A53QCX89X01 A63AFW32X A68ADT25X01 A70QBZ791X AC120V, 60Hz 75 ohm unbalanced type 8 ohm, 3W + 3W X-Ray Protection, Fail Safe Circuit
2-2 IC Line Up
Table 2 - 1 IC Line - Up
Specifications and IC Data
2-2 Samsung Electronics
Loc No
SF101
SF102
IC201
IC202
IC301
IC603
IC602
IC701
IC801
IC802
IC901
IC902
ICD01
Specification
M3951M
M9260M
TDA8377
TDA8373
LA7510
TDA8350Q
TDA7057AQ
mPC 1460HA
TDA4053
S6709
STR5707
KA7630
SZM322
XL24C02P
TDA9850
Remarks
TXH2048,TXH2869,TXH2879
TXH2545/2555/2556/2740/2755/2756
STEREO MODEL ONLY
STEREO MODEL ONLY
TXH2869/2879
TXH2048/2545/2555/2556/2740/2755/2756
R3679 VERSION UP
Description
SAW FILTER (VIF)
SAW FILTER (SIF)
ONECHIP TV PROCESSOR
ONECHIP TV PROCESSOR
AUDIO IF AMP/4.5M DETECT
VERTICAL AMP IC
SOUND AMP IC
VOLUME CONTROL IC
SWITCHING IC
POWER IC
MULTI REGULATOR IC
MICOM
EEPROM
MTS IC
No
1
2
3
4
5
6
7
8
9
10
11
12
13
2-3 Semiconductor Base Diagrams
Specifications and IC Data
Samsung Electronics 2-3
ELECTROLYTIC­CONDENSER
IC
DIODE
XLS24C02P (PIN 8) TDA8375 (PIN 56) RM168E (PIN 42) TDA9850 (PIN 22) TDA4053 (PIN 16)
IC
TRANSISTOR TRANSISTOR
TDA8133 TDA8356
KA7812 KA7809
IN
G
out
C2331-Y KSR1010
TRANSISTOR
TRANSISTOR
KSC2073 KSA940 2SD1887 2SD1880 KSD5072
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 KCT52A 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, Test Pattern, Set 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.
VS 32 VA 27 HS 46 EWA 52 EWP 31 EWC 32 EWT 31 VZM 25 MAT off VOL 0 PLA 6
*FACTORY MODE*
¯
Press VOL
Press CH
Press VOL or
SB 3
POWER OFF
Adjustment Mpx Adjust Test Pattern Set Option Byte Factory 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 VZM 25 MAT off VOL 0 PLA 6
AGC 15 VCO 62 SBT 7 SCT 11 SCR 8 STT 8 RG 32 GG 32 BG 32 SCO 20 VSL 26
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
Alignment and Adjustments
Samsung Electronics 3-3
MEMORY SPECIFICATION
TXH2740/55/56
15 62
7 7 8
8 32 32 32 20 26 32 27 46 52 31 32 31 25 off
0
0
7
7
9 20 10
0 off
Table 3 - 1 Memory Specification
FUNCTION
A D J U S T
M
E N T
M
P X
MODE
(OSD)
AGC VCO
SBT SCT
SCR
STT
RG GG
BG SCO VSC
VS
VA
HS
EWA EWP EWC EWT VZM MAT
VOL PLA
ST
SP
LEV AL1 AL2 AL3
ADJ
TXH2869/TXH2879
15 62
7 7 8
8 32 32 32 20 35 32 15 48 38 49 32 31 25 off
0
6
7
7
9 20 10
0 off
TXH2545/55/56
15 62
7 7 8
8 32 32 32 20 38 32 45 46 52 31 32 31 25 off
0
0
7
7
9 20 10
0 off
TXH2048
15 62
7 7 8
8 32 32 32 20 30 32
7 42 38
0
0 31 25 off
0
6
7
7
9 20 10
0 off
No
1 2 3 4 5 6 7 8
9 10 11 12 13 14 15 16 17 18 19 20 21 22
1
2
3
4
5
6
7
Alignment and Adjustments
3-4 Samsung Electronics
3-2-2 Test Pattern (Aging Mode)
1. This mode can be used to confirm that the convergence and purity adjustments are correct.
2. Access the Test Pattern parameters by pressing the CHANNEL keys
(,) while the Service Mode is on. The cursor will move to the
test pattern. Press the VOLUME keys. On-screen display:
3-2-3 V2 Tri-Norma Option Table
3-2-3(A) OPTION BYTE 0
RED GREEN BLUE
Table 3-2 Option Byte 0
DATA
D0
D1
D2
D3
D4
D5
D6
D7
FUNCTION
0 = AIR/STD/HRC/IRC 1 = AIR/STD/HRC/AFN
0 = NORMAL 1 = NO SIGNAL REACH 20MIN AUTO POWER OFF
O = AUTO MUTE 1 = NO AUTO MUTE
0 = HELP OSD OK IN OTHER LANGEUAGE 1 = HELP OSD NO
0 = NO AUTO POWER ON 1 = AUTO POWER ON
0 = MPX 1 = NO MPX
0 = NON LINEAR SHARPNESS 1 = LINEAR SHARPNESS
0 = NR EXECUTE 1 = NR SKIP
REMARK
OPTION
FIX = “0”
FIX = “1”
FIX = “0”
FIX = “0”
OPTION
FIX = “0”
FIX = “1 “
OPTION BYTE 0
REMARK
OPTION
FIX = “0”
FIX = “0”
OPTION
OPTION
OPTION (MONO = 0) OPTION (STEREO = 1)
Alignment and Adjustments
Samsung Electronics 3-5
3-2-3(B) OPTION BYTE 1
Table 3-3 Option Byte 1
DATA
D0
D1
D2
D3
D4
D5
D6
D7
FUNCTION
00 = TV/VIDEO 01 = TV/VIDEO/S-VIDEO 11 = NO ASSIGNED
0 = VID : 0 1 = VID : 1
0 = RB 10 STEP UP 1 = RB 5 STEP UP
0 = NO COMBFILTER 1 = COMBFILTER
0 = 4 : 3 CRT 1 = 12.8 : 9 CRT (Q MODEL)
0 = INTERNAL A/V SWITCH 1 = EXTERNAL A/V SWITCH
NOT USED NOT USED
OPTION BYTE 1
BYTE 1
60 40 50 51 40 51 51 70 71
MODEL
THX2048
TH2545 TXH2555 TXH2556 TXH2740 TXH2755 TXH2756 TXH2869 TXH2879
BYTE 0
84 84 84 84 84 84 84 84 84
3-2-4 (C) OPTION BYTE
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
3-2-4 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 MODE *
Press VOL
Execute
Press CH
¯
¯
¯
Adjustment Mpx Adjust Test Pattern Set Option Byte Factory Reset
Adjustment Mpx Adjust Test Pattern Set Option Byte Factory 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.
Alignment and Adjustments
3-8 Samsung Electronics
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
Samsung Electronics 3-9
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 6­pole 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 TDA8373 or TDA8377A 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
_
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 1.0F/L ( 22Ó low-light 1.2F/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 37 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 1.0 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 10.
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 : TXH2545,TXH2755,TXH2555, TXH2556, TXH2756,TXH2740, 6.3 + 0.5 : TXH2048, TXH2869,TXH2879.
Alignment and Adjustments
3-10 Samsung Electronics
<TOSHIBA PATTERN>
High-Light
Low-Light
SIZE
DC
29”
2.8
26”
2.4
22”
2.4
HEIGHT
LIGHT
29”
37 + 3
26”
45 + 3
22”
45 + 3
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