Samsung TXH2048 Service Manual

COLOR TELEVISION RECEIVER

Chassis : KCT57A Model: TXH2048 TXH2740

TXH2545 TXH2755 TXH2555 TXH2756 TXH2556 TXH2869

TXH2879

COLOR TELEVISION RECEIVER CONTENTS

Precautions

Specifications and IC Data

Alignment and Adjustment

Troubleshooting

Exploded View and Parts List

Electric Parts List

Block Diagram

PCB Layout Diagram

Wiring Diagram

Schematic Diagrams

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

TXH2869/2879

TXH2048/2545/2555/2556/2740/2755/2756

R3679 VERSION UP

Description

SAW FILTER (VIF)

SAW FILTER (SIF)

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

2-3 Semiconductor Base Diagrams

Specifications and IC Data

Samsung Electronics 2-3

ELECTROLYTICCONDENSER

DIODE

XLS24C02P (PIN 8) TDA8375 (PIN 56) RM168E (PIN 42) TDA9850 (PIN 22) TDA4053 (PIN 16)

TRANSISTOR TRANSISTOR

TDA8133 TDA8356

KA7812 KA7809

out

C2331-Y KSR1010

TRANSISTOR

KSC2073 KSA940 2SD1887 2SD1880 KSD5072

E B C

KSC815Y KSA539-Y

M3951M M9260M

SAW-FILTER

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

2 3 4 5 6

7 8

10 11 12

13 14 15 16

56 55 54 53 52 51

50 49

47 46 45 44 43 42 41

37 36 35

31 30 29

SOUND IF INPUT

EXT AUDIO INPUT

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

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

9 20 10

0 off

Table 3 - 1 Memory Specification

FUNCTION

A D J U S T

E N T

P X

MODE

(OSD)

AGC VCO

SBT SCT

SCR

STT

RG GG

BG SCO VSC

EWA EWP EWC EWT VZM MAT

VOL PLA

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

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

9 20 10

0 off

TXH2048

15 62

7 7 8

8 32 32 32 20 30 32

7 42 38

0 31 25 off

9 20 10

0 off

1 2 3 4 5 6 7 8

9 10 11 12 13 14 15 16 17 18 19 20 21 22

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

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”

OPTION

FIX = “0”

FIX = “1 “

OPTION BYTE 0

REMARK

OPTION

FIX = “0”

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

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

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

LOCATION

DEFLECTION YOKE

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

RED

4-Pole Magnet Movement

GREEN

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

High-Light

Low-Light

SIZE

29”

2.8

26”

2.4

22”

2.4

HEIGHT

LIGHT

29”

37 + 3

26”

45 + 3

22”

45 + 3

+ 45 hidden pages