Samsung cft24907 service manual

COLOR TELEVISION RECEIVER

Chassis : KS2A(N) (REV.2) Model : CFT24907X/SMS

COLOR TELEVISION RECEIVER CONTENTS

Precautions

Reference Information

Specifications

Alignment and Adjustments

Troubleshooting

Exploded Views and Parts List

Electrical Parts List

Block Diagrams

Wiring Diagram

Schematic Diagrams

10.

ELECTRONICS

Printed in Korea

AA82-00036A

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 people—particularly children—might 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 unit’s 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 unit’s 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

“horizontal disable” or “hold-down”.)

Heed the high voltage limits. These include the X–ray 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 manufacturer’s 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 “integral implosion” 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 “in-line” picture tubes are equipped with a permanently attached deflection yoke; do not try to remove such “permanently attached” 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 original—even 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 unit’s 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 instrument’s ground lead to the instrument chassis ground before connecting the positive lead; always remove the instrument’s 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 (“solid state”) 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 power— 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 “anti-static”; 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)

CAUTION

These servicing instructions are for use by qualified service personnel only. To reduce the risk of electric shock do not perform any servicing other than that contained in the operating instructions unless you are qualified to do so.

Reference Information

Samsung Electronics 2-1

2. Reference Information

2-1 Tables of Abbreviations and Acronyms

A Ah Å dB dBm

°C °F °K F G GHz g H Hz h ips kWh kg kHz kΩ km km/h kV kVA kW I MHz

Ampere Ampere-hour Angstrom Decibel Decibel Referenced to One Milliwatt Degree Celsius Degree Fahrenheit degree Kelvin Farad Gauss Gigahertz Gram Henry Hertz Hour Inches Per Second Kilowatt-hour Kilogram Kilohertz Kilohm Kilometer Kilometer Per Hour Kilovolt Kilovolt-ampere Kilowatt Liter Megahertz

MV MW MΩ m µA µF µH µm µs µW mA mg mH mI mm ms mV nF

Ω

pF Ib rpm rps s V VA W Wh

Megavolt Megawatt Megohm Meter Microampere Microfarad Microhenry Micrometer Microsecond Microwatt Milliampere Milligram Millihenry Milliliter Millimeter Millisecond Millivolt Nanofarad Ohm Picofarad Pound Revolutions Per Minute Revolutions Per Second Second (Time) Volt Volt-ampere Watt Watt-hour

Table 2-1 Abbreviations

Reference Information

2-2 Samsung Electronics

Table 2-2 Table of Acronyms

ABL AC ACC AF AFC AFT AGC AM ANSI APC APC A/V AVC BAL BPF B-Y CATV CB CCD CCTV Ch CRT CW DC DVM EIA ESD ESD FBP FBT FF FM FS GND G-Y H HF HI-FI IC IC IF

Automatic Brightness Limiter Alternating Current Automatic Chroma Control Audio Frequency Automatic Frequency Control Automatic Fine Tuning Automatic Gain Control Amplitude Modulation American National Standards Institute Automatic Phase Control Automatic Picture Control Audio-Video Automatic Volume Control Balance Bandpass Filter Blue-Y Community Antenna Television (Cable TV) Citizens Band Charge Coupled Device Closed Circuit Television Channel Cathode Ray Tube Continuous Wave Direct Current Digital Volt Meter Electronics Industries Association Electrostatic Discharge Electrostatically Sensitive Device Feedback Pulse Flyback Transformer Flip-Flop Frequency Modulation Fail Safe Ground Green-Y High High-Frequency High Fidelity Inductance-Capacitance Integrated Circuit Intermediate Frequency

I/O L L LED LF MOSFET MTS NAB NEC NTSC OSD PCB PLL PWM QIF R RC RF R-Y SAP SAW SIF SMPS S/N SW TP TTL TV UHF UL UV VCD VCO VCXO VHF VIF VR VTR VTVM TR

Input/output Left Low Light Emitting Diode Low Frequency Metal-Oxide-Semiconductor-Field-Effect-Tr Multi-channel Television Sound National Association of Broadcasters National Electric Code National Television Systems Committee On Screen Display Printed Circuit Board Phase-Locked Loop Pulse Width Modulation Quadrature Intermediate Frequency Right Resistor & Capacitor Radio Frequency Red-Y Second Audio Program Surface Acoustic Wave(Filter) Sound Intermediate Frequency Switching Mode Power Supply Signal/Noise Switch Test Point Transistor Transistor Logic Television Ultra High Frequency Underwriters Laboratories Ultraviolet Variable-Capacitance Diode Voltage Controlled Oscillator Voltage Controlled Crystal Oscillator Very High Frequency Video Intermediate Frequency Variable Resistor Video Tape Recorder Vacuum Tube Voltmeter Transistor

REMARK

Refer to Table 2-3-1

Refer to Table 2-3-2

VM Option

DH01

Option

DDR01

LOC. NO

IC201S

IC601 IC901 IC902

IC602

HIC201

IC301 DH01

DAMPER-D

IC801S

D801S

PC801S

DDR01

IC804 IC803

IC903 IC904

Q909 Q910

TU01 D813

IC501

Table 2 - 3 IC Line - Up

Reference Information

Samsung Electronics 2-3

2-2 IC Line Up

BOARD

MAIN

CRT

SPEC

VDP3130Y-B1

MSP3440G-B6

SIM408A

24WC16

TDA7297 DRGB001

LA7845 KSD5703 FMP-3FU

KA3A1265RD

D5SB60 PC123Y

KA78R05

KA7806

KA78R08

KA78RM33 KIA7025AP

2N7000

TAFC-H0051

FML-G12S

STV5109

DESCRIPTION

Video Processor NTSC Sound Processor MICOM, Caption (MTP)

EEPROM Audio AMP

RGB Drive AMP Hybrid IC Vertical IC

Horizontal Drive IC

SPS Controllor Bridge Diode

Photo Coupler Regulator

6V Regulator 8V Controlled Regulator

3.3V Regulator MICOM Reset IC

IIC Level Shifter

Main Tuner with IF Block Rectifier Diode

Video Output AMP R.G.B Drive

2-4 Samsung Electronics

Reference Information

SPEC

VDP3108B VDP3130Y

FUNCTION

Basic 1H Comb Filter 2H Comb Filter, DVD Input

REMARK

Table 2-3-1 VIDEO IC

SPEC

TDA7297

FUNCTION

7W x 2CH, 10W x 2CH

REMARK

Table 2-3-2 SOUND AMP

Specifications

Samsung Electronics 3-1

3. Specifications

Specifications are subject to change.

Television

System

Antena Input

Multi

Power

Consumption

Requirements

Frequency

Sound

Output

Effect

Jacks

Front

(AV2)

Back

NTSC-M, PAL N.M

120W (Applied When 29” Flat) Free Volts(100V-240Volts) Free Voltage 50/60Hz 15W x 2CH 10W x 2CH

5W x 2CH Vitual Dolby Turbo Sound Pseudo Stereo RCA Input

S-VHS Head-Phone

2 AV Input

DVD Input(YPbPr) AV2 Monitor Audio Output

S-VHS

75ohms, Coaxial Cable

Not Present R815

Option

Option Option

Option

Option Option

3-2 Samsung Electronics

MEMO

Alignment and Adjustments

Samsung Electronics 4-1

4. Alignment and Adjustments

4-1 General Alignment Instructions

1. Usually, a color TV-VCR 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 objectionable color shading; if color shading is present, demagnetize, perform 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.

4-2 Automatic Degaussing

A degaussing coil is mounted around the picture tube, so that external degaussing after moving the TV should be unnecessary. But 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 is moved or turned in a different direction, the power should be OFF 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 turning power OFF.

If color shading persists, perform the following Color purity and Convergence adjustments.

4-3 High Voltage Check

CAUTION : There is no high voltage adjustment on this chassis. The B+ power supply should be +135 volts (with 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. Adjust the Brightness and contrast controls to both extremes. Ensure that the high voltage does not exceed 30 KV under any conditions.

Alignment and Adjustments

4-2 Samsung Electronics

4-5 SCREEN Adjustment

1. Input Toshiba Pattern

2. Enter “Service Mode”.(Refer to “4-8-1 Service Mode”)

3. Select “G2-Adjust”.

4. Set the values as below.

4-4 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.

5. Turn the SCREEN VR until “MRCR G B” and “MRWDG” are green and those value are about 100. (The incorrect SCREEN Voltage may result that “MRCR G B” and “MRWDG” should be red)

INCH / CRT

14” / SDI

15PF / SDI

21” 1.7R / SDI

20V 10.0R/SDI

21PF / TSB

21PF / LG

21PF / SDI

25PF / SDI

27V 1.3R / SDI

27V 1.0R/SDI

25V 1.0R/SDI

23V 1.3R/SDI

IBRM

205

220

205

220

230

225

210

205

WDRV

CDL

100

180

115

180

230

220

160

170

150

120

COLR G B

(Smallest Value)

100

120

150

180

140

Table 1. Screen Adjustment Table

REGION

Normal

Alignment and Adjustments

Samsung Electronics 4-3

4-6 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.

4-7 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. Enter the “Service Mode”. (Refer to “4-8 Service Mode”)

4. Warm up the TV set at least for 30 minutes.

5. Input a Toshiba pattern signal.

6. Enter the “Video Adjust1”.

- Adjust “Sub Contrast” so that Y (luminance) becomes 65 ft ± 3.

- Use “Red Drive” and “ Blue Drive” to adjust High-Light (x : 275, y : 265)

- Adjust “Sub Bright” so that Y (luminance) becomes 1.2ft ± 0.3.

- Use “Red Cutoff” and “Blue Cutoff” to adjust Low-Light (x : 275, y : 265).

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.

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