LG CD-962A, AX Service manual

SERVICING PRECAUTIONS

NOTES REGARDING HANDLING OF THE PICK-UP

1. Notes for transport and storage

1) The pick-up should always be left in its conductive bag until immediately prior to use.

2) The pick-up should never be subjected to external pressure or impact.

2. Repair notes

1) The pick-up incorporates a strong magnet, and so should never be brought close to magnetic materials.

2) The pick-up should always be handled correctly and carefully, taking care to avoid external pressure and impact. If it is subjected to strong pressure or impact, the result may be an operational malfunction and/or damage to the printed-circuit board.

3) Each and every pick-up is already individually adjusted to a high degree of precision, and for that reason the adjustment point and installation screws should absolutely never be touched.

4) Laser beams may damage the eyes! Absolutely never permit laser beams to enter the eyes! Also NEVER switch ON the power to the laser output part (lens, etc.) of the pick-up if it is damaged.

5) Cleaning the lens surface If there is dust on the lens surface, the dust should be cleaned away by using an air bush (such as used for camera lens). The lens is held by a delicate spring. When cleaning the lens surface, therefore, a cotton swab should be used, taking care not to distort this.

6) Never attempt to disassemble the pick-up. Spring by excess pressure. If the lens is extremely dirty, apply isopropyl alcohol to the cotton swab. (Do not use any other liquid cleaners, because they will damage the lens.) Take care not to use too much of this alcohol on the swab, and do not allow the alcohol to get inside the pick-up.

Storage in conductive bag

Drop impact

NEVER look directly at the laser beam, and don

¡˙t let

contact fingers or other exposed skin.

Magnet

How to hold the pick-up

Pressure

Cotton swab

Conductive Sheet

NOTES REGARDING COMPACT DISC PLAYER REPAIRS

1. Preparations

1) Compact disc players incorporate a great many ICs as well as the pick-up (laser diode). These components are sensitive to, and easily affected by, static electricity. If such static electricity is high voltage, components can be damaged, and for that reason components should be handled with care.

2) The pick-up is composed of many optical components and other high-precision components. Care must be taken, therefore, to avoid repair or storage where the temperature of humidity is high, where strong magnetism is present, or where there is excessive dust.

2. Notes for repair

1) Before replacing a component part, first disconnect the power supply lead wire from the unit

2) All equipment, measuring instruments and tools must be grounded.

3) The workbench should be covered with a conductive sheet and grounded. When removing the laser pick-up from its conductive bag, do not place the pick-up on the bag. (This is because there is the possibility of damage by static electricity.)

4) To prevent AC leakage, the metal part of the soldering iron should be grounded.

5) Workers should be grounded by an armband (1MΩ)

6) Care should be taken not to permit the laser pick-up to come in contact with clothing, in order to prevent static electricity changes in the clothing to escape from the armband.

7) The laser beam from the pick-up should NEVER be directly facing the eyes or bare skin.

Armband

Conductive Sheet

Resistor (1 Mohm)

ESD PRECAUTIONS

Electrostatically Sensitive Devices (ESD)

Some semiconductor (solid state) devices can be damaged easily by static electricity. Such components commonly are called Electrostatically Sensitive Devices (ESD). Examples of typical ESD devices are integrated circuits and some field-effect transistors and semiconductor chip components. The following techniques should be used to help reduce the incidence of component damage caused by static electricity.

1. Immediately before handling any semiconductor component or semiconductor-equipped assembly, drain off any electrostatic charge on your body by touching a known earth ground. Alternatively, obtain and wear a commercially available discharging wrist strap device, which should be removed for potential shock reasons prior to applying power to the unit under test.

2. After removing an electrical assembly equipped with ESD devices, place the assembly on a conductive

surface such as aluminum foil, to prevent electrostatic charge buildup or exposure of the assembly.

3. Use only a grounded-tip soldering iron to solder or unsolder ESD devices.

4. Use only an anti-static solder removal device. Some solder removal devices not classified as "anti-static" can

generate electrical charges sufficient to damage ESD devices.

5. Do not use freon-propelled chemicals. These can generate electrical charges sufficient to damage ESD

devices.

6. Do not remove a replacement ESD device from its protective package until immediately before you are

ready to install it. (Most replacement ESD devices are packaged with leads electrically shorted together by conductive foam, aluminum foil or comparable conductive materials).

7. Immediately before removing the protective material from the leads of a replacement ESD device, touch the

protective material to the chassis or circuit assembly into which the device will by installed.

CAUTION : BE SURE NO POWER IS APPLIED TO THE CHASSIS OR CIRCUIT, AND OBSERVE ALL OTHER

SAFETY PRECAUTIONS.

8. Minimize bodily motions when handing unpackaged replacement ESD devices. (Otherwise harmless motion

such as the brushing together of your clothes fabric or the lifting of your foot from a carpeted floor can generate static electricity sufficient to damage an ESD device).

2. AM IF Adjustment

Figure 4.

4. AM Tracking Adjustment

Figure 3.

3. AM Coverage Adjustment

Figure 2.

Loop Ant.

SSG SET

L71

VTVM

OSCILLOSCOPE

Terminal

GND

Output

VOLTMETER

SET

PIN 2

GND

Loop Ant.

SSG

SETL71

VTVM

OSCILLOSCOPE

Terminal

GND

Output

SET Frequency Adjustment Adjustment

522kHz(9kHz Step) L72 1.0V ± 0.05V

SSG Frequency SET Frequency Adjusting part Adjustment Remark

1008kHz(9kHz Step)

T2 450kHz±1kHz Maximize the output

SSG Frequency SET Frequency Adjusting part Adjustment

603kHz(9kHz Step) L71

1404kHz(9kHz Step) TC71

Maximize the output

Figure 5.

5. FM IF Adjustment

6. FM Coverage Adjustment

Figure 7.

7. FM Tracking Adjustment

Figure 6.

VOLTMETER

SET

PIN 2

GND

SSG

SET

VTVM

OSCILLOSCOPE

Terminal

GND

PIN1 GND

Output

SSG

SET

VTVM

OSCILLOSCOPE

Terminal

GND

PIN1 GND

Output

SSG Frequency SET Frequency Adjusting part Adjustment Remark

90MHz 90MHz T1 10.7MHz Maximize the output

SET Frequency Adjusting Part Adjustment

76MHz L2 1 ± 0.05V

SSG Frequency SET Frequency Adjusting part Adjustment

78.6MHz 78.6MHz L1

101.75MHz 101.75MHz TC1

Maximize the output

10. LW IF Adjustment

Figure 12.

12. LW Tracking Adjustment

Figure 11.

11. LW Coverage Adjustment

Figure 10.

Loop Ant.

SSG SET

L71

VTVM

OSCILLOSCOPE

Terminal

GND

Output

VOLTMETER

SET

PIN 2

GND

Loop Ant.

SSG

SETL71

VTVM

OSCILLOSCOPE

Terminal

GND

Output

SET Frequency Adjustment Adjustment

153kHz L82 1.3 ± 0.05V

SSG Frequency SET Frequency Adjusting part Adjustment Remark

999kHz(9kHz Step), 1000kHz(10kHz Step) T2 450kHz±1kHz Maximize the output

SSG Frequency SET Frequency Adjusting part Adjustment

164kHz L71 254kHz TC81

Maximize the output

TAPE DECK ADJUSTMENT

1. AZIMUTH ADJUSTMENT

Figure 2. Azimuth Adjustment Connection Diagram

2. MOTOR SPEED ADJUSTMENT

Figure 3. Motor Speed Adjustment Connection Diagram

3. RECORD BIAS ADJUSTMENT

Figure 4. Record Bias Adjustment Connection Diagram

CH1 CH2

Speaker Out

Playback Mode

Head

Test Tape MTT-114

L ch

R ch

GND

Dual-trace synchroscope

Electronic Voltmeter

L out

R out

Unit

Head

Playback Mode

Unit

Speaker Out

GND

L out

R out

Record/Playback head

Test Tape MTT-111

Frequency Counter

Deck Mode Test Tape Test Point Adjust for Adjustment

Playback MTT-114 L/R Output R/L Maximum Azimuth adjusting screw

Deck Mode Test Tape Test Point Adjust for Adjustment

Rec/Pause MTT-5511 Q140 EMITTER 70kHz±800Hz L140

Deck Mode Test Tape Test Point Adjust for Adjustment

Playback MTT-111N L/R Output 3kHz±90Hz VR250 Playback MTT-111N L/R Output 5.4kHz~6.3kHz CONFIRM

Test Tape MTT-5511

Head

Record/Playback and Pause Mode

Unit

PN102

Frequency Counter

Record/Playback head

GND

CDP ADJUSTMENTS

When change the pick-up must be confirm as follow

1. TRACKING BALANCE CONFIRMATION

1. Connect the oscilloscope to TEO and REF.

2. Access from 1 st selection to last section of test disc (YEDS-18)

3. Confirm the normal state of tracking error signal (T.B deviation : less than ±3%)

2. RF WAVEFORM CONFIRMATION

1. Connect the oscilloscope to RF and REF.

2. Put a test disc (SONY YEDS-18) into unit and playback the 18th selection of the test disc.

3. Confirm the normal state of RF waveform.

4. Confirm the less than 30nS of Jitter Meter reading.

OV(DC Mode) T.B deviation(%)

= X %

A=B

A+B

A-B

100

3T, 4T 5T,6T 11T

EYE-PATTERN EYE-PATTERN

OK NG

• Connection : 1. IC501 pin 54.(TEO)

2. IC501 pin 50

• Inspection : Check tracking servo circuit.(RWD)

• Connection : 1. IC501 pin 54 .(TEO)

2. IC501 pin 50

• Inspection : Check tracking servo circuit.(FWD)

FOCUS GAIN TRACKING GAIN

• Connection : 3. IC502 pin 1 and 2 . Test disc : YEDS-43

• Inspection : Check focus servo circuit.

• Connection : 3. IC502 pin 26 and 27 Test disc: YEDS-43

• Inspection : Check tracking servo

circuit.

TRACKING ERROR(REW) TRACKING ERROR(FWD)

MAJOR WAVEFORM

∆V1=0.00V TRIG 1=1.0V ∆V2=0.00V

DLY>=0.85ms

1V 1V PEAKDET 1ms 1ms

SAVE

∆T=0.00ms

∆V1=0.00V TRIG 2=1.0V ∆V2=0.00V SREF 2 A

DLY>=0.85ms

1V 1V PEAKDET 1ms 1ms

∆T=0.00ms

∆V1=0.000V TRIG 1=0.09V

DLY>=4.25ms

0.5V PEAKDET 5ms 5ms

SAVE

∆T=0.00ms

∆V1=0.0% TRIG 1=-82%

DLY>=0.170s

>1V PEAKDET 0.2s 50ms

SAVE

∆T=0.000s

TRACKING COIL DRIVE E.F. BALANCE

• Connection : 1. IC501 pin 54 . (TEO)

2. IC501 pin 50

• Inspection : - Confirm tracking servo circuit.

- Check IC501 (Cold solder joint

or short circuit)

• Connection : 1. IC501 pin 54 .

• Inspection : Confirm tacking servo balance deviation rate

READING

• Connection : 7. IC501 pin 48 .

8. IC501 pin 40 (FOK)

• Inspection : Check IC501 pin 4 to IC501 pin

48 (Pattern defective)

∆V1=0.00V TRIG 1=-0.1V ∆V2=0.00V

DLY>=0.425s

1V 2V PEAKDET 0.5s 50ms

SAVE

∆T=0.000s

∆V1=3.96V TRIG 1=1.1V

DLY>=1.70ms

1V PEAKDET 2ms 2ms

SAVE

∆T=0.00ms

∆V1=0.00V TRIG 1=0.2V ∆V2=0.00V

DLY>=0.425s

2V 5V PEAKDET 0.5s 50ms

SAVE

∆T=0.000s

• Connection : 9. IC502 pin 17 and 18

• Inspection : - Check IC501 pin 43 to IC502 pin 20 (Pattern defective)

- Check voltage. (IC502 pin 20 )

• Connection : 10. IC501 pin 74 .

• Inspection : Check objective Lens of Pickup clear or not

• Connection : 11. IC502 pin 1 and 2 .

• Inspection : - Is focus search signal output to IC501 pin 48 ?

• Connection : 12. IC501 pin 33 .

• Inspection : Check IC503 and surrounding circuit (Cold solder joint or short circuit)

TRIG 1=1.1V

∆V2=0.000V

DLY>=0.085s

0.5V PEAKDET 0.1s 50ms

SAVE

∆T=0.000s

TRIG 1=24%

DLY>=0.670ms

50mV 0.5ms 0.5ms

∆V1=0.00V TRIG 1=0.3V

DLY>=0.085s

2V PEAKDET 1s 50ms

SAVESREF 3 A

∆T=0.00s

>2V

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