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.

Storage in conductive bag

Drop 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.

NEVER look directly at the laser beam, and don¡˙t let contact fingers or other exposed skin.

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.

Pressure

Magnet

Pressure

How to hold the pick-up

Cotton swab

Conductive Sheet

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.

4

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

	Resistor
Resistor	(1 Mohm)
(1 Mohm)	Conductive
	Sheet

5

CAUTION

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).

6

2. AM IF Adjustment

		L71	VTVM	OSCILLOSCOPE
SSG	Loop Ant.		SET
			Output
			Terminal
			GND

Figure 2.

SSG Frequency	SET Frequency	Adjusting part	Adjustment	Remark
1008kHz(9kHz Step)		T2	450kHz±1kHz	Maximize the output

3. AM Coverage Adjustment

SET		VOLTMETER			SET Frequency	Adjustment	Adjustment
					522kHz(9kHz Step)	L72	1.0V ± 0.05V
	PIN 2
	GND

Figure 3.

4. AM Tracking Adjustment

SSG	Loop Ant.		VTVM	OSCILLOSCOPE
		L71	SET
			Output
			Terminal
			GND

Figure 4.

	SSG Frequency	SET Frequency	Adjusting part	Adjustment
	603kHz(9kHz Step)		L71	Maximize the output
	1404kHz(9kHz Step)		TC71

8

5. FM IF Adjustment

	VTVM	OSCILLOSCOPE
SSG	SET
	Output
PIN1	Terminal
GND	GND

Figure 5.

SSG Frequency	SET Frequency	Adjusting part	Adjustment	Remark
90MHz	90MHz	T1	10.7MHz	Maximize the output

6. FM Coverage Adjustment

VOLTMETER

SET

SET Frequency

Adjusting Part

Adjustment

76MHz

L2

1 ± 0.05V

PIN 2

GND

Figure 6.

7. FM Tracking Adjustment

SET

VTVM

OSCILLOSCOPE

SSG

Output

PIN1

Terminal

GND

GND

Figure 7.

SSG Frequency

SET Frequency

Adjusting part

Adjustment

78.6MHz

78.6MHz

L1

Maximize the output

101.75MHz

101.75MHz

TC1

9

10. LW IF Adjustment

SSG		L71	SET	VTVM	OSCILLOSCOPE
	Loop Ant.
			Output
			Terminal
			GND
			Figure 10.
SSG Frequency	SET Frequency		Adjusting part	Adjustment	Remark
999kHz(9kHz Step), 1000kHz(10kHz Step)			T2	450kHz±1kHz	Maximize the output

11. LW Coverage Adjustment

		VOLTMETER
SET					SET Frequency	Adjustment	Adjustment
					153kHz	L82	1.3 ± 0.05V
	PIN 2
	GND
	Figure 11.

12. LW Tracking Adjustment

SSG	Loop Ant.		VTVM	OSCILLOSCOPE
		L71	SET
			Output
			Terminal
			GND
		Figure 12.
SSG Frequency		SET Frequency	Adjusting part	Adjustment
	164kHz		L71	Maximize the output
	254kHz		TC81

10

TAPE DECK ADJUSTMENT

1. AZIMUTH ADJUSTMENT

Deck Mode	Test Tape	Test Point	Adjust for	Adjustment
Playback	MTT-114	L/R Output	R/L Maximum	Azimuth adjusting screw

	Head
		L ch
	Test Tape	R ch
	MTT-114

Electronic	Dual-trace
Voltmeter	synchroscope
Playback Mode Speaker Out
L out	CH1 CH2
Unit	GND
R out

Figure 2. Azimuth Adjustment Connection Diagram

2. MOTOR SPEED ADJUSTMENT

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

Head	Speaker Out	Frequency Counter
	Playback Mode
Test Tape	L out
	Unit
MTT-111
Record/Playback	R out
	GND
head

Figure 3. Motor Speed Adjustment Connection Diagram

3. RECORD BIAS ADJUSTMENT

Deck Mode	Test Tape	Test Point	Adjust for	Adjustment
Rec/Pause	MTT-5511	Q140 EMITTER	70kHz±800Hz	L140

	Head	Record/Playback	PN102	Frequency Counter
		and Pause Mode
	Test Tape	Unit
	MTT-5511
	Record/Playback			GND
	head

Figure 4. Record Bias Adjustment Connection Diagram

11

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%)

			A
				OV(DC Mode)	T.B deviation(%)
					=	A-B		X	100	%
			B			A+B			2

A=B

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.

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

OK	NG
EYE-PATTERN	EYE-PATTERN

13

MAJOR WAVEFORM
	TRACKING ERROR(REW)
V1=0.00V		TRIG 1=1.0V	T=0.00ms
V2=0.00V			SAVE
1			1
2			2
			DLY>=0.85ms
1V	1V	PEAKDET 1ms 1ms

•Connection : 1. IC501 pin 54.(TEO)

2.IC501 pin 50

•Inspection : Check tracking servo

circuit.(RWD)

TRACKING ERROR(FWD)

V1=0.00V		TRIG 2=1.0V			T=0.00ms
V2=0.00V		SREF	2	A
					DLY>=0.85ms
1V	1V	PEAKDET 1ms				1ms

•Connection : 1. IC501 pin 54 .(TEO)

2.IC501 pin 50

•Inspection : Check tracking servo

circuit.(FWD)

FOCUS GAIN
V1=0.000V	TRIG 1=0.09V	T=0.00ms
			SAVE
			4
3
		DLY>=4.25ms
0.5V	PEAKDET 5ms		5ms

• Connection : 3. IC502 pin 1 and 2 .

Test disc : YEDS-43

• Inspection : Check focus servo circuit.

TRACKING GAIN

V1=0.0%	TRIG 1=-82%	T=0.000s
			SAVE
		DLY>=0.170s
>1V	PEAKDET 0.2s		50ms

• Connection : 3. IC502 pin 26 and 27

Test disc: YEDS-43

• Inspection : Check tracking servo circuit.

14

	TRACKING COIL DRIVE
V1=0.00V		TRIG 1=-0.1V	T=0.000s
V2=0.00V				SAVE
1
				1
2
			DLY>=0.425s
1V	2V	PEAKDET 0.5s		50ms

•Connection : 1. IC501 pin 54 . (TEO)

2.IC501 pin 50

•Inspection : - Confirm tracking servo circuit.

-Check IC501 (Cold solder joint or short circuit)

E.F. BALANCE

V1=3.96V	TRIG 1=1.1V	T=0.00ms
			SAVE
		DLY>=1.70ms
1V	PEAKDET 2ms		2ms

•Connection : 1. IC501 pin 54 .

•Inspection : Confirm tacking servo balance

deviation rate

		READING
V1=0.00V		TRIG 1=0.2V	T=0.000s
V2=0.00V				SAVE
7
8
			DLY>=0.425s
2V	5V	PEAKDET 0.5s		50ms

•Connection : 7. IC501 pin 48 .

8.IC501 pin 40 (FOK)

•Inspection : Check IC501 pin 4 to IC501 pin

48 (Pattern defective)

15

TRIG 1=1.1V	T=0.000s	TRIG 1=24%
V2=0.000V	SAVE

9

10

	DLY>=0.085s		DLY>=0.670ms
0.5V	PEAKDET 0.1s 50ms	50mV	0.5ms 0.5ms

•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

V1=0.00V TRIG 1=0.3V	T=0.00s
SREF 3 A	SAVE

12

11

		DLY>=0.085s
	2V	PEAKDET 1s	50ms			>2V
• Connection : 11. IC502 pin 1 and			2 .		• Connection : 12. IC501 pin 33 .
• Inspection : - Is focus search signal output to					• Inspection : Check IC503 and surrounding
		IC501 pin 48 ?				circuit (Cold solder joint or short
						circuit)

16