LG MCD112 Mini System.pdf

Internal Use Only

Website http://biz.lgservice.com

MINI Hi-Fi SYSTEM

SERVICE MANUAL

MODEL : MCD112 (MCS112F)

CAUTION

BEFORE SERVICING THE UNIT, READ THE “SAFETY PRECAUTIONS”

IN THIS MANUAL.

P/NO : AFN72956656

APRIL, 2009

CONTENTS

SECTION 1

GENERAL

SERVICING PRECAUTIONS ................................1-2

• NOTES REGARDING HANDLING

OF THE PICK-UP

• NOTES REGARDING COMPACT DISC

PLAYER REPAIRS

3. PS9829B ....................................................3-15

4. PT6324 .......................................................3-15

5. STR-S6757IF1905......................................3-16

6. TAS5142 .....................................................3-17

7. U1739EJ2V1UD00/KF2_E .........................3-18

WIRING DIAGRAM .............................................3-19

BLOCK DIAGRAMS ...........................................3-21

1. SMPS BLOCK DIAGRAM .........................3-21

2. MAIN & FRONT BLOCK DIAGRAM .........3-23

ESD PRECAUTIONS ............................................1-4

LOCATION OF USERS CONTROLS ....................1-5

SCHEMATIC DIAGRAMS ...................................3-25

1. SMPS SCHEMATIC DIAGRAM ................3-25

2. MAIN SCHEMATIC DIAGRAM..................3-27

3. AMP SCHEMATIC DIAGRAM ...................3-29

4. DECK SCHEMATIC DIAGRAM.................3-31

5. FRONT SCHEMATIC DIAGRAM .................3-33

6. KEY-L SCHEMATIC DIAGRAM ...................3-35

7. KEY-R SCHEMATIC DIAGRAM...................3-36

SPECIFICATIONS .................................................1-7

SECTION 2

EXPLODED VIEWS

CABINET EXPLODED VIEW ................................2-1

TAPE DECK MECHANISM EXPLODED VIEW ....2-3

1. TAPE DECK MECHANISM

(A/S & A/S : RIGHT A/S DECK) ..................2-3

2. TAPE DECK MECHANISM

(A/S & A/S : LEFT A/S DECK) ....................2-5

PRINTED CIRCUIT BOARD DIAGRAMS ...........3-37

1. MAIN P.C.BOARD .....................................3-37

2. FRONT P.C.BOARD ..................................3-41

3. SMPS P.C.BOARD ....................................3-43

4. KEY-L P.C.BOARD ....................................3-44

5. KEY-R P.C.BOARD ...................................3-44

CD MECHANISM EXPLODED VIEW ...................2-7

SPEAKER EXPLODED VIEW ..............................2-9

MODEL : MCS112F .........................................2-9

SECTION 4

CD PART ELECTRICAL

CD ELECTRICAL

TROUBLESHOOTING GUIDE ..............................4-1

1. CD PART TROUBLESHOOTING ................4-1

2. USB PART TROUBLESHOOTING..............4-9

PACKING ACCESSORY VIEW ...........................2-13

SECTION 3

AUDIO PART ELECTRICAL

AUDIO ELECTRICAL

TROUBLESHOOTING GUIDE ..............................3-1

1. POWER (SMPS) .........................................3-1

2. P-SENS .......................................................3-2

3. VKK CHECK................................................3-2

4. MICOM PART CHECK I ..............................3-2

5. MICOM PART CHECK II .............................3-3

6. IC103(KS4CD21CS) CHECK ......................3-4

7. FLD DISPLAY CHECK ................................3-5

8. PWM MODULATION PART CHECK ...........3-6

9. POWER AMP PART CHECK ......................3-7

10. AUX FUNCTION CHECK ............................3-8

11. TUNER FUNCTION CHECK .......................3-9

12. TAPE FUNCTION CHECK ........................3-10

13. TAPE PLAY PART CHECK ........................3-11

14. TAPE REC PART CHECK .........................3-12

WAVEFORMS OF MAJOR CHECK POINT .......4-10

SCHEMATIC DIAGRAMS ...................................4-13

1. CD SCHEMATIC DIAGRAM .....................4-13

2. USB SCHEMATIC DIAGRAM ...................4-15

PRINTED CIRCUIT BOARD DIAGRAM .............4-17

CD P.C.BOARD .............................................4-17

SECTION 5

REPLACEMENT

PARTS LIST ............................................5-1

INTERNAL BLOCK DIAGRAM OF ICs ..............3-13

1. ES6838 .......................................................3-13

2. HA12237F. ..................................................3-14

Only for training and service purposes

1-1

LGE Internal Use Only

SECTION 1 GENERAL

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.

LGE Internal Use Only

1-2

Only for training and service purposes

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 mag-

netism 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.

CLEARING MALFUNCTION

You can reset your unit to initial status if malfunction occur(button malfunction, display, etc.).

Using a pointed good conductor(such as driver), simply short the RESET jump wire on the inside of

the volume knob for more than 3 seconds.

If you reset your unit, you must reenter all its settings(stations, clock, timer)

NOTE : 1. To operate the RESET jump wire, pull the volume rotary knob and release it.

2. If you wish to operate the RESET jump wire, it is necessary to unplug the power cord.

Only for training and service purposes

1-3

LGE Internal Use Only

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 inte-

grated circuits and some field-effect transistors and semiconductor chip components. The following tech-

niques 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 know 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).

[CAUTION. GRAPHIC SYMBOLS]

THE LIGHTNING FLASH WITH ARROWHEAD SYMBOL. WITHIN AN EQUILATERAL

TRIANGLE, IS INTENDED TO ALERT THE SERVICE PERSONNEL TO THE PRESENCE

OF UNINSULATED "DANGEROUS VOLTAGE" THAT MAY BE OF SUFFICIENT MAGNI-

TUDE TO CONSTITUTE A RISK OF ELECTRIC SHOCK.

THE EXCLAMATION POINT WITHIN AN EQUILATERAL TRIANGLE IS INTENED TO

ALERT THE SERVICE PERSONNEL TO THE PRESENCE OF IMPORTANT SAFETY

INFORMATION IN SERVICE LITERATURE.

LGE Internal Use Only

1-4

Only for training and service purposes

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