LG LMD-2340-A, LMD-2540-A, LMD-5540, LMD-6540 Service manual

- 1-1 -

[CONTENTS]

❍ SECTION 1.GENERAL

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

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

❍ SECTION 2.ELECTRICAL SECTION

• TROUBLESHOOTING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

• BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-11

• SCHEMATIC DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-13

• WIRING DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-27

• PRINTED CIRCUIT BOARD DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-29

❍ SECTION 3.DVD PART

• DVD ELECTRICAL TROUBLESHOOTING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1

• INTERNAL BLOCK DIAGRAM of ICs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7

• SCHEMATIC DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-27

• PRINTED CIRCUIT BOARD DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-33

❍ SECTION 4. EXPLODED VIEWS

• CABINET AND MAIN FRAME SECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

• TAPE DECK MECHANISM (A/R & A/S : LEFT A/S DECK) . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5

• TAPE DECK MECHANISM (A/R & A/S : RIGHT A/R DECK) . . . . . . . . . . . . . . . . . . . . . . . . .4-7

❍ SECTION 5. SPEAKER PART . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-1

❍ SECTION 6. REPLACEMENT PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . . .6-1

- 1-2 -

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.

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

Conductive Sheet

Cotton swab

Pressure

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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 (1M Ω)

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.

Resistor (1 Mohm)

Conductive Sheet

Resistor (1 Mohm)

Armband

RESET jump wire

VOLUME

VOLUME KNOB

DOWN

- 1-4 -

❏ 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 sur-

face 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 APROWHEAD SYMBOL. WITHIN AN EQUILATERAL TRIANGLE, IS INTENDED TO ALERT THE SERVICE PERSONNEL TO THE PRESENCE OF UNINSULATED “DANGEROUS VOLTAGE” THAT MAY BE OF SUFFICIENT MAGNITUDE TO CONSTITUTE A RISK OF ELECTRIC SHOCK.

THE EXCLAMATION POINT WITHIN AN EQUILATERAL TRIANGLE IS INTENDED TO ALERT THE SERVICE PERSONNEL TO THE PRESENCE OF IMPORTANT SAFETY INFORMATION IN SERVICE LITERATURE.

- 1-6 -

- 2-1 -

SECTION 2. ELECTRICAL

VKK CHECK

P-SENS CHECK

PN903 PIN5, CN302 PIN5 DC -33V check

IC301 PIN51 DC -33V check

ZD900 voltage check (+5.1V)

IC301 PIN26 check

ZD901(+) -33V check

D901(+) waveform check

D901 replacement

R902 check ZD900 replacement

Q902 TURN ON check

C919(-) -33V

up to

check

D908, D909 replacement

Troubleshooting check

Q902 replacement

normal

❏ TROUBLESHOOTING GUIDE

YES

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POWER CHECK

Every kinds of Fuse check

IC700 “12”(+VH2), 6(-VH2) PIN DC power output check

Fuse replacement

PN900 PIN1, 5 DC voltage output check

D900 PIN2, 3 AC check replacement

D900 replacement

Transformer replacement

CN901 PIN5 +12V(D) power check

CN901 PIN6, 7 DC +16V over power check

D901 AC voltage input check

Transformer replacement

IC902(7812) assemble check replacement

YES

NO NO

CN901 PIN3 +6.2V(D) power check

D913 AC voltage input check

IC902(7812) assemble check replacement

Transformer replacement

CN901 PIN6, 7 DC +16V up to power check

CN901 PIN5 +12V(D) power check

IC901(7805) assemble check replacement

YES

CN901 PIN4 +12V(A) power check

CN901 PIN6, 7 DC +16V over power check

D901 AC voltage input check

IC301

76 PWR-CTRL “HIGH” check

PATTERN check

Transformer replacement

IC301 replacement

CN901 PIN8 PWR - CTRL “HIGH” check

IC903(78R12) assemble check replacement

YES

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CN901 PIN11 +8V(A) power check

Transformer replacement

CD/DVD/KARAOKE FUNCTION CN901 PIN9 PIN DVDCTRL “HIGH” check

PATTERN Check

IC301 PIN81 DVD-CTRL “HIGH”check

IC301 “81” +16 PIN DC +16 over power check

IC301

replacement

YES

CN901 PIN5 +12V(D) power check

IC904(78R08) check

replacement

D913 AC voltage input check

IC902(7812)

assemble

check

replacement

Transformer replacement

CN901 PIN12 +5V power check

IC901 PIN10 DC +8V over power check

IC905(78R05) power check

D902/D903 AC power input check

YES

NO NO

CN901 PIN14 +3.3V power check

CN901 PIN10 DC +8V over power check

IC907(7805)/IC906(78R33) power check

D902/D903 AC power input check

Transformer replacement

YES

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Muting circuit Troubleshooting (if MUTE)

IC301 PIN91 F-MUTE “HIGH” check

Q791 “C” PORT “HIGH” check

Q700/Q750 “C” PORT SIGNAL check

IC301 PIN2 WOOFER-MUTE “HIGH” check

Q741 “C” PORT “HIGH” check

Q740 “C” PORT signal check

Q740 replacement

Q700/Q750 replacement

Muting mode check IC301 replacement

Q791 “E” PORT “HIGH” check

Q791 replacement

normal

Muting mode check IC301 replacement

Q741 “E” PORT HIGH check

Q741 replacement

PATTERN check

YES

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Q700/750 “C” signal check

JK700 SPEAKER output check

IC602 input check

Q795 “E” HIGH check

RY700 +12V(A) power check

RY700 replacement

IC601 input check

IC602 replacement

IC601 replacement

IC605 replacement

Q1725 TURN-ON check

Speaker short check

Q1720 “B” (+), (-) DC voltage check

IC700 replacement

+12V(A) power Troubleshooting refer

IC605 input check

each function TROUBLESHOOTING refer

no sound

YES

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AUX FUNCTION SPEAKER output

TAPE FUNCTION SPEAKER output

IC700 output check(Front -L/R)

Output sound Troubleshooting refer

IC601 PIN5, 24 input check(AUX -L/R)

IC601 replacement

IC602 PIN2, 9 input check (FRONT -L/R)

IC602 replacement

IC700 input check (Front -L/R)

IC602 PIN2, 19 input check

(FRONT -L/R)

IC700 replacement

IC602 replacement

JK600 AUX input signal cable or

external component sound output check

IC601 PIN4, 25 input check (IN -L/R)

IC605 PIN4, 11 input check

IC202 PIN5, 20 output check(TAPE -L/R)

IC605 replacement

IC601 replacement

IC601 PIN5, 24 input check(IN-L/R)

IC601 replacement

Specific FUNCTION MODE has no sound

YES

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CD/DVD function speaker output

IC602 PIN2, 19: F-L/R, 3, 17

PIN : R-L/R, PIN18: CNT input check

IC602 replacement

IC601 replacement

IC601 PIN3, 26 input check

(DVD -L/R)

PN600 PIN2, 4, 8, 10, 12

output check (DVD F-L/R, R-L/R, CNT)

PATTERN check

DVD Troubleshooting refer

TUNER FUNCTION SPEAKER output

IC602 PIN2, 19 input check

(FRONT -L/R)

IC602 replacement

IC601 replacement

TUN100 PIN2 VCC +9V check

TUN100 PLL -CE/CLK/DI/DO ter-

minal DATA correspondence check

IC601 PIN4, 25 input check

(FRONT -L/R)

IC605 PIN3, 5 input check

(TUNER -L/R)

Pattern check

Power +12V(A) check

YES

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IC301 U-COM IC Troubleshooting

IC301 pin17, 46, 72, 90 +5V power check

IC301 PIN26 5V check (POWER-SENS)

X301 oscilates or not

When IC301 pin11 voltage input Low➞High

IC301 replacement

CN302 PIN6 DC +5.6V check

PATTERN check

Troubleshooting Refer

P-SENS refer

X301 replacement

RESET circuit check

YES

IC501(EXPENDER IC) Troubleshooting

IC501

16 +5V power check

IC501 PIN2, 3 pin CLK Data check

CONTROLL function check

normal

Troubleshooting Refer

IC301 TROUBLESHOOTING refer

IC301, IC501 pattern check

IC301 PIN3, 4 Data check (CD, TAPE FUNCTION change)

IC501(BU2090F) replacement

YES

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IC700(AMP IC) Troubleshooting

10, 14 Signal input check

2(+VH2), 1(-VH2) power check

PIN3, 4, 5, 6 signal output check

Muting circuit refer

PIN3, 4, 5, 6 DC check

Power IC replacement

YES

TAPE PLAY

IC202 “18”pin VCC check

IC202 “5, 20”pin signal output check

Muting circuit check

Troubleshooting check refer

Deck Mecha operation check

IC202 replaement

Deck Mecha replaement

YES

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IC501 Troubleshooting refer

TAPE REC check (A252, Q202 On: R273, R223 High

IC202

11, 14 signal input check

IC202

9, 16 output check

IC201 ‘6”(12V) ,

4 High check

L203

5, 6 oscilates or not

DECK replaement

Q253, Q203 Base “Low” check

Q253, Q203

replaement

IC202 PIN18 VCC check

IC501 Troubleshooting check

C236(+) power input check

Troubleshooting check refer

IC501 Troubleshooting check

Q208

replaement

L203

replaement

Q208 Base 0.6V check

Q208 Collector Low

Q207

replaement

normal

YES

Dubbing check (“NORMAL”or “HIGH”) check

Q252, 202 “OFF”//”ON”: R273, 223 “LOW”// “HIGH”

Q253, 203 “OFF”//”ON”: R225, 275 “LOW”// “HIGH” IC501 Troubleshooting check

REC check refer

YES

❏ BLOCK DIAGRAM

2-11 2-12

2-13 2-14

❏ SCHEMATIC DIAGRAMS

• MAIN SCHEMATIC DIAGRAM

2-15 2-16

• MAIN(AMP), SUB POWER SCHEMATIC DIAGRAM

2-17 2-18

• MAIN(DECK) SCHEMATIC DIAGRAM

2-19 2-20

• FRONT SCHEMATIC DIAGRAM

2-21 2-22

• MIC SCHEMATIC DIAGRAM

2-23 2-24

• POWER, A/V JACK SCHEMATIC DIAGRAM

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