LG LMSW-550, LMU-550-D, LMW-550-A Service manual

3CD CHANGER DVD

SERVICE MANUAL

MODEL: LM-W550A LM-U550D LMS-W550

SERVICE MANUAL MODEL: LM-W550A LM-W550A, LM-U550D LMS-W550

- 1-1 -

[CONTENTS]

❍ SECTION 1. GENERAL

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

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

• SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-5

❍ SECTION 2. ELECTRICAL SECTION

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

• AUDIO PART TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

• BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-21

• SCHEMATIC DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-23

• WIREING DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-35

• PRINTED CIRCUIT DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-37

❍ SECTION 3. EXPLODED VIEWS

• CABINET AND MAIN FRAME SECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-1

• TAPE DECK MECHANISM (A/R & A/S : RIGHT A/R DECK) . . . . . . . . . . . . . . . . . . . . . . . . .3-3

• TAPE DECK MECHANISM (A/R & A/S : LEFT A/S DECK) . . . . . . . . . . . . . . . . . . . . . . . . . . .3-5

• CD MECHANISM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-7

❍ SECTION 4. SPEAKER PART

• SPEAKER PART . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1

❍ SECTION 5. REPLACEMENT PARTS LIST

• REPLACEMENT PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-1

- 1-2 -

❏ 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

Pressure

SECTION 1. GENERAL

- 1-3 -

• 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

UP

- 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.

- 1-5 -

❏ SPECIFICATIONS

NOTE : Specification are subject to change without notice in the course of product improvement.

- 1-6 -

- 2-1 -

VKK CHECK

P-SENS PART CHECK

CN701 3PIN DC -33V check

IC301 51PIN voltage check

SMPS Assy CN942 ➝ 5PIN 5V operation check

MAIN PCB CN701 5PIN 5V

MAIN PCB CN301 4PN 5V check

Refer to SMPS Troubleshooting

Refer to SMPS Troubleshooting

CN701 contact condition check

MAIN PCB PATTERN disconnection check

❏ TROUBLESHOOTING GUIDE

YES

YES

NO

NO

FRONT PN301 4PIN 5V check

FRONT IC304 operation status checck

u-COM 26PIN 5V check

YES

YES

YES

YES

YES

YES

NO

NO

Input voltage 4V or higer, output voltage

2.1V or higer operation check

IC304 KIA7042 replacement

SECTION 2. ELECTRICAL

- 2-2 -

Muting circuit Troublrshooting (MUTE condition)

Q752(A102) Base “HIGH”

Q604, Q605(D1302) BASE “HIGH” check

c-COM operation status check

Replace each related TR

Q603(A102) operation status check

Replace when Q603(A102) is defective

c-COM 2PIN(A-MUTE) LINE check

CN942/CN701 connection status
check

MUTE

YES

YES

YES

YES

NO

NO

NO

Unfelt voice

Input check (AUX ➝ 9.36 TUNER ➝ 6/39 TAPE ➝ 7/38CD ➝ 8/37PIN)

Check input and operation status for each function

YES

NO

IC601 20/25PIN output check

Refer to IC401(NJW1190) IC specification

YES

NO

IC601 input check (22/23PIN)

c-COM check and (CLK/DATA check)

YES

NO

IC601 output check (24PIN)

NORMAL

Check IC401 24PIN cover 8V and power circuit

YES

NO

Power operation staus check (DC12V)

R634 180(9.1)V check

YES

YES

NO

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Specific FUNCTION MODE unfelt voice

TAPE

IC202 9PIN (PB MUTE) operation check

c-COM 301 3.4PIN CLK/DATA operation check

DECK HEAD WIRE connection status check

Refer to IC201 Troubleshooting

IC201 input check (HAED input) “A” DECK 32,39 “B” DECK 34,37

YES

YES

NO

IC202 14PIN HIGH operation check

Q212(A102) BASE LOW check

Q201.202(GATE) HIGH operation check

NO

IC201 output check (5, 26PIN)

IC401 7, 38 signal input check

YES

NO

Replace IC202

YES

NO

Q212(A101) EMITTER 5V check

Q213(C103 COLLECTOP LOW) operation check

Replace Q213(C103)

YES

NO

YES

Q201,202 (DRAIN) GND check

YES

Replace defective parts

YES

Q212(A102) COLLECTOR 5V operation check

YES

Replace defective parts

YES

NO

A

A

- 2-4 -

AUX

JK601 signal input check

IC401 9,36PIN signal input check

YES

YES

MIC

IC401 1PIN input check

Refer to IC404 Toubleshooting

YES

YES

TUNER

Refer to TUNERMODULE

IC401 6,39PIN signal input check

YES

YES

CD

Check CN601 1,3PIN signal anad Refer to CD Troubleshooting

IC601 8,37PIN signal input check

YES

YES

MAIN PCB PATTERN check

NO

B

- 2-5 -

IC301 Troubleshooting

MIC PCB

IC406 6PIN power check and 2PIN input check

YES

MIC input pattern disconnection check and
after MIC insertion

NO

IC406 7PIN output check

YES

MIC MUTE operation status check

NO

PN401 3PIN output check

YES

NORMAL

YES

IC406 7PIN output check

NO

Replace IC406

NO

Check PN401 connection status
and IC301 20PIN status check

NO

JK401 input check

Q302 collector HIGH operation
check

Q302 (Replace C102)

IC301 17,46,72,90 power impression check

SMPS power 5V check

YES

NO

PN301 20PIN 5V impression chck

PN301 4PIN 5V P-SENS terminal check

YES

NO

X301 ossillates or not?

Replace X301

YES

NO

When IC301 11PIN power insert High ➝ LOW ➝ High

Replace IC301

Reset circuit check

YES

NO

Q302(C102M) operation staus check

NORMAL

YES

YES

NO

B

- 2-6 -

IC401 (NJW1190) Troubleshooting

IC401 24PIN power impression check

Refer to SMPS power check

YES

NO

IC401 22,23 Pulse waveform check (VOL UP,DOWN check while rotating VOL UP, DOWN

IC401 20,25 PIN waveform output check

IC301 10,8PIN check

IC401 7,37PIN(TAPE) input waveform check

YES

YES

YES

YES

NO

Replace IC601

NO

IC401 6,39(TUNER) PIN input waveform check

TAPE Troubleshooting

NO

IC401 8,37(CD) PIN input waveform check

TUNER module replacement

NO

YES

NO

IC401 9, 36(AUXO input waveform check

CD Troubleshooting

Nomal

Replace IC401

NO

MICOM(10,8) - IC601(21,22) PATTERN check

YES

IC301 Troubleshooting

NO

IC302, 202 (BU2090) Troubleshooting

IC301, 201 16PIN power impression check

SMPS power check

YES

NO

IC302,202 95,2,3PIN CLK data check

CONTROL function check

IC301 95,34,4PIN data check(When switching CD, TAPE FUNCTION)

NORMAL

YES

YES

NO

Replace IC302, 202 IC301, IC501 PATTERN check

NO

Pattern check between IC301 and IC501

YES

Refer to IC301 Troubleshooting

NO

- 2-7 -

AMP MODULE Troubleshooting

PN301, PN702 assembly status check

1. PN301(7,8), PN702(13,14) PWM DATA.CLK operation status check, PN301
PWM/CS534012PIN STA518A PWDN25 check

2. PN702:13PWM_SDA, 14PWM_SCL check

YES

NO

YES

NO

PN 7PIN 3.3V check power check

12.288MHz oscillation check

27PIN 3.3V check

YES

YES

YES

YES

YES

YES

SMPS power check

CS5340 2PIN MCLK/PS9813 48CLK_IN

Replace when 12.288 is defective

NO

IC702 41, 42, 43, 44 operation status check

SMPS power check

NO

IC801 power cehck

IC801 25,28PIN RESET check

NORMAL

OK

SMPS 32V power check

NO

IC301 79,81 PN301 12,14PIn check

NO

Play check

IC201 16PIN VCC power impression

IC201 5, 26PIN Signal Output check

IC201 14PIN Muting circuit check

Refer to SMPS power cehck

Replace IC201

Replace Deck Mecha

Deck Mecha operation performance check

YES

YES

YES

NO

NO

NO

- 2-8 -

Rec check (Q252, Q202 ON :R273, R223 High)

IC401 11,34 OUT check

IC401 each input 6, 39. TAPE. 7, 38. CD 8,38 AUX

9.36PIN signal input check

IC201 7,24PIN input check

IC201 10,21PIN output check

REC input check

Input LINE check

YES

YES

YES

NO

NO

L203 2,3PIN oscillation check

After REC output check, Replace defective IC

YES

NO

YES

NO

YES

NO

YES

NO

YES

NO

IC202 14PIN operation status check

IC202 4PIN operation check

Q205 Base 0.6V impression check

YES

Q213, 212 operation status check

YES

DECK replacement

YES

NO

Refer to power check

Q204 Collector Low

IC202 Troubleshooting check

Q203 replacement

Q204 replacement

NORMAL

L203 replacement