LG LMSU-2350, LMSU-4050, LMSU-4050-W, LMSU-5050, LMSU-5050-S Service manual

3CD CHANGER
HI-FI SYSTEM

SERVICE MANUAL

P/N : 3829RAP006B JULY, 2005

MODEL: LM-U2350A, LMS-U2350

LM-U4050A, LMS-U4050, LMS-U4050W
LM-U5050A, LMS-U5050, LMS-U5050W, LMS-U5050S

SERVICE MANUAL MODEL: LM-U2350A, LMS-U2350, LM-U4050A, LMS-U4050, LMS-U4050W, LM-U5050A, LMS-U5050, LMS-U5050W, LMS-U5050S

CAUTION

BEFORE SERVICING THE UNIT, READ THE “SAFETY PRECAUTIONS” IN THIS MANUAL.

- 1-1 -

[CONTENTS]

❍ SECTION 1. GENERAL

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

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

• SPECIFICATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-5

❍ SECTION 2. ELECTRICAL SECTION

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

• INTERNAL BLOCK DIAGRAM of ICs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-10

• BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-15

• SCHEMATIC DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-19

• WIREING DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-43

• PRINTED CIRCUIT DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-45

❍ 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 -

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

Pressure

- 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

[General][CD]

[Tuner]

AM

FM

(MW)

[

Speakers

]

[Subwoofer]

[

TAPE

]

Power supply Refer to the back panel of the unit.
Power consumption 200 W 110 W

Weight 8.5 kg
External dimensions (W x H x D) 280 x 370 x 400 mm
Frequency response 40 - 18000 Hz
Signal-to-noise ratio 75 dB
Dynamic range 70 dB
Tuning Range 87.5 - 108.0 MHz or 65 - 74 MHz, 87.5 - 108.0 MHz
Intermediate Frequency 10.7 MHz
Signal to Noise Ratio 60/55 dB
Frequency Response 60 - 10000 Hz
Tuning Range 522 - 1620 kHz or 520 - 1720 kHz
Intermediate Frequency 450 kHz
Signal to Noise Ratio 30 dB
Frequency Response 120 - 2000 Hz
Output Power Front : 270 W + 270 W (LM-U5050 model only)

250 W + 250 W (LM-U4050/U2350 model only)
Surround : 110 W + 110 W (LM-U5050 model only)
Subwoofer : 350 W (LM-U5050/U4050 model only)

T.H.D 0.7%
Frequency Response 42 - 20000 Hz
Signal-to-noise ratio 80 dB
Tape Speed 3000 ± 3 % (MTT-111. NORMAL-SPEED)
Wow Flutter 0.25 % (MTT -111, JIS-WTD)
F.F/REW Time 120 sec (C-60)
Frequency Response 125 - 8000 Hz
Signal to Noise Ratio 40 dB
Channel Separation 50 dB (P/B)/45 dB (R/P)
Erase Ratio 55dB (MTT-5511)

Type Bass Reflex 3Way 3 Speaker Bass Reflex 2Way 2Speaker
Impedance 6Ω 24Ω
Frequency Response 55 - 20000 Hz 60 - 20000 Hz
Sound Pressure Level 86 dB/W (1m) 86 dB/W (1m)
Rated Input Power 270 W 250 W 110 W
Max. Input Power 540 W 500 W 220 W
Net Dimensions (W x H x D) 250 X 300 X 415 mm 187 X 258 X 415 mm
Weight 9.3 kg 4.3 kg

Speaker Name

Subwoofer (LMS-U5050W/U4050W)

Type 1 Way 1 Speaker
Impedance 6Ω
Frequency Response 45 - 15000 Hz
Sound Pressure Level 84 dB/W (1m)
Rated Input Power 350 W
Max. Input Power 700 W
Net Dimensions (W x H x D) 279 X 320 X 415 mm
Weight 10.0 kg

LM-U5050

MODEL

SECTION

LM-U4050 LM-U2350

[

Amp

]

Front speaker (L/R)

LMS-U5050 LMS-U4050/U2350

Surround speaker (L/R)

[LMS-U5050S]

Speaker Name

- 1-6 -

- 2-1 -

SECTION 2. ELECTRICAL

❏ ELECTRICAL TROUBLESHOOTING GUIDE

■ SMPS POWER CIRCUIT

P-SENS PART

VKK CHECK

SMPS ASSY CN902 ➞ 7PIN 5.1V CHECK

MAIN PCB CN710 7PIN 5.1V CHECK

MAIN PCB CN304 5PIN 5.1VCHECK

FRONT PN302 36PIN 5.1VCHECK

FRONT IC306(RESET IC)

STATE CHECK

U-COM IC304 26PIN 5VCHECK

SMPS TROUBLESHOOTING CONSULT

CN710 CONNECTION STATE CHECK

MAIN PCB PATTERN CUTTING AND

SHORT CHECK

IC306 INPUTVOLTAGE4V,
OUTPUTVOLTAGE.2.1VSTATECHECK

IC306 KIA7042 CHANGE

NO

NO

NO

YES

YES

YES

YES

YES

CN710 10PIN DC -33V CHECK

IC304 51PIN VOLTAGE CHECK

SMPS TROUBLESHOOTING CONSULT

NO

YES

- 2-2 -

MICOM (IC301) CHECK

P-CTRL CHECK

"P-SENS" CHECK

"RESET" IC304 11 PIN CHECK

(HIGH

➞

LOW ➞HIGH)

X301 VIBRATION SIGNAL CHECK

IC301 CHANGE

PN302 33 PIN "P-CTRL" CHECK (HIGH)

CN710 5 PIN CHECK

SMPS TROUBLESHOOTING CONSULT

IC304 VDD(17,46,72,90) PIN VOLTAGE

CHECK

P-SENS TROUBLESHOOTING CONSULT

Q303 STATE CHECK

TR "Q303" CHANGE

SMPS TROUBLESHOOTING CONSULT

MICOM IC304 STATE CHECK

SMPS + MAIN BORD-TO-BORD CHECK

MAIN CN710 6 PIN CHECK

PN302 35 PIN +5.6V(MI) CHECK

X301 CHANGE

NO

NO

NO

NO

YES

YES

YES

YES

NO

NO

YES

YES

- 2-3 -

MUTING TROUBLESHOOTING (MUTE STATE)

EXPEND IC(IC305/501/502) STATE

Q752(A102) BASE "HIGH"

Q701, Q751(D1302) BASE "HIGH"

CHECK

16 PIN VDD VOLTAGE CHECK

3 "EXP-CLK" CHECK

2 "EXP-DATA" CHECK

4 PIN ~ 15 PIN EACH PORT STATE

CHECK

EXPEND IC OK

MUTE

EXPEND IC(IC305) 5PIN HIGH STATE
CHECK

Q752(A102)STATE CHECK

Q752(A102) FAULTY IS CHANGE

EACH PART TR CHANGE

D332/D553/D551(1SS133) CHECK

D332/D553/D551(1SS133)
CHANGE

PCB PATTERN CHECK

PCB PATTERN CHECK

MICOM (IC304) 4/84/85 PIN
CHECK(CLK1/2/3)

MICOM (IC304) 3 PIN CHECK

EXPEND IC FAULTY IS CHANGE

NO

NO

NO

NO

NO

NO

NO

NO

NO

YES

YES

YES

YES

YES

YES

YES

YES

YES

YES

YES

YES

- 2-4 -

SPECIFIC FUNCTION MODE HAS NO SOUND (NJW1190) IC601

IC201 INPUT CHECK(HEAD

INPUT)"A"DECK 32,39 "B"DECK 34,37

DECK HEAD WIRE

CONNECTION STATE CHECK

IC502 10PIN(PB MUTE) STATE

STATE CHECK

IC502 4PIN(REC SW) "LOW"

STATE REC

Q212 (C) "HIGH" CHECK

Q213 (C) "LOW" CHECK

IC502 13 PIN "REC-BAIS" HIGH

CHECK

L203(4.7MH) COIL VIBRATION

SIGNAL CHECK

IC601 7 /32 INPUT REC'

SIGNAL CHECK

IC502 4PIN(REC SW) "HIGH"

CHECK

IC601(NJW1190)

TROUBLESHOOTING CONSULT

IC502 2 PIN/3 PIN

CHECK(DATA/CL

IC502 16 PIN VDD CHECK

IC502 EXPEND IC CHANGE

IC201 OUTPUT CHECK(5,26 PIN)

IC601 3,36PIN INPUT SIGNAL CHECK

IC601 17,22 PIN OUTPUT SIGNAL

CHECK

DECK OUTPUT

1)

1)

YES

YES

YES

YES

YES

YES

YES

YES

YES

YES

YES

YES

NO

NO

NO

NO

NO

- 2-5 -

AUX

JK601 SIGNALINPUT CHECK

IC601 5,34 PIN SIGNALINPUTCHECK

IC601 17,22 PIN OUTPUT SIGNAL

CHECK

MAIN PCB PATTERN CHECK

IC601(NJW1190)

TROUBLESHOOTING CONSULT

MAIN PCB PATTERN CHECK

IC601(NJW1190)

TROUBLESHOOTING CONSULT

AUX OUTPUT

CD

CN709 1,3PIN SIGNALCHECK CD

TROUBLESHOOTINGCONSULT

IC601 4,35PIN SIGNALINPUTCHECK

IC601 17,22 PIN OUTPUT SIGNAL

CHECK

CD OUTPUT

YES

YES

YES

YES

YES

YES

YES

YES

NO

NO

NO

NO

- 2-6 -

TUNER

TU101 3 /5 SIGNAL CHECK

IC601 2,37 PIN SIGNALINPUTCHECK

IC601 17,22 PIN OUTPUT SIGNAL

CHECK

TU101 2 PIN "+9V"

VOLTAGE CHECK

TU101 6,7,8,9 PIN CHECK

(PLL-CE, PLL-DI, CLK, PLL-DO)

TUNER MODULE CHANGE

TUNER OUTPUT

MIC

CN303 7 PIN "MIC-SIGNAL" CHECK

IC601 44 PIN SIGNAL CHECK(OW601

PATTERN)

IC601 17,22 PIN OUTPUT SIGNAL

CHECK

CN303 4 MIC-SENSE CHECK

PN400 3 PIN "+12V"CHECK

TR CHANGE

MIC MUTE CHECK(Q409/ Q408)

IC402 8 PIN SIGNAL INPUT CHECK

PN400 9 "VOL-IN"CHECK

IC402 2 PIN SIGNAL INPUT CHECK

PN400 10 PIN "VOL-OUT"CHECK

MIC OUTPUT

<MIC PCB>

YES

YES

YES

YES

YES

YES

YES

YES

YES

YES

YES

YES

NO

NO

NO

NO

NO

- 2-7 -

IC601(NJW1190) TROUBLESHOOTING

IC601 24PIN VOLTAGE INPUT CHECK

IC601 19,20 SDA, SCA PULSE WAVE

CHECK (VOL UP, DOWN TURN CHECK)

IC601 17.22 PIN WAVE OUTPUT CHECK

IC601 OK

FUNCTION INPUT PORT SIGNAL

CHECK(NJW1190 TROUBLESHOOTING)

SMPS VOLTAGE CHECK CONSULT

IC301 10,8PIN CHECK

IC301 TROUBLESHOOTING

IC601 CHANGE

NO

NO

NO

YES

YES

YES

YES

YES

YES

YES

YES

YES

AMP MODULE TROUBLESHOOTING

IC501 9 PIN(AMP-PWR)HIGH CHECK

EXPEND IC TROUBLESHOOTING CONSULT

PROTECTION " HIGH" ➞ SMPS VOLTAGE

AND AMP ON/ OFF STATE CHECK

AMP MODULE CHECK : MOS FET BOTH

ARE READ SHORT ➞AMP DEAD

AMP MODULE CHANGE

IC305 9 PIN(AMP-PWR) HIGH CHECK

IC701 11 PIN "AMP-ON/OFF" HIGH

CHECK

IC701 12 PIN "PROTECTION" LOW

CHECK

PN702 3 PIN "PROTECTION"CHECK

(HIGH ➞ LOW)

NO

NONO

IC701 3 ,20 & 5 ,18 EACH +65V &-65V

CHECK

SMPS TROUBLESHOOTING CONSULT

YES

NO

- 2-8 -

IC701 9 ,14 ±9V CHECK

IC701 10 , 13 INPUT SIGNAL CHECK

IC701 5 ,17 OUTPUT SIGNAL CHECK

OK

SMPS TROUBLESHOOTING CONSULT

REC INPUTCHECK CHECK

INPUT LINE CHECK

IC202 4PIN STATECHECK

Q205 BASE 0.6V CHECK

VOLTAGE CHECK CONSULT

IC202 TROUBLESHOOTING CHECK

Q204 CHANGE

L203 CHANGE

Q204 COLLECTOR LOW

Q203 CHANGE

OK

REC OUTPUTCHECK AFTER FAULTY IS ICCHANGE

YES

YES

YES

YES

YES

YES

YES

YES

YES

YES

NO

REC CHECK (Q252,Q202 ON :R273,R223 HIGH)

IC601 24PIN VOLTAGE INPUT CHECK

IC201 7,24 PIN INPUT CHECK

IC201 10.21 PIN OUTPUT CHECK

L203 2,3PIN CHECK

IC202 14 PIN STATESTATE CHECK

Q213.212 STATE STATECHECK

DECK CHANGE

IC401 EACH INPUTTUNER6,39.TAPE.

7.38.CD. 8.38.AUX.9.36 PIN SIGNAL
INPUT CHECK

NO

NO

NO

NO

NO

NO

NO

NO

- 2-9 -

DUBBING CHECK ("NORMAL OR REC"//"HIGH")

IC401 11,34 OUTCHECK

REC INPUTCHECK CHECK

INPUT LINE CHECK

IC201 7,24 PIN INPUT CHECK

IC201 10.21PIN OUTPUT CHECK

IC401 EACH INPUTTUNER6,39.TAPE.

7.38.CD.8.38.AUX.9.36PIN SIGNAL
INPUT CHECK

YES

YES

YES

NO

NO

- 2-10 -

❏ INTERNAL BLOCK DIAGRAM of ICs

• HA12237F

BLOCK DIAGRAM