LG MCV902, MCS902F, MCS902S, MCS902W, MCS902AW Service Manual

MINI Hi-Fi SYSTEM

SERVICE MANUAL

MODEL : MCV902

(MCS902F, MCS902S, MCS902W, MCS902AW)

CAUTION

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

.

MODEL : MCV902 (MCS902F, MCS902S, MCS902W, MCS902AW)

SERVICE MANUAL

P/NO : AFN32840808

http://biz.lgservice.com

JANUARY, 2007

1-1

CONTENTS

SECTION 1
GENERAL

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

• NOTES REGARDING HANDLING OF THE PICK-UP

•

NOTES REGARDING COMPACT DISC PLAYER REPAIRS

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

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

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

SECTION 2
EXPLODED VIEWS

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

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

1. TAPE DECK MECHANISM

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

2. TAPE DECK MECHANISM

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

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

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

1. MODEL : MCS902F...........................................2-9

2. MODEL : MCS902S.........................................2-11

3. MODEL : MCS902W........................................2-13

4. MODEL : MCS902AW .....................................2-15

PACKING ACCESSORY VIEW.................................2-17

SECTION 3
AUDIO PART ELECTRICAL

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

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

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

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

4. MICOM (IC302) CHANGE.................................3-3

5. P-CTRL CHECK.................................................3-3

6.

MUTING TROUBLESHOOTING (MUTE STATE)

.......3-4

7. EXPEND IC (IC501/502) STATE.......................3-4

8. FUNCTION MODE HAS NO SOUND

(NJW1190) IC601...............................................3-5

9. IC601(NJW1190) TROUBLUSHOOTING ........3-8

10. AMP MODULE TROUBLESHOOTING ............3-9

11. REC CHECK

(Q201, Q202 ON : R276, R226 HIGH) ...........3-10

12. DUBBING CHECK

("NORMAL OR REC" // "HIGH") ......................3-11

INTERNAL BLOCK DIAGRAM OF ICs ...................3-12

1. HA12237F.........................................................3-12

2. NJW1190 ..........................................................3-13

3. AF330W20FT ...................................................3-13

4. AF350W01FT ...................................................3-15

WIRING DIAGRAM ....................................................3-18

BLOCK DIAGRAM.....................................................3-20

SCHEMATIC DIAGRAMS .........................................3-22

1. SMPS (POWER) SCHEMATIC DIAGRAM ....3-22

2.

SUB SMPS (POWER) SCHEMATIC DIAGRAM

....3-24

3. AUDIO MAIN SCHEMATIC DIAGRAM..........3-26

4. DECK SCHEMATIC DIAGRAM ......................3-28

5. USB, AUX2 & HEADPHONE AMP

SCHEMATIC DIAGRAM .................................3-30

6. I/O JACK SCHEMATIC DIAGRAM.................3-33

7. AMP SCHEMATIC DIAGRAM.........................3-34

8. WOOFER AMP SCHEMATIC DIAGRAM ......3-36

9. FRONT SCHEMATIC DIAGRAM ...................3-38

PRINTED CIRCUIT DIAGRAMS...............................3-40

1. MAIN P.C.BOARD............................................3-40

2. SMPS (POWER) P.C.BOARD ........................3-42

3. SUB SMPS (POWER) P.C.BOARD ...............3-43

4. FRONT P.C.BOARD ........................................3-44

5. AMP P.C.BOARD .............................................3-46

6. WOOFER AMP P.C.BOARD...........................3-48

SECTION 4
CD PART ELECTRICAL

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

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

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

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 DIAGRAM .................................4-17

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

SECTION 5
REPLACEMENT PARTS LIST

........5-1

1-2

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.

SERVICING PRECAUTIONS

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 (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.

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 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
MAGNITUDE 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.

1-5

LOCATION OF USERS CONTROLS

FRONT / BACK PANEL

1. • DISC SKIP button

• CD SELECT buttons (DISC1, DISC2, DISC3)

• OPEN/CLOSE button

2. DISPLAY WINDOW

3. (POWER) button

4. • XDSS button

• AUTO TUNING DOWN/UP button
REWIND / FAST FORWARD ( ) button

• PRESET DOWN/UP button
BACKWARD PLAY ( ) button : OPTIONAL
FORWARD PLAY ( ) button

• STOP ( ) / CLEAR button

• OAO button

5. • FUNCTION SELECT buttons
[TUNER, TAPE, CD, AUX / AV, USB]

• PLAY MODE/ DEMO button

• PROG. MEMO. button

• REC / PAUSE (RECORD/ RECORD

PAUSE) button

• SET/ RDS(OPTIONAL)/ CD[ ]/ AM-NOISE button

• VOLUME CONTROL KNOB

• EQ button

• SURROUND button

• USER EQ button

• MP3 OPT (MP3 OPTIMIZER) button

• MULTI JOG

MANUAL TUNING
CD SKIP ( )
CLOCK ADJUST

6. PHONES (HEADPHONE JACK) : ø6.3mm

7. PUSH EJECT position - TAPE 1

8. • GAME LINK connector (VIDEO IN, AUDIO L/R)

• USB connector

9. CD DOOR

10.CLOCK button

• TIMER button

• ST./ MONO/ NOR. DUBB. button

• CD SYNC./ HI-DUBB. button

11.• MIC1/ MIC2 (MIC JACK) : ø6.3 mm - OPTIONAL

• MIC VOL. (MIC VOLUME KNOB) - OPTIONAL

12. PUSH EJECT position - TAPE 2

13.SPEAKER TERMINAL (MCV902 model)

14.POWER CORD

15.SPEAKER TERMINAL (MCD502 model)

16.AM/ FM ANTENNA TERMINAL

17.AUX IN (AUXILIARY INPUT connector)

18.VIDEO OUT connector

19.WOOFER SYSTEM connector (MCV902 model)

20.SUB WOOFER SPEAKER TERMINAL

(MCV902 model)

1-6

REMOTE CONTROL

1-7

SPECIFICATIONS

MODEL

MCV902 MCD502

SECTION

Power supply Refer to the back panel of the unit.
Power consumption Refer to the back panel of the unit.

[GENERAL]

Net weight 8.45kg 8kg
External dimensions (WxHxD) 280 X 365 X 370mm

Frequency response 40 ~ 20000Hz

[CD] Signal-to-noise ratio 75dB

Dynamic range 80dB

Tuning range 87.5 ~ 108.0MHz or 65 ~ 74MHz, 87.5 ~ 108.0MHz
Intermediate frequency 10.7MHz

Signal to noise ratio 60/55dB

[TUNER]

Frequency response 140 ~ 10000Hz

Tuning range 522 ~ 1620 kHz or 520 ~ 1720kHz
Intermediate frequency 450kHz

Signal to noise ratio 30dB
Frequency response 140 ~ 1800Hz

Front : 270W + 270W (MCV902 Model)

Output power

250W + 250W (MCV502 Model)

Surround : 110W + 110W (MCV902 Model)

[AMP] Subwoofer : 175W + 175W (MCV902 Model)

T.H.D 0.7%
Frequency response 42 ~ 20000Hz

Signal-to-noise ratio 75dB

Ta pe speed 3000 3% (MTT-111. NORMAL-SPEED)
Wow flutter 0.25% (MTT -111, JIS-WTD)

F.F/REW Time 120sec (C-60)

[TAPE] Frequency response 125 ~ 8000Hz

Signal to noise ratio 43dB
Channel separation 50dB (P/B) / 45dB (R/P)

Erase ratio 55dB (MTT-5511)

Speaker name

Front speaker (L/R) Surround speaker (L/R)
MCS902F / MCS502F MCS902S

Type Bass reflex 2 way 2 speaker Bass reflex 2 way 2 speaker
Impedance 6Ω 24Ω
Frequency response 60 ~ 20000Hz 70 ~ 20000Hz

[Speakers] Sound rressure level 86dB/W (1m) 83dB/W (1m)

Rated input power 270W / 250W 110W
Max. input power 540W / 500W 220W
Net dimensions (W x H x D) 272 x 455 x 320mm 210 x 450 x 280mm

Net weight (1EA) 9.17kg 4.62kg

Speaker name MCS902AW MCS902W
Type 1 way 1 speaker 1 way 1 speaker

Impedance 12Ω 12Ω
Frequency response 55 ~ 1500Hz 55 ~ 1500Hz

[Subwoofer] Sound pressure level 85dB/W (1m) 85dB/W (1m)

Rated input power 175W 175W
Max. input power 350W 350W
Net dimensions (W x H x D) 273 x 370 x 322mm 273 x 370 x 322mm

Net weight (1EA) 7.3kg 7.3kg

* Design and specifications are subject to change prior notice.

FM

AM

(MW)

1-8

MEMO

283

A56

450

301

453

A41

A26

A46

275

450

250

255

288

265

259

268

260

450

450

450

454

248

283

450

450

302

266

265

292

450

450

450

450

261

293

274

274

269

271

289

277

276

454

281

451

282

A43

A00

A46

A47

A52

A51

453

456

450

450

450

291

270

303

452

450

450

450

450

279

280

454

454

305

455

278

285

454

457

FAN

450

CABLE2

CABLE1

CD

MAIN

FRONT

SMPS

SUB

SVC purchase order caution

MAIN board is array coming USB board.
Purchase order board separately supply
incomprehensible.
Supply is possible in Location No A46
state in exploded views.

CABLE5

CABLE6

2-1 2-2

SECTION 2 EXPLODED VIEWS

CABINET EXPLODED VIEW

023

015

022

019

037

021

020

018

017

006

A01

008

007

001

002

003

009

009

011

013

A02

025

2-3 2-4

TAPE DECK MECHANISM EXPLODED VIEW

1. TAPE DECK MECHANISM (A/R & A/S : A/R DECK)

2-5 2-6

016

018

007

008

015

019

021

020

017

A03

009

003

011

013

009

022

025

023

2. TAPE DECK MECHANISM (A/R & A/S : A/S DECK)

2-7 2-8

416

151

159

165

164

417

166

417

167

416

177

175

172

170

419

417

418

418

190

189

188

A30

A32

A26

181

187

186

184

421

421

185

156

155

153

173

168

163

162

441

440

422

A35

417

CD MECHANISM EXPLODED VIEW

2-9 2-10

A80BL

A80L

A80A

858

857

856

855

854

851

850

852

853

860

859

857

862

WIRE81

861

A80BR

A80R

A80A

858

857

856

855

854

851

850

852

853

860

859

857

862

WIRE80

861

SPEAKER EXPLODED VIEW

1. MODEL : MCS902F

2-11 2-12

A60BR

A60R

A60A

WIRE60

659

658

660

656

657

655

654

651

650

652

653

661

662

A60BL

A60L

A60A

WIRE61

659

658

660

656

657

655

654

651

650

652

653

661

662

2. MODEL : MCS902S

2-13 2-14

A90A

A90B

WIRE92

959

958

957

960

951

952

950

A91

961

962

958

3. MODEL : MCS902W

2-15 2-16

A90AW

A90BW

950A

WIRE91

WIRE90

953

954

955

956

963

958

959

957

951

952

A90

961

962

958

960

4. MODEL : MCS902AW

2-17

PACKING ACCESSORY VIEW

3-1

ELECTRICAL TROUBLESHOOTING GUIDE

SECTION 3 AUDIO PART ELECTRICAL

1. POWER (SMPS)

NO POWER

CHECK AC

LINE PATTERN

CONNECT

THE OPEN LINE

CHECK F901 FUSE REPLACE FUSE

CHECK BD901 + TO

- PIN IMPEDANCE

LOW IMPEDANCE

CHANGE ASSY

CHECK C986

VOLT(5.6V)

CHECK LINE SHORT

CHECK CONNECTION

CN902, CN903

NO SOUND

INSERT POWER CORD

AFTER 10 SECONDS

CHECK THE AMP
MODULE SHORT

CHECK C961, C951

VOLT (OVER 40V)

CHANGE

FR971, 972, 974, 975

CHECK C958, C968

VOLT (OVER 9V)

PORTECTION CHECK NO SOUND LISTS

DISPLAY INSERT POWER

CORD AFTER 1 MINUTE

3-2

2. P-SENS

P-SENS PART

YES

YES

SMPS ASS'Y CN902

- -> 7PIN 5.1V CHECK

SMPS TROUBLESHOOTING CONSULT

NO

YES

MAIN PCB CN710
7PIN 5.1V CHECK

CN710 CONNECTION STATE CHECK

NO

YES

MAIN PCB CN304
6PIN 5.1V CHECK

MAIN PCB PATTERN CUTTING

AND SHORT CHECK

IC304 KIA7042 CHANGEµ-COM IC302 1PIN 4.4V CHECK

NO

YES

FRONT PN304 35 PIN 5.1V CHECK

YES YES

FRONT IC304(RESET IC)

STATE CHECK

IC304 INPUT VOLTAGE 5V OVER

STATE CHECK AND OUTPUT VOLTAGE 4V

OVER STATE CHECK

NO

3. VKK CHECK

VKK CHECK

YES

YES

CN710 10PIN DC

-32V CHECK

SMPS TROUBLESHOOTING CONSULT

NO

IC301 50PIN VOLTAGE CHECK

3-3

5. P-CTRL CHECK

P-CTRL CHECK

YES

YES

PN304 32PIN

"P-CTRL" CHECK (HIGH)

MICOM IC302 STATE CHECK

YES

CN710 5PIN CHECK

SMPS + MAIN BORD-TO-BORD CHECK

NO

NO

SMPS TROUBLESHOOTING CONSULT

4. MICOM (IC302) CHANGE

MICOM (IC302)

CHANGE

IC302 CHANGE

"RESET"

IC302

10PIN CHECK(LOW

--> HIGH)

Q302, Q303

STATE CHECK

NO NO

YES

YES YES

YES

"P-SENS"

CHECK

NO

P-SENS

TROUBLESHOOTING

CONSULT

X301, X302 CHANGE

TR "Q302, Q303"

CHANGE

IC302 VDD

(19, 20, 59) PIN

VOLTAGE

CHECK

PN304 34PIN

+5.6V (MI) CHECK

NO NO NO

YES

X301:9.8304MHz,

X302:32.768KHz

VIBRATION SIGNAL

CHECK

NO

YES

YES

MAIN CN710

6PIN CHECK

SMPS

TROUBLESHOOTI

NG CONSULT