LG MCD206 User manual

MINI Hi-Fi SYSTEM
SERVICE MANUAL
MODEL: MCD206 (MCD206, MCS206F)
CAUTION
BEFORE SERVICING THE UNIT, READ THE “SAFETY PRECAUTIONS”
IN THIS MANUAL.
MODEL: MCD206 (MCD206, MCS206F)SERVICE MANUAL
1102,OCTOBER95369457NFA:ON/P
Website http://biz.lgservice.com
Internal Use Only

CONTENTS
SECTION 1 ........ SUMMARY
SECTION 2 ........ CABINET & MAIN CHASSIS
SECTION 3 ........ ELECTRICAL
SECTION 4 ........ REPLACEMENT PARTS LIST
1-1

SECTION 1
SUMMARY
CONTENTS
SERVICING PRECAUTIONS................................................................................................................... 1-3
ESD PRECAUTIONS .................................................................................................................................. 1-5
SERVICE INFORMATION FOR EEPROM .......................................................................................... 1-6
PROGRAM UPDATE GUIDE................................................................................................................... 1-7
SPECIFICATIONS ....................................................................................................................................... 1-8
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 lens.
6) Never attempt to disassemble the pick-up.
Spring has 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 allow
contact with fingers or other exposed skin.
Magnet
How to hold the pick-up
Conductive Sheet
Cotton swab
Pressure
Pressure
1-3
SERVICING PRECAUTIONS

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 or humidity is high, where strong magnet-
ism 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 (1 MΩ)
6) Care should be taken not to permit the laser pick-up to come in contact with clothing, in order to prevent stat-
ic 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.
Resistor
(1 MΩ)Conductive
Sheet
Resistor
(1 MΩ)
Armband
1-4

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 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 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
ESD PRECAUTIONS

SERVICE INFORMATION FOR EEPROM
POWER ON
Completed
FLD ‘OPT-XXXXXX'
Press Set Front ‘STOP’ Key +
Remote control ‘FWD SKIP’ Key.
Set Front ‘STOP’ Key + Remote
control ‘FWD SKIP’ Key push same
timing during 5 seconds.
FLD Display ‘E2P CLR’
Press ‘POWER’ key.
Press Set Front "Play" Key
and move to appropriate position.
Make changes with
Set Front ‘FWD SKIP’ Key.
FLD Display "NO DISC"
DETECT NEW EEPROM
NAME HEX
OPT 000000 (FM)
OPT 000100 (FM_RDS)
OPT 001010 (FM_AM)
. .
. .
. .
1-6

PROGRAM UPDATE GUIDE
HOW TO UPDATE MCS PROGRAM
(1) Change the file name to download as “(MODEL NAME)_(Version)_(Date).mcs”.
Ex) MCD206_VER07_0328_052010.mcs
(2) Copy the file to the root folder of USB storage.
(3) Put the USB into the set.
Change set function to USB function.
Then the upgrade process will be started with the upgrade information.
FLD Display "UPGRADE".
(4) If the upgrade process is complete,
the set will be rebooted with “SUCCESS” message and set auto power off.
(5) Pull out the USB Storage.
Press the power key.
1-7

SPECIFICATIONS
• GENERAL
Power supply 200 - 240 V , 50 - 60 Hz
Power consumption 50 W
Net Weight 4.8 kg
External dimensions (W x H x D) 272 x 334 x 355 mm
Operating conditions Temperature 5 °C to 35 °C (41 °F to 95 °F)
Operation status: Horizontal
Operating humidity 5 % to 85 %
• TUNER
FM Tuning Range 87.5 to 108.0 MHz or 87.50 to 108.00 MHz
AM Tuning Range (optional) 522 to 1 620 kHz or 520 to 1 710 kHz
• AMPLIFIER
Output Power 100 W x 2
• CD
Frequency Response 40 Hz to 20 kHz
Signal-to-noise ratio 70 dB
Dynamic range 70 dB
• USB
USB Version USB 2.0 or USB 1.1
Bus Power Supply DC 5 V 500 mA
• SPEAKERS
Type 2 Way 2 Speaker
Impedance 4 Ω
Rated Input Power 50 W
Max. Input Power 100 W
Net Dimensions (W x H x D) 201 x 339 x 220 mm
Net Weight(1EA) 2.19 kg
Note : Design and specifications are subject to change prior notice.
1-8

SECTION 2
CABINET & MAIN CHASSIS
CONTENTS
EXPLODED VIEWS..................................................................................................................................... 2-3
1. CABINET AND MAIN FRAME SECTION (MCD206) ............................................................................... 2-3
2. PACKING ACCESSORY SECTION ......................................................................................................... 2-7
3. SPEAKER SECTION (MCS206F)............................................................................................................. 2-8
2-1

2-2
MEMO

2-3 2-4
EXPLODED VIEWS
1. CABINET AND MAIN FRAME SECTION (MCD206)
SMPS
D
A
A47
L
KEY-R
I
H
B
MAIN
USB
G
C
E
F
G
F
E
I
J
K
J
K
L
265
A43
CABLE4
KEY-L
FRONT
264
300
268
267
251
253
A41L
A41R
CABLE6
259
250
CABLE5
CABLE3
B
A
C
D
453
453
453
451
451
451
453
453
453
454
454
454
453
452
452
452
455
452
A26
266
454
453
A45
A44
H
252
258
257
A46
256L
255L
255R
256R
272

2-5 2-6
MEMOMEMO

2-7
2. PACKING ACCESSORY SECTION
Battery808
Remote Controller
900
803T Packing
Bag
804
801
Box802
803B Packing
Instruction Ass'y

2-8
3. SPEAKER SECTION (MCS206F)
A60

SECTION 3
ELECTRICAL
CONTENTS
ELECTRICAL TROUBLESHOOTING GUIDE.................................................................................... 3-2
1. SMPS PART ........................................................................................................................................... 3-2
2. AMP ABNORMAL ................................................................................................................................... 3-4
3. FUNCTION MODE AUDIO ABNORMAL ................................................................................................ 3-5
4. DISPLAY ABNORMAL............................................................................................................................ 3-9
WAVEFORMS............................................................................................................................................. 3-10
1. CD SEARCHING WAVEFORM ............................................................................................................ 3-10
2. SPINDLE DRIVE & MOTOR WAVEFORM .......................................................................................... 3-10
3. CD PLAYING WAVEFORM .................................................................................................................. 3-11
4. CD STOP ACTION WAVEFORM ......................................................................................................... 3-12
5. CD READING WAVEFORM ................................................................................................................. 3-13
6. USB OPERATING WAVEFORM .......................................................................................................... 3-14
7. RADIO OPERATING WAVEFORM ...................................................................................................... 3-14
WIRING DIAGRAM.................................................................................................................................... 3-15
BLOCK DIAGRAMS ................................................................................................................................. 3-17
1. SMPS BLOCK DIAGRAM..................................................................................................................... 3-17
2. CD BLOCK DIAGRAM.......................................................................................................................... 3-19
CIRCUIT DIAGRAMS ...............................................................................................................................3-21
1. SMPS CIRCUIT DIAGRAM .................................................................................................................. 3-21
2 . AMP CIRCUIT DIAGRAM.................................................................................................................... 3-23
3. CD DSP CIRCUIT DIAGRAM ............................................................................................................... 3-25
4 . DISPLAY & CONTROL CIRCUIT DIAGRAM ...................................................................................... 3-27
CIRCUIT VOLTAGE CHART ................................................................................................................. 3-29
PRINTED CIRCUIT BOARD DIAGRAMS.......................................................................................... 3-33
1. MAIN P.C.BOARD ................................................................................................................................ 3-33
2. SMPS P.C.BOARD ............................................................................................................................... 3-35
3. FRONT P.C.BOARD ............................................................................................................................. 3-36
4. KEY P.C.BOARD .................................................................................................................................. 3-37
5. USB P.C.BOARD .................................................................................................................................. 3-38
3-1

3-2
ELECTRICAL TROUBLESHOOTING GUIDE
31 V abnormal
F901 nomal?
TH901 nomal?
BD901 nomal?
Is VCC (9V-25V)
supplied to IC901 pin4?
Replace F901 (Use same type fuse).
Replace TH901.
Replace BD901.
D941 nomal?
Replace ZD908.
Q904 nomal?
Check or replace Q904.
Replace D941.
YES
YES
NO
NO
YES
YES
YES
NO
NO
NO
NO
NO
1. SMPS PART

3-3
5 V abnormal
F901 nomal?
D959 nomal?
TH901 nomal?
BD901 nomal?
IC957 nomal?
Is VCC (9V-25V)
supplied to IC902 Pin5?
Replace F901 (Use same type fuse).
Replace D959.
Replace TH901.
Replace BD901.
Replace IC957.
ZD902 nomal?
Power line of main PCB is short.
D907 nomal?
Check or replace D907.
Replace ZD902.
YES
YES
NO
NO
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
NO
ELECTRICAL TROUBLESHOOTING GUIDE

3-4
ELECTRICAL TROUBLESHOOTING GUIDE
Check U701
pin7,17 high.
Check U601
pin86,87 signal.
Check U701
pin6,8,16,18 whether
PWM signal.
Check U701
pin44,21,22,23,26,27,
32,35,40,41 whether
12V & 22V.
Check U601
pin19 “DAC_CK”,
pin20 “DAC_RCK”,
pin23 “DAC_DATA”
data signal.
Check
U601pin70,71,74,75
PWM signal.
Check U601
pin78 “PWM_DATA”,
pin79 “PWM_CLK”,
pin96 “PWM_RESET”
data signal.
Check U701
pin28,31,36,39 PWM
output signal.
Check the speakers
connection.
Check L701,702
pin2, 4 output signal.
Check U701
pin2,5 data signal.
Check
L703,L704,L705,L706,
C711,C712.
Check FB600, U601.Check R725, U701. Check U601, U602. Check U802.
Check power.
Check
R721,R722,R724,R726. Normal.
Check R727.
NO
NO
NO
NO
NO NO
NO NO
NO
YES
NO
YES
YES
YES
YES
YES
YES
YES
YES
YES
AMP abnormal
YES
2. AMP ABNORMAL

3-5
ELECTRICAL TROUBLESHOOTING GUIDE
Check U604. Check U604 pin10.
YES
Check U604
pin3,13 signal.
Check U602
pin1,2 signal.
Check U602
pin1, 7 signal.
Check U603
pin3, 5 signal.
Check U602
pin12“DAC_BCK”,
pin10 “DAC_LRCK”,
pin9 “DAC_DATA”,
pin11“DAC_MCLK”
data signal.
Check U604
pin5,14 signal.
Normal.
Check JK401 pin1,3.
Check R643, R644.
Check U602.
Check R634, R635.
Check U603.
NO
NO
NO
NO NO NO
YES YES
YES
YES
YES
YES
AUX abnormal
YES
3. FUNCTION MODE AUDIO ABNORMAL