LG MCD23 User manual

MODEL :MCD23(MCS23F)
SERVICE MANUAL
P/NO : AFN62795812
MINI Hi-Fi SYSTEM
SERVICE MANUAL
CAUTION
BEFORE SERVICING THE UNIT, READ THE “SAFETY PRECAUTIONS” IN THIS MANUAL.
MODEL : MCD23(MCS23F)
Website http://biz.lgservice.com
Internal Use Only
MAY, 2008

1-1
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
[CONTENTS]
❍SECTION 1. GENERAL
• SERVICING PRECAUTIONS ................................................................................................ 1-2
• ESD PRECAUTIONS ............................................................................................................ 1-4
• SERVICE INFORMATION FOR EEPROM ............................................................................ 1-5
• PROGRAM DOWNLOAD GUIDE.......................................................................................... 1-6
• SPECIFICATIONS ................................................................................................................ 1-8
❍SECTION 2. EXPLODED VIEWS
•CABINET AND MAIN FRAME SECTION.............................................................................. 2-1
•MECHANISM DECK EXPLODED VIEW .............................................................................. 2-3
•SPEAKER EXPLODED VIEW .............................................................................................. 2-5
•PACKING ACCESSORY VIEW.............................................................................................. 2-6
❍SECTION 3. ELECTRICAL PART
•TROUBLESHOOTING GUIDE .............................................................................................. 3-1
AUDIO PART TROUBLESHOOTING GUIDE ........................................................................ 3-1
CD PART TROUBLESHOOTING GUIDE ............................................................................ 3-10
•WAVEFORMS OF MAJOR CHECK POINT ........................................................................ 3-12
•WIRING DIAGRAM .............................................................................................................. 3-15
•BLOCK DIAGRAMS ............................................................................................................ 3-16
•CIRCUIT DIAGRAMS .......................................................................................................... 3-19
•INTERNAL BLOCK DIAGRAM OF ICs .............................................................................. 3-43
•VOLTAGE CHART................................................................................................................ 3-59
•PRINTED CIRCUIT DIARGAMS ........................................................................................ 3-63
❍SECTION 4. DISASSEMBLY AND ASSEMBLY OF MECHANISM DECK .......... 4-1
❍SECTION 5. REPLACEMENT PARTS LIST ................................................................ 5-1

1-2 Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
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 allow
contact fingers or other exposed skin.
Magnet
How to hold the pick-up
Conductive Sheet
Cotton swab
Pressure
Pressure
SECTION 1. GENERAL

1-3
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
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 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 (1M Ω)
6) Care should be taken not to permit the laser pick-up to come in contact with clothing, in order to prevent sta-
tic 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 Mohm) Conductive
Sheet
Resistor
(1 Mohm)
Armband

1-4 Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
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 gener-
ate 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.
SAFETY PRECAUTIONS

1-5
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
SERVICE INFORMATION FOR EEPROM
POWER ON
Remote control ‘2’+ Front ‘STOP’
push same timing during 5s
Use arrow key ( ) move
to appropriate position and make
changes
Press ENTER key - ‘FLD’write ‘OK’
Remote control ‘2’+ Front ‘STOP’
push same timing
FLD display E2P CLR→Auto power off
Completed option setting
Version Setting MODE
OPT 0 → ‘OPT 0 - 00 ’
OPT 1 → ‘OPT 1 - 00 ’
OPT 2 → ‘OPT 2 - 00 ’
OPT 3 → ‘OPT 3 - 00 ’
OPT 4 → ‘OPT 4 - 00 ’

1-6 Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
PROGRAM DOWNLOAD GUIDE
1. AUDIO USB DOWNLOAD GUIDE
Download program file name must be MCD23.HEX.mcs.
→ If security program (Water Wall) is activated on your PC, you must save the file to the USB storage
device and disable the security software then download the file to your set.
Caution: When downloading the file, you should neither unplug the USB device, change to the other
function, nor power off the device. USB device must be unplugged when the downloading
process is completed.
ON THE VFD DISPLAY SCREEN
NO USB
1. INSERT USB DEVICE AT USB FUNCTION
2. WHEN COMPLETED, REMOVE USB DEVICE.
READ
FIRMWARE
WRITE 00 .. 100
UPDATED
POWER OFF AUTOMATICALLY

1-7
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
2. CD USB DOWNLOAD GUIDE
Download program file name must be LGBOX_HA8M.mcs.
→ If security program (Water Wall) is activated on your PC, you must save the file to the USB storage
device and disable the security software then download the file to your set.
Caution: When downloading the file, you should neither unplug the USB device, change to the other
function, nor power off the device. USB device must be unplugged when the downloading
process is completed.
ON THE VFD DISPLAY SCREEN
NO USB
1. INSERT USB DEVICE AT USB FUNCTION
2. WHEN COMPLETED, REMOVE USB DEVICE.
READ
FIRMWARE
FINISH
UPDATED
POWER OFF MANUALLY

1-8 Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
SPECIFICATIONS
General
Power supply Refer to main label.
Power consumption Refer to main label.
Net Weight 4.7 kg
External dimensions (W x H x D) 270 x 295 x 320 mm
Operating temperature 5°Cto 35°C
Operating humidity 5% to 85 %
Tuner
FM Tuning Range 87.5 - 108.0 MHz or 65.0 - 74.0 MHz, 87.5 - 108.0 MHz
Intermediate Frequency 10.7 MHz
AM Tuning Range 522 - 1,620 kHz or 520 - 1,720 kHz
Amplifier
Output Power 12.5 W + 12.5 W
T.H.D 10 %
Frequency Response 40 - 20000 Hz
Signal-to-noise ratio 75 dB
CD player
Frequency response 40 - 18000Hz
Signal-to-noise ratio 75 dB
Dynamic range 75 dB
Speakers (MCS23F)
Type Bass Reflex 1 Way 1 Speaker
Impedance 4 Ω
Frequency Response 70 - 20000 Hz
Sound Pressure Level 82 dB/W (1m)
Rated Input Power 12.5 W
Max. Input Power 25 W
Net Dimensions (WxHxD) 178 x 298 x 196 mm
Net Weight (1EA) 1.9 kg

2-1 2-2
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
• CABINET AND MAIN FRAME SECTION
I
H
A
B
G
N
N
L
L
M
N
K
AD
K
C
C
A44
A47
A46
266
263
300
267
289
457
450
450
264
450
450
450
450
MAIN
SMPS
291
A26
CD
A41
M
N
D
J
260
255
450
450 E
I
J
E
F
F
G
H
USB
KEY
DECK
FRONT
254
A42
450
253
281
450
455
CABLE1
CABLE4
CABLE3
CABLE2
B
CABLE8
CABLE9
CABLE6 CABLE5
450
450
265
A00
454
454
450
450
A49
A40
A43
454
CABLE7
CABLE7
280
SECTION 2. EXPLODED VIEWS
NOTES) THE EXCLAMATION POINT WITHIN AN
EQUILATERAL TRIANGLE IS INTENDED
TO ALERT THE SERVICE PERSONNEL
TO THE PRESENCE OF IMPORTANT
SAFETY INFORMATION IN SERVICE
LITERATURE.

151
A26
155
159
170
163
162
177
172
167
166
175
180
137
012
012
A01
A02
012 012A
012A
012B
164
173 188
189
190
165
153
156
153A
2-3 2-4 Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
MECHANISM DECK EXPLODED VIEWE DECK MECHANISM EXPLODED VIEW
1. MECHANISM DECK EXPLODED VIEW

2-5
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
• SPEAKER (MCS23F)
SPEAKER EXPLODED VIEW
A80A
A80B
851
852
852
A80
854
853

2-6 Copyright © 2008 LG Electronics. Inc. All right reserved.
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LGE Internal Use Only
808 Battery
900 Remote Control
801 Instruction Ass'y
803 Packing
803 Packing
804 Bag
802 Box
825 Antenna
824 Antenna Loop
818 Portable in Cable
I-POD Stand
814A
OPTIONAL PART
• PACKING ACCESSORY VIEW

3-1
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
AUDIO ELECTRICAL TROUBLESHOOTING GUIDE
1. POWER (SMPS)
SECTION 3. ELECTRICAL PART
NO
YES
YES
Replace the fuse.
Check the FUSE
F901.
NO
YES
Check BD901,LF901,902.
NO Check short of P9702 line.
Check short of P9701,P9702 line.
NO Check short of P9701 line.
NO Replace IC901,902.
Check
the DC V of C905
if DC V is over
400V.
NO
YES
Check the
DC V of C909,C903,C921
If DC V is in 14~19V
And it is steady
Check IC901,902.
YES
YES
Check the
DC V of C981,C945.
If DC V is 6.1V.
YES
Check the
DC V of C950,C951
If DC V is in
31.68V.
POWER (SMPS)
OK

3-2 Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
2. P-SENS 3. VKK PART CHECK
4. MICOM PART CHECK I
NO Check power circuit
Troubleshooting.
YES
P-SENS
Check
the PIN6 of CN1
if DC V is over
5.6V
YES
OK
OK OK
NO Check power circuit
Troubleshooting.
YES
VKK CHECK
Check
the PIN3 o CN1
if DC V is over
-28V.
YES
OK
NO
NO NO Replace IC101
(KIA7042)
Check if IC101 of output
voltage is over4.3V
YES
YES
YES YES
YES
Check voltage of
IC100(LC87Fxxx)PIN4
YES
Refer to SMPS
troubleshooting.
MICOM PART
HECK I
Check P-SENS
(P7904_PIN6)
NO
Check both
End voltage of IC101
(KIA7042)
Check
If input voltage of
IC101 is over 5V
Check the
Periphery of IC101
(KIA7042)

3-3
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
5. MICOM PART CHECK II
6. IC103(S24CS16A01) PART CHECK
NO
NO
YES
YES
YES
YES
YES
YES
YES
Refer to SMPS
troubleshooting.
Check If IC103_PIN8 and
IC100_PIN14,40,55,89 are 5V .
X101:32.768KHz
X100:9.8304MHz
Check the operation.
Check P-SENS
(P7904_PIN6).
Check both
End voltage of D101.
Check
If output of
D101 is 5V.
Check D101.
MICOM PART CHECK II
NO Replace D101.
OK OK
YES
YES
YES
YES
PIN81:DATA
PIN82:CLK
Check MICOM.
NO Check MICOM
Voltage 5V.
CHECK IC100
PIN81,82
NO Replace MICOM.
NO Refer to micom
troubleshooting.
OK OK

3-4 Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
7. FLD DISPLAY PART CHECK
NO
YES
YES YES
YES
Refer to SMPS.
NO
Replace P3302.
Check P3302 Connection.
Check if both end voltage of
F1,F2 are over 3.7V.
VKK : Over 28V
YES
FLD light on?
Check
P7904 PIN1,2,3
Voltage input
YES
Check P7302
Connection and
Power:pin29:FL+26,pin28:FL-22,
pin27:Vkk over 28V,
pin24:+5.6V
YES
Check
IC301(PT6324)Voltage
Pin50 VKK:-28V
PIN:9,52:+5V
YES
YES
Check each
PIN voltage.
IC100
Check IC301
Data communication.
Pin Pin
27pin 3pin STB
26pin 2pin data
28pin 1pin clk
FLD DISPLAY CHECK
OK OK
OK
NO
Replace IC301.
NO Replace IC100.
NO
NO
IF voltage is not 5V.
Check input and output of D301.
IC100 : 27,26,28 PIN Check
DATA INPUT.
26PIN DATA OUT
Check DATA INPUT.
YES
YES
YES
Check IC301.
YES
Check IC100.
OK
YES

3-5
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
8. PWM MODULATION PART CHECK
P7905 PIN9,10
3.3V Check
PWM MODULATION
PART CHECK
Refer to SMPS
Troubleshooting
NO
NO
NO
Check
X601 12.288MHz
Operation.
IC604
PIN86 CLK INPUT
Check
Check
IC100(LC87Fxx)
PIN22:PWM REST
PIN79:PWM SDA
PIN80:PWM SCL
OUTPUT
YES
YES
YES
YES
YES
YES
YES
YES
Check
IC604(PS9830)
DATA INPUT PIN23
PWM WAVE
Check.
Check PWM
Modulator output
FL:PIN75(+),74(-)
FR:PIN71(+),70(-)
OTHER OUTPUT
Check
Check IC604(PS9830)
VDD PIN VOLTAGE
(3,10,22,29,39,47,56,65,72,87,94)
Check X601 PIN2 :3.3V
OK
Replace X601.
NO
YES
Check X601
12.288MHz
OK
Replace R671,R670,R665
NO
YES
Check LINE
Resistor output
SDA:R671,SCL:R670
RST:R665
Refer to CD troubleshooting
NO
Check
CD ASSY Communication
P7403
Check each LINE
Resistor output
NO
Check
IC604(PS9830) DATA
INPUT
OK
YES
YES
OK
Replace IC604.
NO
Check
IC604(PS9830)
YES
OK
NO
NO

3-6 Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
9. PWM MODULATION PART CHECK
YES
YES
NO Refer to SMPS Troubleshooting.
P7905 PIN3:+12V
PIN13,14,15:13.7V
YES
YES
NO Check each line resistor output voltage.
Check each
IC700 PIN1,22,23,44:+12V
INPUT
YES
NO Replace the coil.
Check output
line coil.
POWER AMP PART CHECK
OK
Check each IC700
PIN27,26,32,35,40,41 INPUT VOLTAGE
YES
Check PWM Modulator input
each PIN6,8,16,18.
YES
POWER IC700
PIN28,31,36,39 output.

3-7
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
10. TUNER/TAPE/PORTABLE FUNCTION PART CHECK
OK
Check
IC200 (BU4052)
PIN3,13 each function
output.
Check
IC200 (BU4052)
PIN7:-5.65V
PIN:16:+5.8V
Check IC801
(MC4580)
PIN1,7 output.
Check
IC805 (AK5358A)
PIN1,2 INPUT.
Check
IC805 (AK5358A)
PIN16 data output.
FUNCTION CHECK
Each function
(tuner/tape/portable)
output to IC200(BU4052)
input : L/R_CH.
Check P7501
PIN6(L-CH),PIN8(R-CH).
Each function
output line Check.
Check
IC801 (MC4580)
PIN:-12V
PIN:8:+12V
Check IC805
PIN7:+3.3V
PIN6:+5V
Check IC805
PIN13:RST/PIN12:BCK
PIN:11:MCLK/PIN10:LRCK
PIN9:DATA
Refer to SMPS.
Check CN801 Connection.
IC801(MLC3890)
PIN55 INPUT DATA.
IC801(MLC3890)
DADATA0 OUTPUT.
Check P7905 connection
After replace IC200.
Check CN202 PIN4,5:+5V
PIN11,12: +3.3V
check CN802
PIN1:DA_DATA/PIN2:DA_BCK
PIN3:DA_LRCK/PIN5:CD_RESET
Replace IC805.
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
NO