LG CM8440 Schematic
Mini Hi-Fi System
SERVICE MANUAL
MODEL:
CM8440
(CM8440, CMS8440F/W)
CAUTION
BEFORE SERVICING THE UNIT, READ THE “SAFETY PRECAUTIONS”
IN THIS MANUAL.
MODEL: CM8440 (CM8440, CMS8440F/W)SERVICE MANUAL
4102,APRIL76592196NFA:ON/P
Website http://biz.lgservice.com
Internal Use Only
CONTENTS
SECTION 1 ........ GENERAL
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
HIDDEN KEY MODE................................................................................................................................... 1-6
SERVICE INFORMATION FOR EEPROM .......................................................................................... 1-7
PROGRAM DOWNLOAD & UPDATE GUIDE ................................................................................... 1-8
SPECIFICATIONS ..................................................................................................................................... 1-12
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.
Storage in conductive bag
Drop 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.
NEVER look directly at the laser beam, and don’t allow
contact with fingers or other exposed skin.
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.
Pressure
Magnet
How to hold the pick-up
Cotton swab
Conductive Sheet
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.
1-3
Pressure
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 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 (1 MΩ)
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.
Armband
Resistor
(1 MΩ)
Resistor
(1 MΩ)
Conductive
Sheet
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 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
HIDDEN KEY MODE
Push both Front key and RCU key to activate it for 5 seconds.
1. Disc Lock On/Off (CD Function Only Active)
Front Key : STOP
RCU Key : STOP
2. Check Version and Option code
Front Key : STOP
RCU Key : PLAY/PAUSE
You can change [Audio MCU Version <-> CD Controller Version <-> EEPROM Option] by SKIP+/-.
3. Clear EEPROM
Front Key : STOP
RCU Key : SKIP-
4. Edit EEPROM
Front Key : STOP
RCU Key : SKIP+
You can change the digit of option by SKIP+/-.
You can edit 0~f by REPEAT or PLAY/PAUSE key.
5. Bluetooth DUT
Front Key : STOP
RCU Key : PROGRAM
Bluetooth model only
6. Power Disc Lock On/Off (CD Function Only Active)
Front Key : STOP
RCU Key : EQ
7. Amp Clip On/Off
Front Key : STOP
RCU Key : Mute
Amp Clip Mode Change (Amp Clip On --> Amp Clip Off --> Level Down display)
1-6
SERVICE INFORMATION FOR EEPROM
POWER ON
FLD “NO DISC” status
It is possible at any function.
(ex. It is possible at FLD “NO USB” status, too.)
This is an example.
Remote control ‘ ’ + Front ‘STOP’
push same timing during 5 seconds.
FLD “op0-…..”
Move to appropriate position and
make changes with remote control.
( , , /■ , REPEAT )
Press STOP key
FLD “WRITE OK”
DETECT NEW EEPROM
(OPTION EDIT SCREEN)
NAME
OP0
OP1
OP2
OP3
OP4
OP5
OP6
OP7
OP8
OP9
HEX
05
00
00
00
00
01
81
46
00
00
Remote control ‘ ’ +
Front ‘STOP’ push same timing.
FLD “e2p clr”
Completed
1-7
PROGRAM DOWNLOAD & UPDATE GUIDE
1. AUDIO PROGRAM
Download program file name must be MICOM_CM8540_1311010_0x4D3F.HEX
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. Downloading file proceeds in the same way at
USB1 function and USB2 function.
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 VFD DISPLAY SCREEN
NO USB
↓← Insert USB device at USB function.
SEARCH
↓
MICOM UP
↓
FINISH
↓
Auto POWER OFF
1-8
2. CD PROGRAM
Download program file name must be HG480_CM8540_1401231.bin
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. Downloading file proceeds in the same way at
USB1 function and USB2 function.
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 VFD DISPLAY SCREEN
NO USB
↓← Insert USB device at USB function.
SEARCH
↓
MCS UP
↓
SMJ UP
↓
FINISH
↓
Auto POWER OFF
1-9
3. DEMO PROGRAM
Download program file name must be DEMO_DAT.bin
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. Downloading file proceeds in the same way at
USB1 function and USB2 function.
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 VFD DISPLAY SCREEN
NO USB
↓← Insert USB device at USB function.
SEARCH
↓
DEMO UP
↓
FINISH
↓
Auto POWER OFF
1-10
4. EQ PROGRAM
Download program file name must be EQ_PRG_CM8440_201401110_D2E9.BIN
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. Downloading file proceeds in the same way at
USB1 function and USB2 function.
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 VFD DISPLAY SCREEN
NO USB
↓← Insert USB device at USB function.
SEARCH
↓
EQ UP
↓
FINISH
↓
Auto POWER OFF
1-11
SPECIFICATIONS
• GENERAL
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Dimensions (W x H x D) (290 x 349 x 370) mm
Net Weight (Approx.) 5.9 kg
Operating temperature 5 °C to 35 °C (41 °F to 95 °F)
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• INPUTS
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• TUNER
• AMPLIFIER
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4 x W 083 edom oertS
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006 ,)Bd 0 ,zHk 1( smrV 0.2 NI XUA Ω, RCA jack (L, R)
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• CD
Frequency Response 40 to 20 000 Hz
Signal-to-noise ratio 75 dB
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• FRONT SPEAKER
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6 ecnadepmI Ω
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• SURROUND SPEAKER
rekaeps 1 yaW 1 epyT
6 ecnadepmI Ω
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Net Dimensions (W x H x D) (335 x 445 x 300) mm
gk 8.8 thgieW teN
• SUBWOOFER
rekaeps 1 yaW 1 epyT
6 ecnadepmI Ω
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W 067 rewop tupnI .xaM
Net Dimensions (W x H x D) (332 x 455 x 280) mm
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• Design and specifications are subject to change without notice.
1-12
SECTION 2
CABINET & MAIN CHASSIS
CONTENTS
EXPLODED VIEWS ..................................................................................................................................... 2-3
1. CABINET AND MAIN FRAME SECTION (CM8440) ................................................................................ 2-3
2. MECHANISM DECK SECTION (DP17TM2) ............................................................................................ 2-5
3. PACKING ACCESSORY SECTION ......................................................................................................... 2-7
4. SPEAKER SECTION ................................................................................................................................ 2-8
2-1
MEMO
2-2
EXPLODED VIEWS
1. CABINET AND MAIN FRAME SECTION (CM8440)
M
B
A
H
G
D
E
F
MAIN
A
E
D
B
L
SMPS
M
266
A46
267
443
443
252
251
252
253
A42
A47
443
443
443
268
270
269
272
271
443
443
443
443
443
F
B/T
A52
CABLE4
A44
259
K
MIC & PTB
443
CABLE3
G
H
I
J
443
443
CABLE1
FRONT
CABLE2
I
J
K
291
NFC Tag
A43
A56
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.
L
300
2. MECHANISM DECK SECTION (DP17TM2)
1026
1439
A001
1002
1005
1001
1049
1437
1437
1024
1024
1030
1024
1043
1045
A005
A006
1016
1013
1015
1020
1024
1003
1439
1018
1019
1011
1012
1437
1004
3. PACKING ACCESSORY SECTION
801 Owner’s Manual
808 Battery
825 FM Wire Antenna
900 Remote Control
803 Packing
804 Bag
803 Packing
802 Box
4. SPEAKER SECTION
4-1. FRONT SPEAKER (CMS8440F)
• LEFT SPEAKER
A60L
FRONT SPEAKER (CMS8440F)
• RIGHT SPEAKER
A60R
4-2. SUBWOOFER SPEAKER (CMS8440W)
A90
SECTION 3
ELECTRICAL
CONTENTS
ONE POINT REPAIR GUIDE ............................................................................................................................ 3-2
1. NO POWER ............................................................................................................................................ 3-2
2. NO BOOTING WHEN POWER ON THE SET ....................................................................................... 3-4
3. VFD IS NOT DISPLAYED WHEN POWER ON THE SET ..................................................................... 3-5
4. NO BOOTING IN CD/USB FUNCTION .................................................................................................. 3-6
5. NO OPERATION OF MD (DRIVING THE SERVO MOTORS) ............................................................ 3-11
6. NO SOUND .......................................................................................................................................... 3-16
7. AUDIO OUTPUT IS SMALL OR NO AUDIO OUTPUT ........................................................................ 3-22
8. NO POWER ON (STANDBY LED IS BLINKING) ................................................................................ 3-23
9. SPEAKER NO AUDIO .......................................................................................................................... 3-24
ELECTRICAL TROUBLESHOOTING GUIDE ................................................................................................ 3-25
1. POWER SUPPLY ON SMPS BOARD ................................................................................................. 3-25
2. SYSTEM PART .................................................................................................................................... 3-29
3. NO AUDIO PART ................................................................................................................................. 3-30
WAVEFORMS OF MAJOR CHECK POINT ................................................................................................... 3-35
WIRING DIAGRAM ......................................................................................................................................... 3-39
BLOCK DIAGRAMS ........................................................................................................................................ 3-41
1. SMPS BLOCK DIAGRAM..................................................................................................................... 3-41
2. MAIN SYSTEM BLOCK DIAGRAM ...................................................................................................... 3-43
3. MAIN POWER BLOCK DIAGRAM ....................................................................................................... 3-45
CIRCUIT DIAGRAMS ...................................................................................................................................... 3-47
1. SMPS - POWER #1 CIRCUIT DIAGRAM ............................................................................................ 3-47
2. SMPS - POWER #2 CIRCUIT DIAGRAM ............................................................................................ 3-49
3. MAIN - CD DSP CIRCUIT DIAGRAM .................................................................................................. 3-51
4. MAIN - RF / SERVO CIRCUIT DIAGRAM ........................................................................................... 3-53
5. MAIN - ADC / PWM CIRCUIT DIAGRAM ............................................................................................ 3-55
6. MAIN - AMP CIRCUIT DIAGRAM ........................................................................................................ 3-57
7. FRONT VOLUME CIRCUIT DIAGRAM ................................................................................................ 3-59
8. MIC & PORTABLE CIRCUIT DIAGRAM .............................................................................................. 3-61
CIRCUIT VOLTAGE CHART .......................................................................................................................... 3-63
1. CONNECTORS .................................................................................................................................... 3-63
2. CAPACITORS....................................................................................................................................... 3-64
PRINTED CIRCUIT BOARD DIAGRAMS ....................................................................................................... 3-65
1. SMPS P.C.BOARD ............................................................................................................................... 3-65
2. MAIN P.C.BOARD ................................................................................................................................ 3-69
3. FRONT VOLUME P.C.BOARD ............................................................................................................ 3-73
4. MIC & PORTABLE P.C.BOARD ........................................................................................................... 3-75
3-1
ONE POINT REPAIR GUIDE
1. NO POWER
If the unit doesn’t work by no power problem, repair the set according to the following
guide.
1-1. FUSE / BRIDGE DIODE / THERMISTOR
1-1-1. Solution
Please check and replace F901, BD901, TH900, TH901 on SMPS board.
1-1-2. How to troubleshoot (Countermeasure)
1) Check if the fuse F901 is open or short-circuit.
2) Check if the bridge diode BD901 is short-circuit by over current with a digital multi meter.
3) Check if the NTC thermistor TH900, TH901 is normal or open.
PN901
FH901
12
GP390-02P-TS
T12AH/250V
(12A 250V)
F901
12
TH900
FH902
FNR-14K681T
TH901
VR900
TH902
READY
R-PART:EBG61545701
5ohm
5ohm
1M
1M
1M
R904
!
R905
R906
1M
TP13 TP14
1M
1M
GND
R901
0.22uF/275V
CM903
R902
R903
0.33uF/275V
1000pF/250VAC
R9E1
1M
TP15
R9E2
1M
TP20TP12
TP16
R9E3
1M
1-1-3. Service hint (Any picture / Remark)
!
CM901
2
8
9FL
m
R:EAE62524901
1000pF/250VAC
C903
C909
0
H
2
!
0.33uF/275V
R:EAE62524901
CM902
470pF/250VAC
C901
C902
NC
GND
J901
1
J902
1
J903
1
J904
1
2
LF901
!
2
2
2
6
C90
1uF
/550V
600V/10A
4
1
2
3
4
@Opti
2
BD901
D10XB60
1
25x15
HS906
3
< F901 >
If F901 is not short-circuit,
replace it with a same
specifi cations one.
< BD901 >
If BD901 is short-circuit,
replace it with a new one.
3-2
< TH900, TH901 >
If TH900, TH901 is open,
replace it with a new one.
ONE POINT REPAIR GUIDE
3
R980
25deg >330ohm
NO POWER
If the unit doesn’t work by no ±PVDD problem, repair the set according to the following
guide.
1-2. NO AMP POWER
1-2-1. Solution
Please check and replace F911, Q905, Q906 on SMPS board.
1-2-2. How to troubleshoot (Countermeasure)
1) Check if the fuse F901 is open or short-circuit.
2) Check the Drain-Source or Drain-Gate, Gate-Source Resistance of Q905, Q906 with a digital multi-meter.
If it is short condition, it’s destroyed. Replace it with a new one.
(Please replace 2 FET at the same time although several FET is OK)
1-2-3. Service hint (Any picture / Remark)
PFC_TH
PFC_OUT
380V
C979
P.GND
102PF
22k VINS :285V
24k VINS :260V
FH912
12
F911
6.3A/250V
TP62
TP63
TP64
TP65
R9A6
R945
R944
R9A3
R942
R941
70deg->2.2kohm
12
MARK:G2
12
FH911
1M
1M
1M
1M
1M
1%
24K
TH912
BG
PFC_PTC_SMD
F
C932
C960 1u
C943
R951:24K=> 65KHZ
R951:20K=> 70KHZ
TH914
C978
P.GND
READY
22nF
102PF
ZD904
P.GND
C977
BZX84-C16
TP39
R927
12
10nF
R951
12
ON/OFF:11.3~12.7V
Ivcc:5.8mA
10nF
C933
IC902
2.7K
12K
TP42
TP43
6LG7HG8
VCC
ICE1HS01G-1
VCSL:0.8V
VCSH:1.63V
1
2
CS
FMIN
100nF
C942
3FB4
5
GND
VINS
Vab:5V
Vth:1.25V
ZD915
P.GND
C935
470nF
TP41
TP48
/50V
NC
R993
3.3
R992
3.3
P.GND
FBH:4.5V OVERLOAD
Fixed Blanking Time:20ms
10K
R950
TP38
10nF
C940
BZX84-C10
22nF
C939
R949
P.GND
D934
22
D935
SMFB14
SMFB14
HS905 H/S
HS904
50X15
2
3
2
4
C972
READY
P.GND
BC911
UBW2012-121F
READY
TH913
0
1G
10K
R990
GND
2D
READY
C992
3S
Q905
IPA60R190E6
!
T903
20
19
2
18
3
17
4
16
5
15
6
14
7
13
8
PC90
3
1
R986
TP46
100
R988
TP60
D932
ZD912
4.7
SMFB14
T902
CM9720 PULSE
7
10
W1
W3
W2
1
56
4
12
1G
Q906
10K
IPA60R190E6
D922
1SS355
75
D921
2D
3S
R9A7
150
1W
READY
C993
C934
0.039uF
1250V
C938
68PF
1KV/125C
C982
R9B7
100
D926
R9B8
TP61
4.7
SMFB14
R9B4
TP32
0OHM
BC915
TP47
UBW2012-121F
ZD917
READY
R9B9
P.GND
R9A8
R9C4
12
12
27T/8T:2T
230uH:65uH
!
11
< F911 >
If F911 is not short-circuit,
replace it with a same specifi cations one.
< Q905, Q906 >
If Q905, Q906 is short-circuit,
replace it with a new one.
3-3
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