LG CM9730 User manual

SUPER POWER MINI HI-FI SYSTEM
SERVICE MANUAL
MODEL: CM9730
(CM9730, NS9730F)
CAUTION
BEFORE SERVICING THE UNIT, READ THE “SAFETY PRECAUTIONS”
IN THIS MANUAL.
MODEL: CM9730 (CM9730, NS9730F)SERVICE MANUAL
3102,JANUARY98241957NFA: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 UPGRADE GUIDE ............................................................................................................... 1-8
SPECIFICATIONS ....................................................................................................................................... 1-9
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

1-6
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)
8. Demo ALL Key Lock (CM9520/CM8520 Only)
Front Key : STOP
RCU Key : 9
Demo All Key Lock Change (All Key Lock On --> All Key Lock Off)
- Working on Demo Operation only
- When All Key Lock, Volume Key work only
- After All Key Lock Off, it can unlock Demo Mode
HIDDEN KEY MODE

POWER ON
FLD no disc status
Remote control ‘ ’ + Front ‘STOP’
push same timing during 5 seconds.
FLD ‘OP-0….
Move to appropriate position and
make changes with remote control.
( , , /■ , REPEAT )
Press STOP key
FLD ‘write ok’
Remote control ‘ ’ +
Front ‘STOP’ push same timing.
FLD ‘E2P CLR’
Completed
NAME
OP0
OP1
OP2
OP3
OP4
OP5
OP6
OP7
OP8
OP9
DETECT
* MODEL.SUFFIX
<A> CM9730-DB.DDEULLK
<B> CM9730-FB.DARELLS
<C> CM9730-FB.DGHALLS
NEW EEPROM
(OPTION EDIT SCREEN)
HEX
<A>
05
00
00
00
00
81
80
50
00
01
HEX
<B>
05
00
00
00
00
01
80
42
00
01
HEX
<C>
05
00
00
00
00
01
80
46
00
01
1-7
SERVICE INFORMATION FOR EEPROM

1-8
1. Check the download file name.
MICOM Mpeg EQ
File Name CM9730_”version”.HEX HE004_”version”.BIN EQ_PRG.BIN
* There is the Update File only in the USB storage.
2. Copy the download file to the USB storage.
3. Insert the USB storage on USB1 or USB2 Function.
4. VFD Display
1) MICOM : “WRITE XX”
2) Mpeg : “FIRMWARE”
3) EQ : “EQ DOWN”
5. Complete Update
1) When the Set is turned off automatically after display "UPDATED", remove the USB storage.
2) Unplugged the power cord after display "FINISHED", then remove the USB storage.
Upgrade required time
Upgrade required time is determined depending on the Writing time considering the Download stability.
MICOM Mpeg EQ
Upgrade time about 60sec about 15sec about 5sec
PROGRAM UPGRADE GUIDE

SPECIFICATIONS
1-9
•GENERAL
Power requirements Refer to the main label.
Power consumption Refer to the main label.
Dimensions (W x H x D) 542 x 308 x 421 mm
Net Weight (Approx.) 9.85 kg
Operating temperature 5 °C to 35 °C (41 °F to 95 °F)
Operating humidity 5 % to 90 %
Bus Power Supply USB DC 5 V 500 mA
•INPUTS
AUX IN 2.0 Vrms (1 kHz, 0 dB), 600 Ω, RCA jack (L, R) x 1
PORT. IN 1.2 Vrms (3.5 mm stereo jack)
•TUNER
FM Tuning Range 87.5 to 108.0 MHz or 87.50 to 108.00 MHz
AM Tuning Range 522 to 1 620 kHz, 520 to 1 710 kHz or 522 to 1 710 kHz
•CD
Frequency Response 40 to 20 000 Hz
Signal-to-noise ratio 75 dB
Dynamic range 80 dB
•AMPLIFIER
Output 575 W x 4 (8 Ωat 1 kHz, THD 25 %)
•FRONT SPEAKER
Type Low channel 1 Way 1 speaker
High channel 2 way 2 speaker
Impedance 8 Ω
Rated Input Power 575 W
Max. Input power 1150 W
Net Dimensions (W x H x D) 520 x 720 x 499 mm
Net Weight 35.5 kg
•Design and specifications are subject to change without notice.

MEMO
1-10

SECTION 2
CABINET & MAIN CHASSIS
CONTENTS
EXPLODED VIEWS..................................................................................................................................... 2-3
1. CABINET AND MAIN FRAME SECTION (CM9730) ................................................................................ 2-3
2. MECHANISM DECK SECTION (DP17T) ................................................................................................. 2-5
3. WOOFER SECTION (NS9730F) .............................................................................................................. 2-7
4. PACKING ACCESSORY SECTION ......................................................................................................... 2-9
2-1

MEMO
2-2

D
I
H
G
F
K
X
P
X
L
G
B
Q
Y
V
R
U
Y
Q
M
S
W
K
P
L
W
C
E
V
F
H
U
O
T
A
O
I
M
D
C
E
B
A
R
S
T
276
277
300
272
A54
259
252
252
253
254
251
A42
A52
256 257
257
258
464
255
A43
464
464
464
A48
454
454
462
464
462
464
462
462
454
454
462
462
462
462
462
462
462
462
464
464
464
462
464
464
464
271
A46
281
280
464
281
464
464
A47
273
282
A41
A44A
A44B
A44C
261
262
462
462
VOLUME
MIC
B/T
TUNER
USB
MAIN
SMPS
MULTI
JOG
VFD
CABLE9
CABLE4
CABLE5
CABLE6
CABLE7
CABLE1
CABLE2
CABLE3
CABLE8
EXPLODED VIEWS
1. CABINET AND MAIN FRAME SECTION (CM9730)
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.

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
2. MECHANISM DECK SECTION (DP17T)

A63R
A63L
A62R
A62L
A61R
A61L
A60R
A60L
671
663
662
666
666
666
666
667
667
667
665
671
672
672
652
664
671
650
651
651
652
670
LED Signal Cable
3. WOOFER SECTION (NS9730F)
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.

801 Owner’s Manual
804 Bag
802 Box
808 Battery
AAA
825 FM Wire Antenna
803 Packing
803 Packing
AAA
4. PACKING ACCESSORY SECTION MEMO
900 Remote Control

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 ..................................................................................................................... 3-11
6. NO SOUND .......................................................................................................................................... 3-16
7. AUDIO OUTPUT IS SMALL OR NO AUDIO OUTPUT........................................................................ 3-23
8. NO POWER ON (STANDBY LED IS BLINKING) ................................................................................ 3-24
9. SPEAKER NO AUDIO.......................................................................................................................... 3-25
ELECTRICAL TROUBLESHOOTING GUIDE ................................................................................................ 3-26
1. POWER SUPPLY ON SMPS BOARD ................................................................................................. 3-26
2. SYSTEM PART .................................................................................................................................... 3-30
3. NO AUDIO PART ................................................................................................................................. 3-32
4. NO LIGHTING (WOOFER SPEAKER)................................................................................................. 3-37
WAVEFORMS ................................................................................................................................................. 3-38
WIRING DIAGRAM ......................................................................................................................................... 3-43
BLOCK DIAGRAMS........................................................................................................................................ 3-45
1. SMPS BLOCK DIAGRAM..................................................................................................................... 3-45
2. MAIN SYSTEM BLOCK DIAGRAM...................................................................................................... 3-47
CIRCUIT DIAGRAMS...................................................................................................................................... 3-49
1. SMPS #1 CIRCUIT DIAGRAM ............................................................................................................. 3-49
2. SMPS #2 CIRCUIT DIAGRAM ............................................................................................................. 3-51
3. MAIN - MICOM CIRCUIT DIAGRAM.................................................................................................... 3-53
4. MAIN - PWM CIRCUIT DIAGRAM ....................................................................................................... 3-55
5. MAIN - AMP CIRCUIT DIAGRAM ........................................................................................................ 3-57
6. MAIN - DSP CIRCUIT DIAGRAM......................................................................................................... 3-59
7. MAIN - RF SERVO CIRCUIT DIAGRAM ............................................................................................. 3-61
8. MAIN - ADC CIRCUIT DIAGRAM ........................................................................................................ 3-63
9. VFD CIRCUIT DIAGRAM ..................................................................................................................... 3-65
10. MAIN VOLUME CIRCUIT DIAGRAM ................................................................................................... 3-67
11. MIC CIRCUIT DIAGRAM...................................................................................................................... 3-69
12. MULTI JOG VOLUME CIRCUIT DIAGRAM......................................................................................... 3-71
13. USB CIRCUIT DIAGRAM..................................................................................................................... 3-73
14. AUX / TUNER / SPEAKER LIGHT JACK CIRCUIT DIAGRAM ........................................................... 3-75
15. SPEAKER LED_MAIN CIRCUIT DIAGRAM ........................................................................................ 3-77
16. SPEAKER LED CIRCUIT DIAGRAM ................................................................................................... 3-79
CIRCUIT VOLTAGE CHART .......................................................................................................................... 3-81
PRINTED CIRCUIT BOARD DIAGRAMS....................................................................................................... 3-87
1. SMPS P.C.BOARD............................................................................................................................... 3-87
2. MAIN P.C.BOARD ................................................................................................................................ 3-89
3. VFD P.C.BOARD.................................................................................................................................. 3-93
4. MAIN VOLUME P.C.BOARD................................................................................................................ 3-95
5. MIC P.C.BOARD .................................................................................................................................. 3-95
6. JOG P.C.BOARD.................................................................................................................................. 3-97
7. USB P.C.BOARD.................................................................................................................................. 3-98
8. TUNER P.C.BOARD............................................................................................................................. 3-98
9. SPEAKER LED_MAIN P.C.BOARD..................................................................................................... 3-99
10. SPEAKER LED P.C.BOARD................................................................................................................ 3-99
3-1

3-2
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, TH902 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 ~ TH902 is normal or open.
1-1-3. Service hint (Any picture / Remark)
< F901 >
If F901 is not short-circuit,
replace it with a same
specifications one.
< TH900 ~ TH902 >
If TH900 ~ TH902 is open,
replace it with a new one.
< BD901 >
If BD901 is short-circuit,
replace it with a new one.

3-3
ONE POINT REPAIR GUIDE
NO POWER
If the unit doesn’t work by no ±PVDD problem, repair the set according to the follow-
ing guide.
1-2. NO AMP POWER
1-2-1. Solution
Please check and replace F911, Q911 ~ Q914 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 Q911~Q914 with a digital multi-meter.
 If it is short condition, it’s destroyed. Replace it with a new one.
(Please replace 4 FET at the same time although several FET is OK)
1-2-3. Service hint (Any picture / Remark)
< F911 >
If F911 is not short-circuit,
replace it with a same specifications one.
< Q911 ~ Q914 >
If Q911 ~ Q914 is short-circuit,
replace it with a new one.