LG CM9750 User manual

SERVICE MANUAL
SERVICE MANUAL
CAUTION
BEFORE SERVICING THE UNIT, READ THE “SAFETY PRECAUTIONS”
IN THIS MANUAL.
Internal Use Only
Website http://biz.lgservice.com
JULY, 2015
MODEL: CM9750 (CM9750, CMS9750F)
MODEL: CM9750
(CM9750, CMS9750F)
MINI HI-FI SYSTEM
P/NO : AFN77277023

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 GUIDE...................................................................................................................... 1-8
FOTA UPDATE................................................................................................................................................ 1-11
SPECIFICATIONS ........................................................................................................................................... 1-12
1-2

1-3
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 cot-
ton 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
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 magne-
tism 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 M)
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.
Resistor
(1 M)Conductive
Sheet
Resistor
(1 M)
Armband
1-4

1-5
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.
ESD PRECAUTIONS

1-6
HIDDEN MODE KEYS
Version Check Front Stop + RMC ‘ ’ for 5s
EEPROM Initial Front Stop + RMC ‘ ’ for 5s
EEPROM Edit Front Stop + RMC ‘ ’ for 5s
APD Test Display Front Stop + RMC ‘3’ for 5s
Clip Front Stop + RMC ‘Mute’ for 5s
Disc Lock On/Off Front Stop + RMC ‘Stop’ for 5s
Power Disc Lock On/Off
Front Stop + RMC ‘EQ’ for 5s
or
Front Stop + Front Open for 5s
Demo All Key Lock On/Off Front Stop + RMC ‘9’ for 5s
BT Auto Power On/Off Front/RMC Power Key for 5s
Child Safe On/Off Volume 0(Min) + Front ENTER Key for 3s
HIDDEN KEY MODE

POWER ON
VFD “NO DISC” status
It is possible at any function.
(ex. It is possible at VFD “NO USB” status, too.)
This is an example.
Front ‘STOP’ + Remote control “ ”
push same timing during 5s
FLD “OP00-…..”
Move to appropriate position
And make changes
with RMC “ , , , REPEAT” key.
Press STOP Key
VFD “WRITE OK”
Front ‘STOP’ + Remote control “ ”
push same timing during 5s
VFD “E2P CLR”
Completed
1-7
SERVICE INFORMATION FOR EEPROM

1. AUDIO PROGRAM
Download program file name must be MICOM_CM8450_YYMMDDX.HEX
If security program(Water Wall) is activated on 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
1) (Fast) Format USB device
2) Copy Firmware file to USB device.
NO USB
Insert USB device at USB function
SEARCH

MICOM UP

FINISH

Auto POWER OFF
1-8
PROGRAM DOWNLOAD GUIDE

2. CD PROGRAM
Download program file name must be HG580_CM8450_YYMMDDX.bin
If security program(Water Wall) is activated on 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
1) (Fast) Format USB device
2) Copy Firmware file to USB device.
NO USB
Insert USB device at USB function
SEARCH

FIRMWARE

FINISH

Auto POWER OFF
1-9

3. EQ PROGRAM
Download program file name must be EQ_PRG.BIN
If security program(Water Wall) is activated on 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
1) (Fast) Format USB device
2) Copy Firmware file to USB device.
NO USB
Insert USB device at USB function
SEARCH

EQ UP

FINISH

Auto POWER OFF
1-10

1-11
FOTA UPDATE
Step1 : App connecting
(Check FW version)
Step3 :
Select update button
Step2 :
Device version info
Step7 :
FOTA complete
Step4 :
Download from CDN server
Step6 :
FW Flash Writing
Step5 :
Transfer FW

SPECIFICATIONS
1-12
• GENERAL
Power requirements Refer to the main label.
Power consumption Refer to the main label.
Networked standby : 0.4 W
(If all network ports are activated.)
Dimensions (W x H x D) 450 mm x 160 mm x 335 mm
Net Weight (Approx.) 6.5 kg
Operating temperature 5 °C to 35 °C (41 °F to 95 °F)
Operating humidity 60 %
Bus Power Supply 5 V 500 mA
• INPUTS
AUX IN 2.0 Vrms (1 kHz, 0 dB), 600 Ω, RCA jack (L, R)
PORT. IN 1.2 Vrms (3.5 Ø jack)
MIC 27 mV
• CD
Frequency Response 40 to 20 000 Hz
Signal-to-noise ratio 75 dB
Dynamic range 80 dB
• AMPLIFIER
Total output 3 000 W
FRONT 500 W x 2 (4 Ωat 1 kHz)
WOOFER 1 000 W x 2 (8 Ωat 70 Hz)
THD 25 %
• FRONT SPEAKER
Type Front : 2 Way 2 Speaker
Surround : 1 Way 1 Speaker
Impedance Front : 4 Ω
Surround : 8 Ω
Rated Input Power Front : 500 W
Surround : 1 000 W
Max. Input power Front : 1 000 W
Surround : 2 000 W
Net Dimensions (W x H x D) 414 mm x 562 mm x 376 mm
Net Weight 18.3 kg
• Design and specifications are subject to change without notice.

SECTION 2
CABINET & MAIN CHASSIS
CONTENTS
EXPLODED VIEWS ......................................................................................................................................... 2-3
1. CABINET AND MAIN FRAME SECTION ................................................................................................. 2-3
2. MECHANISM DECK SECTION ................................................................................................................ 2-5
3. PACKING ACCESSORY SECTION ......................................................................................................... 2-7
4. SPEAKER SECTION ................................................................................................................................ 2-8
2-1

2-2

G
H
B
E
C
I
H
D
F
A
MAIN
A
E
F
G
B
J
I
A46
443
273
468
A47
443
274
266
443
443
467
509
468
468
262
FRONT
FRONT_CTRL
NFC Tag
443
443
253
BT CABLE1
A52
443
A45
443
443
263
265
265
443
CABLE2
272
252
252
A42
250
251
251
254
SMPS
K
276
275
468
467
K
263
467
264
443
C
D
498
498
271
498
271
271
271
467
270
A43
J300
EXPLODED VIEWS
1. CABINET AND MAIN FRAME SECTION
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

3. PACKING ACCESSORY SECTION
803 Packing
802 Box
804 Bag
Packing803
900 Remote Control
801 Owner’s manual 808 Batteries
Filter, Ferrite Core
826A

4. SPEAKER SECTION
A60L
A60R

SECTION 3 ELECTRICAL
CONTENTS
ONE POINT REPAIR GUIDE ............................................................................................................................ 3-2
1. NO POWER ............................................................................................................................................ 3-2
2. NO AMP POWER ................................................................................................................................... 3-3
3. NO BOOTING WHEN POWER ON THE SET........................................................................................ 3-4
4. VFD IS NOT DISPLAYED WHEN POWER ON THE SET..................................................................... 3-5
5. AUDIO OUTPUT IS SMALL OR NO AUDIO OUTPUT .......................................................................... 3-6
6. D-PROTECTION IS DISPLAYED ........................................................................................................... 3-7
7. SPEAKER NO AUDIO ............................................................................................................................ 3-8
8. NO BOOTING IN CD/USB FUNCTION .................................................................................................. 3-9
9. NO OPERATION OF MD...................................................................................................................... 3-14
10. NO SOUND........................................................................................................................................... 3-19
ELECTRICAL TROUBLESHOOTING GUIDE................................................................................................. 3-25
1. POWER SUPPLY ON SMPS BOARD.................................................................................................. 3-25
2. SYSTEM PART..................................................................................................................................... 3-28
3. NO AUDIO CHECK............................................................................................................................... 3-29
4. NO LIGHTING (SPEAKER LED) .......................................................................................................... 3-34
WAVEFORMS OF MAJOR CHECK POINT.................................................................................................... 3-35
1. DSP (IC501).......................................................................................................................................... 3-35
2. PWM (IC202) ........................................................................................................................................ 3-36
3. SERVO (IC401)..................................................................................................................................... 3-37
4. MOTOR DRIVER (IC400) ..................................................................................................................... 3-38
5. ADC (IC201).......................................................................................................................................... 3-39
6. USB (CN502) ........................................................................................................................................ 3-39
7. BLUETOOTH (CN504).......................................................................................................................... 3-40
WIRING DIAGRAM.......................................................................................................................................... 3-41
BLOCK DIAGRAMS ........................................................................................................................................ 3-43
1. SYSTEM BLOCK DIAGRAM ................................................................................................................ 3-43
2. SMPS BLOCK DIAGRAM..................................................................................................................... 3-45
3. POWER BLOCK DIAGRAM ................................................................................................................. 3-47
CIRCUIT DIAGRAMS ...................................................................................................................................... 3-49
1. SMPS - POWER #1 CIRCUIT DIAGRAM ............................................................................................ 3-49
2. SMPS - POWER #2 CIRCUIT DIAGRAM ............................................................................................ 3-51
3. MAIN - CD DSP CIRCUIT DIAGRAM................................................................................................... 3-53
4. MAIN - ADC/ PWM CIRCUIT DIAGRAM.............................................................................................. 3-55
5. MAIN - RF SERVO CIRCUIT DIAGRAM.............................................................................................. 3-57
6. MAIN - EXP/ VISENSE CIRCUIT DIAGRAM ....................................................................................... 3-59
7. MAIN - AMP CIRCUIT DIAGRAM......................................................................................................... 3-61
8. MAIN - MIC/ AUX CIRCUIT DIAGRAM ................................................................................................ 3-63
9. FRONT CIRCUIT DIAGRAM ................................................................................................................ 3-65
10. FRONT_CTRL CIRCUIT DIAGRAM..................................................................................................... 3-67
CIRCUIT VOLTAGE CHART........................................................................................................................... 3-69
1. CAPACITORS....................................................................................................................................... 3-69
2. CONNECTORS..................................................................................................................................... 3-70
PRINTED CIRCUIT BOARD DIAGRAMS ....................................................................................................... 3-71
1. SMPS P.C.BOARD ............................................................................................................................... 3-71
2. MAIN P.C.BOARD ................................................................................................................................ 3-75
3. FRONT P.C.BOARD ............................................................................................................................. 3-79
4. FRONT_CTRL P.C.BOARD.................................................................................................................. 3-83
3-1