LG CM2760 User manual

SERVICE MANUAL
SERVICE MANUAL
CAUTION
BEFORE SERVICING THE UNIT, READ THE “SAFETY PRECAUTIONS”
IN THIS MANUAL.
Internal Use Only
JANUARY, 2016
MODEL: CM2760 (CM2760, CMS2760F)
MODEL: CM2760
(CM2760, CMS2760F)
Micro Hi-Fi Audio
P/NO : AFN77360055

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
SOFTWARE UPDATE GUIDE
............................................................................................................................ 1-6
SPECIFICATIONS ............................................................................................................................................. 1-7
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 KEY MODE
HIDDEN
MODE AVAILABLE STATUS ENTRANCE KEY EXIT KEY DISPLAY
Version Check POWER ON STATUS
Front Play
+ RMC ‘Play’
for 5s
RMC ‘PLAY’ for 1.5s
P1501290
OP0 FF
Q1501290
EQCSFFFF
EEPROM INITIAL POWER ON STATUS
Front Play
+ RMC ‘|<<’
for 5s
auto exit “E2P CLR”
EEPROM EDIT POWER ON STATUS
Front Play
+ RMC ‘>>|’
for 5s
Front Play + RMC ‘>>|’ OPT0-9F
( For Example )
APD Test Display POWER ON STATUS
Front Play
+ RMC ‘DELETE’
for 5s
Front Play + RMC ‘DE-
LETE’
APD MM:SS
(AUX modeH:MM:SS)
B2B, Dealer
HIDDEN MODE AVAILABLE STATUS ENTRANCE KEY EXIT KEY DISPLAY
Clip On/Off POWER ON STATUS
Front Play
+ RMC ‘Mute’
for 5s
auto exit
CLIP OFF
00 130 00
CLIP ON
Disc Lock On/Off POWER ON STATUS
Front Play
+ RMC ‘Stop’
for 5s
Front Play + RMC ‘Stop’
for 5s ‘LOCKED’/ ‘UNLOCKED’
Power Disc Lock On/Off POWER ON STATUS
Front Play + RMC
‘SOUND EFFECT’
for 5s
Front Play + RMC
‘SOUND EFFECT’ for 5s ‘LOCKED’/ ‘UNLOCKED’
Demo ALL Key Lock
POWER ON STATUS
Demo Function
Only Active
Front Play + RMC ‘INFO’
for 5s
Front Play + RMC ‘INFO’
for 5s
‘KEY LOCK’/ ‘UNLOCKED’
BT Auto Power On/Off POWER ON STATUS Front/RMC ‘Power’
for 5s
Power normal Key SET
Power off
OFF-AUTO POWER
GOOD BY Scroll
Sound BYPASS POWER ON STATUS Front Play + RMC
‘PROGRAM’ for 5s SOUND EFFECT key display ‘BYPASS’ 3s
1) Prepare USB device without any files.
2) Copy software (“CM2760_FW_2015xxxxx.bin”) into this USB device.
3) Power on the unit, switch to USB function.
4) Plug in USB device which contains software, no need other operations.
5) VFD display “SEARCH” “MCS UP” “FINISH”, then unit auto power off.
SOFTWARE UPDATE GUIDE

SPECIFICATIONS
1-7
• GENERAL
Power requirements Refer to the main label.
Power consumption Refer to the main label.
Networked standby : 0.5 W (If all network ports are activated.)
Dimensions (W x H x D) Approx. 170 mm x 230 mm x 276 mm
Net Weight Approx. 2.2 kg
Operating temperature 5 °C to 35 °C
Operating humidity 5 % to 90 %
• INPUTS
Portable in (PORT. IN) 0.45 Vrms (3.5 mm stereo jack) x 1
• TUNER
FM Tuning Range 87.5 to 108.0 MHz or 87.50 to 108.00 MHz
• AMPLIFIER (RMS OUTPUT POWER)
Total 160 W
Front 80 W (4 Ωat 1 kHz, 10 % THD)
• SYSTEM
Frequency response 80 to 20,000 Hz
Signal-to-noise ratio 80 dB
Dynamic range 75 dB
Bus Power Supply (USB) 5 V 500 mA
• FRONT SPEAKERS
Type 3 Way 3 Speaker
Impedance 4 Ω
Rated Input Power 80 W
Max. Input Power 160 W
Dimensions (W x H x D) Approx. 127 mm x 295 mm x 240 mm
Net Weight Approx. 3.36 kg
• Design and specifications are subject to change without notice.

1-8

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

2-2

MAIN
VFD
BT USB
PORTABLE
H
C
B
C
G
F
E
D
E
D
J
A
F
H
J
B
G
I
A
I
251
A52
A49
A48
A43
513
A46
266
266
516
513
265
265
515
514
513
A42
260
A00
261
261
263
A26
264
265
265
513
270
513
514
514
271
513
514
825
262
517
517
261
262
517
CABLE3
CABLE5
CABLE4
CABLE1
CABLE2
CABLE6
CABLE8
CABLE7
515
515
300
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.

2. PACKING ACCESSORY SECTION
801 Owner’s manual
900 Remote control
808 Batteries
804 Bag
802 Box
Packing
803T
Packing
803B

3. SPEAKER SECTION
A60R
A60L

SECTION 3
ELECTRICAL
CONTENTS
ONE POINT REPAIR GUIDE ............................................................................................................................ 3-2
1. NO POWER PROBLEM ......................................................................................................................... 3-2
2. SPEAKER NO AUDIO OUTPUT ............................................................................................................ 3-3
3. USB NO DETECT................................................................................................................................... 3-4
4. PROTECTION......................................................................................................................................... 3-5
ELECTRICAL TROUBLESHOOTING GUIDE OF AUDIO PART..................................................................... 3-8
1. SMPS POWER CIRCUIT........................................................................................................................ 3-8
2. FLD DISPLAY CHECK ......................................................................................................................... 3-10
3. TOUCH PAD CHECK ........................................................................................................................... 3-11
4. PWM MODULATION PART.................................................................................................................. 3-12
5. POWER AMP PART CHECK ............................................................................................................... 3-13
6. AUX FUNCTION CHECK ..................................................................................................................... 3-14
7. TUNER FUNCTION CHECK................................................................................................................. 3-15
ELECTRICAL TROUBLESHOOTING GUIDE OF CD PART ......................................................................... 3-16
1. CD PART .............................................................................................................................................. 3-16
2. OPEN/ CLOSE NG ............................................................................................................................... 3-17
3. “ READING ” DISPLAY CHECK (= ONLY “CD” DISPLAY).................................................................. 3-17
4. READING OK CHECK (= “NO DISC” DISPLAY) ................................................................................. 3-18
5. USB PART ............................................................................................................................................ 3-22
WAVEFORMS OF MAJOR CHECK POINT.................................................................................................... 3-23
WIRING DIAGRAM.......................................................................................................................................... 3-29
BLOCK DIAGRAM .......................................................................................................................................... 3-31
CIRCUIT DIAGRAMS ...................................................................................................................................... 3-33
1. MAIN - SMPS CIRCUIT DIAGRAM ...................................................................................................... 3-33
2. MAIN - CD CIRCUIT ............................................................................................................................. 3-35
3. MAIN - DSP CIRCUIT DIAGRAM......................................................................................................... 3-37
4. MAIN - AMP/ TUNER CIRCUIT DIAGRAM .......................................................................................... 3-39
5. MAIN - POWER CIRCUIT DIAGRAM................................................................................................... 3-41
6. TOUCH CIRCUIT DIAGRAM................................................................................................................ 3-43
7. VFD/ USB/ PORTABLE CIRCUIT DIAGRAM....................................................................................... 3-45
CIRCUIT VOLTAGE CHART........................................................................................................................... 3-47
1. CONNECTORS VOLTAGE................................................................................................................... 3-47
PRINTED CIRCUIT BOARD DIAGRAMS ....................................................................................................... 3-49
1. MAIN P. C. BOARD .............................................................................................................................. 3-49
2. TOUCH P. C. BOARD .......................................................................................................................... 3-51
3. VFD P. C. BOARD ................................................................................................................................ 3-51
4. USB P. C. BOARD................................................................................................................................ 3-53
5. PORTABLE P. C. BOARD .................................................................................................................... 3-53
3-1

3-2
ONE POINT REPAIR GUIDE
1. NO POWER PROBLEM
No power problem occurs when you power on the unit.
1-1. NO POWER
1-1-1. Solution
Replace X201, IC200, IC202.
1-1-2. How to troubleshoot (Countermeasure)
1) Check X201(Crystal).
 If it does not oscillate, replace X201.
2) Check IC200(Reset IC).
 If its output voltage is not more than +2.7 V, replace IC200.
3) Check IC202(DSP IC).
 After Power is ON if the pin48 of IC202 is not ‘High’, replace IC202.
But, the new flash IC need to write program.
1-1-3. Service hint (Any picture/ Remark)
T13
_
75
U13
_
76
P10
_
77
U14
_
78
P11
_
79
T14
_
80
N11
_
81
T15
_
82
U15
_
83
T16
_
84
U16
_
85
U17
_
86
P12
_
87
P13
_
88
FB2 20
100
X2 00
32.768KHZ
R228 4M 7
C242 22pF C243 22pF
GND
X2 01
24M HZ
R236 1M
C262 33pF
C263 33pF
GND
C238
104
GND
IR
TUN- SDA
TUN- SCL
AUX- DET
TOUC H-SDA
TOUC H-SCL
R235
10R
R234 10R
C236 104
GND
C235
220uF/10V
R241 330K
B1 7 PD[1 4] 130
E13_VSS33IO 131
D1 4_VDD3 3IO 132
A17_PD[15]133
A16_PD[0] 134
B16_P
D[1 ] 135
B15_PD[2 ] 136
A15_PD[3]137
A14_PD[4] 138
B14_PD[5 ] 139 B13_PD[6 ]140
A13_PD[7] 141
E9_V D D12CORE 142
D10_PNTRST143
D13_PGPD 00 144
D9_PTD I145
D12_PGPD01 146
D8_PTM S147
E11_PGPD02 148
D7_PTCK 149
D11_PGPD03150
E7_PTDO 151
D6_PRTCK 152
A 12_PGPA 00153
B12_PGP
A01 154
B11_PGPA02 155
A 11_PGPA 03156
B10
_
VSS33IO
IO3V3
IO1V2
DQ0
DQ1
DQ2 DQ3
DQ4
DQ5
DQ6
DQ7
DQ1 4
DQ15
SF-M ISO SF-M OSI
SF-SCK
SF-CS1
AMP -SD- DET
AMP -OT W -DE T
AMP -PDN
RST
2VCC 3
GND
1
IC200
AZ 809
GND
R2 02 33 R
C203
NC
R2 01 10 K
R2 00
100R
C200
104
C201
NC
C202
NC
D2 00
NC
D2 01
NC
IO3V3
IO3V3
SDRAM (0 ...8)
HP-MUT E
MA0
MA1
MA2
MA3
MA4
MA5
MA6
MA7
MA8
MA9
MA11
MA10
BA1
BA0
RAS #
CAS #
WE#
CS#
DQM 1
R2 05 33 R
R2 06 33 R
MA12
CK E
CL K R2 0 4 33 R
12
34
56
78
RA201
33R 12
34
56
78
RA202
33R
12
34
56
78
RA203
33R 12
34
56
78
RA204
33R 12
34
56
78
RA205
33R
DQM 0
IC202
< MAIN board top view >
IC200
IC200
IC202
IC202
X201
X201

3-3
ONE POINT REPAIR GUIDE
2. SPEAKER NO AUDIO OUTPUT
No audio output problem occurs when you power on the unit.
2-1. NO SOUND
2-1-1. Solution
Reassemble AMP IC heat-sink, replace IC202.
2-1-2. How to troubleshoot (Countermeasure)
1) Reassemble AMP IC heat-sink (heat-sink screw must be assembled tightly).
2) Still NG, please check Q409, Q407, Q408 part out, if it is not appear 12 V.
3) If it is not appear 12 V, check IC202 pin48 output, is a high level.
4) If not high voltage, check whether IC202 damage, flash is lost.
2-1-3. Service hint (Any picture/ Remark)
< MAIN board top view >
IC202
IC202
Q408
Q408
Q407
Q407

3-4
ONE POINT REPAIR GUIDE
3. USB NO DETECT
When USB insert, USB no detect on the unit.
3-1. NO DETECT
3-1-1. Solution
Replace IC205.
3-1-2. How to troubleshoot (Countermeasure)
1) Please check IC205.
 pin1 : 5 V
2) If it is not OK, replace IC205.
3-1-3. Service hint (Any picture/ Remark)
< MAIN board top view >
IC205
IC205

3-5
ONE POINT REPAIR GUIDE
4. PROTECTION
4-1. D(DC) PROTECTION
4-1-1. Solution
Replace IC301(AMP IC) on MAIN board.
4-1-2. How to troubleshoot (Countermeasure)
1) Press the power button, the display is normal, no sound output. (D Protection or S Protection)
2) Check DC Voltage of speaker out Front Left channel + & -(JK300 pin2, 1), Front Right channel + & -
(JK300 pin4, 3).
3) Check resistor crack, cold solder of PWM IC out (R310, R313, R320, R322).
4) If PWM IC out is ok & speaker out(+/-) has DC Voltage, Replace IC301(AMP IC) on MAIN board.
4-1-3. Service hint (Any picture/ Remark)
< MAIN board top view >
IC300 (PWM IC)
IC300 (PWM IC)
IC301 (AMP IC)
IC301 (AMP IC)
R310, R313,
R310, R313,
R320, R322
R320, R322
JK300
JK300