CONFIDENTIAL

SERVICE MANUAL
MINI HI-FI SYSTEM
SERVICE MANUAL

MODEL: OK65
MODEL: OK65

CAUTION
BEFORE SERVICING THE UNIT, READ THE “SAFETY PRECAUTIONS”
IN THIS MANUAL.

P/NO : AFN78511828 SEPTEMBER, 2018

Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 CONTENTS

SECTION 1 ........ GENERAL

SECTION 2 ........ CABINET & MAIN CHASSIS
SECTION 3 ........ ELECTRICAL
SECTION 4 ........ MECHANISM (DM19D)

1-1 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 SECTION 1
SUMMARY

CONTENTS

SERVICING PRECAUTIONS ............................................................................................................................ 1-3

ESD PRECAUTIONS ......................................................................................................................................... 1-5

HIDDEN KEY MODE ......................................................................................................................................... 1-6

1. HIDDEN KEY MODE TABLE
2. HIDDEN KEY MODE DESCRIPTION

PROGRAM DOWNLOAD GUIDE...................................................................................................................... 1-7

FOTA UPDATE STEP USING BT APP .......................................................................................................... 1-10

SPECIFICATIONS ........................................................................................................................................... 1-12

1-2 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 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 cot-
ton swab should be used, taking care not to distort lens.

Pressure
Magnet
Pressure

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 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
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.

Armband

Resistor
(1 M)
Resistor
Conductive
(1 M)
Sheet

1-4 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 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 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 HIDDEN KEY MODE
1. HIDDEN KEY MODE TABLE
HIDDEN MODE ENTRANCE KEY(Audio) EXIT KEY
Front ‘Stop’ 
Version Check Remote Control Key ‘Play’ / for 1.5s
+ Remote Control Key ‘Play’ / for 5s
Front ‘Stop’ 
EEPROM INITIAL Auto exit
+ Remote Control Key ‘ ‘ for 5s

2. HIDDEN KEY MODE DESCRIPTION

2-1. Version Check
- Function : Version Check.
- Entrance Key : Front ‘Stop’ + Remote Control Key ‘Play’ for 5s.
- Exit Key : Remote Control Key ‘Play’ for 1.5s.
- Operation explanation : Remote Control Key OR .

VFD Display (Example) Result

MCS Version

MICOM Version

OPTION Version

DEMO Version

DJ PRO Version

EQ Version

EQ Check sum Version

2-2. EEPROM Initial

- Function : Initialize data stored in EEPROM and BACKUP RAM data.
- Entrance Key : Front ‘Stop’ + Remote Control Key ‘ ‘ for 5s.
- Exit Key : Auto exit.
- Explanation : ‘E2P CLR’ is displayed on the VPD and turn off the power automatically.

1-6 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 PROGRAM DOWNLOAD GUIDE
1. AUDIO PROGRAM
Download program file name must be MICOM_OK55_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 USB 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

1-7 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
2. CD PROGRAM
Download program file name must be HG790_OK75_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 USB 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

1-8 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
3. EQ & DEMO PROGRAM
Download program file name must be EQ_DEMO_PRG_OK55_XXXX.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 USB 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


EQDEMOUP


FINISH


AUTO POWER OFF

1-9 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 FOTA UPDATE STEP USING BT APP
Step1 : App connecting
Step2 : Device version info
(Check FW version)

After connecting the BT App with SET, When touch the “Device Version info” button,
the user could find the “Device Version info” on user could find the current and latest SET
Setting tab. version on pop-up menu.

Step3 : Select update button Step4 : Confirm update

When touch the “Update” button, user could Select the OK button on the caution message.
update the SET firmware using FOTA.

1-10 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 Step5 : Download from CDN server Step6 : Transfer FW

1st step is download from CDN server to After completed the download from server,
smart phone. The progress bar is displayed smart phone start to transfer the firmware to the
on BT App. SET. The progress bar is displayed on BT App.

Step7 : FW Flash Writing Step8 : FOTA complete

After completed the download from the smart When finishing the flash memory writing, pop-up
phone, the SET overwrite the firmware to flash message about finish is displayed and the SET
memory. auto power off.

1-11 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 SPECIFICATIONS
 GENERAL
Power requirements Refer to the main label on the unit.
Power consumption Refer to the main label on the unit.
Dimensions (W x H x D) Approx. 330 mm x 925 mm x 360 mm
Operating temperature 5 °C to 35 °C (41 °F to 95 °F)
Operating humidity 60 %

 INPUTS
Analog audio in (AUX IN) 2.0 Vrms (1 kHz, 0 dB), 600 Ω, RCA jack (L, R)
Portable in (PORT. IN) 1.0 Vrms (3.5 mm stereo jack) x 1
Microphone (MIC 1/2) Sensitivity 20 mV (1 kHz), 6.3 mm jack x 2

 TUNER
FM Tuning Range 87.5 to 108.0 MHz or 87.50 to 108.00 MHz

 SYSTEM
Frequency Response 40 to 20,000 Hz
Signal-to-noise ratio More than 75 dB
Dynamic range More than 80 dB
Bus Power Supply (USB) 5V 500 mA
Available Digital Input Audio Sampling Frequency 32 kHz, 44.1 kHz, 48 kHz, 88.2 kHz, 96 kHz

 AMPLIFIER (RMS Output power)

Total output 500 W RMS
HIGH 160 W RMS × 2 (4 Ω at 1kHz, 10% THD)
LOW 180 W RMS (4 Ω at 200Hz, 10% THD)

 Design and specifications are subject to change without notice.

1-12 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 SECTION 2
CABINET & MAIN CHASSIS

CONTENTS

DISASSEMBLY INSTRUCTIONS ..................................................................................................................... 2-2

EXPLODED VIEWS ........................................................................................................................................... 2-9

1. CABINET AND MAIN FRAME SECTION ................................................................................................. 2-9
2. DECK MECHANISM SECTION .............................................................................................................. 2-11
3. PACKING ACCESSORY SECTION ....................................................................................................... 2-13

2-1 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 DISASSEMBLY INSTRUCTIONS
1) Remove the 6 screws.

Figure 1. Panel Side L/R disassembly - 1

2) Disassemble each of the two screws located inside the handle.

Figure 2. Panel Side L/R disassembly - 2

2-2 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
3) Pull out Cover Side Assembly L/R in the backward direction.

Figure 3. Panel Side L/R disassembly - 3

4) Remove the 3 screws.

Figure 4. Panel Top disassembly - 1

2-3 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
5) Remove the two screws on the left and right sides.

Figure 5. Panel Top disassembly - 2

6) As shown in the figure, remove the Panel Top by pushing the front part and lifting the rear part.

Figure 6. Panel Top disassembly - 3

2-4 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
7) Remove the 9 screws on the Panel Rear.

Figure 7. Panel Rear disassembly

8) Bracket MD + Frame Main Screw 4 EA Disassembly

Figure 8. Main Set disassembly - 1

2-5 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
9) Remove the Set LED Connector / Speaker LED Connector / Speaker Network cable.

Figure 9. Main Set disassembly - 2

10) Power Cable Disconnection

Figure 10. Main Set disassembly - 3

2-6 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
11) Grasp both sides and pull upward to remove the assembly.

Figure 11. Main Set disassembly - 4

12) Complete removal of the Main Set.

Figure 12. After detaching the Main Set

2-7 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
2-8 Copyright © 2018 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
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.
260L
D

CABLE2

255
266
RMC

BT A41 262 K J 270

A51 A

A46
MAIN
256 CABLE3 B
C
B D H
G
257 E

265

259
258 277
L
258
E

G
255

263
261

A44
L
K 260R
A A00
H

SMPS CABLE5
M M

J A47
A50 N
521 276
TOP CN803 A60
272
275
274 521
273
272
251
251 521
272
C

300
N CABLE1

2-9 2-10 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
2. DECK MECHANISM SECTION (DM19D)

A00

1030

1049

1015

A005

2-11 2-12 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
3. PACKING ACCESSORY SECTION

825 FM Wire Antenna

826 Filter, Ferrite Core 900 Remote Control

AM
AN
T

O/ PO
M WE
RC
OR
D


R/
C

2-13 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
2-14 Copyright © 2018 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
 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 ........................................................................................................................ 3-9
6. NO SOUND ........................................................................................................................................... 3-14

ELECTRICAL TROUBLESHOOTING GUIDE................................................................................................. 3-23

1. POWER (SMPS) ................................................................................................................................... 3-23
2. MCS PART CHECK .............................................................................................................................. 3-26
3. FLD DISPLAY CHECK ......................................................................................................................... 3-27
4. PWM MODULATION CHECK ............................................................................................................... 3-28
5. POWER AMP PART CHECK ............................................................................................................... 3-29
6. TUNER / AUX FUNCTION CHECK ...................................................................................................... 3-30
7. TUNER FUNCTION CHECK................................................................................................................. 3-31
8. CD FUNCTION CHECK ........................................................................................................................ 3-32
9. USB FUNCTION ................................................................................................................................... 3-33

WAVEFORMS OF MAJOR CHECK POINT.................................................................................................... 3-34

1. DSP (IC501) .......................................................................................................................................... 3-34
2. SDRAM (IC502) .................................................................................................................................... 3-35
3. SERVO (IC401)..................................................................................................................................... 3-36
4. MOTOR DRIVER (IC400) ..................................................................................................................... 3-37
5. ADC (IC301).......................................................................................................................................... 3-38
6. USB (CN502) ........................................................................................................................................ 3-38
7. BLUETOOTH (CN504).......................................................................................................................... 3-39

WIRING DIAGRAM .......................................................................................................................................... 3-41

BLOCK DIAGRAM .......................................................................................................................................... 3-43

CIRCUIT VOLTAGE CHART ........................................................................................................................... 3-45

1. IC VOLTAGE......................................................................................................................................... 3-45
2. FAN MOTOR VOLTAGE ...................................................................................................................... 3-46
3. SMPS CAPACITOR & ZENER DIODE ................................................................................................. 3-46
4. MAIN CAPACITOR ............................................................................................................................... 3-47
5. CONNECTOR VOLTAGE ..................................................................................................................... 3-48

PRINTED CIRCUIT BOARD DIAGRAMS ....................................................................................................... 3-53

1. SMPS P.C.BOARD DIAGRAM ............................................................................................................. 3-53
2. MAIN P.C.BOARD DIAGRAM .............................................................................................................. 3-57
3. TOP P.C.BOARD DIAGRAM ................................................................................................................ 3-61
4. JACK & RMC P.C.BOARD DIAGRAM ................................................................................................. 3-65
5. SPEAKER LED P.C.BOARD DIAGRAM .............................................................................................. 3-65

3-1 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 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/ THERMISTOR/ BRIDGE DIODE

1-1-1. Solution
Please check and replace F901, TH901 or TH903, BD901 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 NTC thermistor TH900 or TH903 is normal or open.
3) Check if the bridge diode BD901 is short-circuit by over current with a digital multi-meter.

1-1-3. Service hint (Any picture/ Remark)

!

F H9 0 1 F901 FH902
LIVE 1 2 1 2 OTW1 1
(BK/BN) 1 2 2
!
1 2 RBU605M

HS900
2

100nF/275VAC
OTW2
R901
!

!
470K

BD901
100nF/275VAC

!
1 3
SVC681-14

TP901

1
L1

L1
2

4
1

1
L1

L1
2
4

4
R900 1.5M

NUTRAL 4
LF901

LF901-*1

LF902-*1

LF902
R902
470K

T8AL/250V

CM902
(WH/BL)
TP902
CM901
VR901

F901-*1 3

L2

L2
L2

L2
!

2
3

3
4
2
3

3
R903
470K

PN901 T5AL/250V
!

(5A 250V) OTW3

GP390-02P-TS 1 2
1 2
OTW4
CY902
GND

TH903
TH901 DSC 3D-15 MSFC
TH902
!

CY901
Y_GND

CY900
!

C903-*3 C903-*2 C903-*1

270uF 180uF 330uF

C903
330uF 450V

< F901 > <TH901 or TH903 > < BD901 >

If F901 is not short-circuit, If TH901 or TH903 is open, If BD901 is short-circuit,
replace it with a same replace it with a new one. replace it with a new one.
specifications one.

3-2 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 ONE POINT REPAIR GUIDE
NO POWER
If the unit doesn’t work by no PVDD problem, repair the set according to the following guide.

1-2. FUSE/ FET

1-2-1. Solution
Please check and replace F901, Q901 on SMPS board.

1-2-2. How to troubleshoot (Countermeasure)

1) Check if the fuse F901 is open or short-circuit.
2) Check the anode-cathod voltage of D951 with a digital multi-meter, it is normally 0.2 ~ 0.3 V.
 If it doesn’t have any voltage, it’s destroyed. Replace it with a new one.

1-2-3. Service hint (Any picture/ Remark)

T903

!
P2
P1

1R9582
2200uF/50V

1R9572

R959

R960
47K

47K

47K
2200uF/50V

47K
C952-*1

C953-*1

C952 C953
3 16
2200uF/63V 2200uF/63V
S3

15
MED62731209
HS952
S2

25x15
1

3
2

GND
GND
ZD932 Z02W20VY

14 C951
2C

! HS955
S1

470P/1KVDC
MED61841613
T904
1N
3A

18 TP915
D951

2 17 13 SF20A400HPI
GND
1.8K
R955
N6
N5
N3
N1

16
22K 1%
N4

R951

4 15

TP914
N2

5 14
1R9522
2.2K
R956

7 12
1K

6 13 TP910
1uF R954
P3

7 12
C956 1K

11
R953

TP912
1K
N7

8 11
9
R961

220

R972 1.5K

3B
KRC103S
R971 2K

! TP913
Q950
R962

220

IC951
1E
1
4

2C
PC903

TP911
3

< SMPS circuit >

3-3 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 ONE POINT REPAIR GUIDE
2. NO BOOTING WHEN POWER ON THE SET
The set doesn’t work when press the power button on the top board or the remote control.

2-1. IC501
2-1-1. Solution
Replace IC501 on MAIN board.

2-1-2. How to troubleshoot (Countermeasure)

1) Check the +12 V (CN201) and 3.3 VA (IC202) in standby mode.
 If there is no 12 VA, check the SMPS and if doesn’t appear 3.3 VA, check IC202.
2) Check +12 V, +5.1 VA, 3.3 VA, DVCC_5V and DVCC_3.3V when power on the set.
- If the set doesn’t work regardless of what the KEY1 changes high to low while pressing the power button.
X500 and X501 work normally but, if you can not power on the set, replace the IC501 with a new one
on the main board.

2-1-3. Service hint (Any picture/ Remark)

X500 IC501
(24 MHz)
X501
(32.768 kHz)

< MAIN board top view >

R5B78
PWR_CTRL

< MAIN board bottom view >

3-4 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 ONE POINT REPAIR GUIDE
3. VFD IS NOT DISPLAYED WHEN POWER ON THE SET
When power on the set, any icons or characters on VFD are not displayed.

3-1. VFD (VFD801)

3-1-1. Solution
Please check and replace VFD301 on TOP FRONT board.

3-1-2. How to troubleshoot (Countermeasure)

1) Check if VFD_12V, DVCC_3.3V and VCC_5V are output from SMPS to VFD via the main board.
2) Check if the IC501 outputs VFD_CLK, VFD_STB, and VFD_DAT to the top board.
3) Check if the VFD grid current amplifier circuit on the top board.
Check the drive signal to the transistor’s(Q801,2) base.
 If the control signals from VFD (DGND, VDD) isn’t output, replace VFD with a new one.

3-1-3. Service hint (Any picture/ Remark)

knukTX
knuk Y\ nuk
}mk†XY}
}mk†XY} Y[ }m†XY}
YZ k}†\UW}
}jj†\}
}jj†\} YY k}†\UW}
k}jj†ZUZ}
k}jj†ZUZ} YX k}†ZUZ}
}mk†jsr
}mk†jsr R810(TP841) about
YW }mk†jsr
}mk†z{i
}mk†z{i
X` }mk†z{i
Q801 Emitter 30 Vp-p
}mk†kv
}mk†kv X_ }mk†kh{
knukTY
knuk X^ knuk
RZUZ}h X] RZUZ}h
RZUZ}h
X\ nuk
shukpunnlhy
shukpunnlhy X[ shukpunnlhy
rl€Z
rl€Z XZ rl€Z
rl€Y
rl€Y XY rl€Y
rl€X
rl€X XX rl€X
tpj†}†h < Waveform of the grid current driver>
tpj†}vs†h XW tpj†}vs†h
tpj†}†i
tpj†}vs†i ` tpj†}vs†i
zjyh†h
zjyh†h _ zjyh{jo†h
zjyh†i
zjyh†i ^ zjyh{jo†i
mpsl†z†i
mpsl†z†i ] mpsl†z†i
mpsl†z†h
mpsl†z†h \ mpsl†z†h
thpu†}†i
thpu†}†i [ thpu†}vs†i
thpu†}†Th
thpu†}†h Z thpu†}vs†h
Y GGGGGGnuk
X nuk
knuk
ju_W[
knuk

< TOP FRONT circuit >

3-5 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 ONE POINT REPAIR GUIDE
4. NO BOOTING (IN CD/USB FUNCTION)
After you turn on power key and displayed message in the following order (HELLO  VOL XX 
CD or USB) on VFD, it will not display other message on VFD, and it will not boot-up normally.

4-1. NO DVCC_3.3V, 1.2 VA

4-1-1. Solution
Please check and replace IC202, IC205 on MAIN board.

4-1-2. How to troubleshoot (Countermeasure)

1) Check Voltage of IC202 pin3 on MAIN board.
 If IC202 pin3 (about 3.3 V) & pin1 Input 5.1 VA doesn’t come out, check IC201 & +12 V from SMPS board.
2) If IC201 pin2 (about 5.1 V) is normal, check voltage of IC205 pin3 (about 1.2 VA).
If IC205 pin3 (about 1.2 VA) doesn’t come out, check R218, R219, R221.
If there’s no defective component then replace IC205.
3) PWR_CTRL is high, check R214, R233 and if there’s no defective component then check DVCC_3.3V
short with GND.
PWR_CTRL (IC204 pin3) is high (about 3.2 V)
 If PWR_CTRL isn’t high, check pin D11 of IC501 & R512, R513
4) If PWR_CTRL is high, check R5B78 and if there’s no defective component then replace IC204.

4-1-3. Service hint (Any picture/ Remark)

IC201

IC203
IC202
IC205

< MAIN board top view >

IC204

< MAIN board bottom view >

3-6 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 ONE POINT REPAIR GUIDE
NO BOOTING (IN CD/USB FUNCTION)
After you turn on power key and displayed message in the following order (HELLO  VOL XX 
CD or USB) on VFD, it will not display other message on VFD, and it will not boot-up normally.

4-2. CRYSTAL (X500)

4-2-1. Solution
Replace X500 on MAIN board.

4-2-2. How to troubleshoot (Countermeasure)

1) If 3.3 VA & 1.2 VA is normal, check reset ‘High’ of IC501 pin T12 on MAIN board.
 If MAIN_RESET isn’t high, check MICOM (IC101) pin40.
2) If MAIN_RESET is high, check the soldering status of 24 MHz crystal (X500).
3) If the crystal (X500) doesn’t oscillate, check R5B4, R5B6, C5B2, C5B5 around crystal (X500).
 If there’s no defective component, then replace X500.

4-2-3. Service hint (Any picture/ Remark)

XI

IC501 XO
X500

X500
< MAIN board top view >
< Signal waveform >

3-7 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 ONE POINT REPAIR GUIDE
NO BOOTING (IN CD/USB FUNCTION)
After you turn on power key and displayed message in the following order (HELLO  VOL XX 
CD or USB) on VFD, it will not display other message on VFD, and it will not boot-up normally.

4-3. SERIAL FLASH (IC503)

4-3-1. Solution
Please check and replace IC503 on MAIN board.

4-3-2. How to troubleshoot (Countermeasure)

1) If the crystal (X500) does oscillate, check serial flash (IC503) on MAIN board.
 Check pin8 (VCC), pin6 (CLK), pin1 (CS), pin2 (DO), pin5 (DI) of below waveform.
2) If pin1, 2, 5, 6 doesn’t come out, check registers (R5B72 ~ 5) of IC503.
 If registers of IC503 is OK, then replace IC503. (it need to download program.)
3) After change IC503, if It is still not below waveform, check IC501 (DSP IC).

4-3-3. Service hint (Any picture/ Remark)

VCC

CS#

CLK

IC503 DO

< MAIN board bottom view > < Signal waveform >

3-8 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 ONE POINT REPAIR GUIDE
5. NO OPERATION OF MD
When no sound output in the CD function, you can not listen to music reading data from a CD
disc if the servo motors in MD don’t work. This step is for checking the SPINDLE MOTOR among
them.

5-1. SPINDLE MOTOR

5-1-1. Solution
Replace IC400 on MAIN board.

5-1-2. How to troubleshoot (Countermeasure)

1) Check the SPDO signal from pin16 of IC401.
 If no signal, check DVCC_3.3V and X400.
2) Check the SPIN+ & SPIN- from IC400 to CN401 for driving SPINDLE motor. It is about 3.6 Vp-p.
 If no signal, check M_5 V for IC400.
3) Check if the FFC cable is solidly connected between CN401 and MD.
4) Check the MD.
 If the spindle motor is sort-circuit or has any trouble, it can not rotate CD discs.
Please check the function after changing another MD.

5-1-3. Service hint (Any picture/ Remark)

SP+: pin17
IC400 SP-: pin18

IC401

< Waveform of SP- & SP+ < MAIN board bottom view >
for driving SPINDLE motor >

3-9 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 ONE POINT REPAIR GUIDE
NO OPERATION OF MD
When no sound output in the CD function, you can not listen to music reading data from a CD
disc if the servo motors in MD don’t work. This step is for checking the SLED MOTOR among
them.

5-2. SLED MOTOR

5-2-1. Solution
Replace IC400 on MAIN board.

5-2-2. How to troubleshoot (Countermeasure)

1) Check the SLDO signal from pin15 of IC401.
 If no signal, check DVCC_3.3V and X400.
2) Check the SPED+ & SLED- from IC400 to CN401 for driving SPINDLE motor. It is about 2.9 Vp-p.
 If no signal, check M_5 V for IC400.
3) Check if the FFC cable is solidly connected between CN401 and MD.
4) Check the MD.
 If the spindle motor is sort-circuit or has any trouble, it can not rotate CD discs.
Please check the function after changing another MD.

5-2-3. Service hint (Any picture/ Remark)

SP+
IC400 SLED+: pin11
SLED-: pin12

SP-
IC401

< Waveform of SLED- & SLED+ < MAIN board bottom view >
for driving SLED motor >

3-10 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 ONE POINT REPAIR GUIDE
NO OPERATION OF MD
When no sound output in the CD function, you can not listen to music reading data from a CD
disc if the servo motors in MD don’t work. This step is for checking the TRAY OPEN / CLOSE
MOTOR among them.

5-3. TRAY OPEN/ CLOSE MOTOR

5-3-1. Solution
Replace IC400 on MAIN board.

5-3-2. How to troubleshoot (Countermeasure)

1) Check MOT_OPEN & MOT_CLOSE signals from pin P5, L4 of IC501 to IC400.
 If no signal, check M_5V to IC400.
2) Check LOAD± from IC400 to CN401 for driving the tray open / close motor. It is about 3.85 Vp-p.
 If no signal, check M_5V to IC400. If it has any trouble, replace it with a new one.
3) Check if the FFC cable is solidly connected between CN401 and MD.
4) Check the MD.
 If the tray motor is sort-circuit or has any trouble, it can not open or close the tray.
Please check the function after changing another MD.

5-3-3. Service hint (Any picture/ Remark)

M_CL: pin6
LO- M_OP: pin7
IC400
LO+(RED) LO+: pin9
LO-: pin10

MOT_OPEN IC401

MOT_CLOSE
< Waveform < MAIN board bottom view >
for driving tray open/ close motor >

3-11 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 ONE POINT REPAIR GUIDE
NO OPERATION OF MD
When no sound output in the CD function, you can not listen to music reading data from a CD
disc if the pickup module in MD doesn’t work. This step is for checking the LASER TRACKING
ACTUATOR.

5-4. LASER TRACKING ACTUATOR

5-4-1. Solution
Replace IC400 on MAIN board.

5-4-2. How to troubleshoot (Countermeasure)

The tracking actuator makes the laser beam be positioned in the center of a track on CD disc.
1) Check the TRD signal from pin14 of IC401.
 If no signal, check DVCC_3.3V and X400.
2) Check TR- & TR+ from IC400 to CN400 for driving the tracking actuator.
 If no signal, check M_5V for IC400.
3) Check if the FFC cable is solidly connected between CN400 and MD.
4) Check the MD.
 If the pickup module has any trouble, it can not move the laser beam on the left or right side.
Please check the function after changing another MD.

5-4-3. Service hint (Any picture/ Remark)

IC400 TR+: pin16

TR-: pin15

IC401

< Waveform of TR± < MAIN board bottom view >

for driving tracking actuator >

3-12 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 ONE POINT REPAIR GUIDE
NO OPERATION OF MD
When no sound output in the CD function, you can not listen to music reading data from a CD
disc if the pickup module in MD doesn’t work. This step is for checking the LASER FOCUSING
ACTUATOR.

5-5. LASER FOCUSING ACTUATOR

5-5-1. Solution
Replace IC400 on MAIN board.

5-5-2. How to troubleshoot (Countermeasure)

The focusing actuator makes the laser beam keep a regular interval with the surface of a CD disc.
1) Check the FDO signal from pin13 of IC401.
 If no signal, check DVCC_3.3 and X400.
2) Check F- & F+ from IC400 to CN400 for driving the focusing actuator.
 If no signal, check M_5V for IC400.
3) Check if the FFC cable is solidly connected between CN400 and MD.
4) Check the MD.
 If the pickup module has any trouble, it can not move the laser beam on the top or bottom side.
Please check the function after changing another MD.

5-5-3. Service hint (Any picture/ Remark)

IC400 F+: pin14

F-: pin13

IC401

< Waveform of F± < MAIN board bottom view >

for driving focusing actuator >

3-13 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 ONE POINT REPAIR GUIDE
6. NO SOUND
There is no sound output by DIGITAL AUDIO AMP DAMAGE, repair the set according to the
following guide.

6-1. DIGITAL AUDIO AMP DAMAGE

6-1-1. Solution
Replace IC701, IC702 on MAIN board.

6-1-2. How to troubleshoot (Countermeasure)

1) Check PWM_FL±, PWM_FR± & PWM_SW± signals from IC601 to IC701 & 702 each input function.
 If no signal, check if I2S audio signals are entered to IC601.
2) Check PVDD.
 If PVDD is abnormal, check the SMPS.
3) Check AMP_12V for driving the gate of AMP IC.
a. All the powers are normal, but if AMP_12V is low, there is possible for AMP IC to be damaged.
b. Remove L705, L706, L707 and L708 one by one.
When removed a inductance, if AMP_12V is recovered, the IC connected to it was damaged.
c. Replace the IC with a new one.
4) Check the impedance between IC701/IC702_OUT_A/OUT_B & GND.
a. If the impedance is 0 Ω, the IC must be damaged.
b. After removing the heat sink, replace it with a new one.

6-1-3. Service hint (Any picture/ Remark)

L706

IC702

L705

L708
IC601
IC701

L707

< MAIN board top view >

3-14 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 ONE POINT REPAIR GUIDE
NO SOUND
There is no sound output in the CD FUNCTION, repair the set according to the following guide.

6-2. CD FUNCTION
6-2-1. Solution
Replace IC501 on MAIN board.

6-2-2. How to troubleshoot (Countermeasure)

1) Check CD_BCK, CD_LRCK, & CD_DATA signals from IC501 to IC401.
 If no signal, check if the RF & servo signals from MD is entered to IC401.
Refer to the “No operation of MD” guide on Item 5.
2) Check the following I2S signal flow. < I2S audio signal Interface >
- MCS_BCK : IC501_pin E1 --> IC601_pin23
- MCS_LRCK : IC501_pin D1 --> IC601_pin22 (44.1 kHz)
- MIX_DATA0_OUT : IC501_pin E2 --> IC601_pin24
- MIX_DATA2_OUT : IC501_pin R2 --> IC601_pin26
 If there is any trouble, check the power for each IC.
The power is normal but, if the signal waveform to the IC is distorted or no signal,
replace it with a new one.

6-2-3. Service hint (Any picture/ Remark)

IC501

< Waveform of I2S audio interface signals > < MAIN board top view >

+3.3VA
D4 VDD33IO
E5 VSS33IO
VFD_CLK R5B7 100 B1 PGPA09
VFD_PWR_CTRL R5B8 100 C1 PGPA10
R5B9 100 C2 PGPA11
VFD_STB NC
R5B37 D2 PGPA12
MCS_MCLK R5B10 D1
MCS_LRCK 100 PGPA13
R5B11 100 E1 PGPA14
MCS_BCK R5B22
MIX_DATA0_OUT 33 E2 PGPA15
DIR_SCL
DSPI_MCLK
R5B23
R5B42
33
33
E4
F2
PGPB00
PGPB01 IC501
R5B43 33 F1 PGPB02
DSPI_LRCK R5B44
DSPI_BCK 33 G1 PGPB03
G2 PGPB04
DSPI_ADATA R5B12 33 F4
BT_ADC_SCL PGPD04
R5B19 100 H2 PGPB05
MIC_DATA_IN R5B13 33 G5
DEBUG_CON_OUT DFT_TX PGPD13
H1 PGPB06(Boot[0])
G4 PGPD14
J1 PGPB07(Boot[1])
H4 PGPD15
J2 PGPB08
J4 VDD12INT
J5 VSS12INT

< MAIN - CD DSP circuit >

3-15 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 ONE POINT REPAIR GUIDE
NO SOUND
There is no sound output in the USB Function, repair the set according to the following guide.

6-3. USB FUNCTION

6-3-1. Solution
Replace IC204 on MAIN board.

6-3-2. How to troubleshoot (Countermeasure)

1) Check +5V_USB to USB board.
 If the USB LED are turned on, the voltage is okay, if so not, check USB_5V to pin4, 5 of CN803.
2) Check USB D1± or USB D2± from MAIN board to TOP board.
a. Check 2.0_D1±signals(pin U7, U8 ) or 1.1_D1± signals(pin A7, A8 ) to IC501.
b. Check USB± signals to CN502(pin1, 2, 7, 8).
 If there is any trouble, check the power for IC207.
The power is normal but, if the signal waveform to the IC is distorted or no signal,
replace it with a new one.
3) Check if “Digital audio AMP block” on item 6-1 is normal.

6-3-3. Service hint (Any picture/ Remark)

D+
IC501
D-

CN502

USB D-/D+ (CN502 pin1, 2 & pin7, 8) < MAIN board top view >
< Waveform of USB D± signal >

3-16 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 ONE POINT REPAIR GUIDE
NO SOUND
There is no sound output in the AUX Function, repair the set according to the following guide.

6-4. AUX FUNCTION

6-4-1. Solution
Replace IC301 on MAIN board.

6-4-2. How to troubleshoot (Countermeasure)

1) Check AUX_L/R signals to IC301 (pin1, 2).
2) Check if DSPI_BCK, LRCK, MCLK are entered from IC501 to IC301.
3) Check if ADC_DATA is entered from IC301 to IC501.
 If no signal, check AVCC_3.3V & DVCC_3.3V (ADC) for IC301. If is NG, replace it a new one.
4) Check the following I2S signal flow from IC501 to IC601. (Refer to Item 6-2.)
 If there is any trouble, check the power for each IC. The power is normal but, if the signal waveform
to the IC is distorted or no signal, replace it with a new one.
5) Check if the digital audio AMP block is okay. Refer to “Digital Audio AMP” guide on Item 6-1.
 If AMP is damaged, replace it with a new one.

6-4-3. Service hint (Any picture/ Remark)

IC301

Pin15:DSPI_MCLK
Pin16:DSPI_LRCK
Pin17:DSPI_BCK

< AUX function signal flow > < MAIN board bottom view >

3-17 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 ONE POINT REPAIR GUIDE
NO SOUND
There is no sound output in the TUNER function, repair the set according to the following guide.

6-5. TUNER FUNCTION

6-5-1. Solution
Replace IC301 on MAIN board.

6-5-2. How to troubleshoot (Countermeasure)

1) Check if TUNER_LR is entered from pin13, 14 of IC302 to IC301(pin27, 28)
 If no signals, check AVCC_3.3V for tuner power.
 Check if the tuner control signals (CLK, DAT, CE, RST, SLT) are entered from IC501 to IC302.
If it doesn’t work, replace IC302 with a new one.
2) Check if MCS_BCK, MCS_LRCK, & MCS_MCLK are entered from IC501 to IC201.
3) Check if ADC_DATA is entered from IC301 to IC501.
 If no signal, check AVCC_3.3V & DVCC_3.3V (ADC) for IC301. If is NG, replace it with a new one.
4) Check the following I2S audio signal flow from IC501 to IC601. (Refer to Item 6-2.)
 If there is any trouble, check the power for each IC.
The power is normal but, if the signal waveform to the IC is distorted or no signal,
replace it with a new one.
5) Check if the digital audio AMP block is okay. Refer to “Digital Audio AMP” guide on Item 6-1.
 If AMP is damaged, replace it with a new one.

6-5-3. Service hint (Any picture/ Remark)

IC301
Pin15:DSPI_MCLK
Pin16:DSPI_LRCK
Pin17:DSPI_BCK

Pin1:A_IN_L
Pin2:A_IN_R

< TUNER function signal flow > < MAIN board bottom view >

3-18 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 ONE POINT REPAIR GUIDE
NO SOUND
There is no sound output in the PORTABLE Function, repair the set according to the following guide.

6-6. PORTABLE FUNCTION,

6-6-1. Solution
Replace IC301 on MAIN board.

6-6-2. How to troubleshoot (Countermeasure)

1) Check if PT_LR signals to IC301 (pin29, 30).
2) Check if DSPI_BCK, LRCK, MCLK are entered from IC501 to IC301.
3) Check if ADC_DATA is entered from IC201 to IC501.
 If no signal, check AVCC_3.3V & DVCC_3.3V (ADC) for IC301. If is NG, replace it with a new one.
4) Check the following I2S audio signal flow from IC501 to IC601. (Refer to Item 6-2.)
 If there is any trouble, check the power for each IC.
The power is normal but, if the signal waveform to the IC is distorted or no signal,
replace it with a new one.
5) Check if the digital audio AMP block is okay. Refer to “Digital Audio AMP” guide on Item 6-1.
 If AMP is damaged, replace it with a new one.

6-6-3. Service hint (Any picture/ Remark)

Pin15:DSPI_MCLK IC301
Pin16:DSPI_LRCK
Pin17:DSPI_BCK

Pin29:PT_L
Pin30:PT_R

< PORT. IN function signal flow > < MAIN board bottom view >

3-19 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 ONE POINT REPAIR GUIDE
NO SOUND
There is no sound output in the MIC IN function, repair the set according to the following guide.

6-7. MIC IN function

6-7-1. Solution
Replace IC206 on MAIN board, ICA301 on MIC & RMC board.

6-7-2. How to troubleshoot (Countermeasure)

1) Check MIC_SI & MIC_S2 signal to pin6, 8 of CN301.
 If no signal, Check the signals to pin6 & 8 of CNA301 on the MIC & RMC board.
Check if the signal is entered from pin6 & 8 of CNA301 to pin6, 8 of CN301.
2) Check if MIC_SIG is entered from pin2 of JK302 & JKA303 to pin2, 13 to ICA301 (PRE AMP).
3) Check if the amplified signal comes out from pin3 &12 of ICA301.
 If no signal output, check DVCC_3.3V for ICA301, replace ICA301 with a new one if it has a problem.
4) Check if DSPI_BCK, LRCK,MCLK are entered from IC501 to IC301.
Check if MIC_DATA_IN is entered from pin19 of IC301 to pin H2 of IC501.
 If no signal, check AVCC_3.3V & DVCC_3.3V for IC301.
If it is abnormal, change replace it a new one.
5) Check the following I2S signal flow from IC301 to IC501.
 If there is any trouble, check the power for each IC.
If the signals are abnormal, replace it a new one.
6) Check if the digital audio AMP block is okay. Refer to “Digital Audio AMP” guide on item 6-1.
 If AMP is damaged, replace it with a new one.

6-7-3. Service hint (Any picture/ Remark)

IC301

ICA301 Pin15:DSPI_MCLK
Pin16:DSPI_LRCK
Pin17:DSPI_BCK

< MIC & RMC board top view > < MAIN board bottom view >

3-20 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 ONE POINT REPAIR GUIDE
NO SOUND
There is no sound output in the Bluetooth function, repair the set according to the following guide.

6-8. BLUETOOTH FUNCTION

6-8-1. Solution
Replace IC501 on the MAIN board or bluetooth module on the FRONT Panel.

6-8-2. How to troubleshoot (Countermeasure)

1) Check BT_RX, BT_TX signal to pin6, 4 of CN504.
 If no signal, check the signal to pin4, 6 and pin10 (3.3 VA) of on the Bluetooth module
and cable connection state.
 If there are no signal out from module, replace new module.
2) Check if BT_RX/TX is entered from pin6, 4 of CN504 to pin L1,K1 to IC501 (DSP).
3) Check if MCS_BCK, MCS_LRCK & MIX_DATA IN is entered from IC501 to IC601.
 If no signal, check +3.3 VA & +1.2 VA for IC501.
If it is abnormal, change replace it a new one.
4) Check the following I2S signal flow from IC501 to IC601.
 If there is any trouble, check the power for each IC.
If the signals are abnormal, replace it a new one.
5) Check if the digital audio AMP block is okay. Refer to “Digital Audio AMP” guide on item 6-1.
 If AMP is damaged, replace it with a new one.

6-8-3. Service hint (Any picture/ Remark)

B/T Module

CN504
BT_RX,
BT_TX

IC501 IC601

MCS_BCK PWM
MCS_LRCK
MIX_DATA0_OUT

AMP

< Bluetooth function signal flow > < MAIN board top view >

3-21 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 ONE POINT REPAIR GUIDE
NO SOUND
There is no sound output in the OPTICAL function, repair the set according to the following guide.

6-9. OPTICAL FUNCTION (OPTIONAL)

6-9-1. Solution
Replace IC304 on the MAIN board.

6-9-2. How to troubleshoot (Countermeasure)

1) Check DSPI_BCK, LRCK, MCLK, ADATA of IC304(pin27, 28, 29, 31).
 If no signal, check the signal from JK302 pin1 to IC304 pin1
and cable connection state.
 If there are no signal out from JK302, replace new connector and cable.
2) Check if MCS_BCK, MCS_LRCK & MIX_DATA IN is entered from IC501 to IC601.
 If no signal, check +3.3 VA & +1.2 VA for IC501.
If it is abnormal, change replace it a new one.
3) Check the following I2S signal flow from IC501 to IC601.
 If there is any trouble, check the power for each IC.
If the signals are abnormal, replace it a new one.
4) Check if the digital audio AMP block is okay. Refer to “Digital Audio AMP” guide on item 6-1.
 If AMP is damaged, replace it with a new one.

6-9-3. Service hint (Any picture/ Remark)

IC304 JK302

BT_RX,
BT_TX

IC501 IC601

MCS_BCK PWM
MCS_LRCK
MIX_DATA0_OUT

IC304
AMP

< OPTICAL function signal flow > < MAIN board top view >

3-22 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 ELECTRICAL TROUBLESHOOTING GUIDE
1. POWER (SMPS)

No 12 VA

YES
NO
F901 normal? Replace F901 (Use the same fuse).

YES
NO
BD901 normal? Replace BD901.

YES
NO
TH901(TH903) normal? Replace TH901.

YES

Is Vcc NO
(10 V ~ 18 V) supplied to
D902 normal?
IC901 pin2?

NO

YES Check or replace D902.

NO
D921/ D922 normal? Replace D921/ D922.

YES

Is there NO
about 2.5 V at Replace IC941.
IC941 pin1?

YES
NO
D951 normal? Replace D951.

YES
NO
ZD932 normal? Replace ZD932.

YES

Power line of main PCB is short.

3-23 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 ELECTRICAL TROUBLESHOOTING GUIDE

No PVDD

YES
NO
F901 normal? Replace F901 (Use the same fuse).

YES
NO
BD901 normal? Replace BD901.

YES
NO
TH901(TH903) normal? Replace TH901.

YES
Is Vcc NO
(10 V ~ 18 V) supplied to NO
D903 normal?
IC901 pin2?
YES

YES Check or replace D903.

NO
Q911 base HIGH?

YES

• Check P_CTRL HIGH signal from MCS.

• Check PC902.

Check or replace Q911.

NO
Q901 normal? Replace Q901.

YES
NO
D951 normal? Replace D951.

YES

Is there about 2.5 V NO

Replace IC951.
at IC951 pin1?

YES

Power line of main PCB is short.

3-24 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 ELECTRICAL TROUBLESHOOTING GUIDE

No LED

YES

Is Vcc (DVCC_5V) NO
Check or replace IC203 block.
supplied to IC206, IC209?

YES

NO
Is SPLED & XFLED_5V is normal? Check or replace IC206, IC209.

YES

Check or replace LED harness cable.

No VFD

YES

NO
VFD_12V is normal? Check or replace Q202, Q205.

YES

NO
VFD_3.3V is normal? Check or replace Q203, Q206.

YES

NO
VFD_CLK, STB, DO is normal? Check or replace R808, R811, R814.

YES

Check or replace VFD.

3-25 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 ELECTRICAL TROUBLESHOOTING GUIDE
2. MCS PART CHECK

MCS PART CHECK

YES

Check if voltage NO
Refer to SMPS troubleshooting.
of CN201 pin1, 2: 12 V.

YES

Check if IC202, IC205 NO

Check and change IC202, IC205.
have 3.3 VA & 1.2 VA output.

YES

Check if IC204 NO
Check and change IC204.
have DVCC_3.3V output.

YES

X501: 32.768 kHz, X500: 24 MHz

Check the operation.

YES

OK

3-26 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 ELECTRICAL TROUBLESHOOTING GUIDE
3. FLD DISPLAY CHECK

FLD DISPLAY CHECK

YES

Check NO Refer to SMPS/MPEG

CN201 pin1, 2: 12 V input
troubleshooting.
voltage.

YES

Check
if both end voltage NO Check DVCC_5V
of FL+, FL- are over 1.85 V VH : Q801, Q802, D801~D804.
VH : over 29 V.

YES

Check CN804 NO NO
connection and DVCC_3.3V of Check CN804 connection. Check each pin voltage.
VDD(C806+).

YES

Check
IC501 -> VFD801 NO Check data
data communication IC501 pin C2, B3, B1.
STB/ DATA/ CLK.

YES

FLD light on?

YES

OK

3-27 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 ELECTRICAL TROUBLESHOOTING GUIDE
4. PWM MODULATION CHECK
PWM MODULATION PART
CHECK

YES

Check CN201 NO Refer to

pin1, 2: 12 V. SMPS troubleshooting.

YES

• Check IC601(TAS5548) 3.3 V - pin9, 14, 35, 50.

• Check X601 (12.288 MHz).

YES

Check NO NO
Check X601 Replace X601(12.288 MHz).
X601(12.288 MHz)
(12.288 MHz).
operation.

YES YES

Check IC601 pin21 CLK input. OK

YES

Check IC501 (MLC3730) NO Check line resistor output NO

pin U13: RESET, pin L14: SDA RST: R508, SCL: R510, Replace R508, R510, R509.
pin L13: SCL output. SDA: R509.

YES YES

OK

Check Check
IC601(TAS5548) input data NO NO Refer to
CD Assy communication
pin24 PWM wave. Pin22, 23, 24. CD troubleshooting.

YES YES

Check IC601 NO
Check each line resistor output.
input data.

YES

OK

Check
PWM modulator output NO NO
FL: Pin48(-),49(+). FR: Pin46(-),47(+). Check IC601. Replace IC601.
Other output
check.

YES YES

OK OK

3-28 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 ELECTRICAL TROUBLESHOOTING GUIDE
5. POWER AMP PART CHECK

POWER AMP PART CHECK

YES

Check CN201 pin1, 2: 12 V, NO

Refer to SMPS troubleshooting.
pin8, 9, 10: 48.5 V (35.5 V).

YES

Check IC701, IC702

Pin51, 52, 42, 43, 38, 39, 30, 31 input voltage.

YES

Check IC701, IC702 NO

Check each line resistor output voltage.
pin64: AMP_12V input.

YES

Check PWM modulator input

IC701 pin4, 5/ IC702 pin4, 5, 10, 11.

YES

Check IC701, IC702

pin28, 29, 36, 37, 44, 45, 52, 53.

YES

NO
Check output line coil. Replace the coil.

YES

OK

3-29 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 ELECTRICAL TROUBLESHOOTING GUIDE
6. TUNER / AUX FUNCTION CHECK

FUNCTION CHECK

YES

Check NO
IC301 pin27, 28, 1, 2 Check IC302, JK301.
input.

YES

Check NO Check IC301 NO

IC301 pin18 Pin8: ADC_3.3V Check CN201 pin1, 2: 12 V.
output data. Pin13, 14: DVCC_3.3V.

YES

NO
IC501 output data. Replace IC501.

YES

OK

3-30 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 ELECTRICAL TROUBLESHOOTING GUIDE
7. TUNER FUNCTION CHECK

TUNER FUNCTION CHECK

YES

NO Check tuner IC(IC302)

Check tuner IC302 operation.
voltage (Pin11:AVCC_3.3V).

YES

NO
Check IC301 Pin27, 28. Check tuner data line R & C.

YES

Refer to function check.

3-31 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 ELECTRICAL TROUBLESHOOTING GUIDE
8. CD FUNCTION CHECK

CD FUNCTION

YES

Can the NO NO Is motor_open/close ok?

Is load +,- ok? (IC400 pin6, 7)
disc insert?

YES
YES YES
Check IC400.

NO
Is motor ok? (about 12 Ω) Check loading motor.

Check IC400 (Motor drive IC).

NO

NO NO Focus,
Disc reading IM driving
tracking, sled signal
is ok? (Focus and tracking) is ok?
is ok?

YES YES

Is no signal at speaker? Is the MD (PN401 pin22)

about 190 mV?

YES NO

Check NO
the signal of IC401. Check Vcc of IC401. Check MD (pick-up).

YES

Check NO NO
the signal (16.9344 MHz) Check cristal (X400). Replace cristal (X400).
at IC401 pin49.

YES

Check IC501 NO
input/output and Replace IC501.
control line.

YES

Refer to function check.

3-32 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 ELECTRICAL TROUBLESHOOTING GUIDE
9. USB FUNCTION

USB FUNCTION

YES

Plug-in USB device.

YES

NO NO
Display “NO USB”. Check USB_5V. Check CN502.

YES
YES

Check USB_D+, D- NO Check USB jack

Display “READ”. (R5B69,R5B70,C5B11,C5B14, (CN801, CN802).
ZD505,ZD506).

YES
YES

Check IC501 NO
Display “NO FILE”. Replace IC501.
(pin U7, U8/ A7, A8).

YES

Check USB audio file in USB device

(MP3, WMA file is playable)

3-33 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 2
1
1. DSP (IC501)

T1 R5B48 33
DIR_RST P5 R5B50 100 PGPC07
MOT_OPEN U1 R5B52 33 PGPE00
ADC_DATA_IN P6 R502 100 PGPC08
CD_MCK U2 R5B55 100
CD_RW PGPE01
TUNER_CE P7 R503 100 PGPC09
U3 R5B58 470 PGPE02
CD_DIN_OUT R5B59
N7 100 PGPC10
XI

MOT_MUTE

XO
T3 R5B62 1K PGPE03
CD_BUSY P8 R5B63
TUNER_RST 100 PGPC11
1.2VAA U4 PGPE04

ZD506
DF3D6.8MS
C5B12 T4 VDD12CORE
DGND 100nF U5 VSS12CORE

DGND
USB_5V R5B68 R5 B6 7 T5 VDD33USB20

CLOSE TO THE IC PIN

2.2K 4. 7K T6 PUID20
C5B13 C5B16 100nF U6 PUVBUS20
FL500 100nF T7 VDD33USB20
3.3VA
L5B4 U7 VSS33USB20
2.0_D1+ R5B71 T8 PUDP20
44.2 U8

(R5B94 both side)

2.0_D1- PRTUNE20
DGND T9 PUDN20
90ohm,150mA, DCR1.4ohm P9 VSS33USB20
1.2VA N9
DGND VDD12USB20
L5B5 C5B17 U9 VSS12USB20
+3.3VA
100nF U10 VDD33OSC
PXI U11 PXI

IC501
PXO U12 PXO
1.2VAA DGND
T10 VSS33OSC

1K
CHIP_RESET T11 PDD12ALIVE

R5B83
T12 PTEST
REMOCON T13 PRESETN
R508 100 U13 PREMOCON(PGPE[10])
PWM_RST R5B87 100 P10
TUNER_CLK PHUARTRX(PGPE[11])

DGND
U14 PGPE05
TUNER_DAT R5B90 330 P11 PSPDIFRX(PGPE[12])

ZD501
T14 PGPE06

DF3D6.8MS
R506 100 N11 PEXTSRC0(PGPE[13])

Fig 1-1. X501: Crystal of RTC 32.768 MHz

PWM_MUTE
R505 100 T15 PGPE07
BEAT_DET U15 PEXTSRC1(PGPE[14])
MCS_RTC_3.0A T16 PWAKEUP
U16
C5B18 NC U17
P12
C5B19 P13
100nF

10M

DGND
C5B20

R5B94
100nF

3-34
C5B21
220uF

330K
C5B22

R5B95

X501
4
3

1uF

1
2

32.768KHZ
L5B6

L5B7

18pF
18pF

C5B24
C5B23
DGND

DGND
1.2VA
XI

XO

3
C5B2 12pF

1.5K

DGND
R5B4

3
2
1M
R5B6

X500 24MHz
INPUT/OUTPUTFLOAT 4
FLOATINPUT/OUTPUT 1
C5B5 12pF

4
PXI
PXO
WAVEFORMS OF MAJOR CHECK POINT

( MAIN DSP : R5B6, C5B5 )

Fig 1-2. X500: Crystal of system 24 MHz

Only for training and service purposes.

Copyright © 2018 LG Electronics Inc. All rights reserved.
2. SDRAM (IC502)

Fig 2. SDRAM

3.3VAA (SDRAM)

8 IC502
1
6
54
VDD VSS
2 53
M00 DQ0 DQ15 M15
3 52
VDDQ VSSQ
4 51
M01 DQ1 DQ14 M14
5 50
M02 DQ2 DQ13 M13
6 49
VSSQ VDDQ
7 48
M03 DQ3 DQ12 M12
8 47
M04 DQ4 DQ11 M11
9 46
VDDQ VSSQ
10 45
M05 DQ5 DQ10 M10
11 44
M06 DQ6 DQ9 M09
12 43
VSSQ VDDQ
13 42
M07 DQ7 DQ8 M08
14 41
VDD VSS

A15
R5B115
15

16
LDQM NC
40

39
5
DRM_WEN WE UDQM A16
22
17 38
DRM_CAS CAS CLK DRM_CLK
18 37
DRM_RAS RAS CKE DRM_CKE
19 36
DRM_SEL CS A12 A12
20 35
A13 BS0 A11 A11
21 34
A14 BS1 A9 A09
22 33
A10
A00
23

24
A10/AP

A0
A8
A7
32
31
7 A08
A07

A01 A1 A6 A06
25 30
A02 A2 A5 A05
26 29
A03 A3 A4 A04
27 28
VDD VSS
C5B60

10pF
NC

DGND DGND

3-35 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
3. SERVO (IC401)

XI

11
XO

10

Fig 3-2. CD-16M

Fig 3-1. X400: Crystal 16.9344 MHz
(IC401 pin31)

IC401
VDD_CORE
DIN/DOUT

SUBDATA
SUBSYQ

RESETB

RXI RXO
SUBCK

XBUFO
CLK88
WFCK

DGND

DGND
DVDD

BUSY
MCK

R/W

CLK

R423
17
18
19
20

21

22
23

24
25

26
27
28
29
30
31
32

1M
R422
C424 RFGND RFGND
X400 100nF C431
DVCC3.3V

220 100nF R419

16.9344MHz
33
9 10
VDD_CORE
RFGND

RFGND
C445 C444
15pF 15pF 11
CD_SUBSYQ

RFGND
CD_RW
CD_MCK

CD_BUSY
CD_DIN_OUT

CD_16M
CD_RESB

3-36 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
4. MOTOR DRIVER (IC400)

16
12
13 17

14
15

Fig 4-1. LO- & LO+ / MOT_OPEN &MOT_CLOSE Fig 4-2. SL- & SL+ for Driving SPINDLE Motor
for Driving TRAY Motor (IC400 Pin11, 12)
(IC400 Pin6, 7, 9, 10)

18

19

Fig 4-3. SP- & SP+ for Driving SPINDLE Motor

(IC400 Pin17, 18)

1 28
FD0 VINFC MUTE MOT_MUTE
2 27
TRB_1 BIAS VREF
3 26
REGO 2 VINTK TRD
4 25
SLD0 VINSL+ TRB_2
15 5
REGO 1 RESET
24

MOT_CLOSE
13 6
FWD VINLD
23
SPD0
7 22
MOT_OPEN REV GND
MGND
M_5V
IC400 R417
5.6K
14 8
Vcc1 VCTL
21

12 9 20
R416
15K

MGND
220uF

LOAD+ VOTR- VCCD

C427
16V

10 19
100nF

100nF
C428
C440

LOAD- VOTR+ Vcc2 M_5V

11 18
SLED+ VOSL+ VOLD- SPIN-
MGND 12 17
SLED- VOSL- VOLD+ SPIN+
F-
17 13
VOFC- VOTK-
16 19 TR+
C415
F+
16 47nF 14
VOFC+ VOTK+
15 18 TR-

3-37 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
5. ADC (IC301) 6. USB (CN502)

20

21
23
22
24

Fig 5. ADC I2S Fig 6. USB D+/D-

(IC301 Pin15, 16, 17) (CN502 Pin1, 2, 7, 8)

PT_R
C317 C321 R322 R332
1nF 10uF 5.6K
100K
ADC AGND
C318
1nF
C322
10uF
R323
5.6K
AGND
PT_L
IC301
R333
100K
1 VINR3/VIN3P 30 AGND
VINL2/VIN1M TUNER_R
2 VINL3/VIN4P 29 C315 C319 R310 R334
1nF 10uF 2.7K Volume(USB)<-> Main
3
VINR2/VIN2M
VINR4/VIN3M
VINL1/VIN1P
28
C316 C320 R311
100K
AGND
23
4 VINL4/VIN4M 27 AGND 1nF 10uF 2.7K CN502
R501 4.7
TUNER_L USB_5V
UBW2012-121F

VINR1/VIN2P D2+ 1 2.0_D1+

5 26 R335
TP511
MicBias MD0 R305 DVCC_3.3V D2- 2 2.0_D1-
10K 100K TP507 R504 4.7
6 25
L513

MS/AD DGND 3
VREF AGND
7 A 24 TP301 USB_5V

8
AGND
D MC/SCL
MOSI/SDA
23
R307
R306
100
100 TP302
BT_ADC_SCL
USB_5V 24 4

5
TP513
C534 C537 C536
NC NC 100nF

AVDD ADC_DIR_DAT TP512

ZD507

DGND 6 DGND
9 22
XO MISO/GPIO0 D1+ 7
TP516
1.1_D+
10 GPIO1/IntA/DMIN 21 D1- TP515
8 1.1_D- DGND
XI
11 20
LDO
GPIO2/IntB/DMCLK
23
12

13
DGND GPIO3/IntC
19
18
R308 33 TP304
TP310 22 MIC_DATA_IN 24
DOUT R312 33 ADC_DATA_IN
14
DVDD
IOVDD BCK
17 R313 33 21 TP311
DSPI_BCK
15 16 R318 33 TP312
SCKI(3.3V) LRCK DSPI_LRCK
R309 33 TP313
DSPI_MCLK
DGND

20

3-38 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
7. BLUETOOTH (CN504)

25 B T_TXBT_TX
BT_TX

26 BT_RX
BT_RX

BT_RST
27
BT_RST

Fig 7. BT_TX / BT_RX / BT_RST

3.3VA
BT Module<-> Main R5B1 4.7K
R5B2 4.7K
CN504
L505
SDA 1 BT_DAT
SCL 2
TP502
TP501
L506
C522
25 BT_ADC_SCL
GND 3 C514 33pF
TP503 33pF NC L507
TXD 4 BT_TX
TP504
GND 5
BTGND DGND L508
RXD 6 BT_RX
TP505
RTS 7 BT_RTS
TP506
CTS
RESET
8
TP508
26 BT_CTS

VDD
9

10
TP509
27 BT_RST

TP510
3.3VA
C510 10uF
C509100nF
C508 10uF
C561 10uF

100pF

100pF
100pF
100nF

100pF
C513
C515
C524

C532
C512

L502

DGND

3-39 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
3-40 Copyright © 2018 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
WIRING DIAGRAM

Harness
FAN
FFC

3pin
AUX FAN
FM
Por t abl e
WAFER JACK
JK303

Speaker
CN302 JK301

3pi n

3pin
3pin
DI R Speaker
CS8422 PWM
AUX Unit

Heat si nk
USB I C304 PART TAS5548

4pin
4pin
I C601
USB1

I C301

Speaker
8pin

4pi n
8pin
CN502
USB
SDRAM
I C502
23pin

RF par t
23pin

I C400
MAIN Board
I C501
MD MLC3730
RF par t
10pin
10pin

Mot or
I C401 Mi com #1 LED CTRL
I C101 Mi com #2
I C111
BT Wir el ess 25pi n MI C
WAFER WAFER WAFER WAFER WAFER
CN504 CN103 CN102 CN301 CN201
10pin 26pin 25pin 8pin 12pin

10pin 26pin 25pin 8pin ICA301

12pin
MIC AMP
DRV632
Front Board
BT WIRELESS SMPS
[option] TOP Control Board
MIC1 RMC MIC2

3-41 3-42 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
BLOCK DIAGRAM

OPTICAL OK75 : O
24MHz IN OK55 : X
CD_RESB_16M_SUBSYQ
(VCC50)
_DIN OUT_BUSY 24.576MHz

P/UP AC,BD,E,F,PD,CD_LD
SERVO CD_RW/MCK/LRCK/BCK
,
ANALOG INPUT Block
( x4 ) CD_DATA DIR
SPDO/SLDO PTB

DSPI_MCLK/LRCK/
/ FDO/TRD

BT_ADC_DIR_SCL
PTB_L/R

/ ADC_DIR_DAT
M PORTABLE IN
LOAD± ,SLED± , MOT_MUTE/CLOSE/OPEN

DIR_INT/RST/
Motor Drive

BCK/ADATA
SPIN± ,TR± ,F± AUX

CSD/TEMP
AUX_L/R
DECK OP_SW,CL_SW 32.768MHz
AUX IN
MECHANISM 24M
Hz ADC
TUNER_L/R TUNER
Si4705 FM
(+3.3V_CD, VCC1.2) (FM/)
MD Block DRM_WEN/CAS/ ADC_DATA (for AUX)
RAS/SEL/CLK/CKE MIC_DATA_IN, ADC_DATA_IN
32MB M00_15,A00_16 MIC 1
BT_ADC_DIR_SCL / ADC_DIR_DAT For MIC
SDRAM DRV603 MIC 2
DSPI_MCLK/LRCK/BCK
SF_MOSI/MISO
16MB SF_CS/SCK Main DSP
Flash For RCU
IR Receiver
OK75 : USB1/2 SF_MOSI/MISO
8MB SF2_CS/SCK
OK55 : USB1 S/Flash FRONT Block

TOP OK75
BT_PCM_BUFFER

BLOCK
(+3.3VA,5V,+12V)
D1+/ -, D2S+/ - PWM + AMP Block LPF (OK55)
VFD_STB/CLK/DO MCS_LRCK/BCK
BT_TX_RX

2.0 1.1
USB1 USB2 MAIN V_A/B,
PWM_SCL/DAT
Front-L 295W
KEY 1/2/3, LANDING_GEAR AMP (160W)
PWM_RST/MUTE
MIX_DATAx_OUT
OK75 : O 295W
VFD Front-R
OK55 : X MIX_DATA0~2
(160W)
Volume/ MCS_CS/RX/TX PWM
Key/switch Micom
SW(PBTL)
Party #1/#2 AMP 410W
( 48Pin ) (180W)
Thruster
Multi Speaker Sparkle X-Flash
Lighting Lighting FAN
Lighting

WL_SCL/SDA/INT/MSG_RDY
TOP Block WL_SPI_DI
DSP_I2S_LRCK/BCK, [OK75 : Total 1 000W] [OK55 : Total 500W]
Wireless To Wireless DSP_C_WF
FRONT : 295W X FRONT : 160W X 2CH
1MB WL_SPI_CLK/
Block
Option S/Flash CS/DO/WP 2CH WOOFER : 180W X 1CH
WOOFER : 410W X 1CH

3-43 3-44 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
CIRCUIT VOLTAGE CHART
1. IC VOLTAGE 2. FAN MOTOR VOLTAGE
Rating -20 % NO. Check MODE SPEC Check Result Check Method
SPEC Measured Voltage IC function IC TC TEMPERATURE
NO. SYMBOL Rating +20 %
(V, mV) SPEC Check the Voltage
Voltage (V) Voltage (V) Description of operation on the CN462
FAN MOTOR
1 12V 11.98V Pin3(FAN_DC),
IC101 Input Voltage
1 VDD : -0.5~+6.5V VDD : 3.1 ~ 3.3V VDD : 3.29V IC,Microcontrollers 125 °C Not connect FAN
IC,Microcontrollers
Module.(12V)
IC111
2 VDD : -0.5~+6.5V VDD : 3.1 ~ 3.3V VDD : 3.28V Sub IC,Microcontrollers 125 °C During the FAN
IC,Microcontrollers VOL14 : 4.6~5.6V
FAN MOTOR VOL14 : 5.1V Operate, Check
IC201 Vin : 12VA, Vin : 12.01VA, High Efficiency 3A, 24V, 500kHz 2 VOL15~40 :
3 VIN : 4.5V TO 24V 125 °C Operation Voltage VOL15~40 : 8.7V the Voltage of FAN
DC,DC Converter Vout : 5.1VA Vout : 5.15VA Synchronous Step Down Converter 7.8~9.6V
Module.
IC202 Vin : 3.3VA, Vin : 5.15VA
4 VIN : 2.7V TO 5.6V Step-Down Converters 125 °C
DC-DC Converter Vout : 3.3V Vout : 3.34VA
IC203 Vin : 12VA, Vin : 12.01VA, High Efficiency 3A, 24V, 500kHz
5 VIN : 4.5V TO 24V 125 °C
DC,DC Converter Vout : 5.1VA Vout : 5.11V Synchronous Step Down Converter
IC204 Vin : 5.1VA, Vin : 3.34VA ultra-low RDS(ON) switch
6 VIN : 2.5V TO 5.5V 125 °C
Limit Switch Vout : 5V Vout : 3.29V with current limiting

7
IC205
VIN : 2.7V TO 5.6V
Vin : 5.1VA, Vin : 5.14VA,
Step-Down Converters 125 °C
3. SMPS CAPACITOR & ZENER DIODE
DC-DC Converter Vout : 1.2VA Vout : 1.22V
IC206 Vin : 5.1VA, Vin : 5.1VA ultra-low RDS(ON) switch Capacitor
8 VIN : 2.5V TO 5.5V 125 °C
Limit Switch Vout : 5.0V Vout : 5.0V with current limiting NO LOC SPEC Sales AREA
IC207 Vin : 5.1VA, Vin : 5.15VA ultra-low RDS(ON) switch 450V/
9 VIN : 2.5V TO 5.5V 125 °C 1 C903 W/W
Limit Switch Vout : 5V Vout : 5.14V with current limiting 330uF
IC208 Vin : 5.1V Vin : 5.14VA 450V/
10 VIN : 4.5V TO 5V Step-Down Converters 125 °C 2 C904 W/W
DC-DC Converter Vout : 3.3V Vout : 3.3V 330uF
IC209 Vin : 5.1A, Vin : 5.1VA ultra-low RDS(ON) switch SMPS ZENER DIODE
11 VIN : 2.5V TO 5.5V 125 °C
Limit Switch Vout : 5.0V Vout : 5.0V with current limiting
NO LOC CHECK
IC301 4ch Audio ADCs
12 VIN : -0.3V to 3.9V AVDD : 3.3V AVDD : 3.31V 125 °C 1 ZD902, ZD906 13V
4ch Audio ADC with Universal Front End Input Mux
2 ZD901, ZD904 33V
IC302
13 VDD:3~3.6V VDD:3.3V AVDD:3.32V Tuner ic 150 °C
TUNER 3 ZD905, ZD912 20V
IC304
14 VDD:3~3.6V VDD:3.3V AVDD:3.32V Optical 125 °C
OPTICAL
IC400 VCC1 : 4.3~13.2V VCC1 : 5.0V VCC1 : 5.11V
15 5-channel BTL Driver 150 °C
Motor Driver VCC2 : 4.3~VCC1 VCC2 : 5.0V VCC2 : 5.11V
IC401
VDD1 : 2.7~3.6V (Analog) Servo signal processor
16 digital servo signal pro- VCC : 3.3V VCC : 3.28V 125 °C
VDD_CORE : 1.4~1.65V for compact disc player
cessing
IC501
VDD33 : 3.3VA VDD : 3.33VA
17 IC,Digital Signal Proces- Digital Power 3.3V or 1.2V IC,Digital Signal Processors 150 °C
VDD12 : 1.2VA VDD : 1.21VA
sors
IC502
18 VDD : 3.0~3.6V VCC : 3.3V VCC : 3.33V 4 M x 4 BANKS x 16 BITS SDRAM 150 °C
SDRAM
IC503
19 VDD : 3.0~3.6V VCC : 3.3V VCC : 3.33V SERIAL FLASH MEMORY 150 °C
Serial Flash Memory
IC504
20 VDD : 3.0~3.6V VCC : 3.3V VCC : 3.33V SERIAL FLASH MEMORY 150 °C
Serial Flash Memory
IC505 3-PIN MICROPROCESSOR RESET
21 VIN:1.1~5.5V Vin : 3.1~3.3VA Vin : 3.32VA 125 °C
RESET CIRCUITS
IC601
22 VCC : 2.97V TO 3.63V VDD : 3.3V VDD : 3.27V Digital Audio Processor 125 °C
Sound/Audio Processor
IC700~IC702 VDD : 11.68V VDD : 11.68V PROTECTED DIGITAL AUDIO
23 VCC : 11.6V To 12.4V 125 °C
AUDIO AMPLIFIER PVDD : 48.2V PVDD : 48.2V AMPLIFIER
ICA301 2-VRMS Audio Line Driver
24 VDD:3~3.6V VDD : 3.3V VDD : 3.32V 150 °C
Line Driver With Adjustable Gain

3-45 3-46 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
4. MAIN CAPACITOR 5. CONNECTOR VOLTAGE
110V-20% 220V+20% LOCATION Voltage(V) LOCATION
NO. LOCATION NO. Value NO. Connector Name PIN NO. PIN MANE
(88V/60Hz) V (288V/50Hz) V NO. Vin Vout NO.
1 C257 470uF +12V 12.06 1 D2+ 0.01 0.01
2 C271 220uF USB_5V 5.03 2 D2- 0.07 0.07
3 C345 220uF DVCC_3.3V 3.28 3 DGND 0.00 0.00
4 C402 100uF DVCC_5V 5.03 4 USB_5V 5.17 5.17
1 CN502 MAIN  TOP(USB) CN803
5 C404 47uF DVCC_3.3V 3.27 5 USB_5V 5.17 5.17
6 C409 47uF DVCC_3.3V 3.27 6 DGND 0.00 0.00
7 C416 47uF DVCC_3.3V 3.27 7 D1+ 0.03 0.03
8 C418 3.3uF VREF 1.63 8 D1- 0.01 0.01
9 C427 220uF M_5V 5.03 1 SDA 0.12 0.12
10 C481 100uF FAN_DC 11.98 2 SCL 3.33 3.33
11 C5B21 220uF VDD_CORE 1.26 3 GND 0.00 0.00
12 C614 100uF DVCC_3.3V 3.28 4 TXD 3.33 3.33
13 C713 10uF +12V 11.91 5 GND 0.00 0.00 BT
2 CN504 MAIN  BT Moudle
14 C714 10uF +12V 11.91 6 RXD 3.33 3.33 Module
15 C748 680uF +B +66V 48.30 7 RTS 1.49 1.49
16 C749 680uF -B -66V 48.30 8 CTS 1.51 1.51
17 C752 680uF +B +66V 48.30 9 RESET 3.33 3.33
18 C753 680uF -B -66V 48.30 10 VDD 3.33 3.33
19 C801 100uF USB_5V 5.21 1 GND 0.00 0.00
20 C802 47uF F- 3.07 2 GND 0.00 0.00
21 C805 1uF VFD_12V 11.95 3 MAIN_VOL_A 3.33 3.33
22 C806 1uF DVCC_3.3V 3.29 4 MAIN_VOL_B 3.32 3.32
23 C813 100uF USB_5V 5.21 5 FILE_S_A 3.29 3.29
24 C821 47uF F+ 5.18 6 FILE_S_B 3.29 3.29
25 C831 1uF VH 29.81 7 SCRATCH_B 3.29 3.29
26 C832 1uF VH 20.90 8 SCRATCH_A 3.29 3.29
27 C833 1uF VH 20.90 9 MIC_VOL_B 3.29 3.29
28 C834 1uF VH 16.80 10 MIC_VOL_A 3.29 3.29
29 C903 330uF 122.30 372.10 11 KEY1 3.27 3.27
30 C904 330uF 122.30 372.10 12 KEY2 3.27 3.27
31 C933 2200uF 12.10 12.10 MAIN  TOP 13 KEY3 3.27 3.27
3 CN102 CN804
12511HS-25SS-K
32 C934 470uF 12.10 12.10 LANDING
14 3.33 3.33
GEAR
33 C952 2200uF 49.10 49.10
15 GND 0.00 0.00
34 C953 2200uF 49.10 49.10
16 +3.3V 3.35 3.35
17 DGND 0.00 0.00
18 VFD_DAT 3.14 3.14
19 VFD_STB 3.14 3.14
20 VFD_CLK 3.14 3.14
21 DV_3.3V 3.33 3.33
22 DV_5.0V 5.05 5.05
23 DV_5.0V 5.05 5.05
24 VF_12V 12.02 12.02
25 GND 0.00 0.00

3-47 3-48 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
CONNECTOR VOLTAGE
LOCATION Voltage(V) LOCATION LOCATION Voltage(V) LOCATION
NO. Connector Name PIN NO. PIN MANE NO. Connector Name PIN NO. PIN MANE
NO. Vin Vout NO. NO. Vin Vout NO.
1 12V 12.06 12.06 1 OPEN_SW 3.29
2 12V 12.06 12.06 2 LO- 0.00
3 DGND 0.00 0.00 3 CLOSE_SW 3.33
4 P_CTRL 3.33 3.33 4 LO+ 0.01
5 DGND 0.00 0.00 5 GND 0.00
7 CN401 MAIN  MD MD
6 DGND 0.00 0.00 6 SP+ 2.47
4 CN201 MAIN  SMPS CN901
7 DGND 0.00 0.00 7 SL+ 2.47
8 PVDD 48.30 48.30 8 SP- 2.47
9 PVDD 48.30 48.30 9 SL- 2.47
10 PVDD 48.30 48.30 10 NC 0.00
11 DGND 0.00 0.00 1 SW+ 24.40
12 PVDD CTRL 2.83 2.83 2 SW- 24.40
1 RMC3.3VA 3.33 3.33 3 FL+ 24.40
8 CN701 MAIN  SPK SPK
2 RMC 3.19 3.19 4 FL- 24.40
3 DGND 0.00 0.00 5 FR+ 24.40

MAIN  MIC 4 MIC_3.3V 3.28 3.28 6 FR- 24.40

5 CN301 CNA301
SMW200-H8G 5 MIC_DET 3.29 3.29 1 GND 0.00 0.00
6 MIC_S1 0.00 0.00 2 SPRK_U_LD3 0~3 0~3
7 MIC_GND 0.00 0.00 3 SPRK_U_LD2 0~3 0~3
8 MIC_S2 0.00 0.00 FLASH_
4 0~3 0~3
BLUE_L
1 NC/FHM-VCC 5.05
5 FLASH_RED_L 0~3 0~3
2 RF 0.02
MAIN  SPARKLING 6 GND 0.00 0.00
3 DVD_LD 0.02 9 CN106 LIGHTING(UP) CNS101
1.25MM 7 GND 0.00 0.00
4 MON(COM)/5V 0.02
8 SPRK_U_RD5 0~3 0~3
5 DVD_VR 0.03
9 SPRK_U_RD4 0~3 0~3
6 GND 0.00
FLASH_
7 VREF/VC 1.63 10 0~3 0~3
BLUE_R
8 VCC 5.05
11 FLASH_RED_R 0~3 0~3
9 F 1.63
12 GND 0.00 0.00
10 E 1.63
1 MULTI_LED_B 0~3 0~3
11 A 1.63
2 MULTI_LED_G 0~3 0~3
6 CN400 MAIN  MD 12 D 1.63 MD
3 MULTI_LED_R 0~3 0~3
13 C 1.63
4 GND 0.00 0.00
14 B 1.63
5 GND 0.00 0.00
15 F(+) 2.47
6 SPRK_D_LD3 0~3 0~3
MAIN  SPARKLING
16 T(+) 2.46
10 CN107 LIGHTING(DN) 7 SPRK_D_LD2 0~3 0~3 CNS102
17 T(-) 2.46 1.25MM
8 SPRK_D_LD1 0~3 0~3
18 F(-) 2.47
9 GND 0.00 0.00
19 SW_PDIC 4.69
10 GND 0.00 0.00
20 GND 0.00
11 SPRK_D_LD6 0~3 0~3
21 CD_LD 0.02
12 SPRK_D_LD5 0~3 0~3
22 MON_MPD 0.21
13 SPRK_D_LD4 0~3 0~3
23 CD_VR 0.00

3-49 3-50 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
CONNECTOR VOLTAGE
LOCATION Voltage(V) LOCATION
NO. Connector Name PIN NO. PIN MANE
NO. Vin Vout NO.

MAIN  SPARKLING 14 GND 0.00 0.00

10 CN107 LIGHTING(DN) CNS102
1.25MM 15 GND 0.00 0.00

1 GND 0.00 0.00

11 CN462 MAIN  FAN CONTROL 2 NC 0.00 0.00 FAN
3 FAN_DC 8.70 8.70
1 SPKLED_B 0~3 0~3
2 SPKLED_G 0~3 0~3
12 CNS103 SPAKLING DN  SPK LED CNS301
3 SPKLED_R 0~3 0~3
4 GND 0.00 0.00
1 GND 0.00 0.00
2 GND 0.00 0.00
FLASH_
3 0~3 0~3
BLUE_L_UP
FLASH_
4 0~3 0~3
BLUE_L_UP
13 CNF103 FRONT  FRONT CNF101
FLASH_
5 0~3 0~3
RED_L_UP
FLASH_
6 0~3 0~3
RED_L_UP
7 GND 0.00 0.00
8 GND 0.00 0.00
1 GND 0.00 0.00
2 GND 0.00 0.00
FLASH_
3 0~3 0~3
BLUE_R_UP
FLASH_
4 0~3 0~3
BLUE_R_UP
14 CNF104 FRONT  FRONT CNF102
FLASH_
5 0~3 0~3
RED_R_UP
FLASH_
6 0~3 0~3
RED_R_UP
7 GND 0.00 0.00
8 GND 0.00 0.00

3-51 3-52 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
PRINTED CIRCUIT BOARD DIAGRAMS
1. SMPS P.C.BOARD DIAGRAM
(TOP VIEW)

3-53 3-54 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
SMPS P.C.BOARD DIAGRAM
(BOTTOM VIEW)
NOTE) Warning
Parts that are critical with respect to risk
of fire or electrical shock.

3-55 3-56 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
2. MAIN P.C.BOARD DIAGRAM
(TOP VIEW)

3-57 3-58 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
MAIN P.C.BOARD DIAGRAM
(BOTTOM VIEW)

3-59 3-60 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
3. TOP P.C.BOARD DIAGRAM
(TOP VIEW)

3-61 3-62 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
TOP P.C.BOARD DIAGRAM
(BOTTOM VIEW)

3-63 3-64 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
4. JACK & RMC P.C.BOARD DIAGRAM
(TOP VIEW) (BOTTOM VIEW)

5. SPEAKER LED P.C.BOARD DIAGRAM

(TOP VIEW) (BOTTOM VIEW)

3-65 3-66 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
3-67 3-68 Copyright © 2018 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
 SECTION 4
MECHANISM (DM19D)

CONTENTS
DECK MECHANISM DISASSEMBLY
1. Cover Top ............................................................................................................................................... 4-2
2. Clamp Assembly ..................................................................................................................................... 4-2
2-1. Plate ................................................................................................................................................. 4-2
2-2. Magnet ............................................................................................................................................. 4-2
2-3. Clamp............................................................................................................................................... 4-2
3. Tray Disc ................................................................................................................................................. 4-3
4. Pick Up Assembly ................................................................................................................................... 4-4
5. Base Up/Down ........................................................................................................................................ 4-4
6. Belt Loading ............................................................................................................................................ 4-5
7. Gear Pulley ............................................................................................................................................. 4-5
8. Gear Loading .......................................................................................................................................... 4-5
9. Guide ....................................................................................................................................................... 4-5
10. Deck PCB Assembly ............................................................................................................................... 4-5
11. Motor Assembly ...................................................................................................................................... 4-5
12. FFC Cable ............................................................................................................................................... 4-5

DECK MECHANISM EXPLODED VIEW (DM19D) ........................................................................................... 4-6

4-1 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 DECK MECHANISM DISASSEMBLY

(S1)
1 1 Clamp
Assembly
Cover Top

Clamp Assembly

Plate

Magnet

Clamp

< Figure A > < Figure B >

1. Cover Top 2. Clamp Assembly

1) Remove the 2 screws (S1). 1) Place the Clamp Assembly as Figure B.
2) Remove the Cover Top. 2) Bending the Cover Top in direction of
arrow (2) as Figure B.
3) Separate the Clamp Assembly from the
Cover Top.
2-1. Plate
1) Turn the Plate to a counterclockwise direction
and then lift up the Plate.
2) Remove the Plate.
2-2. Magnet
Remove the Magnet.
2-3. Clamp
Remove the Clamp.

4-2 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 DECK MECHANISM DISASSEMBLY

Emergency eject hole

MD Sub
(H1) Assembly

1
Tray Disc

1 2 2 1

< Bottom side view >

3
Tray Disc
< Figure D >

2 Tray Disc
3) Grasp the both sides of the Tray Disc and lift
it up as Figure D, and then pull the Tray Disc
< Figure C > until it is separated from the MD Sub Assembly
completely.
3. Tray Disc
1) Insert and push a flat-head screwdriver in the
Guide
Emergency eject hole (H1) at the right side, so
that the Tray Disc is ejected about 15 ~ 20 mm.
2) Pull the Tray Disc until it is locked.

Tray Disc

< Figure E >

Note
• When reassembling place the Guide as Figure E.

4-3 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 DECK MECHANISM DISASSEMBLY

Gasket Tape
Base Up/Down

(D)
2
RE B
OR BR D LK
N N
Deck PCB (B)
Assembly
BK
RE
D
(L2) 3

1
2

(H2)
< Bottom side view >

(S2) Base Main

3
5 Figure G-3

(C)
(A) Guide
Rubber FFC Cable
Damper Pick Up
4 Assembly (B)
Base
Up/Down
Figure G-1 Figure G-2

< Figure G >

5. Base Up/Down
Unlock the Locking Tab (L2) in direction of arrow
< Figure F > and then lift up the Base Up/Down to separate it
from the Base Main.

Note
4. Pick Up Assembly
• When reassembling move the Guide in direction
1) Detach the Gasket Tape. of arrow (A) until it is positioned as Figure G-1.
2) Disconnect the wires (BLK, RED, BRN, ORN) • When reassembling insert the (B) portion of the
from the Deck PCB Assembly by desoldering. Base Up/Down in the (C) portion of the Guide as
3) Remove the 4 screws (S2). Figure G-2.
4) Disconnect the FFC Cable from the Pick Up • When reassembling insert the (D) portion of the
Assembly. Base Up/Down in the Hole (H2) of the Base Main
as Figure G-3.
5) Remove the 4 Rubber Dampers.

4-4 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 DECK MECHANISM DISASSEMBLY

Base Main

(A)
Figure H-1

Guide
(B)

Gear Loading

Gear Pulley

(L3)

Base Main

< Bottom side view >

Belt Loading
(L4)
RE B
OR BR D LK
N N

RE
BK D

Deck PCB
< Bottom side view > Motor < Bottom side view > Assembly
Assembly
Deck PCB
(S3) Assembly

< Figure H >

6. Belt Loading 10. Deck PCB Assembly

Remove the Belt Loading. 1) Disconnect the wires (RED, BK) form the
Deck PCB Assembly by desoldering.
7. Gear Pulley
2) Remove the 1 screw (S3).
Unlock the Locking Tab (L3) in direction of arrow
and then separate the Gear Pulley from the Base 3) Separate the Deck PCB Assembly from the
Main. Base Main.

8. Gear Loading 11. Motor Assembly

Remove the Gear Loading. Unlock the Locking Tab (L4) in direction of
arrow and then separate the Motor Assembly
9. Guide from the Base Main.
1) Move the Guide in direction of arrow (A) as 12. FFC Cable
Figure H-1.
2) Separate the Guide from the Base Main. Remove the FFC Cable.

4-5 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.
 DECK MECHANISM EXPLODED VIEW (DM19D)

A00

1030

1049

1015

A005

4-6 Copyright © 2018 LG Electronics Inc. All rights reserved.

Only for training and service purposes.