LG LAS355B Service Manual

SERVICE MANUAL

CAUTION

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

Internal Use Only

Website http://biz.lgservice.com

AUGUST, 2015

MODEL: LAS355B (LAS355B, S35A1-W)

MODEL: LAS355B

(LAS355B, S35A1-W)

Sound Bar

P/NO : AFN77277036

CONTENTS

SECTION 1 ........ GENERAL

SECTION 2 ........ CABINET & MAIN CHASSIS

SECTION 3 ........ ELECTRICAL

SECTION 4 ........ REPLACEMENT PARTS LIST

1-1

SECTION 1

GENERAL

CONTENTS

ESD PRECAUTIONS ......................................................................................................................................... 1-3

HIDDEN KEY MODE ......................................................................................................................................... 1-4

SERVICE INFORMATION FOR EEPROM ........................................................................................................ 1-4

MCS / EQ HIDDEN KEY GUIDE ....................................................................................................................... 1-5

MCS / EQ PROGRAM UPDATE GUIDE ........................................................................................................... 1-5

SPECIFICATIONS ............................................................................................................................................. 1-6

1-2

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.

1-3

HIDDEN KEY MODE

HIDDEN MODE KEYS

EEPROM EDIT Main set ‘-’ (Volume) + Remote control ‘OPTICAL’

EEPROM CLEAR (Initialize) Main set ‘-’ (Volume) + Remote control ‘Treble/Bass’

VERSION CHECK Main set ‘-’ (Volume) + Remote control ‘LG TV’

up Sound Effect

down NIGHT

right F.Skip (Right)

left B.Skip (Left)

enter AV Sync

SERVICE INFORMATION FOR EEPROM

POWER ON

OPT Status

Main set ‘-’ (Volume) + Remote control ‘OPTICAL’

VFD " OPT.."

Use arrow key [Sound Effect, NIGHT, F.Skip (Right), B.Skip (Left)] to move to appropriate position and make changes

Remote control ‘AV SYNC’

Display VFD “E2P CLR”

Power off automatically

Power cord unplug

1-4

MCS / EQ HIDDEN KEY GUIDE

1. Version & Option Check

1) Power on.

2) Press main set “-” (volume -) key and remote control "LG TV" key during 3 seconds.

3) Check MCS version. Ex) P1412120

4) Press remote control “F.Skip (Right)” 1 time. Check EQ version. Ex) Q1412020

5) Press remote control “F.Skip (Right)” 1 time. Check option. Ex) 10010000

2. Initialize

1) Power on.

2) Press main set “-” (volume -) key and remote control “Treble/Bass” during 3 seconds.

3) Display VFD “E2P CLR”.

4) Power off automatically.

5) Power cord unplug.

MCS / EQ PROGRAM UPDATE GUIDE

1. Preparation

- Remote control.

- Do format USB Memory to FAT32 File system.

- USB : Update ﬁ le exist only in the USB Memory stick. Ex ) LAS355B : MCS  E:￦LAS355B_FW_201412221.bin (if USB driver is E:￦) EQ  E:￦EQ_PRG_LAS355B_141219_0_4112.bin (if USB driver is E:￦)

2. Update

1) Power on.

2) Change the USB function.

3) Insert USB.

4) Display in VFD. MCS : “MCS UP”  “FINISH”  Power off. EQ : “EQ UP”  “FINISH”  Power off.

5) Loading is shown while updating. Never remove USB or AC cord.

6) After update ﬁ nish, show FINISH in VFD and power of automatically.

7) Power cord un-plug.

1-5

SPECIFICATIONS

• GENERAL (LAS355B)

Power requirements Refer to the main label on the unit. Power consumption Refer to the main label on the unit. Networked standby : 0.5 W (If all network ports are activated.) Dimensions (W x H x D) 880 mm x 59 mm x 90 mm Net Weight (Approx.) 1.9 kg Operating temperature 5 °C to 35 °C Operating humidity 5 % to 90 %

INPUT/OUTPUT

OPT. IN 3 V (p-p), Optical jack x 1 PORT. IN 0.5 Vrms (3.5 mm stereo jack) x 1 Available Digital Input Audio Sampling Frequency 32 kHz, 44.1 kHz, 48 kHz, 96 kHz

USB

Version 2.0 Bus Power Supply 5 V 500 mA

AMPLIFIER

Total 120 W Front 25 W x 2 (6 Ω) Subwoofer 70 W (4 Ω) THD 10 %

• SUBWOOFER (S35A1-W)

Type 1 Way 1 Speaker Impedance 4 Ω Rated Input Power 70 W Max. Input Power 140 W Dimensions (W x H x D) 156 mm x 300 mm x 288 mm Net Weight (Approx.) 2.9 kg

• BLUETOOTH

Codec SBC

• Designs and specifications are subject to change without prior notice.

1-6

SECTION 2

CABINET & MAIN CHASSIS

CONTENTS

EXPLODED VIEWS ........................................................................................................................................... 2-3

1. MAIN SET SECTION ................................................................................................................................ 2-3

2. SUBWOOFER SECTION .......................................................................................................................... 2-5

3. PACKING ACCESSORY SECTION ......................................................................................................... 2-7

2-1

2-2

503

251

A42

262

B/T

CABLE5

CABLE6

CABLE7

CABLE3

CABLE8

CABLE7

CABLE6

506

257

A53

258

A54

258

504

257

506

A45

504

503

263

506

266

504

505

259

A52

264

504

300

USB

DISPLAY

MAIN

SMPS

CABLE2

CABLE1

CABLE4

A47

505

504

A43

A46

505

A48

265

256

A55

KEY

EXPLODED VIEWS

1. MAIN SET 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. SUBWOOFER SECTION

A900

3. PACKING ACCESSORY SECTION

801 Owner’s manual

806 Optical cable

808 Batteries

900 Remote control

803 Packing, Main

820A

826 Filter, Ferrite Core

USB adapter

835 Wall bracket

836 Screws

837 Cover foot

804 Bag

802 Box

2-8

SECTION 3

ELECTRICAL

CONTENTS

ONE POINT REPAIR GUIDE ............................................................................................................................ 3-2

1. NO POWER PROBLEM (PVDD) ............................................................................................................ 3-2

2. POWER ON ERROR .............................................................................................................................. 3-3

3. NO SOUND (PORTABLE FUNCTION) .................................................................................................. 3-4

4. NO BLUETOOTH .................................................................................................................................... 3-5

5. NO SOUND (OPTICAL) .......................................................................................................................... 3-6

ELECTRICAL TROUBLESHOOTING GUIDE ................................................................................................... 3-7

1. POWER SUPPLY CIRCUIT .................................................................................................................... 3-7

2. FRONT CIRCUIT .................................................................................................................................... 3-8

3. TEST & DEBUG FLOW ........................................................................................................................ 3-10

4. AMP PROTECTION .............................................................................................................................. 3-13

WAVEFORMS OF MAJOR CHECK POINT .................................................................................................... 3-14

1. CRYSTAL .............................................................................................................................................. 3-14

2. FLASH MEMORY ................................................................................................................................. 3-15

3. TACT KEY ............................................................................................................................................. 3-16

4. USB ....................................................................................................................................................... 3-17

5. REMOTE CONTROL ............................................................................................................................ 3-18

6. OPTICAL ............................................................................................................................................... 3-19

7. PORTABLE ........................................................................................................................................... 3-20

8. AUDIO PWM ......................................................................................................................................... 3-21

9. AUDIO AMP .......................................................................................................................................... 3-23

WIRING DIAGRAM .......................................................................................................................................... 3-25

BLOCK DIAGRAM .......................................................................................................................................... 3-27

CIRCUIT DIAGRAMS ...................................................................................................................................... 3-29

1. SMPS CIRCUIT DIAGRAM .................................................................................................................. 3-29

2. MAIN - DSP CIRCUIT DIAGRAM ......................................................................................................... 3-31

3. MAIN - POWER CIRCUIT DIAGRAM ................................................................................................... 3-33

4. MAIN - PWM & AMP CIRCUIT DIAGRAM ........................................................................................... 3-35

5. DISPLAY/ KEY/ USB CIRCUIT DIAGRAM ........................................................................................... 3-37

CIRCUIT VOLTAGE CHART ........................................................................................................................... 3-39

PRINTED CIRCUIT BOARD DIAGRAMS ....................................................................................................... 3-41

1. SMPS P. C. BOARD DIAGRAM ........................................................................................................... 3-41

2. MAIN P. C. BOARD DIAGRAM ............................................................................................................ 3-43

3. DISPLAY P. C. BOARD DIAGRAM ...................................................................................................... 3-45

4. KEY P. C. BOARD DIAGRAM .............................................................................................................. 3-45

5. USB P. C. BOARD DIAGRAM .............................................................................................................. 3-45

3-1

ONE POINT REPAIR GUIDE

CON402 pin5

1. NO POWER PROBLEM (PVDD)

No power problem occurs when you power on the unit

1-1. Solution

Replace SMPS board.

1-2. How to troubleshoot (Countermeasure)

1) Check the PWR_VCC voltage 15 V at pin5. When you check the no power at this point, then replace SMPS board.

C411

C178

100NF

1uF

R444

3.3R

32VA

ZD402

C438

16V

1uF

ZD403

R443

18V

3.3R

CON402

32V 32V GND GND

PWR_VCC

EC400

10uF/50V

L424

600RH

100NF

C439

EC406

100uF/50V

PVDD

PWR_VCC

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

CON402 pin5

R463

< MAIN board top view >

3-2

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