LG LAS350B Service Manual
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LG LAS350B Service Manual

2.1 ch sound bar
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Internal Use Only
Website http://biz.lgservice.com
2.1 ch Sound Bar
SERVICE MANUAL
MODEL: LAS350B
(LAS350B, S35A1-W)
CAUTION
BEFORE SERVICING THE UNIT, READ THE "SAFETY PRECAUTIONS"
IN THIS MANUAL.
P/NO : AFN77152011
FEBRUARY, 2015

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  • Page 1 Internal Use Only Website http://biz.lgservice.com 2.1 ch Sound Bar SERVICE MANUAL MODEL: LAS350B (LAS350B, S35A1-W) CAUTION BEFORE SERVICING THE UNIT, READ THE “SAFETY PRECAUTIONS” IN THIS MANUAL. P/NO : AFN77152011 FEBRUARY, 2015...
  • Page 2 CONTENTS SECTION 1 ..GENERAL SECTION 2 ..CABINET & MAIN CHASSIS SECTION 3 ..ELECTRICAL SECTION 4 ..REPLACEMENT PARTS LIST...

  • Page 3: Table Of Contents

    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...

  • Page 4: Esd Precautions

    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.

  • Page 5: Hidden Key Mode

    Main set ‘-’ (Volume) + Remote control ‘MUTE’ 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’ Sound Effect down NIGHT right F.Skip (Right) left B.Skip (Left)

  • Page 6: Mcs / Eq Hidden Key Guide

    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.

  • Page 7: Specifications

    SPECIFICATIONS • GENERAL (LAS350B) Power requirements 120 V ~ 60 Hz Power consumption 21 W 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 (34.6 inch x 2.3 inch x 3.5 inch) Net Weight (Approx.)
  • Page 8 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...

  • Page 10: Exploded Views

    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. CABLE5 CABLE6 CABLE3 CABLE7 SMPS CABLE2 CABLE4 MAIN CABLE1 DISPLAY CABLE8 CABLE7...

  • Page 11: Subwoofer Section

    2. SUBWOOFER SECTION A900...

  • Page 12: Packing Accessory Section

    3. PACKING ACCESSORY SECTION Owner’s manual 835 Wall bracket Optical cable 836 Screws Batteries 837 Cover foot Remote control Filter, Ferrite Core 804 Bag Packing, Main 802 Box...
  • Page 14 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 ....................

  • Page 15: One Point Repair Guide

    ONE POINT REPAIR GUIDE 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 PVDD voltage 32 V at pin1, 2. When you check the no power at this point, then replace SMPS board. R463 1-3.

  • Page 16: Power On Error

    ONE POINT REPAIR GUIDE 2. POWER ON ERROR No display or Not working. 2-1. IC402 1) Check 3.3 VA at L405. 2) If 3.3 VA is not checked at the point, then find 32 V at pin1 of IC402. 3) 1), 2) is NG.  Replace IC402. L405 L405 IC402 pin1...

  • Page 17: Sound (Portable Function)

    ONE POINT REPAIR GUIDE 3. NO SOUND (PORTABLE FUNCTION) 3-1. Solution Replace IC400 or portable jack (JK504). 3-2. How to troubleshoot (Countermeasure) 1) Please check the soldering status of JK504 2) Please check L501, L502 (PORT_L, PORT_R signal) of portable jack (JK504). If you cannot find input signal, replace JK504.

  • Page 18: Bluetooth

    ONE POINT REPAIR GUIDE 4. NO BLUETOOTH 4-1. Solution Replace IC101 on MAIN board.(No 3.3 V) 4-2. How to troubleshoot (Countermeasure) 1) Please check externally status of Bluetooth cable connection on your eyes.(at CON102 and Bluetooth module) 2) Please check 3.3 V of 3.3VA (at C174). If 3.3 V is OK at L509, please check BT_SDA, BT_SCL, BT_RST (pin53, 51, 25) of IC101 and BT_RX, BT_TX (pin29, 27).

  • Page 19: Sound (Optical)

    ONE POINT REPAIR GUIDE 5. NO SOUND (OPTICAL) 5-1. Solution Replace IC401 on MAIN board. 5-2. How to troubleshoot (Countermeasure) 1) Please check 3.3 V of 3.3 VA at L505 in USB board If you can check 3.3 V, please confirm OPT_DET signal (R428) in MAIN board when optical mode. 2) In spite of process 1), set has abnormal output, then replace IC401.

  • Page 20: Electrical Troubleshooting Guide

    ELECTRICAL TROUBLESHOOTING GUIDE 1. POWER SUPPLY CIRCUIT INSERT POWER CORD. Standby LED is normal? Check power supply circuit. Power on. Is power on? Check circuit. Does it output audio? Check audio circuit.

  • Page 21: Front Circuit

    ELECTRICAL TROUBLESHOOTING GUIDE 2. FRONT CIRCUIT Is the Digitron on correctly? Refer to SMPS part. POWER ON. Check if LED DISPLAY Reconnect it. CON301 is ok? correctly? Check if the front Check if all Check power supply circuit. power is ok? buttons are ok? Check if the remote Check if IC301 is ok?
  • Page 22 ELECTRICAL TROUBLESHOOTING GUIDE FRONT CIRCUIT Check if the power part of the front Refer to power(SMPS). is ok? Check if CON303 is ok? Reconnect it. Check if R306~R309 ok? Replace R306~R309. Refer to MICOM circuit. Check if thepower part of the front Refer to power(SMPS).

  • Page 23: Test & Debug Flow

    ELECTRICAL TROUBLESHOOTING GUIDE 3. TEST & DEBUG FLOW TEST. Check the AC voltage Power PCBA (110 V Check the POWER PART. or 220 V). Switch on the Power PCBA. Are the Refer to SMPS part. DC Voltage outputs OK? (32 V) Are 3.3 V and 5 V DC outputs normal on main Check the POWER PART.
  • Page 24 ELECTRICAL TROUBLESHOOTING GUIDE Power On. Check connection lines Flash between FLASH & MCL3730 Memory operates Show HELLO. and the FLASH access time properly? whether is suitable or not. Check connection lines SDRAM between SDRAM(IC102) & works properly? MCL3730 and the SDRAM is damaged.
  • Page 25 ELECTRICAL TROUBLESHOOTING GUIDE Function transformation to OPT Check the OPT Does it output Check the OPT line, the input signal audio? Changing the OPT Equipment Check if JK502 Check if CON502 is ok? voltage is ok(3.3 V)? Function transformation Replace the JK502(OPT) to PORT Insert AUDIO line Check if MCL3730 Does it output...

  • Page 26: Amp Protection

    ELECTRICAL TROUBLESHOOTING GUIDE 4. AMP PROTECTION “S-PROTEC” appears on the FLD. After unplug power cord, connect again. Power on. “Goodbye” Display, automatic standby Is the IC701 pin16, 17 Replace IC701. “LOW” signal(0 V)? Is the AMP IC Power 12 V: CHECK Q701 Part. 12 V, 32 V normal? 32 V: CHECK SMPS Part.

  • Page 27: Waveforms Of Major Check Point

    WAVEFORMS OF MAJOR CHECK POINT 1. CRYSTAL FIG 1-1. X101 (24 MHz) FIG 1-2. X400, X401 (24.576 MHz) 3-14...

  • Page 28: Flash Memory

    2. FLASH MEMORY FIG 2. VCC, CS#, CLK, DO 3-15...

  • Page 29: Tact Key

    3. TACT KEY 1 ~ 1.13 V 0.72 ~ 0.82 V FIG 3-1. Press VOL + FIG 3-2. Press VOL - 0.424 ~ 0.485 V 9 10 FIG 3-3. Press FUN.KEY C311 FIG 3-4. Press POWER KEY 3-16...

  • Page 30: Usb

    4. USB EC405 C475 100uF/16V FIG 4-1. USB_5V FIG 4-2. USB D+ FIG 4-3. USB D- 3-17...

  • Page 31: Remote Control

    5. REMOTE CONTROL FIG 5-1. Input Voltage 4.7K 100R EC301 100uF/16V C304 100R C302 C301 8050 FIG 5-2. Low Timing Item Measured Spec. IR Receiver Spec: Input Level 3.3 V 2.7 ~ 5.5 V “ Low” Timing 4.4 ms 3.6 ms ~ 5.04 ms “...

  • Page 32: Optical

    6. OPTICAL FIG 6-1. OPT_IN FIG 6-2. OPT_DET 3-19...

  • Page 33: Portable

    7. PORTABLE FIG 7-1. ADC IC 5 V FIG 7-2. ADC IC 3.3 V FIG 7-3. Analog Input Voltage 3-20...

  • Page 34: Audio Pwm

    8. AUDIO PWM(1/2) FIG 8-1. PWM IC 3.3 V FIG 8-2. PWM IC 1.2 V FB426 600RH C457 FB427 C456 600RH FIG 8-3. BCK C444 FIG 8-4. LRCK 3-21...
  • Page 35 AUDIO PWM(2/2) 384.14 kHz FIG 8-5. Front L/R FB701 600RH C705 C707 C708 C709 100R C710 C711 C712 384.17 kHz 100R 2.2k C714 FB702 600RH FIG 8-6. Subwoofer C713 3-22...

  • Page 36: Audio Amp

    9. AUDIO AMP 560R C701 560R C702 560R 560R C732 FIG 9-1. AMP IC PVDD: 32 V C733 PVDD GVDD AMP_PDN FB701 600RH C707 C708 C709 100R FIG 9-2. C710 C711 C712 100R 2.2k C714 FB702 600RH C713 3-23...
  • Page 37 3-24...

  • Page 38: Wiring Diagram

    WIRING DIAGRAM PORT subwoofer USB PCB AC IN F/L SPK F/R SPK BT module CON1 AC IN SMPS MAIN KEY PCB DISPLAY 3-25 3-26...

  • Page 39: Block Diagram

    BLOCK DIAGRAM 70 W/ 4 Ohm Amplifier 25 W/ 6 Ohm PS9860 TAS5612L 25 W/ 6 Ohm +32 V Bluetooth SDRAM MB8811C1B 4 x 16 M FLASH POTABLE IN 32 M PCM1808 USB Port SPDIF Optical in Main chip IC CS8422 FLASH MLC3730...

  • Page 40: Circuit Diagrams

    DESIGN BE MODIFIED OR ALTERED WITHOUT DIFFER FROM THE ACTUAL CIRCUIT USED. THIS 2. Voltages are DC-measured with a digital voltmeter PERMISSION FROM THE LG CORPORATION. ALL WAY, IMPLEMENTATION OF THE LATEST SAFETY during Play mode. COMPONENTS SHOULD BE REPLACED ONLY WITH...

  • Page 41: Main - Dsp Circuit Diagram

    2. MAIN - DSP CIRCUIT DIAGRAM 9 10 C179 R173 4.7K R1B1 R172 R1B2 3904 : WAVEFORM NUMBER 3-31 3-32...

  • Page 42: Main - Power Circuit Diagram

    3. MAIN - POWER CIRCUIT DIAGRAM C471 R435 C472 100uF/16V R436 R437 3904 R438 EC405 C475 100uF/16V R715 EC705 100uF/16V R463 R441 R716 R439 R717 3904 R464 3904 R718 : WAVEFORM NUMBER 3-33 3-34...

  • Page 43: Main - Pwm & Amp Circuit Diagram

    4. MAIN - PWM & AMP CIRCUIT DIAGRAM FB426 600RH C457 FB427 C456 600RH L425 600RH 100R C440 100R 100R 100R C449 100R C441 C448 C444 FB701 C703 600RH C704 C705 C707 C708 C709 C721 C723 4.7K 560R 560R C701 100R 560R 560R...

  • Page 44: Display/ Key/ Usb Circuit Diagram

    5. DISPLAY/ KEY/ USB CIRCUIT DIAGRAM FGND CON301 C305 LED301 DISPLAY_3.3V 100NF HM338-10B LED_ATA7216AW-P12 R305 STB_LED 3.3V DISPLAY_3.3V R302 100R R303 R312 DISPLAY_SDA 4.7K 100R 100R R313 DISPLAY_SCL LED2 D301 D302 FGND RED LED CN/7PIN EC301 FGND R304 STBY-->H 100uF/16V C304 100R C302...

  • Page 45: Circuit Voltage Chart

    CIRCUIT VOLTAGE CHART Designator Description Voltage Spec Measured Voltage 1, 43, 90, 132, 158 3.0~3.6 V 3.28 V 23, 55, 72, 107, 142, 160 1.1~1.3 V 1.19 V 57, 60, 164(USB_VCC) 3.0~3.6 V 3.28 V IC101 Digital Signal Processors 66(USB_VCC) 1.1~1.3 V 1.19 V 68(OSC_VCC)

  • Page 46: Printed Circuit Board Diagrams

    PRINTED CIRCUIT BOARD DIAGRAMS 1. SMPS P. C. BOARD DIAGRAM (TOP VIEW) NOTE) Warning Parts that are critical with respect to risk of fire or electrical shock. (BOTTOM VIEW) 3-41 3-42...

  • Page 47: Main P. C. Board Diagram

    2. MAIN P. C. BOARD DIAGRAM (TOP VIEW) (BOTTOM VIEW) 3-43 3-44...

  • Page 48: Display P. C. Board Diagram

    3. DISPLAY P. C. BOARD DIAGRAM (TOP VIEW) (BOTTOM VIEW) 4. KEY P. C. BOARD DIAGRAM (TOP VIEW) (BOTTOM VIEW) 5. USB P. C. BOARD DIAGRAM (TOP VIEW) (BOTTOM VIEW) 3-45 3-46...
  • Page 49 3-47 3-48...

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