LG LH-T6740 Service Manual

Dvd/cd receiver
Table of Contents

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P/N : 3829RDT050K
NOVEMBER, 2005
DVD/CD RECEIVER

SERVICE MANUAL

CD-R/RW
MODEL: LH-T6740
LH-T6740A
LHS-T6740C, LHS-T6740T, LHS-T6740W

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Summary of Contents for LG LH-T6740

  • Page 1: Service Manual

    DVD/CD RECEIVER SERVICE MANUAL CD-R/RW MODEL: LH-T6740 P/N : 3829RDT050K NOVEMBER, 2005 LH-T6740A LHS-T6740C, LHS-T6740T, LHS-T6740W...
  • Page 2: Table Of Contents

    [CONTENTS] ❍ SECTION 1.GENERAL • SERVICING PRECAUTIONS ..........1-2 •...
  • Page 3: Servicing Precautions

    SECTION 1. GENERAL ❏ 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.
  • Page 4 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.
  • Page 5: 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 6: Specifications

    ❏ SPECIFICATIONS - 1-5 -...
  • Page 7 MEMO - 1-6 -...
  • Page 8: Electrical Troubleshooting Guide

    SECTION 2. AUDIO PART ❏ ELECTRICAL TROUBLESHOOTING GUIDE 1. Power check flow INSERT POWER CORD. TURN ON CHECK POWER PLUG THE RED LED? AND POWER SUPPLY CIRCUIT . TURN POWER ON. IS POWER ON? CHECK POWER SUPPLY CIRCUIT . DOES INITIAL CHECK LASER CIRCUIT .
  • Page 9 2.AUDIO µ.COM CIRCUIT POWER ON Does AV 1/2, TV, AUDIO, Does CD/DVD OPTICAL IN, COAXIAL IN, FM87.5 appear at FLD? appear at FLD? Does it appear Does LOADING DVD Error at appear at FLD? FLD? Check Does no Disc or Connector(PN902)if Reconnet it.
  • Page 10 3.FRONT CIRCUIT (1/2) - 2-3 -...
  • Page 11 4.FRONT CIRCUIT (2/2) - 2-4 -...
  • Page 12: Block Diagram

    ❏ BLOCK DIAGRAM...
  • Page 13 ❏ SCHEMATIC DIAGRAMS • FRONT SCHEMATIC DIAGRAM...
  • Page 14: Schematic Diagrams

    • MICOM SCHEMATIC DIAGRAM 2-10...
  • Page 15 • I//O SCHEMATIC DIAGRAM 2-11 2-12...
  • Page 16 • DSP SCHEMATIC DIAGRAM 2-13 2-14...
  • Page 17 • AMP SCHEMATIC DIAGRAM 2-15 2-16...
  • Page 18 • SMPS-WIDE SCHEMATIC DIAGRAM 2-17 2-18...
  • Page 19 • POWER SCHEMATIC DIAGRAM 2-19 2-20...
  • Page 20 ❏ WIRING DIAGRAMS 2-21 2-22...
  • Page 21 ❏ PRINTED CIRCUIT DIAGRAMS • MAIN P.C. BOARD (COMPONENT SIDE) 2-23 2-24...
  • Page 22 • MAIN P.C. BOARD (SOLDER SIDE) 2-25 2-26...
  • Page 23 • FRONT P.C.BOARD (SOLDER SIDE) • FRONT P.C.BOARD (COMPONENT SIDE) 2-27 2-28...
  • Page 24 • POWER P.C.BOARD 2-29 2-30...
  • Page 25 MEMO MEMO 2-31 2-32...
  • Page 26 SECTION 3. DVD PART ❏ ELECTRICAL TROUBLESHOOTING GUIDE 1. Power check flow - 3-1 -...
  • Page 27 2. System operation flow Power On 1. 8032 initializes SERVO, DSP & RISC registers 2. Write RISC code to SDRAM 3. Reset RISC Show LOGO Tray Closed? Tray Close to Closed position SLED at Inner Side ? SLED Moves to Inner Positi on 1.
  • Page 28 3. Test & debug flow TEST Check the AC Voltage Replace power PCBA or Power PCBA(110V or 220V) AC transformer. Switch on the Power PCBA Is the DC Voltage Repair or Replace Power PCBA outputs OK? (5V,1.8V,3.3V,8V,12V) Make sure the main PCBA don't short on VCCs and switch it on.
  • Page 29 RESET or Power On. Check connection lines between FLASH Flash Memory operates & MT1389 and the FLASH access time Show LOGO? properly? whether is suitable or not. Check connection lines between SDRAM works properly? SDRAM & MT1389 and the SDRAM is damaged.
  • Page 30 Does the SLED move Motor Driver STBY Check the connection line of to inner side when it is at Pin is High? STBY signal. outter position? Is FMSO DC Level higher Check the related circuit of than 1.4V? FMSO. SL+ and SL- output Check the amp circuit on motor properly? driver.
  • Page 31 Check the laser power circuit Laser turns on when LD01 or LD02 output on MT1336 and connecting to reading disc? properly? power transistor. Collector voltage of Check the related circuit on power transistor is OK? laser power transistor Check cable connection between transistor ouput and pick-up head.
  • Page 32 Proper signals on Check connections between Focus ON OK? A,B,C,D of MT1389 MT1389 and pick-up head. Check the FOSO connection on Check FEO signal MT1389 and motor driver. on MT1389 Check FOSO signal on MT1389 Check the related Normal TEO Signal on Track On OK? circuit on MT1389 MT1389?
  • Page 33 Normal Audio output Audio PWM IC received Check connection between MT1379 when disc playback? correct data stream? & Audio PWM IC. Check the related Normal Audio PWM IC circuit of Audio PWM IC. out? Check Audio filter,amplify,mute circuit. Communications between Normal IR.VFD &...
  • Page 34: Details And Waveforms On System Test And Debugging

    ❏ DETAILS AND WAVEFORMS ON SYSTEM TEST AND DEBUGGING 1. SYSTEM 27MHz CLOCK,RESET,FLASH R/W SIGNAL 1) MT1379 main clock is at 27MHz(X501) FIG 1-1 2) MT1336 reset is high active FIG 1-2 - 3-9 -...
  • Page 35 3) RS232 waveform during procedure(Downloading) FIG 1-3 4) Flash R/W enable signal during download(Downloading) FIG 1-4 - 3-10 -...
  • Page 36 2. SDRAM CLOCK 1) MT1379 main clock is at 27MHz(X501) FIG 2-1 3. TRAY OPEN/CLOSE SIGNAL FIG 3-1 - 3-11 -...
  • Page 37 4. SLED CONTROL RELATED SIGNAL (NO DISC CONDITION) FIG 4-1 5. LENS CONTROL RELATED SIGNAL(NO DISC CONDITION) FIG 5-1 - 3-12 -...
  • Page 38 6. LASER POWER CONTROL RELATED SIGNAL (NO DISC CONDITION) FIG 6-1 7. DISC TYPE JUDGEMENT W VEFORM FIG 7-1 - 3-13 -...
  • Page 39 FIG 7-2 (DVD) FIG 7-3 (CD) - 3-14 -...
  • Page 40 FIG 7-4 (CD) 8. FOCUS ON W VEFORM FIG 8-1 (DVD) - 3-15 -...
  • Page 41 FIG 8-2 (CD) 9. SPINDLE CONTROL W VEFORM (NO DISC CONDITION) FIG 9-1 - 3-16 -...
  • Page 42 10. TRACKING CONTROL RELATED SIGNAL(System checking) FIG 10-1 (DVD) FIG 10-2 (CD) - 3-17 -...
  • Page 43 11. MT1389 AUDIO OPTICAL AND COAXIAL INPUT (SPDIF) FIG 11-1 (DVD) 12. MT1389 VIDEO OUTPUT WAVEFORM 1)100% FIG 12-1 - 3-18 -...
  • Page 44 2) COMPOSITE VIDEO SIGNAL FIG 12-2 13. MT1389 AUDIO OUTPUT TO PWM IC ADAT0~3 FIG 13-1 - 3-19 -...
  • Page 45 14. AUDIO OUTPUT FROM PWM IC FIG 14-1 - 3-20 -...
  • Page 46: Block Diagram

    ❏ BLOCK DIAGRAM 1. Overall Block Diagram CVBS - 3-21 -...
  • Page 47 2. SERVO Block Diagram - 3-22 -...
  • Page 48 3. MPEG & MEMORY Block Diagram - 3-23 -...
  • Page 49 4. VIDEO & AUDIO Block Diagram - 3-24 -...
  • Page 50: Dvd Part Schematic Diagrams

    ❏ DVD PART SCHEMATIC DIAGRAMS • MPEG SCHEMATIC DIAGRAM 3-25 3-26...
  • Page 51 • SERVO SCHEMATIC DIAGRAM 3-27 3-28...
  • Page 52: Section 4. Exploded Views

    SECTION 4. EXPLODED VIEWS • CABINET AND MAIN FRAME SECTION NOTE) Refer to “SECTION 6 REPLACEMENT PARTS LIST” in order to look for the part number of each part.
  • Page 53 • DECK MECHANISM EXPLODED VIEW NSP : Non SVC Parts LOCA. NO. LG PART NO. DESCRIPTION SPECIFICATION REMARKS 6721RJ0871A DECK ASSEMBLY,AUDIO HOME THEATER DP-9T(HZ) -MTK138 4861R-0016B CLAMP ASSEMBLY DISC DP7 - SH 3041R-T001A BASE ASSEMBLY MAIN DP-9T-ESS 3041R-T001E BASE ASSEMBLY SLED DP-9T(HZ) -MTK1389 -SAMS 3300R-0547A PLATE...
  • Page 54: Section 5. Speaker Part

    SECTION 5. SPEAKER PART ❏ MODEL: LHS-T6740W - 5-1 -...
  • Page 55 ❏ MODEL: LHS-T6740C - 5-2 -...
  • Page 56 ❏ MODEL: LHS-T6740T - 5-3 -...
  • Page 57 MEMO - 5-4 -...

This manual is also suitable for:

Lhs-t6740cLhs-t6740tLhs-t6740wLh-t6740a

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