LG CMS4750F Service Manual
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LG CMS4750F Service Manual

LG CMS4750F Service Manual

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Internal Use Only
Website http://biz.lgservice.com
Mini Hi-Fi System
SERVICE MANUAL
MODEL: CM4750
(CM4750, CMS4750F/W)
CAUTION
BEFORE SERVICING THE UNIT, READ THE "SAFETY PRECAUTIONS"
IN THIS MANUAL.
P/NO : AFN77277047
AUGUST, 2015

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  • Page 1 Internal Use Only Website http://biz.lgservice.com Mini Hi-Fi System SERVICE MANUAL MODEL: CM4750 (CM4750, CMS4750F/W) CAUTION BEFORE SERVICING THE UNIT, READ THE “SAFETY PRECAUTIONS” IN THIS MANUAL. P/NO : AFN77277047 AUGUST, 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 SUMMARY CONTENTS SERVICING PRECAUTIONS ........................1-3 ESD PRECAUTIONS ..........................1-5 HIDDEN KEY MODE ........................... 1-6 SERVICE INFORMATION FOR EEPROM ..................1-7 PROGRAM DOWNLOAD & UPDATE GUIDE ................... 1-8 1. MCS PROGRAM ............................1-8 2. EQ PROGRAM ............................1-9 SPECIFICATIONS .............................

  • Page 4: Servicing Precautions

    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 5 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 6: 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 7: Hidden Key Mode

    HIDDEN KEY MODE Push both Front key and RCU key to activate it for 5 seconds. 1. Disc Lock On/Off (CD Function Only Active)  Front Key : STOP  RCU Key : STOP 2. Check Version and Option code ...

  • Page 8: Service Information For Eeprom

    SERVICE INFORMATION FOR EEPROM POWER ON FLD no disc status or AUX status. Remote control ‘Fwd skip’ + Front ‘STOP’ push same timing during 5 seconds. FLD ‘OP-0…. Move to appropriate position and make changes with remote control ‘skip, mode, play’ key. Press ENTER key FLD ‘write ok’...

  • Page 9: Program Download & Update Guide

    PROGRAM DOWNLOAD & UPDATE GUIDE 1. MCS PROGRAM Download program file name must be - HG520_FW_CM4750_DATE.bin If security program (Water Wall) is activated on your PC, you must save the file to the USB storage device and disable the security software, then download the file to your set. Caution: When downloading the file, you should neither unplug the USB device, change to the other function, nor power off the device.

  • Page 10: Eq Program

    2. EQ PROGRAM Download program file name must be EQ_PRG_CM4750_***.BIN If security program (Water Wall) is activated on your PC, you must save the file to the USB storage device and disable the security software, then download the file to your set. Caution: When downloading the file, you should neither unplug the USB device, change to the other function, nor power off the device.

  • Page 11: Specifications

    • CD Frequency Response 100 to 20 000 Hz Signal-to-noise ratio 75 dB Dynamic range 75 dB • FRONT SPEAKER Model CMS4750F Type 2 Way 2 Speaker Impedance 4 Ω Rated Input Power 300 W Max. Input power 600 W...
  • Page 12 SECTION 2 CABINET & MAIN CHASSIS CONTENTS EXPLODED VIEWS ............................. 2-3 1. CABINET AND MAIN FRAME SECTION (CM4750) ................2-3 2. MECHANISM DECK SECTION (DP17TM3) .................... 2-5 3. PACKING ACCESSORY SECTION ......................2-7 4. SPEAKER SECTION ..........................2-8...

  • Page 14: Exploded Views

    EXPLODED VIEWS 1. CABINET AND MAIN FRAME SECTION (CM4750) 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 SMPS CABLE1 FRONT 260R CABLE4 MAIN...

  • Page 15: Mechanism Deck Section (Dp17Tm3)

    2. MECHANISM DECK SECTION (DP17TM3) 1439 1002 A001 1005 1001 1026 1003 1004 1030 1024 1437 1437 1024 1024 1012 1049 1437 1024 1015 1016 1013 1020 1011 A006 1019 A005 1043 1018 1045 1439...

  • Page 16: Packing Accessory Section

    3. PACKING ACCESSORY SECTION 808 Battery 801 Instruction Ass'y 900 Remote Control 825 FM Wire Antenna 803 Packing 804 Bag 803 Packing 802 Box...

  • Page 17: Speaker Section

    4. SPEAKER SECTION 4-1. FRONT SPEAKER (CMS4750F)
  • Page 18 4-2. SUBWOOFER SPEAKER (CMS4750W)
  • Page 19 2-10...
  • Page 20 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 OPERATION OF MD ........................3-6 5. NO SOUND ............................3-11 AUDIO ELECTRICAL TROUBLESHOOTING GUIDE ..............3-17 1.

  • Page 21: One Point Repair Guide

    ONE POINT REPAIR GUIDE 1. NO POWER If the unit doesn’t work by no power problem, repair the set according to the follow- ing guide. 1-1. FUSE & BRIDGE DIODE 1-1-1. Solution Please check and replace F901, BD901, TH901 or TH903 on SMPS board. 1-1-2.
  • Page 22 ONE POINT REPAIR GUIDE NO POWER If the unit doesn’t work by no power problem, repair the set according to the follow- ing guide. 1-2. D951 1-2-1. Solution Please check and replace D951 on SMPS board. 1-2-2. How to troubleshoot (Countermeasure) 1) Check the anode-cathod voltage of D951 with a digital multi-meter, it is normally 0.2 ~ 0.3 V.

  • Page 23: Booting When Power On The Set

    ONE POINT REPAIR GUIDE 2. NO BOOTING WHEN POWER ON THE SET The set doesn’t work when press the power button on the front board or the remote control. 2-1. FLASH MEMORY 2-1-1. Solution Please check and replace IC503 on MAIN board. 2-1-2.

  • Page 24: Vfd Is Not Displayed When Power On The Set

    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 3-1-1. Solution Please check and replace DIG302 on FRONT board. 3-1-2.
  • Page 25 ONE POINT REPAIR GUIDE 4. 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.

  • Page 26: Operation Of Md

    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.
  • Page 27 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.
  • Page 28 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.
  • Page 29 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.
  • Page 30 ONE POINT REPAIR GUIDE 5. NO SOUND There is no sound output in the CD FUNCTION, repair the set according to the follow- ing guide. 5-1. IN THE CD FUNCTION 5-1-1. Solution Please check and replace IC501, IC601 on MAIN board. 5-1-2.

  • Page 31: Sound

    ONE POINT REPAIR GUIDE NO SOUND There is no sound output by DIGITAL AUDIO AMP DAMAGE, repair the set according to the following guide. 5-2. BY DIGITAL AUDIO AMP DAMAGE (IN ALL FUNCTIONS) 5-2-1. Solution Please check and replace IC701, IC702 on MAIN board. 5-2-2.
  • Page 32 ONE POINT REPAIR GUIDE NO SOUND There is no sound output in the USB FUNCTION, repair the set according to the following guide. 5-3. IN THE USB FUNCTION 5-3-1. Solution Please check and replace IC501 on MAIN board & IC302 on USB board. 5-3-2.
  • Page 33 ONE POINT REPAIR GUIDE NO SOUND There is no sound output in the AUX FUNCTION, repair the set according to the following guide. 5-4. IN THE AUX FUNCTION 5-4-1. Solution Please check and replace IC201 on MAIN board. 5-4-2. How to troubleshoot (Countermeasure) 1) Check AUX_L/R signals to IC201 (Pin23, 24).
  • Page 34 ONE POINT REPAIR GUIDE NO SOUND There is no sound output in the TUNER FUNCTION, repair the set according to the following guide. 5-5. IN THE TUNER FUNCTION 5-5-1. Solution Please check and replace IC201, TU500 on MAIN board. 5-5-2. How to troubleshoot (Countermeasure) 1) Check if TUNER_LR is entered from Pin1, 3 of TU500 to IC201(Pin26, 27).
  • Page 35 ONE POINT REPAIR GUIDE NO SOUND There is no sound output in the PORTABLE FUNCTION, repair the set according to the following guide. 5-6. IN THE PORTABLE FUNCTION 5-6-1. Solution Please check and replace IC201 on MAIN board. 5-6-2. How to troubleshoot (Countermeasure) 1) Check PT_L/R signals to IC201 (Pin9, 10).

  • Page 36: Audio Electrical Troubleshooting Guide

    AUDIO ELECTRICAL TROUBLESHOOTIHG GUIDE 1. POWER (SMPS) No 5.6 VA F901 normal? Replace F901 (Use the same fuse). BD901 normal? Replace BD901. TH901(TH903) normal? Replace TH901. Is Vcc (10 V ~ 18 V) supplied to D902 normal? IC901 Pin7? Check or replace D902. D933 / D934 normal? Replace D933 / D934.
  • Page 37 AUDIO ELECTRICAL TROUBLESHOOTIHG GUIDE No PVDD F901 normal? Replace F901 (Use the same fuse). BD901 normal? Replace BD901. TH901(TH903) normal? Replace TH901. Is Vcc (10 V ~ 18 V) supplied to D903 normal? IC911 Pin4? Check or replace D903. Q911 base "H"? •...
  • Page 38 AUDIO ELECTRICAL TROUBLESHOOTIHG GUIDE No 12 V Is Vcc (15 V) Check or replace D935. supplied to IC931? Check P-CTRL “H” signal IC931 Pin4 “H”? from MCS. Check or replace IC931. No VFD Check or replace D931. D931 normal? Check or replace ZD931. ZD931 normal? Q501 / Q502 normal? Check or replace Q501 / Q502.

  • Page 39: Mcs Part Check

    AUDIO ELECTRICAL TROUBLESHOOTIHG GUIDE 2. MCS PART CHECK MCS PART CHECK Check if Refer to voltage of CN501 Pin7 SMPS troubleshooting. is 5.6 VA. Check if IC510 Check and change IC510. have 3.3 V output. Check if IC508 Check and change IC508. have 1.2 V output.

  • Page 40: Fld Display Check

    AUDIO ELECTRICAL TROUBLESHOOTIHG GUIDE 4. FLD DISPLAY CHECK FLD DISPLAY CHECK Check CN501 Pin13,14,15 input Refer to SMPS troubleshooting. voltage. Check if both end voltage of FL+, FL- are over 2.9 V VKK : over 25.6 V. Check CN301 connection and power Check CN301 connection.

  • Page 41: Pwm Modulation Check

    AUDIO ELECTRICAL TROUBLESHOOTIHG GUIDE 5. PWM MODULATION CHECK PWM MODULATION PART CHECK Check Refer to CN501 Pin7,8 SMPS troubleshooting. (5.6 V) • Check IC601(TAS5548) VDD 3.3 V - Pin9,14.35,50. • Check X601 (12.288 MHz). Check Check X601 X601(12.288 MHz) Replace X601(12.288 MHz). (12.288 MHz).
  • Page 42 AUDIO ELECTRICAL TROUBLESHOOTIHG GUIDE Check Check IC601(TAS5548) Refer to CD Assy communication input data CD troubleshooting. Pin22, 23, 24. Pin24 PWM wave. Check Check each line IC601 input resistor output. data. Check PWM modulator output FL: Pin48(-),49(+) Replace IC601. Check IC601. FR: Pin46(-),47(+).

  • Page 43: Power Amp Part Check

    AUDIO ELECTRICAL TROUBLESHOOTIHG GUIDE 6. POWER AMP PART CHECK POWER AMP PART CHECK Check CN501 Pin10: +12 V Refer to SMPS troubleshooting. Pin1,2,3: 47.3 V. Check IC701, IC702 Pin51, 52, 42, 43, 38, 39, 30, 31 input voltage. Check IC701, IC702 Check each line resistor output voltage.

  • Page 44: Tuner / Aux Function Check

    AUDIO ELECTRICAL TROUBLESHOOTIHG GUIDE 7. TUNER / AUX FUNCTION CHECK FUNCTION CHECK Check IC201 (CS5346) Pin23, 24, Check JK200,TU500. 26, 27 input. Check IC201 Check IC201 Pin5: +3.3 V Check CN501 Pin7,8: +5.6 V. (CS5346) Pin41 output Pin14: +5 V. data.

  • Page 45: Tuner Function Check

    AUDIO ELECTRICAL TROUBLESHOOTIHG GUIDE 8. TUNER FUNCTION CHECK TUNER FUNCTION CHECK Check tuner Check tuner module voltage module(TU500) (Pin4: +3.3 V). operation. Check IC501 Pin P8, P10, P11, T15. Check tuner module data. Refer to function check. 3-26...

  • Page 46: Cdp Electrical Troubleshooting Guide

    CDP ELECTRICAL TROUBLESHOOTIHG GUIDE 1. CD FUNCTION CD FUNCTION Can the Is Motor_open/close Is load +,- ok? disc insert? OK? (IC408 Pin6,7) Check IC408. Is Motor ok? Check loading motor. (about 12 ) Focus/ Check IC408 IM driving (Focus and Disc reading tracking/sled signal (Motor drive IC).

  • Page 47: Double Usb Function

    CDP ELECTRICAL TROUBLESHOOTIHG GUIDE 2. DOUBLE USB FUNCTION USB FUNCTION Plug-in usb device. Display “NO USB”. Check USB_5V. Check CN302. Check USB_D+/D- Check USB jack (JK301/ JK302). Display “READ”. (R380,R381/ R382,R383). Check IC501 Display “NO FILE”. Replace IC501. (Pin U7,U8/ A7,A8). Check usb audio fi...

  • Page 48: Waveforms Of Major Check Point

    WAVEFORMS OF MAJOR CHECK POINT 1. SDRAM IC502 PIN38 IC502 PIN53 DATA ADDRESS IC502 PIN35 IC503 PIN1 2. SERVO CD-16 M IC501 PIN M1 3-29...

  • Page 49: Audio Path

    3. AUDIO PATH IC501 PIN N4 CD_BCK IC501 PIN N1 CD_LRCK CD_DATA IC501 PIN N2 DAC_MCLK IC501 PIN D2 DAC_BCK IC501 PIN E1 DAC_LRCK IC501 PIN D1 DAC_DATA IC501 PIN E2 3-30...

  • Page 50: Usb

    4. USB USB_5 V IC501 PIN A8 IC501 PIN A7 3-31...
  • Page 51 3-32...

  • Page 52: Wiring Diagram

    WIRING DIAGRAM 1. [Total CNT : 6 ea] SPK TERMINAL JACK 1. FFC Cable MAIN FRONT : 1 EA MAIN MD: 2 EA 1 CD MD MAIN BT module: 1 EA 2. Harness Single SMPS MAIN : 1 EA MAIN USB: 1 EA MAIN + CD SMPS...

  • Page 53: Block Diagrams

    BLOCK DIAGRAMS 1. SYSTEM BLOCK DIAGRAM TUNER_L/R PWM_RST TUNER FL± IC701 AMP IC TUNER_RST/CE/DAT/CLK FR ± PWM DAT/CLK TAS5631B IC601 TAS5548 REMOCON/KEY PWM_MUTE IC702 AMP IC IC301 DAC_BCK/LRCK/DATA TAS5631B ABOV VFD_STB/CLK/DO AMP_PDN IM(CMS-S79RFVC6) OP_SW,CL_SW AMP_OTW/SD/CLIP/AMP PROTECT DSP IC501 P/UP CP_RESET/SCL/SDA IC511 F±/TR±...

  • Page 54: Smps Block Diagram

    2. SMPS BLOCK DIAGRAM Snubber Block CN901 Main 12 V LDO 12 V SMPS IC Block On/Off 5.6 VA Noise Y-Cap Feedback Filter Photo coupler Block (X-cap P.CTL Y-Cap Photo coupler On/Off Line Filter) Snubber Block PVDD SMPS IC With FET Feedback Block Photo coupler...

  • Page 55: Audio Path Block Diagram

    3. AUDIO PATH BLOCK DIAGRAM FR,FL TAS5631B 300Wx2 12.288 MHz PORTABLE PORTABLE DAC_LRCK DAC_BCK TAS5548 DAC_MCLK TUNER Tuner CS5346 DAC_LRCK (SLAVE) DAC_BCK Woofer TAS5631B Aux in 400Wx1 AMP Block ADC_DATA CD_BCK MLC3730 CD_LRCK (176 PIN) LC78615E CD_DATA Block 24 MHz 32.768 KHz 3-39 3-40...

  • Page 56: Power Diagram

    4. POWER DIAGRAM 25 mA IC301 370 mA ± 5 mA 3 mA Diode Diode delete delete TU500 IC407 IC601 PWR_CTRL TUNER RF IC TAS5548 YST996 2.668A RS1G IC507 DVCC_3.3 V 70 mA 150 mA 10 mA +5.6 VA TJ4220 +5 V IC302 USB PWR...

  • Page 57: Circuit Diagrams

    MODIFIED OR ALTERED WITHOUT PERMISSION IMPLEMENTATION OF THE LATEST SAFETY AND during Play mode. FROM THE LG CORPORATION. ALL COMPONENTS PERFORMANCE IMPROVEMENT CHANGES INTO SHOULD BE REPLACED ONLY WITH TYPES IDENTICAL THE SET IS NOT DELAYED UNTIL THE NEW SERVICE TO THOSE IN THE ORIGINAL CIRCUIT.

  • Page 58: Main - Dsp Circuit Diagram

    2. MAIN - DSP CIRCUIT DIAGRAM 14 13 : WAVEFORM NUMBER EAX66323901-SD(#01)_Rev8_1.1 2015. 01. 05 3-45 3-46...

  • Page 59: Main - Servo Circuit Diagram

    3. MAIN - SERVO CIRCUIT DIAGRAM SERVO EAX66323901-SD(#02)_Rev8_1.1 2015. 01. 05 3-47 3-48...

  • Page 60: Main - Adc/ Pwm Circuit Diagram

    4. MAIN - ADC/ PWM CIRCUIT DIAGRAM ADC/PWM EAX66323901-SD(#03)_Rev8_1.1 2015. 01. 05 3-49 3-50...

  • Page 61: Main - Amp Circuit Diagram

    5. MAIN - AMP CIRCUIT DIAGRAM EAX66323901-SD(#04)_Rev8_1.1 2015. 01. 05 3-51 3-52...

  • Page 62: Front Circuit Diagram

    6. FRONT CIRCUIT DIAGRAM FRONT EAX65586201_Rev2_1.2 2015. 01. 29 3-53 3-54...

  • Page 63: Circuit Voltage Chart

    CIRCUIT VOLTAGE CHART 1. ICs Location Pin No. SPEC EE Mode (V) Margin Playback Mode (V) Margin Location Pin No. SPEC EE Mode (V) Margin Playback Mode (V) Margin MAIN Board IC503 Flash (W25Q64FVSSIG) IC201 ADC(CS5346) 8(VDD) 2.7~3.6 3.24 3.24 5(VLC) 3.13~5.25 3.24...

  • Page 64: Capacitors

    2. CAPACITORS EEMode Play back Value Voltage_ Loca. No. Capacitor Positive Negative Positive Negative Spec Margin Margin (uF) MAIN Board C244 47 uF 16 V 5.08 V 5.08 V 10.92 V 5.08 V 5.08 V 10.92 V C402 100 uF 16 V 5.08 V 5.08 V...

  • Page 65: Printed Circuit Board Diagrams

    PRINTED CIRCUIT BOARD DIAGRAMS 1. SMPS P.C.BOARD (TOP VIEW) (BOTTOM VIEW) NOTE) Warning Parts that are critical with respect to risk of fire or electrical shock. 3-59 3-60...

  • Page 66: Main P.c.board

    2. MAIN P.C.BOARD (TOP VIEW) (BOTTOM VIEW) 3-61 3-62...

  • Page 67: Front P.c.board

    3. FRONT P.C.BOARD (TOP VIEW) (BOTTOM VIEW) 3-63 3-64...

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