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Internal Use Only Website http://biz.lgservice.com MINI HI-FI SYSTEM SERVICE MANUAL MODEL: CM9750 (CM9750, CMS9750F) CAUTION BEFORE SERVICING THE UNIT, READ THE “SAFETY PRECAUTIONS” IN THIS MANUAL. P/NO : AFN77277023 JULY, 2015...
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CONTENTS SECTION 1 ..GENERAL SECTION 2 ..CABINET & MAIN CHASSIS SECTION 3 ..ELECTRICAL SECTION 4 ..REPLACEMENT PARTS LIST...
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.
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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.
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.
HIDDEN KEY MODE HIDDEN MODE KEYS Version Check Front Stop + RMC ‘ ’ for 5s EEPROM Initial Front Stop + RMC ‘ ’ for 5s EEPROM Edit Front Stop + RMC ‘ ’ for 5s APD Test Display Front Stop + RMC ‘3’ for 5s Clip Front Stop + RMC ‘Mute’...
SERVICE INFORMATION FOR EEPROM POWER ON It is possible at any function. (ex. It is possible at VFD “NO USB” status, too.) VFD “NO DISC” status This is an example. Front ‘STOP’ + Remote control “ ” push same timing during 5s FLD “OP00-…..”...
PROGRAM DOWNLOAD GUIDE 1. AUDIO PROGRAM Download program file name must be MICOM_CM8450_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 USB1 function and USB2 function.
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2. CD PROGRAM Download program file name must be HG580_CM8450_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 USB1 function and USB2 function.
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3. EQ PROGRAM Download program file name must be EQ_PRG.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 USB1 function and USB2 function.
SPECIFICATIONS • GENERAL Power requirements Refer to the main label. Power consumption Refer to the main label. Networked standby : 0.4 W (If all network ports are activated.) Dimensions (W x H x D) 450 mm x 160 mm x 335 mm Net Weight (Approx.) 6.5 kg Operating temperature...
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. SMPS MAIN FRONT_CTRL FRONT NFC Tag CABLE2 CABLE1...
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SECTION 3 ELECTRICAL CONTENTS ONE POINT REPAIR GUIDE ..........................3-2 1. NO POWER ............................3-2 2. NO AMP POWER ........................... 3-3 3. NO BOOTING WHEN POWER ON THE SET..................3-4 4. VFD IS NOT DISPLAYED WHEN POWER ON THE SET ..............3-5 5.
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/ BRIDGE DIODE/ FET 1-1-1. Solution Please check and replace F901, BD901, BD902, Q902~Q905 on SMPS board. 1-1-2.
ONE POINT REPAIR GUIDE 2. NO AMP POWER If the unit doesn’t work by no ±PVDD problem, repair the set according to the following guide. 2-1. FUSE/ FET 2-1-1. Solution Please check and replace F911, Q911 ~ Q914 on SMPS board. 2-1-2.
ONE POINT REPAIR GUIDE 3. NO BOOTING WHEN POWER ON THE SET The set doesn’t work when press the power button on the FRONT_CTRL board or the remote control. 3-1. IC501 3-1-1. Solution Replace IC501 on MAIN board. 3-1-2. How to troubleshoot (Countermeasure) 1) Check the 5.6 VA (CN106) and DVCC_3.3 V (IC505) in standby mode.
ONE POINT REPAIR GUIDE 4. VFD IS NOT DISPLAYED WHEN POWER ON THE SET When power on the set, any icons or characters on VFD are not displayed. 4-1. VFD (VFD301) 4-1-1. Solution Please check and replace VFD301 on FRONT board. 4-1-2.
ONE POINT REPAIR GUIDE 5. AUDIO OUTPUT IS SMALL OR NO AUDIO OUTPUT Audio signal output is small or not. when you power on the Middle Power Mini System. 5-1. AMP IC (IC700~IC705) 5-1-1. Solution Replace IC700~IC705 on MAIN board. 5-1-2.
ONE POINT REPAIR GUIDE 6. D-PROTECTION IS DISPLAYED 6-1. AMP FETs 6-1-1. Solution Replace AMP FET on MAIN board. 6-1-2. How to troubleshoot (Countermeasure) 1) This symptom occurs, when DC protection is detected. Main reasons are like below. - When some of AMP FETs dead. 6-1-3.
ONE POINT REPAIR GUIDE 7. SPEAKER NO AUDIO Speaker No Audio 7-1. AMP IC (IC700~IC705) 7-1-1. Solution Replace IC700~IC705 on MAIN board. 7-1-2. How to troubleshoot (Countermeasure) 1) Check supply voltage of AMP(CN110) & PWM signal Normal supply voltage and signal Check AMP IC. Poor supply voltage ...
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ONE POINT REPAIR GUIDE 8. 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. 8-1.
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. 8-2.
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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. 8-3.
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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. 8-4.
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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. 8-5.
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ONE POINT REPAIR GUIDE 9. 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.
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. 9-2.
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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.
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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. 9-4.
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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. 9-5.
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ONE POINT REPAIR GUIDE 10. NO SOUND There is no sound output in the USB function, repair the set according to the following guide. 10-1. USB FUNCTION 10-1-1. Solution Replace IC501 on MAIN board, IC312 on FRONT board. 10-1-2. How to troubleshoot (Countermeasure) 1) Check +5 VU to FRONT board.
ONE POINT REPAIR GUIDE NO SOUND There is no sound output in the AUX function, repair the set according to the following guide. 10-2. AUX FUNCTION 10-2-1. Solution Replace IC201 on MAIN board. 10-2-2. How to troubleshoot (Countermeasure) 1) Check AUX_L/R signals to IC201 (pin23, 24). 2) Check if MCS_BCK, MCS_LRCK, &...
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ONE POINT REPAIR GUIDE NO SOUND There is no sound output in the PORT. IN function, repair the set according to the following guide. 10-3. PORT. IN FUNCTION 10-3-1. Solution Replace IC201 on MAIN board. 10-3-2. How to troubleshoot (Countermeasure) 1) Check PT_L/R signal from FRONT board to MAIN board.
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ONE POINT REPAIR GUIDE NO SOUND There is no sound output in the TUNER function, repair the set according to the following guide. 10-4. TUNER FUNCTION 10-4-1. Solution Replace IC201, TU500 on MAIN board. 10-4-2. How to troubleshoot (Countermeasure) 1) Check if TUNER_L/R is entered from pin1 & 3 of TU500 to IC201(pin26, 27). ...
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ONE POINT REPAIR GUIDE NO SOUND There is no sound output in the MIC IN function, repair the set according to the following guide. 10-5. MIC IN FUNCTION 10-5-1. Solution Replace IC200, IC206 on MAIN board. 10-5-2. How to troubleshoot (Countermeasure) 1) Check MIC_SIG signal to pin33 of CN605.
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ONE POINT REPAIR GUIDE NO SOUND There is no sound output in the Bluetooth function, repair the set according to the following guide. 10-6. BLUETOOTH FUNCTION 10-6-1. Solution Replace IC501 on the MAIN board or B/T module on the Front Panel. 10-6-2.
ELECTRICAL TROUBLESHOOTING GUIDE 1. POWER SUPPLY ON SMPS BOARD No output 5.6 VA Replace F901 (same fuse). Is the F901 normal? Replace BD901 or BD902. Is BD901 or BD902 normal? Is the VCC Is D960/ D961 normal? (11 V ~ 25 V) supplied to IC901 pin4? Power line of MAIN PCB is short.
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ELECTRICAL TROUBLESHOOTING GUIDE No -5 V Is the Is the R965 normal? Check or replace R965, D959. VCC -7 VA supplied to IC953 pin2? Check or replace Q951. Is there Check P_CTL ‘H’ signal at Q953 from μ-com. Base? Check or replace Q953, Q957. Or check line of MAIN PCB is short or not.
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ELECTRICAL TROUBLESHOOTING GUIDE No AMP output Is the Check PFC P.CTL Is the C903, C913 Voltage PFC P.CTL OK? from μ-com. about 395 V? Is the VCC 12 V supplied to Replace D908, Q955, PC903. IC904 pin16? Check or replace IC904, Q907 ~ Q910.
ELECTRICAL TROUBLESHOOTING GUIDE 2. SYSTEM PART Power on. CN605 “HELLO” cable connection Display on MLD Check FFC cable. CN605 pin14, 15, 16, 24 power Check SMPS board. CN605 pin8, 9, 10 data signal Check MAIN board. FL+/- & VKK voltage OK? Replace VFD301.
ELECTRICAL TROUBLESHOOTING GUIDE 3. NO AUDIO CHECK CD FUNCTION Is Motor_open/ close OK? LOAD +, - OK? disc insert? (IC400 pin6, 7) Check IC501. Is motor impedance Check loading motor. about 12 Ω? Check IC400. Focusing/ OPU driving Tracking/ Sled signal Disc reading OK? (Focusing &...
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ELECTRICAL TROUBLESHOOTING GUIDE USB FUNCTION When insert USB, IC312 USB Power Replace IC312. IC501 pin U7, U8, A7, A8 +5 VU OK? USB_D signal OK? AUX FUNCTION IC201 Check audio cable. pin23, 24 AUX input signal IC201 Check IC501. pin42, 43, 44 I2S input signal IC201 Replace IC201.
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ELECTRICAL TROUBLESHOOTING GUIDE PORTABLE FUNCTION IC201 Check FRONT board. pin9, 10 PT_L/R input signal IC201 Check IC501. pin42, 43, 44 I2S input signal IC201 pin41 Replace IC201. ADC_DATA_IN output signal TUNER FUNCTION TU500 IC201 pin26, 27 TUNER_L/R output TUNER_L/R input signal Check +3.3 V of TU500.
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ELECTRICAL TROUBLESHOOTING GUIDE IC501 Check IC501. pin D1, D2, E1 I2S Clock signal IC501 Check IC501. pin E2 I2S data signal IC202 Replace IC202. PWM data output signal 3-32...
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ELECTRICAL TROUBLESHOOTING GUIDE pin47~50 pin45, 46 of IC202, of IC202, FL/FR± signal SW1± signal OK? Check IC202. Check IC202. IC203, IC204 IC205 FL/FR audio signal OK? SW1 audio signal OK? Check IC203, IC204. Check IC205. pin13 of pin13 of IC705 IC700, IC701, IC702, IC703 SW1 audio signal OK? FL/FR audio signal OK?
ELECTRICAL TROUBLESHOOTING GUIDE 4. NO LIGHTING (SPEAKER LED) Power on Check Q610~Q618, Q1103~Q1105. White is turn on? IC601 LED_5V Check IC601. Check speaker. 3-34...
WAVEFORMS OF MAJOR CHECK POINT 1. DSP (IC501) X X I X X I Fig 1-1. Crystal of RTC 32.768 MHz Fig 1-2. Crystal of system 24 MHz (R5D6) X501 ( Main DSP : R508,R509) X500 3-35...
2. SMPS BLOCK DIAGRAM MAIN SMPS (STR-2A153D) Flyback MAIN OPAMP - 5 V TRANS PFC Out u-com / BT 5.6 VA (395 V) USB / MPEG PFC IC LED, VFD (R2A20112A) 14 VA Motor Drive Totem 20 A pole 600 V 12 V FAN/Mic/ Interleaved...
3. POWER BLOCK DIAGRAM IC202 IC101 IC401 IC602 IC604 Expander MICOM RF IC TUNER PCM5101 DRV632 BU2090F PS9860 R5F100G BU9546 77 mA 3.2 mA 80 mA 22 mA 10 mA 10 mA 70 mA DVCC_3.3 V IC505 →MCS_3.3 V +5.6 VA LDO(1 A) MCS_3.3 V TJ4220GDP...
BE MODIFIED OR ALTERED WITHOUT PERMISSION FROM THE ACTUAL CIRCUIT USED. THIS WAY, 2. Voltages are DC-measured with a digital voltmeter FROM THE LG CORPORATION. ALL COMPONENTS IMPLEMENTATION OF THE LATEST SAFETY AND during Play mode. SHOULD BE REPLACED ONLY WITH TYPES PERFORMANCE IMPROVEMENT CHANGES INTO 1.
BE MODIFIED OR ALTERED WITHOUT PERMISSION FROM THE ACTUAL CIRCUIT USED. THIS WAY, 2. Voltages are DC-measured with a digital voltmeter FROM THE LG CORPORATION. ALL COMPONENTS IMPLEMENTATION OF THE LATEST SAFETY AND during Play mode. SHOULD BE REPLACED ONLY WITH TYPES PERFORMANCE IMPROVEMENT CHANGES INTO 2.