LG TH900 Manual
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LG TH900 Manual

LG TH900 Manual

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1. NO POWER
If the unit doesn't work by no power problem, repair the set according to the following guide.
1-1. FUSE/ THERMISTOR/ BRIDGE DIODE
1-1-1. Solution
Please check and replace F901, TH901 or TH903, BD901 on SMPS board.
1-1-2. How to troubleshoot (Countermeasure)
1) Check if the fuse F901 is open or short-circuit.
2) Check if the NTC thermistor TH900 or TH903 is normal or open.
3) Check if the bridge diode BD901 is short-circuit by over current with a digital multi-meter.
1-1-3. Service hint (Any picture/ Remark)
< F901 >
If F901 is not short-circuit,
replace it with a same
specifi cations one.
ONE POINT REPAIR GUIDE
<TH901 or TH903 >
If TH901 or TH903 is open,
replace it with a new one.
3-2
< BD901 >
If BD901 is short-circuit,
replace it with a new one.

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  • Page 1 1-1-2. How to troubleshoot (Countermeasure) 1) Check if the fuse F901 is open or short-circuit. 2) Check if the NTC thermistor TH900 or TH903 is normal or open. 3) Check if the bridge diode BD901 is short-circuit by over current with a digital multi-meter.
  • Page 2 ONE POINT REPAIR GUIDE NO POWER If the unit doesn’t work by no PVDD problem, repair the set according to the following guide. 1-2. FUSE/ FET 1-2-1. Solution Please check and replace F901, Q901 on SMPS board. 1-2-2. How to troubleshoot (Countermeasure) 1) Check if the fuse F901 is open or short-circuit.
  • Page 3 ONE POINT REPAIR GUIDE 2. NO BOOTING WHEN POWER ON THE SET The set doesn’t work when press the power button on the top board or the remote control. 2-1. IC501 2-1-1. Solution Replace IC501 on MAIN board. 2-1-2. How to troubleshoot (Countermeasure) 1) Check the +12 VA (CN202) and 3.3VA (IC503) in standby mode.
  • Page 4 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 (VFD301) 3-1-1. Solution Please check and replace VFD301 on TOP FRONT board. 3-1-2.
  • Page 5 ONE POINT REPAIR GUIDE 4. 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. 4-1.
  • Page 6 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. 4-2.
  • Page 7 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. 4-3.

  • Page 8: Spindle Motor

    ONE POINT REPAIR GUIDE 5. 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 9: Sled Motor

    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 10 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 11 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 12 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 13 ONE POINT REPAIR GUIDE 6. NO SOUND There is no sound output by DIGITAL AUDIO AMP DAMAGE, repair the set according to the following guide. 6-1. DIGITAL AUDIO AMP DAMAGE 6-1-1. Solution Replace IC701, IC702 on MAIN board. 6-1-2. How to troubleshoot (Countermeasure) 1) Check PWM_FL±, PWM_FR±...
  • Page 14 ONE POINT REPAIR GUIDE NO SOUND There is no sound output in the CD FUNCTION, repair the set according to the following guide. 6-2. CD FUNCTION 6-2-1. Solution Replace IC501 on MAIN board. 6-2-2. How to troubleshoot (Countermeasure) 1) Check CD_BCK, CD_LRCK, & CD_DATA signals from IC501 to IC401. ...

  • Page 15: Usb Function

    ONE POINT REPAIR GUIDE NO SOUND There is no sound output in the USB Function, repair the set according to the following guide. 6-3. USB FUNCTION 6-3-1. Solution Replace IC204 on MAIN board. 6-3-2. How to troubleshoot (Countermeasure) 1) Check +5V_USB to USB board. ...

  • Page 16: Aux Function

    ONE POINT REPAIR GUIDE NO SOUND There is no sound output in the AUX Function, repair the set according to the following guide. 6-4. AUX FUNCTION 6-4-1. Solution Replace IC201 on MAIN board. 6-4-2. How to troubleshoot (Countermeasure) 1) Check AUX_L/R signals to IC201 (pin23, 24). 2) Check if MCS_BCK, MCS_LRCK &...

  • Page 17: Tuner Function

    ONE POINT REPAIR GUIDE NO SOUND There is no sound output in the TUNER function, repair the set according to the following guide. 6-5. TUNER FUNCTION 6-5-1. Solution Replace IC201 on MAIN board. 6-5-2. How to troubleshoot (Countermeasure) 1) Check if TUNER_LR is entered from pin1, 3 of TU500 to IC201 (pin26, 27). ...

  • Page 18: Portable Function

    ONE POINT REPAIR GUIDE NO SOUND There is no sound output in the PORTABLE Function, repair the set according to the following guide. 6-6. PORTABLE FUNCTION, 6-6-1. Solution Replace IC201 on MAIN board. 6-6-2. How to troubleshoot (Countermeasure) 1) Check if PT_LR signals to IC201 (pin9, 10). 2) Check if MCS_BCK, MCS_LRCK, &...
  • Page 19 ONE POINT REPAIR GUIDE NO SOUND There is no sound output in the MIC IN function, repair the set according to the following guide. 6-7. MIC IN function 6-7-1. Solution Replace IC206 on MAIN board, ICA301 on TOP FRONT board. 6-7-2.

  • Page 20: Bluetooth Function

    ONE POINT REPAIR GUIDE NO SOUND There is no sound output in the Bluetooth function, repair the set according to the following guide. 6-8. BLUETOOTH FUNCTION 6-8-1. Solution Replace IC501 on the MAIN board or bluetooth module on the FRONT Panel. 6-8-2.
  • Page 21 ELECTRICAL TROUBLESHOOTING GUIDE 1. POWER (SMPS) No 12 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 normal? Replace D933.
  • Page 22 ELECTRICAL TROUBLESHOOTING 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 HIGH? •...
  • Page 23 ELECTRICAL TROUBLESHOOTING GUIDE No LED Is Vcc (DVCC_3.3V) Check or replace IC505 supplied to IC103? Is LED_5V & F_LED_12V is normal? Check or replace IC207, Q210 & Q209. Check or replace IC931. No VFD Check or replace Q209, Q210. VFD_12V is normal? DVCC_5V &...
  • Page 24 ELECTRICAL TROUBLESHOOTING GUIDE 2. MCS PART CHECK MCS PART CHECK Check if voltage Refer to SMPS troubleshooting. of CN202 pin1, 2: 12 V. Check if IC205 Check and change IC205. have 3.3 VA & 1.2 VA output. Check if IC505 Check and change IC505.

  • Page 25: Fld Display Check

    ELECTRICAL TROUBLESHOOTING GUIDE 3. FLD DISPLAY CHECK FLD DISPLAY CHECK Check Refer to SMPS/MPEG CN202 pin1, 2: 12 V input troubleshooting. voltage. Check Check if both end voltage DVCC_5V(Q205 & Q204) of FL+, FL- are over 1.85 V VH : Q801, Q802, D801~D804. VH : over 29 V.
  • Page 26 ELECTRICAL TROUBLESHOOTING GUIDE 4. PWM MODULATION CHECK PWM MODULATION PART CHECK Check CN202 Refer to pin1, 2: 12 V. SMPS troubleshooting. • Check IC601(TAS5548) 3.3 V - pin9, 14, 35, 50. • Check X601 (12.288 MHz). Check Check X601 Replace X601(12.288 MHz). X601(12.288 MHz) (12.288 MHz).

  • Page 27: Power Amp Part Check

    ELECTRICAL TROUBLESHOOTING GUIDE 5. POWER AMP PART CHECK POWER AMP PART CHECK Check CN202 pin1, 2: 12 V, Refer to SMPS troubleshooting. pin8, 9, 10: 48.5 V (35.5 V). Check IC701, IC702 Pin51, 52, 42, 43, 38, 39, 30, 31 input voltage. Check IC701, IC702 Check each line resistor output voltage.
  • Page 28 ELECTRICAL TROUBLESHOOTING GUIDE 6. TUNER / AUX FUNCTION CHECK FUNCTION CHECK Check IC201 (CS5346) Check JK200, TU500. pin23, 24, 26, 27 input. Check IC201 Check IC201 Check CN202 pin1, 2: 12 V. (CS5346) pin41 output Pin5: DVCC_3.3V Pin14: DVCC_5V. data. Check Check IC201 Check IC201...

  • Page 29: Tuner Function Check

    ELECTRICAL TROUBLESHOOTING GUIDE 7. TUNER FUNCTION CHECK TUNER FUNCTION CHECK Check tuner module (TU500) Check tuner module voltage (pin4: DVCC_3.3V). operation. Check IC501 Pin P7, P8, P10, P11. Check tuner module data. Refer to function check. 3-30...
  • Page 30 ELECTRICAL TROUBLESHOOTING GUIDE 8. CD FUNCTION CHECK CD FUNCTION Is motor_open/close ok? Can the Is load +,- ok? (IC400 pin6, 7) disc insert? Check IC400. Is motor ok? (about 12 Ω) Check loading motor. Check IC400 (Motor drive IC). Focus, IM driving Disc reading tracking, sled signal...
  • Page 31 ELECTRICAL TROUBLESHOOTING GUIDE 9. DOUBLE USB FUNCTION USB FUNCTION Plug-in USB device. Check CN502. Check USB_5V. Display “NO USB”. Check USB_D+, D- Check USB jack Display “READ”. (R573, R574, C573, C574 (CN801, CN802). D501, D502). Check IC501 Display “NO FILE”. Replace IC501.

  • Page 32: Waveforms Of Major Check Point

    WAVEFORMS OF MAJOR CHECK POINT 1. DSP (IC501) X X I X X I Fig 1-1. X501: Crystal of RTC 32.768 MHz Fig 1-2. X500: Crystal of system 24 MHz (R5D6 both side) ( MAIN DSP : R508, C503 ) 3-33...
  • Page 33 2. SDRAM (IC502) Fig 2. SDRAM 3-34...
  • Page 34 3. SERVO (IC401) X X I Fig 3-2. CD-16M Fig 3-1. X400: Crystal 16.9344 MHz (IC401 pin31) 3-35...
  • Page 35 4. MOTOR DRIVER (IC400) Fig 4-2. SL- & SL+ for Driving SPINDLE Motor Fig 4-1. LO- & LO+ / MOT_OPEN &MOT_CLOSE (IC400 Pin11, 12) for Driving TRAY Motor (IC400 Pin6, 7, 9, 10) Fig 4-3. SP- & SP+ for Driving SPINDLE Motor (IC400 Pin17, 18) 13 15 3-36...
  • Page 36 5. ADC (IC201) 6. USB (CN502) Fig 5. ADC I2S Fig 6. USB D+/D- (IC201 Pin42, 43,44) (CN502 Pin1, 2, 8, 9) 3-37...
  • Page 37 7. BLUETOOTH (CN504) B B T_TX BT_TX BT_TX BT_RX BT_RX BT_RX BT_RST BT_RST BT_RST Fig 7. BT_TX / BT_RX / BT_RST 3-38...
  • Page 38 WIRING DIAGRAM Tuner AUX IN/OUT IC201 IC504 IC503 IC502 CS5346 5pin FL/FR F/S 1M F/S 16M SDRAM W25Q80 W25Q18 W9825G6KH IC501 MLC3730 IC401 RF IC L718 L705 BU9546 L707 L706 IC400 MAIN Board Motor DR AM5890 USB1 USB2 IC701 IC702 IC206 10pin 10pin...

  • Page 39: System Block Diagram

    BLOCK DIAGRAMS 1. SYSTEM BLOCK DIAGRAM [OM7560 : Total 1000W] WOOFER : 360W X 1CH FRONT : 320W X 2CH 3-41 3-42...

  • Page 40: Power Block Diagram

    2. POWER BLOCK DIAGRAM 300mA IC203 330mA BOOM B LED LED_5V 500mA SN1501019 USB1 USB_5V SMPS BD2242G [3A] 785mA 135mA 500mA [2.1] SPK LED USB2 60mA EXPENDER MOTO DRIVE 350mA Front LED AM5890 25mA 50mA LINE OUT CS5346 DRV632 11mA 11mA MIC ADC EXPENDER...

  • Page 41: Audio Path Block Diagram

    3. AUDIO PATH BLOCK DIAGRAM LINE PWM_ L_IN PWM_ R_IN DRV632 PWM – RCH PWM – LCH PWM – FLCH TAS5548 LRCK PWM –FRLCH TAS5631 PWM –WCH AUX_SDIN2 MIX_SDIN1 MCLK MIX_DATA0 IC201 AUX_DATA LRCK CS5346 33pF MLC3730 ADC_DATA_IN Main DSP CD_16M SERVO CD_BCK...

  • Page 42: Circuit Voltage Chart

    CIRCUIT VOLTAGE CHART 1. IC INPUT VOLTAGE 2. CAPACITOR VOLTAGE 110V/60Hz-10% 230V/50Hz+10% 88 V, 60 Hz 288 V, 60 Hz Locaton/ Parts Parts Name Specifi cation (V, mV) Location Voltage (V) Voltage (V) Voltage (V) Current (mV) Voltage (V) Current (mV) IC101 C231 4.95...
  • Page 43 3. CONNECTOR VOLTAGE Connector Connector Connector Location Pin No. Pin Name Voltage(V) Location Pin No. Pin Name Voltage(V) Location Pin No. Pin Name Voltage(V) Name Name Name 3.3VA 3.29 OPEN_SW 3.25 3.29 CLK_FORM UCOM 0.00 0.01 3.29 DAT_FORM UCOM 0.00 CLOSE_SW 3.25 CN601...
  • Page 44 CONNECTOR VOLTAGE Connector Connector Location Pin No. Pin Name Voltage(V) Location Pin No. Pin Name Voltage(V) Name Name 0.00 SPACE_EXP_DAT 3.11 0.07 SPACE_EXP_CLK 0.00 MAIN 0.07 0.00 CN801 USB1 (2.0) CN851  SPACE USB 5V 5.07 DVCC_3.3V 3.25 LIGHTING 0.00 DGND 0.00 0.00...

This manual is also suitable for:

Th903Bd901F901

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