LG
home theater CM9530, How to repair - No power, No booting, No MD operation, No
power (standby LED blinking), No output from the speaker
REPAIR GUIDENO POWER - 1
If the unit doesn’t work by no power problem, repair the set according to the following guide.
FUSE / BRIDGE DIODE / THERMISTOR
Solution
How to troubleshoot (Countermeasure)
1) Check if the fuse F901 is open or short-circuit.
2) Check if the bridge diode BD901 is short-circuit by over current with a digital multi meter.
3) Check if the NTC thermistor TH900 ~ TH902 is normal or open.
If the unit doesn’t work by no ±PVDD problem, repair the set according to the
following guide.
NO AMP POWER
Solution
Check and replace F911, Q905, Q906 on SMPS board.
How to troubleshoot (Countermeasure)
1) Check if the fuse F901 is open or short-circuit.
2) Check the Drain-Source or Drain-Gate, Gate-Source Resistance of Q905, Q906 with a digital multi-meter.
If it is short condition, it’s destroyed. Replace it with a new one.
(Replace 2 FET at the same time although several FET is OK)
NO
BOOTING WHEN POWER ON THE SET
NO AMP POWER
Solution
Check and replace F911, Q905, Q906 on SMPS board.
How to troubleshoot (Countermeasure)
1) Check if the fuse F901 is open or short-circuit.
2) Check the Drain-Source or Drain-Gate, Gate-Source Resistance of Q905, Q906 with a digital multi-meter.
If it is short condition, it’s destroyed. Replace it with a new one.
(Replace 2 FET at the same time although several FET is OK)
The set doesn’t work when press the power button on the front board or the
remote control.
MICOM (IC101)
Solution
Please check and replace IC101 on MAIN board.
How to troubleshoot (Countermeasure)
1) Check the 5.6 VA (CN106) and 3.7 VA (IC104) in standby mode.
If there is no 5.6 VA, check the SMPS and if doesn’t appear 3.7 VA, check IC104.
2) Check 5.6 VA, 12 V, FL+, FL-, an VKK (39 V) when power on the set.
- If the set doesn’t work regardless of what the KEY1 changes high to low while pressing the power button.
X100 and X101 work normally but, if you cannot power on the set, replace the IC101 with a new one on the MAIN board.
VFD
IS NOT DISPLAYED WHEN POWER ON THE SET
MICOM (IC101)
Solution
Please check and replace IC101 on MAIN board.
How to troubleshoot (Countermeasure)
1) Check the 5.6 VA (CN106) and 3.7 VA (IC104) in standby mode.
If there is no 5.6 VA, check the SMPS and if doesn’t appear 3.7 VA, check IC104.
2) Check 5.6 VA, 12 V, FL+, FL-, an VKK (39 V) when power on the set.
- If the set doesn’t work regardless of what the KEY1 changes high to low while pressing the power button.
X100 and X101 work normally but, if you cannot power on the set, replace the IC101 with a new one on the MAIN board.
When power on the set, any icons or characters on VFD are not displayed.
VFD (DIG301)
Solution
Please check and replace DIG301 on FRONT board.
How to troubleshoot (Countermeasure)
1) Check connection first.(VFD to Volume Board to Board Connector, VFD to Main FFC cable)
2) Check if 4.6~4.9 V, FL+ and FL- are output from SMPS to VFD via the MAIN board.
3) Check if the IC101 outputs VFD_RST, VFD_CLK, VFD_STB and VFD_STB to the FRONT board.
If the there are control signals from VFD (TP306, TP308, TP309), replace VFD with a new one.
VFD (DIG301)
Solution
Please check and replace DIG301 on FRONT board.
How to troubleshoot (Countermeasure)
1) Check connection first.(VFD to Volume Board to Board Connector, VFD to Main FFC cable)
2) Check if 4.6~4.9 V, FL+ and FL- are output from SMPS to VFD via the MAIN board.
3) Check if the IC101 outputs VFD_RST, VFD_CLK, VFD_STB and VFD_STB to the FRONT board.
If the there are control signals from VFD (TP306, TP308, TP309), replace VFD with a new one.
NO
BOOTING IN CD/USB FUNCTION (1)
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.
NO VCC33, VCC12
Solution
Please check and replace IC505, IC509 on MAIN board.
How to troubleshoot (Countermeasure)
1) Check Voltage of IC505 pin2 on MAIN board.
If IC505 pin3 (about 4.9 V) & D500 Input 5.6 VA doesn’t come out, check 5.6 VA from SMPS board.
2) If IC505 pin3 (about 4.9 V) is normal, check the PWR_CTRL (IC505 pin12) is high (about 3.3 V).
If PWR_CTRL isn’t high, check pin63 of IC101 & R179, R59E.
3) If PWR_CTRL is high, check R59D, R59B, and R59C and if there’s no defective component then replace IC505.
4) If 3.3 V (VCC33) is normal, check output (pin2, 4) voltage of IC509.
If 1.2 V of IC509 pin2, 4 doesn’t come out, then replace IC509.
NO BOOTING IN CD/USB FUNCTION (2)
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.
NO VCC33, VCC12
Solution
Please check and replace IC505, IC509 on MAIN board.
How to troubleshoot (Countermeasure)
1) Check Voltage of IC505 pin2 on MAIN board.
If IC505 pin3 (about 4.9 V) & D500 Input 5.6 VA doesn’t come out, check 5.6 VA from SMPS board.
2) If IC505 pin3 (about 4.9 V) is normal, check the PWR_CTRL (IC505 pin12) is high (about 3.3 V).
If PWR_CTRL isn’t high, check pin63 of IC101 & R179, R59E.
3) If PWR_CTRL is high, check R59D, R59B, and R59C and if there’s no defective component then replace IC505.
4) If 3.3 V (VCC33) is normal, check output (pin2, 4) voltage of IC509.
If 1.2 V of IC509 pin2, 4 doesn’t come out, then replace IC509.
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.
CRYSTAL (X500)
Solution
Please check and replace X500 on MAIN board.
How to troubleshoot (Countermeasure)
1) If 3.3 V & 1.2 V is normal, check Reset ‘High’ of IC501 pin153 on MAIN board.
If MAIN_RESET isn’t high, check MICOM (IC101) pin59.
2) If MAIN_RESET is high, check the soldering status of 12 MHz crystal (X500).
3) If the crystal (X500) doesn’t oscillate, check R508, R509, C502, and C503 around crystal (X500).
If there’s no defective component, then replace X500.
NO
BOOTING IN CD/USB FUNCTION (3)
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.
SERIAL FLASH (IC503)
Solution
Please check and replace IC503 on MAIN board.
How to troubleshoot (Countermeasure)
1) If the crystal (X501) does oscillate, check serial flash (IC503) on MAIN board.
Check pin8 (VCC), pin6 (CLK), pin1 (CS#), pin2 (DO), pin5 (DI) waveform.
2) If pin1, 2, 5, 6, 8 doesn’t come out, check damping resistor (R511, R513, R514, R515) of IC503.
If damping resistor of IC503 is OK, then replace IC503. (it need to download program)
3) After change IC503, if It is still not below waveform, check IC501(DSP IC).
NO BOOTING IN CD/USB FUNCTION (4)
(HELLO > VOL XX > CD or USB) on VFD, it will not display other message on VFD, and it will not boot-up normally.
SERIAL FLASH (IC503)
Solution
Please check and replace IC503 on MAIN board.
How to troubleshoot (Countermeasure)
1) If the crystal (X501) does oscillate, check serial flash (IC503) on MAIN board.
Check pin8 (VCC), pin6 (CLK), pin1 (CS#), pin2 (DO), pin5 (DI) waveform.
2) If pin1, 2, 5, 6, 8 doesn’t come out, check damping resistor (R511, R513, R514, R515) of IC503.
If damping resistor of IC503 is OK, then replace IC503. (it need to download program)
3) After change IC503, if It is still not below waveform, check IC501(DSP IC).
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.
SDRAM (IC502)
Solution
Please check and replace IC502 on MAIN board.
How to troubleshoot (Countermeasure)
1) Check below waveform & soldering status of SDRAM (IC502) on MAIN board.
If pin17(#CAS), pin18(#RAS), pin19($CS), pin38(CLK), pin29(address), pin2(DQ) doesn’t come out,
check damping resistor (R508, R506, R504, R507).
2) If resistor is OK, then replace IC502 (SDRAM).
3) After change IC502, if It is still not below waveform, check IC501 (DSP IC)
NO
OPERATION OF MD (1)
When no sound output in the CD function, you cannot 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.
SPINDLE MOTOR
Solution
Please check and replace IC407, IC408 on MAIN board.
How to troubleshoot (Countermeasure)
1) Check the SPDO signal from Pin16 of IC407.
If no signal, check 3.3 V(RF) and X402.
2) Check the SP- & SP+ from IC408 to CN405 for driving SPINDLE motor. It is about 3.6 Vp-p.
If no signal, check +1.8 V and +5 V for IC408.
3) Check if the FFC cable is solidly connected between CN405 and MD.
4) Check the MD.
If the spindle motor is sort-circuit or has any trouble, it cannot rotate CD discs.
Check the function after changing another MD.
NO
OPERATION OF MD (2)
from a CD disc if the servo motors in MD don’t work. This step is for checking the
SPINDLE MOTOR among them.
SPINDLE MOTOR
Solution
Please check and replace IC407, IC408 on MAIN board.
How to troubleshoot (Countermeasure)
1) Check the SPDO signal from Pin16 of IC407.
If no signal, check 3.3 V(RF) and X402.
2) Check the SP- & SP+ from IC408 to CN405 for driving SPINDLE motor. It is about 3.6 Vp-p.
If no signal, check +1.8 V and +5 V for IC408.
3) Check if the FFC cable is solidly connected between CN405 and MD.
4) Check the MD.
If the spindle motor is sort-circuit or has any trouble, it cannot rotate CD discs.
Check the function after changing another MD.
When no sound output in the CD function, you cannot 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.
SLED MOTOR
Solution
Please check and replace IC407, IC408 on MAIN board.
How to troubleshoot (Countermeasure)
1) Check the SLDO signal from Pin15 of IC407.
If no signal, check 3.3 V(RF) and X402.
2) Check the SLED+ & SLED- from IC408 to CN405 for driving SPINDLE motor. It is about 2.9 Vp-p.
If no signal, check +1.8 V and +5 V for IC408.
3) Check if the FFC cable is solidly connected between CN405 and MD.
4) Check the MD.
If the sled motor is sort-circuit or has any trouble, it cannot move the pick-up module.
Check the function after changing another MD.
NO
OPERATION OF MD (3)
from a CD disc if the servo motors in MD don’t work. This step is for checking the
SLED MOTOR among them.
SLED MOTOR
Solution
Please check and replace IC407, IC408 on MAIN board.
How to troubleshoot (Countermeasure)
1) Check the SLDO signal from Pin15 of IC407.
If no signal, check 3.3 V(RF) and X402.
2) Check the SLED+ & SLED- from IC408 to CN405 for driving SPINDLE motor. It is about 2.9 Vp-p.
If no signal, check +1.8 V and +5 V for IC408.
3) Check if the FFC cable is solidly connected between CN405 and MD.
4) Check the MD.
If the sled motor is sort-circuit or has any trouble, it cannot move the pick-up module.
Check the function after changing another MD.
When no sound output in the CD function, you cannot 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.
TRAY OPEN / CLOSE MOTOR
Solution
Please check and replace IC407, IC408 on MAIN board.
How to troubleshoot (Countermeasure)
1) Check MOT_OPEN & MOT_CLOSE signals from Pin62 & 63 of IC501 to IC408.
If no signal, check +1.8 V & + 5 V to IC408.
2) Check LOAD± from IC408 to CN405 for driving the tray open / close motor. It is about 3.85 Vp-p.
If no signal, check +5 V to IC408. If it has any trouble, replace it with a new one.
3) Check if the FFC cable is solidly connected between CN405 and MD.
4) Check the MD.
If the tray motor is sort-circuit or has any trouble, it can not open or close the tray.
Check the function after changing another MD.
NO OPERATION OF MD (4)
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.
TRAY OPEN / CLOSE MOTOR
Solution
Please check and replace IC407, IC408 on MAIN board.
How to troubleshoot (Countermeasure)
1) Check MOT_OPEN & MOT_CLOSE signals from Pin62 & 63 of IC501 to IC408.
If no signal, check +1.8 V & + 5 V to IC408.
2) Check LOAD± from IC408 to CN405 for driving the tray open / close motor. It is about 3.85 Vp-p.
If no signal, check +5 V to IC408. If it has any trouble, replace it with a new one.
3) Check if the FFC cable is solidly connected between CN405 and MD.
4) Check the MD.
If the tray motor is sort-circuit or has any trouble, it can not open or close the tray.
Check the function after changing another MD.
When no sound output in the CD function, you cannot 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.
LASER TRACKING ACTUATOR
Solution
Please check and replace IC407, IC408 on MAIN board.
How to troubleshoot (Countermeasure)
The tracking actuator makes the laser beam be positioned in the center of a track on CD disc.
1) Check the TRD signal from Pin14 of IC407.
If no signal, check 3.3 V(RF) and X402.
2) Check T- & T+ from IC408 to CN404 for driving the tracking actuator.
If no signal, check +1.8 V and +5 V for IC408.
3) Check if the FFC cable is solidly connected between CN404 and MD.
4) Check the MD.
If the pick-up module has any trouble, it cannot move the laser beam on the left or right side.
Check the function after changing another MD.
NO
OPERATION OF MD (5)
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.
LASER FOCUSING ACTUATOR
Solution
Please check and replace IC407, IC408 on MAIN board.
How to troubleshoot (Countermeasure)
The focusing actuator makes the laser beam keep a regular interval with the surface of a CD disc.
1) Check the FOD signal from Pin13 of IC407.
Ö If no signal, check 3.3 V(RF) and X402.
2) Check F- & F+ from IC408 to CN404 for driving the focusing actuator.
If no signal, check +1.8 V and +5 V for IC408.
3) Check if the FFC cable is solidly connected between CN404 and MD.
4) Check the MD.
If the pick-up module has any trouble, it can not move the laser beam on the top or bottom side.
Check the function after changing another MD.
NO POWER ON (STANDBY LED IS BLINKING)
from a CD disc if the pickup module in MD doesn’t work. This step is for checking the
LASER FOCUSING ACTUATOR.
LASER FOCUSING ACTUATOR
Solution
Please check and replace IC407, IC408 on MAIN board.
How to troubleshoot (Countermeasure)
The focusing actuator makes the laser beam keep a regular interval with the surface of a CD disc.
1) Check the FOD signal from Pin13 of IC407.
Ö If no signal, check 3.3 V(RF) and X402.
2) Check F- & F+ from IC408 to CN404 for driving the focusing actuator.
If no signal, check +1.8 V and +5 V for IC408.
3) Check if the FFC cable is solidly connected between CN404 and MD.
4) Check the MD.
If the pick-up module has any trouble, it can not move the laser beam on the top or bottom side.
Check the function after changing another MD.
It doesn’t turn on, and blinks standby LED(Red).
AMP FETs
Solution
Check and replace Q705 ~ Q708, Q711 ~ Q718 on MAIN board.
How to troubleshoot (Countermeasure)
1) This symptom occurs, when DC protection is detected. Main reasons are like below.
- When Some of AMP FETs dead.
* You can see FET after removing heatsink.
* Notice for Service
Before repair Main Assy, you need to discharge SMPS.
After then, open the connector.
You should try to change both of +/- FET and Driver IC as a pair.
Notice for FET service
- In case of RF6775, Metal case, FET Drain, has electric potential. So be careful when you deal with it.
SPEAKER
NO AUDIO
Speaker No Audio
AMP IC
Solution
Please check and replace the component on MAIN board.
How to troubleshoot (Countermeasure)
1) Check supply voltage of AMP(CN101) & PWM signal
Normal Supply voltage and signal. Check AMP IC.
Poor supply voltage > Check SMPS Assy.
Poor signal > Check PWM IC.
2) Check CSD of FET driver IC (IRS2092 : EAN60778301).
CSD has about 5 V on normal state.
When AMP has problem, CSD is LOW state or keep change LOW to HIGH.
AMP IC
Solution
Please check and replace the component on MAIN board.
How to troubleshoot (Countermeasure)
1) Check supply voltage of AMP(CN101) & PWM signal
Normal Supply voltage and signal. Check AMP IC.
Poor supply voltage > Check SMPS Assy.
Poor signal > Check PWM IC.
2) Check CSD of FET driver IC (IRS2092 : EAN60778301).
CSD has about 5 V on normal state.
When AMP has problem, CSD is LOW state or keep change LOW to HIGH.
