REPAIRING AND NOT THROWING AWAY

REPAIRING AND NOT THROWING AWAY

Richtige Fernseher haben Röhren!

Richtige Fernseher haben Röhren!

In Brief: On this site you will find pictures and technical information about Service Modes, Circuit Diagrams, Firmware Update procedure, Disassemble procedure, Universal remote control set-up codes, Troubleshooting and more....

If you go into the profession, you will obtain or have access to a variety of tech tips databases HERE IT IS Master Electronics Repair !.

These are an excellent investment where the saying: 'time-is-money' rules. However, to learn, you need to develop a general troubleshooting approach - a logical, methodical, method of narrowing down the problem. A tech tip database might suggest: 'Replace C536' for a particular symptom. This is good advice for a specific problem on one model. However, what you really want to understand is why C536 was the cause and how to pinpoint the culprit in general even if you don't have a service manual or schematic and your tech tip database doesn't have an entry for your sick TV or VCR.

While schematics are nice, you won't always have them or be able to justify the purchase for a one-of repair. Therefore, in many cases, some reverse engineering will be necessary. The time will be well spent since even if you don't see another instance of the same model in your entire lifetime, you will have learned something in the process that can be applied to other equipment problems.
As always, when you get stuck, checking out a tech-tips database may quickly identify your problem and solution.In that case, you can greatly simplify your troubleshooting or at least confirm a diagnosis before ordering parts.

Happy repairing!
Today, the West is headed for the abyss. For the ultimate fate of our disposable society is for that society itself to be disposed of. And this will happen sooner, rather than later.

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..............The bitterness of poor quality is remembered long after the sweetness of todays funny gadgets low price has faded from memory........ . . . . . .....
Don't forget the past, the end of the world is upon us! Pretty soon it will all turn to dust!

©2010, 2011, 2012, 2013, 2014 Frank Sharp - You do not have permission to copy photos and words from this blog, and any content may be never used it for auctions or commercial purposes, however feel free to post anything you see here with a courtesy link back, btw a link to the original post here , is mandatory.
All posts are presented here for informative, historical and educative purposes as applicable within fair use. NOTHING HERE IS FOR SALE !

Tuesday, 5 February 2019

LG CM9550 TROUBLESHOOTING – NO POWER, NO BOOTING – REPAIR HELP

LG CM9550 Troubleshooting – No power, No booting – Repair help 

If you're not experienced to do work on high end audio devices, please do not attempt to repair this set.  You should have CRO and other testing equipment to go with it.  At least, a Scope-meter is recommended to take waveform and measurements at the digital circuits.
NO POWER
If the unit doesn’t work by no power problem, repair the set according to the following guide.
FUSE / BRIDGE DIODE / THERMISTOR
Solution
Check and replace F901, BD901, TH900, TH901 on SMPS board.
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, TH901 is normal or open.
Scope-meter
NO POWER
If the unit doesn’t work by no ±PVDD problem, repair the set according to the following guide.
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
The set doesn’t work when press the power button on the front board or the remote control.
MICOM (IC501)
Solution
Please check and replace IC501 on MAIN board.
How to troubleshoot (Countermeasure)
1) Check the 5.6 VA (CN106) and DVCC 3.3 V(IC505) in standby mode.
If there is no 5.6 VA, check the SMPS and if doesn’t appear 3.3 V, check IC505.
2) Check 5.6 VA, +12 V, FL+, FL-, an +39 V when power on the set.
- If the set doesn’t work regardless of what the KEY2 changes high to low while pressing the power button.
X500 and X501 work normally but, if you can not power on the set, replace the IC501 with a new one on the main board.
VFD IS NOT DISPLAYED WHEN POWER ON THE SET
When power on the set, any icons or characters on VFD are not displayed.
VFD (DIG300)
Solution
Check and replace DIG300 on FRONT board.
How to troubleshoot (Countermeasure)
1) Check if 39V, FL+ and FL-are output from SMPS to VFD via the main board.
2) Check if the IC501 outputs VFD_RST, VFD_CLK, VFD_CS and VFD_DO to the front board.
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.
NO VCC33, VCC12
Solution
Check and replace IC505, IC509 on MAIN board.
How to troubleshoot (Countermeasure)
1) Check voltage of IC505 pin3 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 pin2) is high (about 3.3 V).
If PWR_CTRL isn’t high, check pinB2 of IC501 & R524, R5F7.
3) If PWR_CTRL is high, check R5F6, R5F4, R5F5 and if there’s no defective component then replace IC505.
4) If 3.3 V (VCC33) is normal, check 1.2 V 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
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
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 pinT12 on MAIN board.
If MAIN_RESET isn’t high, check MICOM (IC101) pin40.
2) If MAIN_RESET is high, check the soldering status of 24 MHz crystal (X500).
3) If the crystal (X500) doesn’t oscillate, check R508, R509, C502, C503 around crystal (X500).
If there’s no defective component, then replace X500.
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.
SERIAL FLASH (IC503)
Solution
Check and replace IC503 on MAIN board.
How to troubleshoot (Countermeasure)
1) If the crystal (X500) does oscillate, check serial flash (IC503) on MAIN board.
Check pin8(VCC), pin6(CLK), pin1(CS), pin2(DO), pin5(DI) of below waveform.
2) If pin1, 2, 5, 6, 8 doesn’t come out, check damping resistor (R564, R563, R535, R536, R534) 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
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
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 (R568, R506, R570, R544, R547).  If resistor is OK, then replace IC502 (SDRAM).
3) After change IC502, if it is still not below waveform, check IC501 (DSP IC)
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.
DSP IC (IC501)
Solution
Check and replace IC501(MLC3730) on MAIN board.
How to troubleshoot (Countermeasure)
1) After check them by previous pages about no booting, if the set is still no booting, Check soldering status of IC501.
2) If below bootstrap waveform doesn’t come out, then replace IC501(DSP IC).
 
 
 Troubleshooting LG CM9550 – LG NS9550F Servo, Sound, Standby LED Blink - Repair help 
NO OPERATION OF MD (DRIVING THE SERVO MOTORS)
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.
SPINDLE MOTOR
Solution
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 X400.
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 can not rotate CD discs.
Check the function after changing another MD.
NO OPERATION OF MD (DRIVING THE SERVO MOTORS)
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.
SLED MOTOR
Solution
Check and replace IC407, IC408 on MAIN board.
How to troubleshoot (Countermeasure)
1) Check the SLDO signal from Pin23 of IC407.
If no signal, check 3.3 V(RF) and X400.
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 (DRIVING THE SERVO MOTORS)
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.
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 Pin K4 & L4 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 cannot open or close the tray.
Please check the function after changing another MD.
NO OPERATION OF MD (DRIVING THE SERVO MOTORS)
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.
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 Pin22 of IC407.
If no signal, check 3.3 V(RF) and X400.
2) Check TR- & TR+ 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.
Please check the function after changing another MD.
NO OPERATION OF MD (DRIVING THE SERVO MOTORS)
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 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 Pin21 of IC407.
If no signal, check 3.3 V(RF) and X400.
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 cannot move the laser beam on the top or bottom side.
Please check the function after changing another MD.
NO SOUND
There is no sound output in the USB FUNCTION, repair the set according to the following guide.
IN THE USB FUNCTION
Solution
Please check and replace IC501 on MAIN board & IC300 on USB board.
How to troubleshoot (Countermeasure)
1) Check +5VU to USB board.
If +5.6 VA to pin2 of IC300 (LDO) doesn’t come out, check pin4, 5 of CN304.
If +5.6 VA is normal & +5VU of IC300 pin3 doesn’t come out, then replace IC300.
2) Check if “Digital audio AMP block”
NO SOUND
There is no sound output in the AUX FUNCTION, repair the set according to the following guide.
IN THE AUX FUNCTION
Solution
Please check and replace IC202 on MAIN board.
How to troubleshoot (Countermeasure)
1) Check AUX_L/R signals to IC202 (Pin7, 8).
2) Check if MCS_BCLK, MCS_LRCLK, & MCS_MCLK are entered from IC501 to IC202.
3) Check if ADC/MIC_DATA is entered from IC202 to IC501.
If no signal, check +5 V & +3.3 V(ADC) for IC202. If is NG, replace it a new one.
4) Check the following I2S signal flow from IC501 to IC600.
If there is any trouble, check the power for each IC. The power is normal but, if the signal waveform to the
IC is distorted or no signal, replace it with a new one.
5) Check if the digital audio AMP block is okay.
If AMP is damaged, replace it with a new one.
NO SOUND
There is no sound output in the PORT. IN FUNCTION, repair the set according to the following guide.
IN THE PORT. IN FUNCTION
Solution
Please check and replace IC202 on MAIN board.
How to troubleshoot (Countermeasure)
1) Check PT_L/R signal from JOG board to MAIN board.
2) Check if PT_LR is entered pin4 & 5 of CN3J01 ð pin4 & 5 of CN3V02 ð Pin21 & 20 of CN3V01.
3) Check POT_L/R signals to IC202(pin21, 22).
4) Check if ADC_BCK, ADC_LRCK, & DAC_MCLK are entered from IC501 to IC202.
5) Check if ADC_DATA is entered from IC202 to IC501.
If no signal, check +5 V & +3.3 V(ADC) for IC202. If is NG, replace it a new one.
6) Check the following I2S signal flow from IC501 to IC600.
If there is any trouble, check the power for each IC. The power is normal but , if the signal waveform to the IC is distorted or no signal, replace it with a new one.
7) Check if the digital audio AMP block is okay. Refer to “Digital Audio AMP” guide.
If AMP is damaged, replace it with a new one.
NO SOUND
There is no sound output in the TUNER FUNCTION, repair the set according to the following guide.
IN THE TUNER FUNCTION
Solution
Please check and replace IC202, TU500 on MAIN board.
How to troubleshoot (Countermeasure)
1) Check if TUNER_LR is entered from Pin1 & 3 of TU101 to IC202(Pin23, 24).
If no signals, Check +3.3 V for Tuner power.
Check if the Tuner control signals (CLK, DAT, CE, RST, GPO2) are entered from IC101 to TU101.
If it doesn’t work, replace TUNER with a new one.
2) Check if MCS_BCK, MCS_LRCK, & MCS_MCLK are entered from IC501 to IC202.
3) Check if ADC_DATA is entered from IC202 to IC501.
If no signal, check +5 V & +3.3 V(ADC) for IC202. If is NG, replace it a new one.
4) Check the following I2S audio signal flow from IC501 to IC600.
If there is any trouble, check the power for each IC. The power is normal but,
if the signal waveform to the IC is distorted or no signal, replace it with a new one.
5) Check if the digital audio AMP block is okay. Refer to “Digital Audio AMP” guide.
If AMP is damaged, replace it with a new one.
NO SOUND
There is no sound output in the MIC IN FUNCTION, repair the set according to the following guide.
IN THE MIC IN FUNCTION
Solution
Please check and replace ICM101 or IC202 on the Main Board.
How to troubleshoot (Countermeasure)
1) Check MIC_SIG signal to pin40 of CN105.
If no signal, check the signal to pin1 of CN380 on the MIC board.
Check if the signal is entered from pin1 of CN380 to MAIN board.
2) Check if MIC_SIG is entered from pin40 of CN105 to pin3 to ICM101 (MIC AMP).
3) Check if the amplified signal comes out from pin4 of ICM101.
If no signal output, check +12 V for ICM101, replace ICM101 with a new one if it has a problem.
4) Check if MCS_BCK, MCS_LRCK & MCS_MCLK are entered from IC501 to IC202.
5) Check if ADC_DATA is entered from IC202 to IC501.
If no signal, check +5 V & +3.3 V (ADC) for IC202. If is NG, replace it a new one.
6) Check the following I2S audio signal flow from IC501 to IC600.
If there is any trouble, check the power for each IC. The power is normal but,
if the signal waveform to the IC is distorted or no signal, replace it with a new one.
7) Check if the digital audio AMP block is okay. Refer to “Digital Audio AMP” guide.
If AMP is damaged, replace it with a new one.
NO SOUND
There is no sound output in the BLUETOOTH FUNCTION, repair the set according to the following guide.
IN THE BLUETOOTH FUNCTION
Solution
Please check and replace IC501 on MAIN board and Bluetooth module on front panel.
How to troubleshoot (Countermeasure)
1) Check BT_RX, BT_TX signal to Pin4, 6 of CN504.
If no signal, check the signal to Pin4, 6 and Pin10(3.3 V) of on the Bluetooth module and cable connection state.
If there are no signal out from module, replace new module.
2) Check if BT_RX/TX is entered from Pin4, 6 of CN504 to Pin PGPB10, PGPB11 to IC501 (DSP).
3) Check if MCS_BCK, MCS_LRCK is entered from IC501 to IC600.
If no signal, check VCC12(+1.2 V) for IC501. If it is abnormal, change replace it a new one.
4) Check the following I2S signal flow from IC501 to IC600.
If there is any trouble, check the power for each IC. If the signals are abnormal, replace it a new one.
5) Check if the digital audio AMP block is okay. Refer to “Digital Audio AMP” guide.
If AMP is damaged, replace it with a new one.
AUDIO OUTPUT IS SMALL OR NO AUDIO OUTPUT
Audio signal output is small or not. when you power on the Middle Power Mini System.
IC700 ~ IC705
Solution
Please check and replace IC700 ~ IC705 on MAIN board.
How to troubleshoot (Countermeasure)
1) Please check if this system is on bass blast mode. C, RL and RR make sound only on bass blast mode.
2) Check the IC700 ~ IC705 on your eyes.
3) Check the audio signal output check (Pin13 of IC700 ~ IC705).  First, check the Audio Data input (Pin3 of IC700 ~ IC705).
4) If the audio signal output has no output, try to change IC which has no output.
5) Lastly, check Speaker Terminal (TM701, TM702)
.NO POWER ON (STANDBY LED IS BLINKING)
It doesn’t turn on, and blinks standby LED(Red).
AMP FETs
Solution
Please 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.
SPEAKER NO AUDIO
Speaker No Audio
AMP IC
Solution
Please check and replace IC700 ~ IC705 on MAIN board.
How to troubleshoot (Countermeasure)
1) Check supply voltage of AMP(CN110) & 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
Posted By: FRANK at 02:20
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