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 !

Thursday, 14 March 2019

LG CM4730 MINI HI-FI SYSTEM - NO POWER, NO SOUND TROUBLESHOOTING – SMPS AND MAIN AMPLIFIER SCHEMATIC (CIRCUIT DIAGRAM)

LG CM4730 Mini Hi-Fi System - No Power, No sound troubleshooting – SMPS and Main amplifier schematic (circuit diagram)

LG CM4730 Mini Hi-Fi System  (CM4730, CMS4630F, CMS4530W) – Power and amplifier boards schematics, How to troubleshoot  No power, No sound - Hidden Key functions
HIDDEN KEY MODES
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
Front Key : STOP
RCU Key : PLAY/PAUSE
You can change [Audio MCU Version <-> CD Controller Version <-> EEPROM Option] by SKIP+/-.
3. Clear EEPROM
Front Key : STOP
RCU Key : SKIP-
4. Edit EEPROM
Front Key : STOP
RCU Key : SKIP+
You can change the digit of option by SKIP+/-.
You can edit 0~f by REPEAT or PLAY/PAUSE key.
5. Bluetooth DUT
Front Key : STOP
RCU Key : PROGRAM
Bluetooth model only
6. Power Disc Lock On/Off (CD Function Only Active)
Front Key : STOP
RCU Key : EQ
7. Amp Clip On/Off
Front Key : STOP
RCU Key : Mute
Amp Clip Mode Change (Amp Clip On --> Amp Clip Off --> Level Down display).
8. Demo ALL Key Lock (CM9520/CM8520 Only)
Front Key : STOP
RCU Key : 9
Demo All Key Lock Change (All Key Lock On --> All Key Lock Off).
- Working on Demo Operation only.
- When All Key Lock, Volume Key work only.
- After All Key Lock Off, it can unlock Demo Mode.
PROGRAM DOWNLOAD & UPDATE
AUDIO PROGRAM
Download program file name must be CM4530_xxxxxxx.HEX
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. USB device must be unplugged when the downloading process is completed
CD PROGRAM
Download program file name must be HF000_CM4530_xxxxxxxx_xx.bin
Tip) With B/T : HF000_CM4530_xxxxxxxx_xx.bin
Without B/T : HF400_CM4530_xxxxxxxx_xx.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. USB device must be unplugged when the downloading process is completed.
EQ PROGRAM
Download program file name must be EQ_PRG_CM4730_xxxxxxxxx_xxxx.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. USB device must be unplugged when the downloading process is completed.
No Power - Troubleshooting
SMPS Schematic
SMPS PWB Component and foil sides
NO POWER
If the unit doesn’t work by no power problem, repair the set according to the following
FUSE & BRIDGE DIODE
Check and replace F901, BD901, TH901 on SMPS board.
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 TH901 is normal or open.
D929
Check and replace D929 on SMPS board.
How to troubleshoot
1) Check the Anode-Cathode Voltage of D929 with a digital multi-meter, it is normally 0.2 ~ 0.3 V.   If it doesn’t have any voltage, it’s destroyed. Replace it with a new one.
NO SOUND
There is no sound output in the CD FUNCTION, repair the set according to the following 
IN THE CD FUNCTION
Check and replace IC601, IC801 on MAIN board.
How to troubleshoot 
1) Check CD_BCLK, CD_LRCK, & CD_DOUTA signals from IC302 to IC801.   If no signal, check if the RF & servo signals from MD is entered to IC302.
2) Check the following I2S signal flow. < I2S audio signal Interface >
- DAC_BCK : IC801_Pin85 --> IC601_Pin23
- DAC_LRCK : IC801_Pin86 --> IC601_Pin22 (44.1 kHz)
- DAC_DATA : IC801_Pin81 --> IC601_Pin24
- DAC_MCLK : IC801_Pin84 --> IC401_Pin44
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.
3) Check if “Digital audio AMP block”. 
Main amplifier Schematic
NO SOUND
There is no sound output by DIGITAL AUDIO AMP DAMAGE, repair the set according to the following.
BY DIGITAL AUDIO AMP DAMAGE (IN ALL FUNCTIONS)
Check and replace IC701, IC702 on MAIN board.
How to troubleshoot (Countermeasure)
1) Check FL±, FR± & SW± signals from IC601 to IC701 & 702 each input function.   If no signal, check if I2S audio signals are entered to IC601.
2) Check PVDD.   If PVDD is abnormal, check the SMPS.
3) Check +12 V for driving the gate of AMP IC.
a. All the powers are normal, but if +12 V is low, there is possible for AMP IC to be damaged.
b. Remove L707, L708, L709 and L712 one by one.
When removed a inductance, if +12 V is recovered, the IC connected to it was damaged.
c. Replace the IC with a new one.
4) Check the impedance between IC701/IC702_OUT-A/OUT-B & GND.
a. If the impedance is 0 Ω, the IC must be damaged.
b. After removing the heat sink, replace it with a new one.
There is no sound output in the USB FUNCTION, repair the set according to the following.
IN THE USB FUNCTION
Check and replace IC801 on MAIN board & IC502 on USB board.
How to troubleshoot
1) Check +5VU to USB board.   If the USB LED are turned on, the voltage is okay, if so not, check +5.6 V to pin6 of CN502.
2) Check USB D± from MAIN board to USB board.
a. Check USB_DM/DP signals to IC801 (pin117, 118).
b. Check USB± signals to CN502 (pin1, 2, 4, 5).   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.
3) Check if “Digital audio AMP block “normal.
There is no sound output in the AUX FUNCTION, repair the set according to the following guide.
IN THE AUX FUNCTION
Check and replace IC401 on MAIN board.
How to troubleshoot (Countermeasure)
1) Check AUX_L/R signals to IC401 (Pin7, 8).
2) Check if DAC_BCK, DAC_LRCK, & DAC_MCLK are entered from IC801 to IC401.
3) Check if ADC_DATA is entered from IC401 to IC801.   If no signal, check +5 V & +3.3 V(ADC) for IC401. If is NG, replace it a new one.
4) Check the following I2S signal flow from IC801 to IC602.  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.
There is no sound output in the TUNER FUNCTION, repair the set according to the following guide.
IN THE TUNER FUNCTION
Check and replace IC401, TU100 on MAIN board.
How to troubleshoot
1) Check if TUNER_LR is entered from Pin1,3 of TU100 to IC401(Pin23, 24).  If no signals, Check +3.3 V for Tuner power.  Check if the Tuner control signals (CLK, DAT, CE, RST, SLT) are entered from IC102 to TU100.
If it doesn’t work, replace TUNER with a new one.
2) Check if DAC_BCK, DAC_LRCK, & DAC_MCLK are entered from IC501 to IC401.
3) Check if ADC_DATA is entered from IC401 to IC801.  If no signal, check +5 V & +3.3 V(ADC) for IC401. If is NG, replace it with a new one.
4) Check the following I2S audio signal flow from IC801 to IC601. (Refer to Item 5-1.)  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.
Click on the pictures to magnify
Posted By: FRANK at 02:06
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