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!

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Friday, 1 March 2019

LG RAD226B - RAS376BF - MINI HI-FI SYSTEM – TROUBLESHOOTING

LG RAD226B - RAS376BF - Mini Hi-Fi System – Troubleshooting

NO SOUND
There is no sound output in the TUNER FUNCTION.
check and replace IC401, TU100 on MAIN board.
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 IC202.
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 audio signal flow from IC801 to IC602. (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.
There is no sound output in the AUX FUNCTION
Check and replace I1) 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. (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.C401 on MAIN board.
There is no sound output in the USB FUNCTION
Check and replace IC801 on MAIN board & IC505 on USB board.
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 pin4 of CN501.
2) Check USB D± from MAIN board to USB board.
a. Check USB_DN/DP signals to IC801(pin116, 117).
b. Check USB± signals from IC504 to CN501 (pin2, 3).
=> 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”.
There is no sound output by DIGITAL AUDIO AMP DAMAGE [BY DIGITAL AUDIO AMP DAMAGE (IN ALL FUNCTIONS)]
Check and replace IC700, IC701(Only RAT376) on MAIN board.
1.Check FL±, FR± & SW± signals from IC602 to IC700 & 701 each input function.
=> If no signal, check if I2S audio signals are entered to IC602.
Refer to “I2S audio signal interface” on Item 5-1.
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 L711, L712, L713 and L714 one by one.
When removed a inductance, if +12 V is recovered, AMP IC connected to it was damaged.
c. Replace AMP IC with a new one.
4) Check the impedance between IC700/IC701_OUT-A/OUT-B & GND.
a. If the impedance is 0 Ω, AMP IC must be damaged.
b. After removing the heat sink, replace it with a new one.
There is no sound output in the CD FUNCTION
Check and replace IC602, IC801 on MAIN board.
1) Check CD_BCK, CD_LRCK, & CD_DATA signals from IC302 to IC801.
=> If no signal, check if the RF & servo signals from MD is entered to IC302.
Refer to the “No operation of MD” guide on Item 4.
2) Check the following I2S signal flow. < I2S audio signal Interface >
- DAC_BCK: IC801_Pin87 --> IC602_Pin4
- DAC_LRCK : IC801_Pin88 --> IC602_Pin5 (44.1 kHz)
- DAC_DATA : IC801_Pin83 --> IC602_Pin6,9
- DAC_MCLK : IC801_Pin86 --> 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”
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.
Check and replace IC301, IC302 on MAIN board.
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 IC302.
> If no signal, check 3.3 V(RF) and X301.
2) Check F- & F+ from IC301 to CN301 for driving the focusing actuator.
> If no signal, check +1.8 V and +5 V for IC301.
3) Check if the FFC cable is solidly connected between CN301 and MD.
4) Check the MD.
> If the pickup module has any trouble, it can not move the laser beam on the top or bottom side.
Please check the function after changing another 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.
Check and replace IC301, IC302 on MAIN board.
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 IC302.
=> If no signal, check 3.3 V(RF) and X301.
2) Check TR- & TR+ from IC301 to CN301 for driving the tracking actuator.
=> If no signal, check +1.8 V and +5 V for IC301.
3) Check if the FFC cable is solidly connected between CN301 and MD.
4) Check the MD.
=> If the pickup module has any trouble, it can not move the laser beam on the left or right side.
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.
Check and replace IC301, IC302 on MAIN board.
1) Check MOT_OPEN & MOT_CLOSE signals from Pin104, 105 of IC801 to IC301.
=> If no signal, check +1.8 V & + 5 V to IC301.
2) Check LOAD± from IC301 to CN303 for driving the tray open / close motor. It is about 3.85 Vp-p.
=> If no signal, check +5 V to IC301. If it has any trouble, replace it with a new one.
3) Check if the FFC cable is solidly connected between CN303 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 servo motors in MD don’t work. This step is for checking the SLED MOTOR among them.
Check and replace IC301, IC302 on MAIN board.
1) Check the SLDO signal from Pin15 of IC302.
=> If no signal, check 3.3 V(RF) and X301.
2) Check the SLED+ & SLED- from IC301 to CN303 for driving SPINDLE motor. It is about 2.9 Vp-p.
=> If no signal, check +1.8 V and +5 V for IC301.
3) Check if the FFC cable is solidly connected between CN303 and MD.
4) Check the MD.
=> If the sled motor is sort-circuit or has any trouble, it can not move the pickup 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 SPINDLE MOTOR among them
Check and replace IC301, IC302 on MAIN board.
1) Check the SPDO signal from pin16 of IC302.
=> If no signal, check 3.3 V(RF) and X301.
2) Check the SPIN- & SPIN+ from IC301 to CN303 for driving SPINDLE motor. It is about 3.6 Vp-p.
=> If no signal, check +1.8 V and +5 V for IC301.
3) Check if the FFC cable is solidly connected between CN303 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.
VFD IS NOT DISPLAYED WHEN POWER ON THE SET.  When power on the set, any icons or characters on VFD are not displayed.
Check and replace DIG502 on FRONT board.
1.Check if VKK, FL+ and FL- are output from SMPS to VFD via the MAIN board.
2) Check if IC102 outputs VFD_D0, VFD_CLK and VFD_STB to the FRONT board.
3) Check the GR signal(pulse signal) of IC501 on the FRONT board.
Check the SG signal(pulse signal) of IC501 on the FRONT board.
=> If the GR and SG signal isn’t output, replace IC501 with a new one.
=> If the GR and SG signal is output, replace DIG502 with a new one.
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.
FLASH MEMORY - check and replace IC101 on MAIN board.
1.Check 3.7 V to CN304 and CN105 in standby mode.
=> If there is no 3.7 V, check the SMPS.
2) Check 5.6 V, 12 V, F+, F- and PVDD 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.
X101 and X102 work normally but, if you cannot power on the set, replace IC101 with a new one on the MAIN board.

Posted By: FRANK at 06:02
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