In many cases, due to our lack of knowledge of LCD TVs, we are always in a hurry or overwhelmed when we encounter TV faults. Today, Xiao Bian has checked out the fault repair of common Konka LCD TVs for everyone, hoping to help everyone.
Three Powerless Series Indicators are Off
Nothing happens when the power is turned on because the power is not sent to the SZ board or the power board itself is faulty. Failure of the power board itself in the LC-TM2018. For the L817 of the SZ board, the L817 is much less open to three.
For this kind of troubleshooting ideas, there is no 12V voltage output on pin 2 of the XS817. If there is no 12V, then the fault is on the power board. In our LC-TM2018, because it is a relatively simple switching power supply, Because it is relatively simple to do, coupled with the relatively poor quality of the capacitors it uses, it often results in no power output.
There are two main problems with our power board. One is burn insurance. If once this problem arises, the rectifiers V901 and N901 can be checked first. There is another problem that is more obvious. A look at the top of the power supply board's output filter capacitor is explosive.
If this happens, just replace the three capacitors of the same type. This problem is mainly due to the quality of the capacitor itself.
If L817 has 12V on one end and there is no voltage on the other end, it must be caused by L817's long-term operation under a large power supply, resulting in a large resistance or open circuit. If its resistance only becomes larger, it can be turned on at this time, but there is automatic shutdown after the moment of starting.
To deal with this kind of problem, as long as you replace the new inductor, you can choose to cross a thin line when there is no inductor. In this position, the inductor is mainly used to isolate high-frequency interference between the power supply board and the SZ board. Make the image better.
If you replace the new L817, but the TV can not be switched on, then as long as the L814 voltage to the ground, because the L814 power supply for the N801, N802, and finally for the CPU power supply, once he opened the CPU can not work properly, resulting in the machine can not be opened.
There is a sound at startup, but the display is off
This situation can explain that the power supply, that is, the sound image processing is basically working, it is mainly caused by the power supply for the screen lamp is not right. This problem can be checked first if the power supply has 12V power supply to the high voltage board. If not, then Check whether the L503 power supply to him is normal.
In this model, L503 open circuit caused this problem is many, if the L503 output voltage is also normal, the screen is still not lit, then we must consider the problem of the boost board, you can put on a new boost board to look at, generally In terms of screen damage, the chance of bad screens is very small. If a new boost board is replaced and the power supply control signals are all normal, the screen is still off. That means the screen is broken and the screen is changed.
Boot sound normal white screen
90% of normal white screen faults due to boot sound are due to poor cable contact. This is mainly due to the poor contact between the LC-TM2018 and the slot in a prolonged high temperature work environment.
The solution is to remove the cable and plug it in again. It is best to stick it with a tape and put it on the shelf of the cable and slot, so that it won't be white screen afterwards. If you don't stick tape after inserting the cable, it will take a long time to return the same problem.
Can't choose the station, or there is no remote control program will beat, or appear screen box
This problem is caused by a partial short circuit in the button, so long as the button is pressed to eliminate the malfunction.
Case:
Symptom Description Konka lc-tm2018 LCD TV power indicator light is turned on, but no image, black screen, carefully check the screen, vaguely see the image screen.
The circuit analysis guides the LCD TV power indicator light to be able to vaguely see the image screen, but the black screen fault is a typical performance of the inverter circuit failure in the TV. The TV has image shadows and the indicator light indicates its power circuit. And the basic image processing circuit is normal. The black screen indicates that the backlight is not lit. It should focus on detecting whether the inverter circuit and the backlight itself are normal.
Troubleshooting Guide Since the voltage amplitude of the AC signal output by the inverter circuit is relatively high, it is usually possible to use induction to determine the general location of the fault.
1. Use an oscilloscope probe to detect the AC signal radiated in the socket near the backlight socket. Under normal circumstances, the 2-log AC signal waveform can be observed on the oscilloscope. If the signal waveform is normal and the lamp is poor, the backlight is damaged. Replace the backlight of the same model after the fault can be ruled out.
2. If there is no radiation signal on the backlight socket, then the oscilloscope probe should be placed close to the core of the step-up transformer. Under normal circumstances, it should be able to induce 20-40v AC voltage.
3. If there is no signal from the step-up transformer, then use an oscilloscope probe near the shell of the drive field effect transistor. At this time, it can also induce 2V AC signal.
4. If the driving field effect transistor senses no signal waveform, the driver IC of the preceding stage can be detected along with the signal flow. Oscilloscope probes are generally used to detect the signal waveforms at their input and output. If there is an input signal and no output signal, the integrated circuit may be damaged. Replace the integrated circuit to eliminate the fault.
Three Powerless Series Indicators are Off
Nothing happens when the power is turned on because the power is not sent to the SZ board or the power board itself is faulty. Failure of the power board itself in the LC-TM2018. For the L817 of the SZ board, the L817 is much less open to three.
For this kind of troubleshooting ideas, there is no 12V voltage output on pin 2 of the XS817. If there is no 12V, then the fault is on the power board. In our LC-TM2018, because it is a relatively simple switching power supply, Because it is relatively simple to do, coupled with the relatively poor quality of the capacitors it uses, it often results in no power output.
There are two main problems with our power board. One is burn insurance. If once this problem arises, the rectifiers V901 and N901 can be checked first. There is another problem that is more obvious. A look at the top of the power supply board's output filter capacitor is explosive.
Konka LCD TV
If this happens, just replace the three capacitors of the same type. This problem is mainly due to the quality of the capacitor itself.
If L817 has 12V on one end and there is no voltage on the other end, it must be caused by L817's long-term operation under a large power supply, resulting in a large resistance or open circuit. If its resistance only becomes larger, it can be turned on at this time, but there is automatic shutdown after the moment of starting.
To deal with this kind of problem, as long as you replace the new inductor, you can choose to cross a thin line when there is no inductor. In this position, the inductor is mainly used to isolate high-frequency interference between the power supply board and the SZ board. Make the image better.
If you replace the new L817, but the TV can not be switched on, then as long as the L814 voltage to the ground, because the L814 power supply for the N801, N802, and finally for the CPU power supply, once he opened the CPU can not work properly, resulting in the machine can not be opened.
Konka LCD TV
There is a sound at startup, but the display is off
This situation can explain that the power supply, that is, the sound image processing is basically working, it is mainly caused by the power supply for the screen lamp is not right. This problem can be checked first if the power supply has 12V power supply to the high voltage board. If not, then Check whether the L503 power supply to him is normal.
In this model, L503 open circuit caused this problem is many, if the L503 output voltage is also normal, the screen is still not lit, then we must consider the problem of the boost board, you can put on a new boost board to look at, generally In terms of screen damage, the chance of bad screens is very small. If a new boost board is replaced and the power supply control signals are all normal, the screen is still off. That means the screen is broken and the screen is changed.
Konka LCD TV
Boot sound normal white screen
90% of normal white screen faults due to boot sound are due to poor cable contact. This is mainly due to the poor contact between the LC-TM2018 and the slot in a prolonged high temperature work environment.
The solution is to remove the cable and plug it in again. It is best to stick it with a tape and put it on the shelf of the cable and slot, so that it won't be white screen afterwards. If you don't stick tape after inserting the cable, it will take a long time to return the same problem.
Can't choose the station, or there is no remote control program will beat, or appear screen box
This problem is caused by a partial short circuit in the button, so long as the button is pressed to eliminate the malfunction.
Konka LCD TV
Case:
Symptom Description Konka lc-tm2018 LCD TV power indicator light is turned on, but no image, black screen, carefully check the screen, vaguely see the image screen.
The circuit analysis guides the LCD TV power indicator light to be able to vaguely see the image screen, but the black screen fault is a typical performance of the inverter circuit failure in the TV. The TV has image shadows and the indicator light indicates its power circuit. And the basic image processing circuit is normal. The black screen indicates that the backlight is not lit. It should focus on detecting whether the inverter circuit and the backlight itself are normal.
Troubleshooting Guide Since the voltage amplitude of the AC signal output by the inverter circuit is relatively high, it is usually possible to use induction to determine the general location of the fault.
1. Use an oscilloscope probe to detect the AC signal radiated in the socket near the backlight socket. Under normal circumstances, the 2-log AC signal waveform can be observed on the oscilloscope. If the signal waveform is normal and the lamp is poor, the backlight is damaged. Replace the backlight of the same model after the fault can be ruled out.
Detecting backlight signal socket
2. If there is no radiation signal on the backlight socket, then the oscilloscope probe should be placed close to the core of the step-up transformer. Under normal circumstances, it should be able to induce 20-40v AC voltage.
Step-up transformer monitoring
3. If there is no signal from the step-up transformer, then use an oscilloscope probe near the shell of the drive field effect transistor. At this time, it can also induce 2V AC signal.
Drive field effect transistor housing
4. If the driving field effect transistor senses no signal waveform, the driver IC of the preceding stage can be detected along with the signal flow. Oscilloscope probes are generally used to detect the signal waveforms at their input and output. If there is an input signal and no output signal, the integrated circuit may be damaged. Replace the integrated circuit to eliminate the fault.
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