What is the reason why the LG42 LCD TV automatically shuts down after 20 minutes of being turned on

There are several reasons why LCD TVs form automatic shutdown:

1. The power supply system is unstable, which can also cause the occurrence of automatic shutdown faults, and a UPS backup power supply with voltage stabilization function can be considered.

2.Fault phenomenon: After the LCD TV is turned on with the curtain drawn, the picture and sound appear, and then the screen is turned off. Repeat the above phenomenon after rebooting with the remote control.

3.Fault phenomenon: It will automatically shut down after watching for a few minutes, and it can be turned on with remote control when it is turned off, and it will be automatically turned off after it is turned on. Very often.

4. Then use the elimination method to check the memory, graphics card, CPU, CPU fan, motherboard, etc.

5. There may be a problem with the BIOS settings, enter the BIOS to restore the default settings or take out the battery of the motherboard, reverse the buckle discharge, and wait for 5 minutes to reverse install it. Purpose: To restore the default values of the BIOS settings and eliminate the automatic reboot or shutdown of the BIOS cooling presets.

6. Then check the power supply, the power supply quality is poor, aging or the power is too small, can not meet the power supply needs of the computer accessories, you can replace the high-power and high-quality power supply, if troubleshooting, it is the automatic shutdown fault caused by the power supply.

Hello! This kind of fault is generally caused by poor thermal stability or the gradual increase of hot leakage current, so we should focus on checking the working state of high-power components with large working current, and in addition, in the actual maintenance, it is found that some solder joints with poor contact can work normally in the cold state, and separation will occur with the increase of temperature, so the suspicious solder joints should also be repaired.

Possible reasons why the TV works fine after turning it on, but it turns off automatically after a few minutes:

1. The power supply, line vibration and scanning, microprocessor and other circuits of the TV may have faults caused by virtual soldering.

2. There is an abnormality in the switching power supply.

3. The AD board in the TV controls the over-voltage protection or over-current protection of the switch part of the high-voltage board.

4. The X-ray protection of the TV and the thermal stability of a component are poor.

Solution: You need to directly solder the 2 pins of the switch control together. It is recommended to consult professional maintenance personnel to deal with it.

Extended Information: Troubleshooting Common TV Sets:

1. The TV does not turn on.

The most common problem is encountering this kind of problem.

1. First see if the indicator light is on, if the indicator light is not on, first check whether there is a problem with the power socket, if the socket is electrified, and then check whether the power switch on the TV is on, if the above two points are normal, then there is a problem with the power strip.

2、The indicator light is on,If the indicator light is on, the remote control does not turn on,Generally, there is a manual switch on the TV,You can try whether the manual switch can be turned on。 If it can be opened, it can be basically determined that it is a problem with the remote control, and the remote control can be replaced.

3. After the TV power light flashes, it becomes ever-bright, and the TV flashes white light at the moment of start-up, at this time, the failure of the TV should be the damage of the TV's backlight driver board, but it is not excluded that it is caused by a problem with the TV backlight tube.

4、The TV will automatically shut down after a few seconds of booting,This kind of problem,If it is a TV bought in the last three years,Basically, there is a problem with the system,If the TV is more than three years,It may be that the screen supercharged version or the motherboard is broken,It also needs maintenance personnel to repair。

Second, there is sound but no image.

When this problem occurs, the first thing to see is whether the screen is bright.

1. If there is a bright light behind the screen and the screen is gray, it is basically a screen problem, 2. There is no bright light on the screen at all, it may be that the screen LVDS cable has been corroded by moisture for a long time and the connection is interrupted. Or the screen cannot be started due to the failure of the screen supercharger version.

3、The screen alternates red, yellow and blue colors,This is generally caused by screen self-test,The inside of the TV is damp,Corrosion of internal components,The screen has not been able to find the signal,It will also cause screen self-test。

4. If it is a directly connected antenna, the high frequency head will also cause this problem, but this kind of problem rarely appears, if it is just a high flat head problem, you can see that the screen is bright at the moment of shutdown.

What is the reason why the LCD TV will automatically turn off after a few minutes of turning it on? Hello dear, 1. The internal circuit of the TV is soldered and the TV is automatically shut down; Generally, it is necessary to check the solder joints at the switching power supply and line scan output circuit of the TV, and you can focus on checking the components with larger volume and higher temperature; After finding the virtual solder joint of the TV, you can re-solder it with an electric soldering iron. 2. The X-ray protection circuit of the TV is faulty, resulting in the automatic shutdown of the TV; Measure the voltage of the X-ray protection pin, if there is any abnormality, it will be judged as a fault and need to be replaced; 3. The TV will automatically shut down due to overvoltage protection; When the output voltage of the power supply of the TV is higher than the set value, the overvoltage protection circuit will take effect, and then the switching power supply of the TV will stop working, resulting in automatic shutdown; 4. When the current load circuit of the TV causes excessive current for some reason, the overcurrent protection of the TV will work, so that the power supply circuit of the TV will stop working and automatically shut down; 5. Generally, the automatic shutdown is caused by the hardware failure of the TV, and non-professionals are recommended to contact the after-sales service of the TV for maintenance.

It may be caused by the defect of the lock switch in the TV electromechanical, which is specifically introduced below:

1. Possible causes:

The switch circuit of the TV is soldered or damp, resulting in poor contact, resulting in frequent automatic start-up;

The high-voltage instability of the motherboard circuit of the TV leads to frequent automatic turning on and off;

If it is a problem caused by the hardware failure of the TV, it is recommended to contact the after-sales service of the TV for testing and warranty.

2. Solution:

Turn off the power and unplug the power cord. (Be careful not to touch the high-pressure plate). Flat-mounted TV, mainly to protect the surface of the LCD. Unscrew the back cover and open the back cover of the TV with all the screws;

Locate the switch board on the top of the TV and remove the switch circuit board. Use a soldering iron to replace the 6-pin self-locking switch, or simply solder the 2 pins of the switch control together.

If the above measurements are normal, it means that there is no fault in the switching power supply circuit, otherwise it is a fault in the switching power supply circuit, if it is a problem with the switching power supply circuit, then the main thing should be to check the power supply protection circuit components such as: thyristor protection circuit components. Even if the above are normal, if the power-on test is still not good, then measure whether the voltage of all DC-DC voltage conversion circuit chips on the motherboard is normal for each output pin, if it is normal, then focus on measuring the voltage on the motherboard and the voltage of ten 5V, when the voltage is low or the voltage of ten 5V is low, it is very easy to have automatic shutdown failure.

Hope this helps<>

Eat whales] LG TV turns on and watches for a few minutes and automatically shuts down, what is the reason why it turns on automatically after the red light flashes.

Hello for you to answer: this situation is a circuit board fault, this fault first measure whether the configuration disturbance voltage at the output end of the main switching power supply circuit is normal. If the above measurements are normal, it means that the switching power supply circuit is not faulty, otherwise it is the switching power supply circuit fault, if it is a switching power supply circuit problem, then the main power supply protection circuit components should be checked, such as:

Thyristors can be used to protect circuit components. Even if the above are normal, if the power-on test machine is still not good, then measure it, the width of the motherboard or there is a DC-DC voltage conversion circuit chip, whether the voltage of each output pin to the ground is normal, if it is normal, then focus on measuring the voltage on the motherboard and the voltage of ten 5V, when the voltage is low or the voltage of ten 5V is low, it is very easy to have an automatic shutdown failure. Hope it helps you Fan Dan <>

Eat whale] electric slag can only be turned on with the remote control (the manual switch fails),The screen turns off after a few minutes,The power indicator Sun Linghe flashed and the screen turned on again after a while,But it has exited the page that is being sent to see。

Appears to have overheat protection.

Is the indoor temperature very high?

It is likely that the protection circuit is turned on. Initiate. During maintenance, the voltage of the key point can be measured to determine whether the protection of the seepage is lifted and the protection is lifted, and the phenomenon of the obstacle is observed and the maintenance of the Qinxing is observed.

Or start the disturbance overvoltage protection: one is to check the main power supply voltage regulation control circuit chip that causes the slow slag voltage, and the other is to detect whether the overvoltage protection sampling circuit ZD5 and ZD4 are leakage. Imaginary calendar.

If you don't know how to detect and find after-sales service, it's good.

According to different situations,The reason why the internal switching power supply of the TV will automatically shut down immediately after turning on is different,Because the TV has a sensitive overvoltage、Overcurrent、Automatic protection to turn off the rotten branch circle function,The following situations may automatically shut down:

1.Shut down just after seeing the image, it is the small electrolytic capacitance of the switching regulator power supply circuit that degrades, causing the switch tube to run out of control and cause the output voltage to be too high;

2.As soon as the machine is turned on, it shuts down after hearing a squeak, which is the gap between the soldering of the pins of high-voltage and high-power devices and the ignition of the printed plate;

3.A few seconds after turning on the machine, a bright line appears on the screen, that is, the machine is turned off, which is a field scanning circuit failure;

4.If the boot amplitude is insufficient to shut down, the filter capacitance of the row tube will change the value, so that the state of the line switch will not match the current increase;

5.After the power is turned on, the high voltage is too high or the brightness is out of control, and the grating is particularly bright to shut down the ray protection;

6.The boot indicator light is activated, but there is no accompanying sound, and the grating returns to the standby to shut down, which is a serious AC leakage fault in the circuit components. Of course, there are also protection circuit components deterioration, resulting in protection malfunction shutdown faults.