The TV screen is black, but there is sound. What to do with this problem?
You were watching TV when suddenly the screen went out and the picture disappeared. You tried turning the TV off and on again, but the screen is still black. At the same time except for the image all the other functions of the TV set are preserved: the channels are switched, there is sound and it can be adjusted both with the remote control and from the TV set panel. In some cases, if you in a dark room to shine a flashlight on the TV screen, you can find the image contours in the backlighting area. What are the reasons for this faulty behavior TV? What could be out of order? Let’s get to the bottom of this.
Pay Attention! In this article we look only at LCD TVs with a lamp or LED backlight.
What to do if there is sound but no picture with certain types of problems
When the TV turns into a radio, it is, to put it mildly, upsetting. However, in order not to aggravate the situation, this malfunction must be dealt with. As a rule, the repair is engaged after the problem is clarified. Consider in which cases intervention is required and how it is performed. If there is snow on the screen, it may be due to a lack of signal on the program.
Problems in the network
If there is no picture on the TV screen, it may be due to a poor Internet connection in the first place (this is typical when a movie is viewed over the Internet). Also, loss of picture on the TV can occur due to insufficient Wi-Fi signal. Lack of picture is often caused by low speed or no connection to the Internet.
Partial disconnection or complete damage to the cable
Loose connection of the cable in the sockets of the TV set can cause loss of picture, but not sound. To be sure of this, experts recommend pulling and reinserting the plugs of aerial and electrical cables in their sockets when the TV is off. Check each wire for oxidized contacts. If the video signal is lost, you should try to restart the set-top box, check the tightness of the HDMI cable or the wire which synchronizes the two devices. As a rule, the problem is solved by replacing the connection cable. A small tear in the wire can be repaired with your own hands, if it occurred not in the connector housing. If the electrical wire connector is “loose” it must be changed urgently. Even the slightest damage to the cable insulation is dangerous for further use. This threatens not only to short circuit the TV contacts, but also to injure a person.
The Inverter Failure
Usually owners of Samsung, LG, Sony, Sharp and other brand TVs face the problem of inverter failure. Signs of this are: a strong distortion of the screen. The sound can come on at once and the picture can be a few minutes late. The inverter can be repaired with a soldering iron and knowledge of electronics. Here it is important to perform careful and competent soldering. The inverter is a large board with many parts. Only an expert can determine what is broken on it.
Faulty power supply
This problem often has similar symptoms as the breakdown of the inverter. However, here you need to wire every contact on the board. Step by step the following should be done:
- Remove the housing cover, and then carefully inspect the integrity of the wires, the presence of breaks and visible damage on them;
- we pay attention to the capacitors. It is extremely important that there are no bloated parts (they can later rupture and damage the TV);
- Test the voltage with a special tool. It should not deviate from the norm, specified in the documentation of the TV;
- it happens that the TV reacts to all kinds of tapping. This indicates poor contact in the power supply, so the contacts must be carefully checked, and, if necessary, to switch better.
In the TV power supply unit, there are often problems with the capacitors sewn in. Ideally, it is better to replace the whole power supply. But, it will be cheaper than a new unit.
REMEMBER! It is recommended to check the TV with the power off. It can be switched on only if each part is replaced one by one. Nevertheless, you should not abuse the frequent loading!
TV matrix breakage
Failure of the matrix is considered the most unfavorable problem. To replace it you will have to prepare a large sum of money for repair. Sometimes it is better to buy a new TV. Defect of the matrix can occur in case of careless actions of the owners: bumps, drops, depressions. Less often the hardware fails due to a factory defect. To detect such a problem you can see a jumping picture, the image on the half of the screen, or the appearance of vertical stripes of different colors. When the matrix ruptures, a clear indentation is visible in the place of damage, and the image is completely absent.
Damage to the video processor
Breakdown of the video processor can occur gradually or all at once. It is often accompanied by the following signs:
- The appearance of color distortions and improper display of shades;
- The disappearance of one of the colors;
- The sound can be accompanied by image braking or just a blue screen.
No picture on LG TV: causes, solutions
LG televisions are very popular among consumers thanks to their matrixes. But even the most high-quality equipment, after some time, can fail to work. The malfunction can occur due to a breakage of any module or due to a software failure. Some problems can be corrected by yourself: to do this, you should carry out a visual diagnosis of the TV and its components. Let’s consider the cases when the LG LCD TV broadcasts sound, but the image is absent, or the picture is transmitted incorrectly, or the color rendition is broken.
First of all let’s consider the cases when the malfunction can be eliminated independently. When troubleshooting and diagnosing yourself it is not recommended to disassemble LG TV set to avoid aggravating the problem:
- Turn off the LG TV and unplug it from the power outlet for 15-20 minutes. System malfunction may have occurred.
- Deactivate the power-saving mode if the picture is constantly blinking and brightness level is decreased.
- If the picture is blurry or doubled, try the “Trumotion” feature.
- If the picture has become dim, then check and adjust the brightness settings.
- If the color is distorted, try the default setting.
- If a dotted trimmer line appears along the screen, then change the 16:9 aspect ratio.
Another reason why the LG TV does not light up the screen and which is not related to the breakage of the TV itself, is the functionality of the cable box and the wires that connect to it. Check the antenna cable and HDMI cable. The problem may be a malfunction on the ISP side or a broken cable set-top box. Inspect the cable for kinks or kinks, check the connectors for continuity. Try disconnecting TV set, pulling plugs from connectors and reconnecting.
If the previous steps gave no result, it is most likely that the defect is located inside the TV set. It will be necessary to address to LG service center, as it will be necessary to diagnose the internal nodes and disassemble the TV. The most likely faults:
- Power supply failure. As a consequence, the screen does not light up.
- Capacitor burned out. In this case the screen lights up and then quickly goes out.
- Failure of the matrix, in this case there is backlighting, but the picture is incomplete.
- Defective matrix plume will be indicated by periodic loss of picture.
- If you notice that there is no picture on the LG TV, but the sound works, then the inverter is defective.
- If the backlight is broken, the picture will blink or ripple.
- If the video processor is damaged, the picture will be delayed or distorted in color.
- Malfunction of the decoder is accompanied by the appearance of wide stripes on the screen.
Let’s discuss each case in detail. If you noticed that the LG TV has sound but no picture or the picture jerks, the power supply is defective. The master will diagnose and fix the problem with the following algorithm:
- Will disconnect the TV power, unscrew the back cover and check the cables and stubs, replace the necessary.
- Test the buttons and fuses for proper operation.
- Replace charred or melted resistors, if any.
- Measure the output voltage of the power adapter.
- Check power supply solder joints, and if needed, re-solder.
If the house is a frequent power surges, the capacitors can burn out. The main sign is a fading display, but there can also be a double image after a short time, and loss of brightness. A specialist, after removing the back cover of the LG TV, will find a blown or exploded capacitor, which will be replaced with a new one. Most likely you will need to replace the capacitor along with the fuse.
If the matrix is broken, the image can be only in half of the screen, the display can “fade” in all possible colors of the rainbow. The matrix can fail due to a short circuit, but it happens very rarely, more often the breakage is associated with moisture, with a strong shock or a fall of the TV. In this case, you can only replace the matrix, or buy a new LG TV.
If the matrix flat cable is damaged, the repair is much cheaper, especially when the problem is detected at an early stage. It will be enough to re-solder the damaged segments of the flat cable. In more complicated cases the flat cable will be replaced completely. If you see this problem, you may see intermittent loss of picture, interference and ripples during broadcasting, you may see horizontal or vertical black and white or color stripes.
A damaged inverter has many signs, but the main ones are the correct transmission of sound, but ripples on the screen, or the absence of the image completely. The picture may take a very long time to load. The TV screen becomes dim and then goes out immediately after you turn it on. Or there can be an image, but it will be very dark. Trouble in the inverter most often appears in the lamps, transformers or controllers on the board. Only a technician from an LG service center can repair.
Also the reason for the lack of images can be a faulty backlight. In this case, the LEDs in the LED backlight malfunction. This defect is manifested by a blink or a rippling image. LG service center will replace defective LEDs.
The damage to the video processor can not appear immediately, but gradually. Color distortion or incorrect color display will appear, or one of the colors may disappear completely. The picture may begin to lag and the sound accompaniment will precede it, the screen will glow blue. In this case the specialists will replace the video processor with a new one.
Appearance of wide stripes on the LG TV screen indicates breakage of the decoder. Such breakage will entail replacing all the nodes of the TV and it will be easier and cheaper to buy a new machine.
When to contact the service center
Self-repair is limited to fixing software failures and problems with cables. Difficult hardware failure, because of which there is no image on the TV Samsung, it is advisable to entrust the masters of the service center.
The most common breakdown is a faulty inverter. This module provides the voltage to the lamp, it also regulates the launch backlight. The investor is represented in the form of one or more blocks of chips. It depends on a TV model. The accessory is located near the power supply.
Before proceeding with the repair, specialists check the presence of incoming voltage. Pulsations should be absent. After that, the wizard looks at how the command to start the lamps from the motherboard. Most of the time the failure appears at this stage.
If the failure is not detected, the backlight elements are replaced. Re-testing is performed. If the system works properly, the repair is complete.
Sometimes the problem doesn’t go away after replacing the bulbs, which means that the problem is much more serious than initially thought. First a visual inspection is performed. Technicians try to determine if there are any burned-out links.
Quite often break field transistor keys, but their replacement may not give results or will solve the problem for a short period of time. The fact is that replacing the keys eliminates the consequence of the fault, but not the cause. Therefore, the defect occurs repeatedly during the subsequent use of the TV.
Another weak point of inverters is the high-voltage transformers. There is a heavy load on these elements. Accordingly, the natural wear and tear occurs extremely quickly. Replacing the transformers also solves the problem.
The second type of hardware failure is the backlight bulbs. Engineers simply replace defective lamps with original components. Lack of image can be a consequence of cathode burnout. Such a problem can be solved as follows. The screws that secure the board are unscrewed. The matrix is not opened, because masters use a special tool to disconnect the component. Dust does not get inside the matrix.
The manufacturers of TV-devices assure that you should replace the bulbs only together with the matrix. Disconnecting the lamp is done as gently as possible. Basically, the part is glued to other elements of the system. High temperature causes the bulb to be soldered to the chip.
The cable, which provides the connection of the lamp to the circuit board, is disconnected and only then the component is removed. A new lamp is attached in the same way.
Power board burnout is another reason why there is sound, but no picture. This component has several forms, it all depends on the size of TV-device. For example, compact models are equipped with boards in the shape of a block. Larger televisions are equipped with a chassis-shaped circuit board. Masters service center quickly disassemble the TV, and then replace faulty elements.
The weakest point of any power board is the filter capacitors. When the damaged elements are replaced, the power supply, lamps and inverter are connected.
Hardware repair is really a very expensive procedure, but attempts to change the inverter, lamps or power board yourself will lead to an aggravation of the malfunction. Therefore it is better to apply to a service center.
What are the malfunctions
First it is necessary to determine which hardware module is not functioning properly. To do this, you need to analyze the symptoms. The fact that there is no picture can manifest itself in different ways. For example, the TV screen goes out and then turns on, or there are streaks, dark dots, blackouts, spots, ripples. The most common symptoms of TV failure:
- There is no picture on the TV, but there is sound. Dark screen, if you turn off the sound, it may seem that the TV does not work at all;
- Image distortion. Streaks appear on the screen. Sometimes they occur immediately after turning on the TV, but they can also appear already during the operation of the device;
- Monochrome image. green, red or white screen. Dynamic scenes or other changes are not visible, only one color is displayed;
- broadcast is there, but there is too much interference and all sorts of other defects that make viewing impossible;
- The picture periodically disappears, blinks, changes in brightness level, as well as the strength of the glow. Failure appears intermittently or occurs constantly.
Sometimes there is no picture on the TV, but the sound is due to poor signal reception. In this case the cause of the problem is the antenna or coaxial cable. Mainly a black screen and the defects described above signal the presence of hardware failures. If you have the necessary tools, then the equipment can be normalized, but only if the user will follow the instructions.
A common breakdown, when the TV plays sound, but the screen does not work
On repair forums TV masters often discuss the failure, in which the screen does not light. At the same time the sound and backlighting of the TV control buttons may work. Most often this defect is observed on cheap devices of little-known brands.
It’s also not uncommon to fake popular TVs from LG, Samsung, Toshiba and others. Inexpensive models are equipped with low-quality backlight modules. As a result of a short use of the TV, the screen goes out.
And it can be saved only by replacing the diode strip or related equipment. The tape usually consists of an aluminum sheet with a few diodes on it (5, 6 or 7 pieces).
Ribbons are placed on a substrate at a certain distance from each other so that the light is distributed all over the screen. If the test determines that one of the diodes is out of order, it is replaced with a new one. To quickly fix the failure, sometimes they put the diode cut out of other tapes.
But this approach can only temporarily fix the failure. Since each ribbon can have its own specific voltage. When changing this equipment, there is also a need to adjust the backlight inverter driver. If one or several diodes are out of order, dark spots may appear on the screen.
Black screen on the TV when you turn on, as well as the presence of sound does not mean that the breakdown may be serious. Before you get to the internal modules of the device, you need to check other possible causes.
When the sound is output separately
When you connect a home theater or laptop, often at the TV brand LG or Samsung displays a video signal, but the sound comes from the speakers.
In such a situation, there can be more reasons for the lack of image:
- Faulty Wire. And we are talking not about a partial damage, but a complete failure. You need to replace it and the problem is solved.
- Wrong TV channel. You need to switch to the one that outputs the signal from the connector used to connect the equipment.
It will be more difficult if several devices are connected to the TV, because.к. The problem of the lack of an image can be not in the device itself, but in the device that plays the content.
The best way to check and find a faulty device by wireless connection. In this case it will immediately become clear whether the problem is in the TV or the same home theater.
Step 1. Identify the nature of the failure
According to the characteristic features of the breakdown, it is easy to identify what caused it.
Blown screen refers to the failure of such hardware components:
- If any interference appears on the screen, it indicates that there is a problem with the antenna. When the signal is stable and there is no interference and channels can be switched, but there is no picture of TV programs, it is a failure of the radio channel or of the connected/inbuilt TV tuner;
- If the screen does not work and you see only one-color fill (the color itself is not important) or TV does not show a certain color, the video amplifier or the main video processor in the device is broken;
- If the TV has no picture and the sound is “hissing” or absent at all, you need to replace the video processor;
- A band in the middle of the screen indicates that the color is disturbed due to a broken line scan transformer.
If this is the first time you’ve encountered the problem, the first place to start is to turn off your TV and plug it in using a different outlet.
Often the problems appear due to malfunction in the electrical system. If the problem is of a permanent nature, find out which component is most likely to be at fault.
It is very important to determine the type of failure. Without this you won’t be able to make a successful repair. If you don’t have technique repair skills and special devices for diagnostics, we advise to use the services of a qualified master or service center.
The table below will help you to get a quicker understanding of the possible nature of the breakdown:
|No picture (TV seems to be turned off)||Backlight Diodes/inverter/system board/power supply unit|
|Picture size does not fit the screen||Frame sweep/violation in the power grid|
|Appearance of a vertical band||Transformer|
|Horizontal banding||Power supply and / or not working frame scan|
|Occurrence of dead pixels||LCD matrix|
|Severe diminished brightness||LCD screen|
|Color flooding of the TV screen||Color and/or video amplifier malfunction|
Reasons of disappearance of the image
The most common cause of the fact that the image on the TV LZ is lost. hardware breakdowns. What to do in such situations? How to restore the correct transmission of digital or analog TV? It is necessary to perform diagnostics to determine the failed module.
Immediately after determining the damaged component, it must be replaced. This can be done independently. However, this option is relevant, provided that you have the necessary skills and equipment. If you do not know how to repair the TV, then contact the service center.
Now let’s move directly to the consideration of the main reasons for the disappearance of the image.
Power supply unit has burned out
If there is sound but the picture is constantly jerking, the screen is dark, brightness has dropped, or other defects have appeared, it means that the LCD TV power supply does not work properly.
Users who are not familiar with the structure of LG LED TVs, on no account should not try to repair them yourself. Call a specialist who can quickly determine the cause of malfunctioning TV.
However, the diagnosis can still be carried out independently at home:
- Start by discharging capacitors. Unplug the TV. Unscrew the locking screws and then remove the back cover. Check the cables and cables, maybe some of them are damaged. Be sure to test the buttons and fuses to make sure they work.
- Inspect the power supply for melted or charred resistors, capacitors. If there are such elements, they should be replaced immediately.
- Measure the voltage of the output circuits of the power adapter. The received readings should correspond to the parameters indicated on the printed circuit board or in the technical documentation.
- Voltage fluctuations. For example, if the voltage level reaches 200V, look for the reason of failure in the primary circuit.
- If you have tapped on the TV body and the picture returned to normal for a few seconds, the problem is caused by poor quality soldering of the power supply unit elements.
Resoldering contacts and other elements should be carried out by professional equipment. The use of improvised means is fraught with aggravating the initial malfunction.
If the quality of the audio signal is not questionable, but there is no image, you should definitely check the integrity of the connecting elements. We are talking about the cable. Which one?? The answer to this question depends directly on the signal source. Therefore, it is necessary to inspect:
- antenna cable;
- HDMI cable;
- The cord connected by your cable TV provider;
- Ethernet cable (provided that the Smart TV is used).
To determine the cause of the black screen, use special software. For example, the utility Moninfo. It allows you to identify problems related to audio and video transmission. If the program detects malfunction, you need to carefully examine the cable for damage.
Failure of the matrix is perhaps the most common reason that the TV screen has no picture. Damage to the matrix can also cause a variety of other symptoms:
Why doesn’t the matrix work? The component fails due to short circuits and mechanical damage. Faulty matrix cannot be repaired. That’s why the replacement of the part is carried out. If the defects began to appear for no reason, for example, a sharp darkening of the image. It is likely that the matrix elements are damaged, and replacing them is much cheaper than replacing the whole module.
Is it possible to change the matrix yourself at home? Theoretically it is possible. However, it will be extremely difficult for someone who has never repaired televisions. In addition you need to install the original matrix instead of the broken part. It is very difficult to buy original components.
Capacitors burned out
In liquid crystal televisions, capacitor problems are caused by power surges. Signs of faulty capacitors:
- The picture is double;
- No picture;
- The TV set switches off at random;
- Low brightness level;
- Incorrect color transfer.
To get the device working correctly again, you need to disassemble it. You will see a damaged capacitor and blown fuse on the board.
If the failure is not eliminated in time, the failure will worsen. After a while there will be violations in the power supply. The set of procedures aimed at diagnosing, is identical to the situation with the breakage of the matrix.
Replacing capacitors is a complicated type of TV hardware repair. The slightest inaccuracy will provoke aggravation of the malfunction. Therefore, it is wise to trust the specialists of the service center to fix the problem.
Sometimes the LG TV image disappears due to damage to the matrix plume. The breakdown is manifested in the form of the following signs:
- The image periodically disappears;
- Unsatisfactory picture quality. there appeared interference, ripples;
- Horizontal or vertical black and white or color stripes appeared.
The specifics of repair will directly depend on the specifics of the damage to the plume. If the malfunction was able to detect at an early stage, then the masters of the service center will re-solder the damaged sections of the loop, restoring the work of the TV. In some situations, it is necessary to change the matrix plume completely.