LCD TV screen replacement
A variety of effects can appear here. Some problems disappear by themselves when, for example, the technique warms up, while others remain.
The matrix needs repair in the following cases:
- slowdown of frames;
- the appearance of thin vertical stripes;
- flickering of the screen in dynamic scenes;
- wide multicolored stripes.
Solemnly! Similar problems can appear when the control chip fails.
To correctly identify the causes of the breakdown, you must first of all eliminate problems with peripheral and internal equipment: check the tail, attachment, video accelerator and color block.
Advice! It will also be useful to try out the warranty periods. If they did not come out, then the device with any malfunctions should be taken to the service center.
Replacing the screen in an LCD or LED TV is not a difficult task, but it requires the utmost care, since you can make a trick not only very thin loops on a new matrix, although it itself, since it is very sensitive to bends. Some other TV malfunctions can also be repaired by hand.
TN (TN film)
The crystals here are aligned horizontally and are at a slight angle to each other, forming a spring. Devices with TN-matrix are distinguished by good response speed and low cost. A noticeable drawback of this technique is modest viewing angles.
In this case, the crystals are lined up together. IPS TVs offer maximum viewing angles while maintaining the presence of this image quality. But due to the specifics of the technology, the liveliness of the response is noticeably increased. The cost of IPS matrices is noticeably higher than TN.
Back side passage
To replace the matrix in an LG, Samsung or any other TV, including a plasma TV, you will need to unscrew all the fasteners that hold the rear panel of the unit and remove the stand if it is a desktop model of the device. Because screws of different lengths can be screwed in in different places on the back cover, you need to take note of their location.
There are designs of television sets in which a special hatch is provided for the rear wall (for example, on an LG TV) for servicing during the warranty period. When removing the cover, you need to be careful not to damage the cables going to it. Also, at this time, disconnect the modules that may be on the cover from the board. Retribution of the screen is carried out in a similar way for a plasma TV.
Sometime when the cover is removed, you will see in front of you the metal connection of the LCD TV matrix, on which all the electronic boards of the device and the cables connected to them are fixed. You will need to be careful when disconnecting the loops (they cannot be loosened in unequal directions, but you need to pull, carefully, in a straight line). Disconnect them from all boards and modules of the unit. In order not to get confused how to pour them back, you can take a picture of their location before dismantling the LG TV matrix.
Let the TV set start working correctly, you will need to coordinate the new matrix with all the modules. Execution) of this, you need to turn on the device, enter the service menu, and make the settings. The way it is done is indicated in the instructions for the unit.
Types of matrices
On the market, you can find TVs with different types of matrices, but it is customary to take devices built using TN and IPS technology as a basis. And everything else in the world (PLS, VA, etc.) is derivatives.
What is an LCD (multidimensional) table
This is the main element of TV technology, which is responsible for image formation. The beginning is a flat container where a layer of liquid crystals is applied between two plates. The latter, when voltage is applied, change the intensity of the glow.
The first individual crystal that comes across, it is also a pixel, carries three colors. silver-blue, red and green. Light, passing through a particular color, forms the final image. That is, here we have a kind of bundle of mini-projectors.
Power supply unit (PSU)
This node supplies power to all modules of the TV receiver, including the motherboard. Although the power supply has different types of protection, in some cases they turn out to be ineffective.
If the power supply burns out, or some of the elements that make up it fail, then the following symptoms appear:
- TV does not turn on;
- the indicator blinks or does not light at all;
- the device turns off spontaneously;
- when turned on, the indicator starts to glow and immediately goes out;
- when the TV is on, the screen goes black, but the sound does not disappear.
What can be repaired by yourself
Since LCD TV is a rather complex electronic device, only some problems can be eliminated on your own, and even then, provided that you have minimal knowledge and skills in radio electronics. So, you can yourself:
- troubleshoot problems with the remote control or lack of TV signal;
- repair the power supply;
- replace backlight bulbs.
Replacing the matrix itself, if it is damaged, is not always justified from a financial point of view, since its price is approximately 80% of the cost of the device.
Remote control problems
If you try to turn on the device from the remote control, but it does not respond to your actions, then first of all, you should check the suitability of the batteries. Depleted batteries should be replaced. If dirt has accumulated under the buttons on the remote control, you will also not be able to use it. Disassemble it and clean any dirt from the contacts. Another reason for the remote control to stop working is when it falls, damaging the quartz emitter, which will need to be replaced. In the case when the remote control was flooded with liquid, and drying did not help bring it back to life, then you will have to throw it away and purchase a new one.
Power supply repair
In order to understand in general how to look for and troubleshoot a power supply unit, the whole process can be followed on the example of repairing a DAEWOO TV.
Make sure the unit is unplugged before proceeding with the repair.
- Unscrew the screws holding the back panel and remove it (if the panel is held by latches, then try not to break them).
- After removing the cover, you will see the PSU on the left, and the motherboard on the right.
- If you look closely at the power supply board, you can see 3 transformers on it. The one at the bottom is the mains rectifier choke, the top (large) one supplies power to the inverter, to the right (from the large transformer) there is a power supply transformer used in standby mode. Diagnostics should start with the latter, because thanks to it, the standby mode of the device turns on.
- Typically, this transformer, during normal operation, should give a voltage of 5V at the output. You can use the diagram to find the contact you want. But if you look closely at the board, you will notice that opposite the required contact there will be a 5V marking.
- First, it is required to exclude an open circuit. Touch the probe of the contact device (5V), and with the other probe touch the cathode of the diode located on the radiator. The next photo shows that there is no open circuit.
- After that, fix one probe on the metal case, and with the other touch the same contact (5V) to measure the voltage (the TV must be turned on). If the device shows a value less than 5V, then we can conclude that the transformer is not working at full power. A drop in voltage can cause swollen or “dried” capacitors that must be removed to replace.
- You will need to remove the board before replacing the capacitors. But first, carefully pull out the cables going to the PSU from the main board, and also disconnect all the wires connecting the board to other TV nodes. In order not to get confused when assembling with the connection of loops, it is recommended to photograph their initial placement.
- Unscrew the screws holding the PSU board and remove it. Be careful, because the capacitors on the board are charged, you can get severe electric shock. Therefore, after removing the board, you need to discharge them, for example, with a screwdriver.
- Next, you need to solder the defective parts, and solder the new capacitors in compliance with the polarity.
- Assemble (in accordance with the photos taken earlier).
- Measure the voltage after assembly again (by turning on the machine). Now it is within 5V, which is the norm.
Replacing capacitors is the simplest operation a DIYer can perform. In other cases, you cannot do without special knowledge, and it is better to entrust the elimination of the malfunction to a specialist, since your wrong actions can cause the motherboard to burn out.
Replacing backlight bulbs
You can also replace burnt-out backlight lamps installed in the matrix yourself. The lamp replacement process will be demonstrated using the Sharp as an example. Using this description, you can change the lamps in LCD matrices of TVs of other brands.
- Unplug the TV and remove the back panel of the unit.
- Using the utmost care, disconnect all cables connected to the matrix.
- Next, detach the control panel. It is not necessary to remove it completely, as the panel will have to be used to turn on the lamps.
- Check that all cables have been disconnected, then remove the case with the boards screwed on it. It is recommended to take photographs of all actions during disassembly of the TV, so that there are no difficulties when reassembling and connecting all nodes.
- Unscrew the front bezel before removing the die. Gently snapping off the fasteners, remove the filters and matrix.
- Connect the device to the network and press several keys on the control unit to enter the service menu. These steps will help you turn on the lamps.
- The next photo shows that the fifth lamp from above does not light up and needs to be replaced.
- Replace lamp and reassemble.
- When the assembly is complete, you need to reset the lamp error counter. To do this, you need to find the required line in the TV service menu, and then reset by selecting “OK”.
All the main components of the device are under the control of the motherboard: inverter, timing controller, power supply. The motherboard contains a processor, memory, tuner, converters, etc. If any malfunction occurs with the main board, the following symptoms may appear:
- it is impossible to configure the device,
- inputs do not work,
- the picture on the screen is displayed with noise,
- difficulties with management.
When an LCD TV needs repair
LCD TVs have now practically supplanted television sets with a ray tube. LCD panels are characterized by high picture quality, smaller dimensions (slim body), which allows them to be hung on the wall, and less power consumption. But, despite all these advantages over older TV models, LCD TVs have not become less damaged. Therefore, if your LCD TV is out of order, you have 3 options:
- make repairs at a service center;
- call the master at home;
- repair the equipment yourself.
But first you need to decide what kind of malfunction appeared in your TV. Is it worth contacting a specialist or can you repair your LCD TV yourself??