The DNS E24D20 TV (chassis: T.EME380.61, matrix: CX240LEDM) is being repaired, the owner complains: “it took a long time to turn on”. When turned on, the backlight turns on, then the LED starts blinking in green and red for a long time, after which the screen goes out for a moment and everything repeats from the beginning.
An autopsy did not reveal swollen capacitors, the supply voltage from the power supply is normal, there are no ripples.
Symptoms indicate that the TV is loading the firmware, but something goes wrong and a reset occurs. But, as it turned out, this does not always happen. If you have patience and wait, then after a random number of such resets, the TV will still turn on and work quite normally. This behavior was somewhat puzzling: after all, if the firmware “flew off” or the memory chip itself, which stores the firmware, is faulty, then how does the TV manage to work?
Entering the service menu for this TV is MENU, 1147. Resetting the settings does nothing, flashing via USB is impossible (although there is a USB Update item in the menu, but it does something else - it probably reinitializes USB).
There is nothing to do, the firmware will have to be changed through the programmer. First, we read the native firmware from the SPI Flash 25Q64 microcircuit. This is necessary just in case, because there may not be any firmware for DNS E24D20 on the Internet or they may be incorrect. We read 8 megabytes with the programmer.
A search on the Internet leads to the fact that there are no open source firmware for the DNS E24D20 T.EME380.61 TV. They are present only on sites where downloading them is extremely difficult, up to extortion of money, viewing ads, after which, by the way, it is still impossible to download. Comes to the rescue. DNS site. On it, the firmware for this TV is completely open. Downloading, comparing with the native one - for the most part the same, but there are several different pieces. This confirms the assumption that the native firmware still flew off.
We clean the microcircuit, but we receive an error message: writing is prohibited. We programmatically remove the write protection, program the microcircuit and install it back into the TV. It turns on successfully and quickly, prompting you to make the initial settings in the menu. We search for channels - the TV works great, turns on, again, quickly.
The TV itself made a double impression. On the one hand, it works pretty well for its class, all connections inside are made on connectors, it is convenient to repair. On the other hand, the parts of its case and even the PCB itself are so flimsy that they bend when touched. Not otherwise, this model is the first step towards a flexible TV.
The TV is in standby mode (red LED is on). It does not respond to pressing the "On" button on the TV case, or any button on the remote control. What to do?
It is forbidden to write answers that do not bring any benefit to the questioner from the series: “bring it to the service”, “contact the ASC”, “unprofitable”, etc. Answers like these will be considered a rating cheat, the answers will be deleted, and the account will be blocked.
If you undertake to help people, answer fully. Explain why, if you recommend, for example, reflashing your phone, then write how to do it. If you write that repairs are unprofitable, explain why.
Check the capacities in the power supply and the signal flow to the processor.
It is impossible to imagine a modern apartment or house without video and audio equipment. This equipment is used every day and therefore breaks down more often than others. There are several ways to repair TVs: send the technician to a service center, call a qualified technician at home, or make repairs with your own hands.
Before you start repairing a TV, you first need to make sure what the problem is. This will also help if you do the repair yourself, and then when the master comes, you will be able to explain the situation to him.
There are several types of malfunctions that can most often be found when a TV breaks down.
The technique does not turn off. In independence, a CRT TV or a modern LCD model has broken down, this malfunction is associated with a blown fuse. Only different models have distinctive details from each other. You should also pay attention to the diode bridge - perhaps it was he who burned out.
In both domestic and imported models, the potential can often go astray, for the function of which the posistor is responsible.
If the plasma TV monitor is broken, then the problem, most often, is interference or drops, light or dark stripes may appear, color changes while watching a program or movie.
The problem may be a broken cord or a faulty outlet.
If we take into account all the troubles listed above, it is worth saying that the most difficult breakdown is considered to be a screen malfunction. For example, light reflections appear on your monitor after the liquid hits the matrix or the TV is hit, then it is better to carry it to the teleservice. Here it will certainly be repaired, and if the warranty period has not expired, then it will be free of charge or at a reduced price.
See also - How to choose a TV for your home in 2018?
You can try to fix some malfunctions of TVs yourself. And it doesn't matter here - these are LCD models, LCD or LED, it is not necessary to call the wizard if you are confident in your abilities. But caution never hurts, because such TV models are not cheap, and without having any repair experience or knowledge in this area, you can only harm and aggravate the breakdown.
Before you start repairing LED or LCD TVs, you must carefully read the instructions, and also study the principle of operation of your model. Anyone, even one far from this field, will understand that the repair of TVs such as LCD or LED will differ from CRT models. In the latter case, you are guaranteed not to run into a faulty PTC thermistor. The main thing here is to determine the problem, why does the backlight not work?
If you are repairing LCD, LED models, then the only difference here will be what kind of backlight is used. If it is an LCD TV, then the backlighting is produced using fluorescent or fluorescent lamps. For TVs, LED backlighting is produced using LEDs. At this point, the differences between LCD models usually end.
VIDEO The breakdown can only consist in the fact that there is no power, in order to check this on an LCD TV, you can do the following with your own hands:
open the back cover of the model;
remove the wires connected to the matrix;
connect the working lamp to the contacts;
there are also LCD models in which more than one light source is provided. In this case, all sources must be tested. Just dismantle the matrix and plug your TV into the network - you can see which LED is the problem.
When a broken lamp in an LED or LCD TV is identified, it must be replaced. This stage requires maximum care from the master, as well as the manifestation of special attention. In some cases, the lamp is removed without removing the matrix, you just need to move the protective elements with a rubber gasket and pull out the lamp with a soldering iron. Similarly, it is necessary to mount a working light bulb. Now we can congratulate you - you did the repair of the LCD TV with your own hands! Just pay attention to one important nuance - the new light bulb must fully meet the parameters and dimensions of the broken one!
To repair TVs yourself, look carefully at the matrix! If there are "unhealthy" streaks here, then the breakage is in the matrix. Have a new part? Then everything is simple! You change it and turn on the TV, if it works, then you have accurately identified the breakdown.
If the reason for the breakdown of LCD TVs is the screen, then it is best to purchase new models of LCD or LED equipment. It is not recommended to change the screen of LCD and LED models, as it is impractical! This also applies to the LCD matrix.
What could be the problem with a malfunctioning plasma TV? If it is necessary to repair plasma TVs, then proceed in the same way as described above. Just adapt it to your specific case. This description can be applied to any model of plasma TV, just stock up on the necessary tools in advance.
Although today most users prefer to use plasma, many still watch programs on more outdated CRT models. Let's find out how to repair a breakdown in such TVs. Below is a step-by-step instruction that will help you repair your electron beam product with your own hands.
If you do not turn on such a device, check first of all the fuses. In these TVs, the back is made up of panels. Therefore, it is necessary to unscrew that part of the panels. Under such panels you will find a board and the power terminals must be connected to the fuse. They are connected to a conventional incandescent lamp, or rather to its base, after which the TV must be connected to the network. In the event that your equipment is in good working order, the lamp will go out after switching on, otherwise, when the fuse has blown, it will either not work at all, or it will constantly burn.
The diode bridge may also break. It should only be borne in mind that it is necessary to regulate and repair it only after making a dial. In this case, not only a multimeter is used, but also a product passport, which indicates the main parameters of this model.
The most difficult breakdown in a TV with a kinescope is a posistor. To check with your own hands, you must first turn off the power circuit, and then turn it on. In this case, the lamp must be monitored. If the work lamp goes out, then it can be said that the posistor is faulty. To make repairs, it is necessary to adjust the resistance of the network and only ventures to change this part.
But not only the matter may be in the posistor, transistors and capacitors burn out in CRT models. The diagnosis of this breakdown can also be made visually. If the condensate is blackened or cracked, then we replace it with a serviceable analogue. Now you know why the TV does not work and how to fix it yourself.
It is no secret that a breakdown of a television receiver can ruin the mood of any owner. The question arises, where to look for a good master, do you need to take the device to a service center? You need to spend your time on this, and what is important - money. But, before calling the master, if you have basic knowledge of electrical engineering and know how to hold a screwdriver and a soldering iron in your hands, then repairing the TV with your own hands in some cases is still possible.
Modern LCD TVs have become more compact and easier to repair. Of course, there are breakdowns that are difficult to detect without special diagnostic equipment. But most often there are malfunctions that can be detected even visually, for example, swollen capacitors ... With such a breakdown, it is enough to evaporate them and replace them with new ones with the same parameters.
All TV sets are the same in their structure and consist of a power supply unit (PSU), a motherboard and an LCD backlight module (lamps are used) or LED (LEDs are used). It is not worth repairing the motherboard on your own, but the power supply unit and screen backlight lamps are quite possible.
As already mentioned, the design and principle of operation of LED and LCD TVs, regardless of the manufacturer, are the same. Of course, there are some differences, but they do not play a significant role in the diagnosis of faults. Often, in the event of a problem with the power supply, the LCD TV does not turn on at all, while there is no indication, or it turns on for a while and turns off spontaneously. Using an example, we consider the repair of a DAEWOO LCD power supply unit (it can also be applied to plasma), which is not much different from repairing an LG TV, as well as Toshiba, Sony, Rubin, Horizon and similar models.
First of all, before you repair the TV, you need to remove the back panel of the device with a screwdriver by unscrewing the screws. On some models, the rear wall may be latches installed which must be handled with care so as not to break them.
After removing the cover, you will see the power supply unit, consisting of several modules on the left, and the motherboard on the right.
On the power supply board you can see 3 transformers : the bottom one is the mains rectifier choke, the top one on the left (large) feeds the inverter, and on the right is the standby power supply transformer. You need to start checking with it, since it turns on the standby mode of the TV receiver.
Duty transformer when the device is connected to the network, it should give out a voltage of 5 V. In order to correctly find the wire on which you need to measure the voltage, you can use the diagram, or you can see the markings on the case. In this case, opposite the desired contact is written - 5 V.
Measurement is taken first open circuit by connecting one probe to the found contact, and the other to the cathode of the diode on the radiator. In this case, there is no break.
Further, one tester probe can be attached to the body of the device, the other to the previously selected contact, and measure the voltage, having previously connected the telly to the network. In this case, the device shows 1.5 V, instead of the required 5 V. Such readings of the transformer indicate that it is working, but not at full strength. The reason may be dry condenser located below, or swollen - above the transformer.
To remove the parts that have become unusable, it is necessary to remove the power supply board. To do this, first disconnect all wires and the matrix cable coming from the inverter and the system board. So that in the future, after repairing the power supply, you do not get confused where what is connected, you can take a picture of them before disconnecting the wires and loops.
Now you can remove the entire LCD TV power supply by unscrewing the 4 screws. After removing it, it is very important discharge all capacitors to avoid electric shock.
We solder the defective capacitors and replace them with new ones, observing the polarity.
The assembly of the device takes place in the reverse order: the board is screwed into place, all connectors and cables are connected, the rear panel of the unit is closed.
We again measure the voltage on the transformer of the TV's power supply (the device should turn on) and see that it has become 5v. When you unfold the repaired TV receiver, you will see that it works.
As you can see from the review presented above, repairing TV power supplies with your own hands is not such an overwhelming task. Following this description, you can also repair plasma TVs.
Do-it-yourself TV repair with a kinescope, for example, such as: Rubin, Horizon, Sharp 2002sc, LG TVs, as well as repair of the Vityaz TV, begins with checking the power supply unit for operability (this is done if the unit does not turn on). It is checked using incandescent bulbs for 220 V and a power of 60-100 W. But before that, be sure to disconnect the load, namely the horizontal output stage (SR) - connect a lamp instead. The CP voltage ranges from 110 to 150 V, depending on the size of the tube. Must be found in the secondary circuit SR filter capacitor (its values can be from 47 to 220 microfarads and 160 - 200 V), which stands behind the SR power rectifier.
To simulate the load, you need to connect a lamp in parallel to it. To remove the load, for example, in the popular Sharp 2002sc model, it is necessary to find and unsolder the inductor (located after the capacitor), the fuse and the limiting resistance through which the CP stage receives power.
Now you need to connect the power supply to the power supply unit, and measure the voltage under load. The voltage should be between 110 and 130 V if the CRT has a diagonal of 21 to 25 inches (as in the 2002sc model). With a diagonal of 25-29 inches - 130-150 V, respectively. If the values are too high , then it will be necessary to check the feedback circuit and the power supply circuit (primary).
It should be noted that electrolytes dry out and lose capacity during prolonged operation, which, in turn, affects the stability of the module and contributes to an increase in voltage.
When the voltage is too low it is necessary to test the secondary circuits to exclude leaks and short circuits. After that, the diodes for the protection of the power supply of the SR and the diodes for the power supply of the vertical scan are checked. If you are convinced that the power supply unit is working properly, then you need to disconnect the lamp and solder all the parts back. This check can also come in handy when doing DIY Philips TV repairs.
Another common breakdown of the TV that can be eliminated is the burnout of the backlight lamp. In this case, the TV receiver, after switching on, flashes the indicator several times and does not turn on ... This means that after self-diagnosis, the device notices a malfunction, after which the protection is triggered. That is why there is no image on the screen.
For example, a Sharp LSD TV receiver with this malfunction was taken, although in this way it is possible to repair Samsung TVs, Sony Trinitron, Rubin, Horizon, etc.
To fix the TV, you need to remove the back panel from the TV. This requires a screwdriver or screwdriver.
Next, you need to be careful disconnect loops from the matrix.
The next step is to detach the control panel from the case. You do not need to remove it, you will still need it to turn on the device.
The remaining loops also need to be disconnected. Then it is necessary to remove the housing on which the electronic boards are fixed.
Before removing the matrix, unscrew front frame ... We remove the matrix itself and filters, snap off the side mounts.
We connect the power and hold down a few keys to enter service menu ... This will keep the lamps on for a while.
The figure below shows that after turning on the lamps, the 5th from the top turned out to be inoperative. Disconnect it and replace it with a new one - now all the lamps are on when checking.
The assembly takes place in the reverse order.
After that, you need to turn on the TV receiver and enter the service menu for reset lamp error counter ... If this is not done, the device will not work. Entering the menu, you need to find the corresponding line and reset by selecting ok. Now the repair of the LCD TV set is finished. Tests show that the unit is operating normally.
Thus, you can repair the Philips and LG TV with your own hands, and other LCD panels, as well as devices with LED backlight (LED). Owners of the latter type of devices should read the article on repairing LED backlighting, where the whole process is described in detail using the example of an LG TV.
Among the typical and simple reasons that the TV set does not turn on, there may be a remote control or a lack of signal from the antenna cable.
If the TV does not turn on with the remote control, first, you need to make sure the batteries are good. If they are shrunken, replace them. Often the TV set cannot turn on due to contamination of contacts under the buttons. To do this, you can disassemble it yourself, and clean the contacts with a soft cloth from accumulated dirt. If your remote control has been dropped, it is possible damage to the quartz emitter ... In this case, it must be replaced. Well, if you filled the remote control with water or some other liquid, and it did not work after disassembling and drying, then it will have to be replaced with a new one.
You can learn more about fixing the remote control in the following video or article.
When repairing TVs LG, Sharp with LCD, Rubin, Horizon with the same screens, a situation often arises when it does not turn on when the device is in good working order. It turns out that the reason may be no TV signal in the antenna cable. This happens due to the operation of the noise suppression protection (in Rubin TVs, they began to install it not so long ago), and the unit goes into standby mode. Therefore, if you find your TV set inoperative, you should not panic, but you need to check the presence of a signal from the transmitting station.
In conclusion, we can say that when you decide to repair a TV set yourself, you should soberly assess your abilities and knowledge in this matter. If you do not feel confident, then it is better to entrust this matter to a telemaster, especially since nobody canceled 220 V, and ignorance of basic safety rules can entail unpleasant consequences.
VIDEO
It's a shame to throw out a TV that costs 50,000 rubles and more, on the contrary, a cheap LCD panel is sometimes easier to buy than to replace the matrix. This takes on significance in private companies, the staffing table contains a master's cell. It is not surprising that there is a keen interest in repairing TVs with your own hands, the breakdown may be insignificant, the gain is obvious. How not to be electrocuted, not to break the device? We plan to discuss with today's review, we will list the main types of faults.
The percentage of models with a cathode-ray tube is large. It is logical to start with them to consider how to repair a TV, because switching power supplies are considered an integral part of any equipment. Liquid crystals, OLED (organic diodes), plasma. Scanning chips use similar principles. The way of building the image is different, but the element base is similar. Consequently, do-it-yourself TV repair moves along the beaten path.
The equipment contains fuses. Let's open a secret: if a force majeure situation (lightning strike, power surge, equipment drop) happens, the protection should break. Almost the end catches up with the microcircuits. Start with the fuse. Of course, if the equipment is devoid of signs of life. In normal mode, the current through the fuse is zero, the repair specialists came up with the fact, put it into service. The burned-out part is removed, a 100-watt light bulb is connected to the terminals.The resistance is relatively high, it will serve as a good current limiter, the electrical circuit will slow down further to burn out.
Note. According to Ohm's law, the power released by a section of a circuit is proportional to the current. By limiting the value, we will avoid burnout of radio components. Actually, this is done by supplementing the circuit with limiting resistors. The light bulb serves the purpose of indication, makes it clear if an electric current is passing. The spiral is heating up, we see the light.
In normal mode, the light will blink, then go out after turning on the TV. Moreover, the device with such an additive works slightly incorrectly. There are two parts that often burn on CRT TVs:
The diode bridge rectifies the current. With a sharp increase in consumption, one branch burns out. Usually two diodes fail. You can determine the suitable ones by dialing. The diode current flows in one direction, in the other the valves are locked. The circuit triangle indicates where the current is going. According to the concepts of circuitry, the current always flows from plus to minus. Accordingly, place the electrodes starting the dial tone. The second curious detail is a posistor operating on an inductive loop, the task of which is to remove the potential from a cathode-ray tube. Otherwise, a characteristic rainbow appears on the screen due to the violation of the movement of electrons. A thermistor or a loop may burn out. It is easy to check the circuit. You will need to turn off, then turn on the power. If the lamp that used to be on is now out, the problem is in the potential removal circuit. You can test the device, for a while it will be able to work normally without a loop.
How to understand whether the posistor is out of order or the loop is burnt out? First, measure the resistance. The posistor has four inputs. Two form a heating circuit, two - remove the potential. The resistance between the first pair will be 300 - 600 ohms, between the second - units of ohms. If you turn off the outputs going to the CRT demagnetization loop, we will exclude the section from work. The verification technique is simple. If the lamp is on with the loop, but not without, then you will have to look for a new lace. Visually - a thick wire that surrounds the cathode ray tube around the perimeter. To check the posistor with 100% accuracy, take the trouble to evaporate. After turning on the power, observe the action of the light bulb.
For reference. You cannot keep the equipment turned on for a long time with a light bulb that replaced the fuse. The device is defective, there is a large current in it. It is enough to turn on for a second to understand whether the light is on or not. Then unplug the TV plug from the outlet. It will allow you to protect the serviceable elements of the chain from the unusual load.
What else will burn? In the power supply at the input there is a large capacitor, next to it is a power transistor. Both parts are ringing. The transistor breaks through the source-drain transition, although other options are possible. If it is noticed that half of the diode bridge has burned out, it speaks eloquently: the fuse has failed. The type of breakdown of the TV indicates: there is still a malfunction inside. But it has already led to the failure of one branch of the diode bridge. Carry out the diagnostics until the lamp refuses to light up at all. The key sign of a properly working TV is a characteristic hum, which indicates that the line scan has turned on.
Forgot to give general instructions on how to repair your TV. The main board is dismantled for convenience, leaving a chance to get an electric shock even from the switched off device. It seems that no one has died yet, they got burns. You will need to discharge the cathode-ray tube electrode. Located under the rubber gasket. Without touching the metal parts with your hands, pry the rubber with a screwdriver, swinging from side to side, remove the electrode. Discharge the rod onto the body. If you see a ground loop nearby, it is better to go to it. It is clear that for a successful procedure, you need to have a European socket with correctly connected terminals on hand.
Clicks will be heard during discharge. Continue to touch the contact while the phenomenon is observed.Any modern TV set has electronics assembled by one board, which controls the operation. Many radioelements are visually assessed for their integrity. Defective capacitors swell, resistors (active elements) turn black. Darkened resistance sometimes stays good. The defect clearly indicates: the radio element closes the circuit of the broken element.
LCD TV repair is similar to the case of CRT models. The posistor is, of course, absent. It's easy to understand the cause of the backlight breakdown. LCD TVs use two types:
discharge gas lamps;
organic or LEDs.
Gas lamps don't look like cousins hanging from ceilings. Rather white straws. To check the power, remove the back panel to see the wires going into the matrix. Carefully disconnect from the connector, taking a working lamp, check the functionality. It happens that a number of discharge light sources are occupied by the illumination. Take the trouble to remove the matrix, turn on the TV, see which lamp does not work, replace it.
The installation scheme of the illuminators is different. In some TVs, you just need to pull out the lamp from the end without disassembling the matrix. The wires come in from both sides, each covered with a rubber gasket. The protective elements should be pushed aside, the lamp should be evaporated. Installing a new one takes place in the reverse order. Try to choose one that is equivalent in size to the replaceable one. The location of the lamp is lateral, less often the top. It happens that there are two or more illuminators. If a vertical or horizontal stripe appears on the matrix, the scanning electrode most likely burned out. Try to turn on the device with a different, known good matrix to check the assumption.
VIDEO
Replacing crystals on cheap TVs is not cost effective. The cost of a new spare part is more than 3000 rubles. It's another matter if you have a similar broken TV set at hand with a working liquid crystal matrix. Then the replacement is registered. Repairing a TV screen is rarely cost-effective.
There is a typical breakdown of modern TVs: they stepped on a cable. The vein is ripped out, sometimes together with the track on the microcircuit. The digital receiver is represented by a small microcircuit (which needs to be shielded), so the assembly is inseparable from the connector. Carefully dismantle the electronics before repairing. Then use glue, soldering iron to repair the part. Repair of the TV antenna will be required after a lightning strike. Users install cymbals, forget the lightning rod.
Video (click to play).
Plasma TVs are being repaired in a similar way. There is no backlight, posistors, therefore, there are fewer problems!
