We repair TV boxes

Repair of set-top boxes for TVs and the search for reasons why they do not work is in demand in a situation where the owner is unable to receive a TV signal without an external receiver. In this case, it is quite possible to diagnose malfunctions on your own, without outside help. Find the source of the problems and understand how to repair digital TV set-top boxes with your own hands, an overview of breakdowns with tips and recommendations for their elimination will help.

If the set-top box connected to the TV does not work, you can start looking for the reasons yourself. Common problems with the disappearance of sound in the receiver or other common malfunctions can be identified and fixed in a short time. Of course, you will need accessories to check a switching power supply or microcircuit, but many problems are discovered with a simple visual inspection. It's worth starting with them.

Diagnostics is necessary in order to determine the appropriateness of the repair. Sometimes it is cheaper to buy a new device, especially if the model is inexpensive.

Set-top boxes of this type have several decoders and ports - eliminating one malfunction, you can easily damage another unit or violate the warranty.

Any diagnostics begins with dismantling the case. Most of the nodes that can fail are located under it. Troubleshooting rules will be specific to each item.

Diagnostics begin with checking the current supply. The disassembled set-top box is connected to the network. Pay attention to the following points.

1. LED indication indicating power on. If it lights up, the equipment start-up sound is heard, power is supplied normally.
2. The indicator is on, but there are no other signs of starting work. It is necessary to check if there is a power supply to the processor. The check is carried out using a multimeter.
3. The indicator does not light up. There is no food. Perhaps he is faulty himself - it is recommended to check, connect the contacts to any other lamp. If there is current, you will have to change the indicator, if there is no current, check the power supply.

Having identified the localization of the problem, you can proceed to its elimination.

If this element fails, the set-top box will not work normally. Most often, the problem is associated with software or hardware failures. Indirect signs of upcoming problems can be considered malfunctions, inaccessibility of options or interface elements. The first thing to do in such a situation is to update the software. Most of the malfunctions are due to the fact that the manufacturer no longer supports the set-top box software.

When hardware problems are detected in the internal memory, the chip simply cannot correctly provide data for reading by the device. The most likely reason is lack of contact. It can be restored by soldering in places of the detected lack of contact. If this measure does not help, it will be cheaper to replace the set-top box with a new one. A software crash can also be fixed. If the interface gives an error, the device will need to be flashed. But the first thing you have to do is update the software.

Failed connectors usually contribute to the fact that the image quality is reduced or the picture completely disappears. There are no obvious software glitches or other signs of malfunction. If the problems are related to the connectors, they can be easily replaced by yourself - you can easily solder the part.

When a "white" noise appears on the screen, check first of all the RF IN output... If it is disconnected from the board, the lack of contact will lead to the fact that there will be clearly noticeable interference during the transmission of the image. All problem contacts should be soldered. It is important to take into account that broadcast noise is more dangerous for digital TV than for analog TV - a weak signal will lead to the fact that the picture will not be broadcast at all, and a corresponding notification will appear on the screen.

When using a cinch-RCA connection, it is quite easy to find a fault (assuming the cable is OK).... No picture while saving sound - breakage in the red socket. "Silent" transmission of the image occurs when a white or yellow input fails.

If the main units of the set-top box are in good working order, the check should be focused on the decoder. This element of the device is responsible for decoding the DVB-T2 signal. If it fails, the set-top box simply will not be able to decode the received signal. To establish the causes, you will need complex software diagnostics via a wired connection to the UART port. Through the Hyper Terminal utility, when connected to a PC, you can perform a check by setting the following values ​​for reading data from the device:

• stop bit 1;
• speed 115200 bps;
• parity - no;
• bit 8.

After entering all the information, you need to connect the receiver to be diagnosed to the power supply. If the firmware is broken, the system after processing the data will display the message: Error decompressing file. If the decoder itself is broken, it is not a software failure, the message will be different. It is advisable to change the hardware only in cases where the set-top box is expensive, it is easier to replace the cheap one. In the event of a software failure, it will be enough to reflash the entire device or the signal decoder itself.

There are several of these details in the construction of a DVB-T2 set-top box. They are responsible for supplying current with different characteristics to the processor of the device. It is possible to determine whether the failure is localized in the converters by starting the device. If the sound is faint and then stops altogether, the cause of the problem is most likely in the capacitor. Each converter will have to be checked for indicators of its rated current - characteristics should be within normal limits.

If voltage problems in the converters cannot be identified, you need to pay attention to the condition of the capacitor itself. Any change to its normal dimensions indicates a malfunction of the part. Also, contacts on the board can be destroyed.

Digital TV receivers are very sensitive to signal quality. If the decoder receives incomplete data, it will not be able to recognize it.... The decay rate of the wave in this case is also higher, which leads to its loss when the signal is unstable. The appearance of "noise" - interference in this case is very critical, problems arise not only in the antenna cable.

Localization of the reasons for poor signal transmission inside the receiver can be in the following nodes.

If the signal is lost from the very beginning, the chances of it arriving at the decoder are zero. Check the attachment point for damage.

If it is defective, the signal will be lost before it reaches decryption. You need to check the voltage on this element.

They are checked at the input and output section of the conductor going from the antenna input to the decoder.

If the contacts inside the device are broken, repairs will not be a very expedient solution. Soldering the damaged contacts will not solve the problem. A complete replacement of the conductor is needed.

Sometimes problems with the voltage supplied to the processor are due to a breakdown in the power supply. A separator installed in it will supply an unsuitable voltage to the converter in the event of a board failure. In this case, the device itself will work, but with great overheating. It is pointless to repair the power supply, it is easier to purchase a new one for replacement.

With minimal damage, broken connections can be restored by soldering at home. With the complete burnout of the contact areas, more serious repairs are required with the replacement of the board. Any mechanical parts - cracked housing, dropped buttons can be replaced without resorting to a workshop.

It is possible to repair set-top boxes at home, but subject to certain rules. It is better to disassemble the receiver for receiving digital television with your own hands on a specially prepared desktop, armed with a full set of tools.

The principle and scheme of work to eliminate the malfunction are selected based on the scale of the breakdown. Sometimes a receiver can only be repaired by replacing a part.

In the design of a digital receiver, the power supply is not represented as a separate remote element, but as a section of the board through which the current from the network passes through the cable. In this case, repairs can be made by connecting an external power supply unit to the device.

The order of work will be as follows.

1. Open the top panel. To do this, in the case, it is enough to remove 2 screws on the sides and on the back cover. The front insert is removable with latches. The board is attached to the case with screws at the bottom and back.
2. Remove the power cord. You won't need it. Prepare a replaceable 5V power adapter with a current of 1-2 A. You can cut off the input plug - the wire will be fixed by soldering.
3. Find the burn-out point on the board. If necessary, clean it from signs of damage to the part.
4. Find the point through which the mains power was supplied. Solder the contacts according to the available polarity values.
5. Lay the wire inside the case, bring out.
6. Connect the set-top box to the network through a new power supply. Connect to TV, check for operability.

If everything is done correctly, the device will work normally.

If, when dismantling the attachment cover, during a visual inspection, it is possible to identify electrolytic capacitors with traces of swelling, these elements should be replaced. To do this, you need the following.

1. Disconnect the device from the network.
2. Remove the printed circuit board. For this, the connecting elements are unscrewed in the housing. It is also better to remove the power cord for a while by removing it from the connector.
3. Unsolder part and pick up a replacement for it.
4. Install a new element with correct polarity. The "minus" on the capacitor is marked with a light-colored strip. On the board, it is marked with a shaded area.

Most often, replacement requires a capacitor at the input of the power supply. If, instead of a flat end, a spherical cylinder is observed, the part should be removed. Interestingly, it is the capacitor that is most often the cause of the problem in which the receiver does not respond to the remote control signals. After re-soldering the part, the malfunction will most likely be eliminated.

If the signal does not pass, a message appears on the screen about the absence of signal or services, the likely location of the breakdown will be the antenna socket. When the contact is loosened, this element is loosened under the influence of the plugs, interference appears. The problem can be easily eliminated by simply soldering all fasteners. This will restore broken connections.

When repairing set-top boxes at home, the main problem is finding replacement parts.

This works in the case of conductors, housing elements, buttons. A swollen capacitor, input or board is replaced with a new part or it is picked up on the radio market, in a service center.

You should not undertake repairs on your own only in a number of cases. Among the most pressing reasons, we note the following.

• Availability of a valid manufacturer's warranty... When you open the case yourself, the seals are broken in most cases. After that, it will no longer be possible to replace even a defective product under warranty. All that remains is to buy a new device. In the event of breakdowns in this case, you must immediately contact the service center recommended by the seller or manufacturer.

• The receiver is an expensive model. When the set-top box is a full-fledged media player with an extended set of options, DIY repairs can lead to the fact that the scale of problems will only increase. In addition, original spare parts for branded receivers are quite expensive, and their Chinese copies can ruin expensive electronics.

The expediency of self-repairing the set-top box is limited by a rather narrow set of its modules. You can rewire the inputs, flash the memory, change the power supply or the converter board.

When doing home renovations, it is important to carefully prepare your work area. You will need an insulating mat - it is convenient to lay out fasteners on it, to perform soldering. The list of mandatory tools must include screwdrivers, a soldering iron, a multimeter.

Repair of a TV set-top box (DVB-T2 receiver) is presented in the video below.