I have two TVs in my house and both of them work through Cadena dvb-t2 set-top boxes and it turned out that at about the same time both of them stopped working. Repair of such a set-top box costs from about 600 to 800 rubles, a new one costs from 1200, it turns out to be expensive anyway. It was decided to try to fix it on my own, for this "googling" the Internet, a solution was found, which I want to show you. As it turned out, this is one of the main breakdowns.
The main symptoms of a breakage of the console:
- when the set-top box is connected to the network, the red indicator lights up and the set-top box does not react to anything anymore.
First of all, we disassemble the prefix and carefully examine its insides, special attention should be paid to capacitors. As shown in the photo (circled in red), the capacitor is swollen, unlike the capacitor (circled in blue), therefore it is no longer working and needs to be replaced.
Then we solder the capacitor, look at the parameters and look for the right one. In this case, 10 volts and 1000 microfarads are needed, as well as 105 degrees Celsius. But in my case, only 10v1000mf and 95Hz were available, and it is a little smaller in size, but as practice has shown, it works great.
Now we solder the new condo in place of the old one and, as you can see in the photo, everything is fine. (marked in blue).
We check the prefix for operability and put the case back.
The fleet of analog TVs is rather reluctant to give way to digital equipment, gradually taking “second” places - in the kitchen, in offices, workshops, garages, etc. At the same time, DVB-T2 set-top boxes and decoders are being transferred. We have already managed to evaluate the advantages of the latter, while some owners also appreciated the disadvantages - the rather low reliability of these devices. As a rule, one of the weakest points of this kind of equipment is a switching power supply - most cases of failures are associated precisely with a malfunction of the power supply, and a PSU failure can lead to such serious consequences that it will be impossible to repair the device. And yet, using the example of two set-top boxes for receiving digital TV, the possibility of repairing them independently will be considered here. The first device is TVK 3101. When turned on, the image had strong distortions, periodically completely disappeared. A few days later, the set-top box began to turn off a few seconds after the manufacturer's logo appeared on the screen.
The second device is the Oriel 740 prefix. This device did not respond to commands from the remote control, the indicator barely noticeably glowed red.
After opening the cases of the set-top boxes, it turned out that in both cases the electrolytic capacitors of the secondary power filters were swollen.
It should be borne in mind that when working with the attachment, special care should be taken - the primary power supply rectifier of the power supply unit converts an alternating voltage of 220 volts into a constant value of about 300 volts, and this potential remains at the terminals of high-voltage electrolytic capacitors for some time after power is removed - up to several tens of seconds . In the pictures, they are located between the pulse transformers and the plugs of the power cords. Before working with the device board, these capacitors must be short-circuited through a resistor with a resistance of 51-62 kOhm.
Both faulty capacitors turned out to be almost the same - 1000 uF, 10 V. The picture shows one of them. The fact that its cover is barely deformed in appearance should not give you the slightest confidence that the part is in good condition - even if some part of the container has been preserved, such a part will have an increased leakage current, which is unacceptable. When replacing, you should select capacitors with the same operating voltage or with a slightly higher one, as in the picture - instead of a 10-volt part, a 16-volt part is shown, and with the same dimensions. Of course, defective parts should be replaced with new ones, not used ones - otherwise the repair will have to be repeated soon.
After the replacement, turn on the set-top box - the indicator lights up brightly, the device responds to the commands of the remote control, the image is stable. But the repair is not over yet...
Traces of flux remained on the board - solder paste, rosin ... High-frequency currents can quite easily pass through such a coating wherever they please. As a result, we can get an unstable image, noise, etc. over time. trouble. Therefore, carefully wash the board with a cotton swab moistened with alcohol or acetone. After such cleaning, wipe the board with a dry cotton swab
We install the board in place, check - it works.
Now we assemble the prefix completely and once again check the performance.
Similarly, we check the second device - the device is working normally, the repair is completed.
In conclusion, I will add that the quality of the power supply of the antenna amplifier also greatly affects the operation of the set-top box. So, with insufficient capacity of the filtering capacitor, signal loss is possible - there have been cases of complete loss of the channels of the second multiplex. To recognize a malfunction of the antenna PSU, it is enough to replace it with a DC source with a voltage of 9-12 volts (for example, a Krona battery or a battery from a computer uninterruptible power supply). If the reception quality improves, then you should replace the antenna power supply with a known good one.
If your DVB-T2 digital set-top box for receiving terrestrial digital TV has stopped working for you, then in some cases you can solve the problem yourself. In this article, we will describe the most common problems that arise during the operation of digital set-top boxes. You can also determine if viewing problems are a defect in the set-top box itself or if the antenna or TV is the problem.
This is one of the most common breakdowns of digital terrestrial set-top boxes. It manifests itself, as a rule, in two versions: the receiver does not show any signs of life at all, or the red indicator of the standby mode is on, but the set-top box does not switch to the operating mode. Most receivers start working immediately after plugging in and do not require turning on with the remote control. If this does not happen, then it is most likely that your power supply is faulty.
The power supply is a weak point in any technique, and digital set-top boxes are no exception. The PSU can fail completely - in this case, not a single indicator lights up on the set-top box at all and the device does not react in any way to connecting to a 220V network. But it often happens that the power supply produces an underestimated voltage or current. In this case, the tuner "trying to turn on" giving some signs of life, but does not go into operating mode.
Solution to the problem: If the power supply is external (as in the picture), then solving this problem is easy and on your own. Power supplies for set-top boxes are usually standard and interchangeable, even from different models and manufacturers. It is enough just to make sure that the new power supply outputs a voltage of 5V and has the same plug at the end of the wire as the old one. You can buy this in specialized stores selling antenna equipment. In most cases, you can ask the seller to connect the power supply to your receiver and make sure that the problem is solved.
It is more difficult if the power supply is built into the console. A characteristic feature of the internal power supply is a conventional plug at the end of the wire. In this case, the power wire is not disconnected from the set-top box itself, as is the case in the external version. In this case, it is best to contact a service center for repair.
This defect is quite rare, but if it is detected, the repair of the receiver is most often impractical. A clear sign of such a malfunction: the appearance of image distortion and a "freeze" of the picture, which appears 5-20 minutes after turning on the digital tuner after which the problem does not go away. Similar symptoms also occur with a weak signal from the antenna, but in the latter case, image distortions do not have a clear connection with the duration of the DVB-T2 receiver.
The problem may be in the same power supply or processor overheating. If the power supply is external, you can try connecting another PSU. If not, then the matter is already in the processor itself and repair of the product in this case is impractical.
Set-top boxes of digital television entered our lives not so long ago, but in addition to positive aspects, they cause a lot of criticism from the side of quality. It is still too early to talk about some statistics and how much they work out for failure, but already now there are quite a few cases of failure in the operation of these TV set-top boxes.
I will list some of the most common malfunctions in which the prefix refuses to work:
The reasons why the tuner does not turn on can be divided into several groups:
In case of any breakdown in the circuit, it can manifest itself in different ways, but the worst thing is that with the same manifestations, the reasons can be completely different. For example, when the tuner is connected to the network, the red light (network indicator) is on, but it does not go further than this, that is, the set-top box does not respond to the remote control and control buttons. This case may apply to any of the groups listed above.
The purpose of the article is not to analyze the device of the set-top box and how to repair it, but to give an idea of how at the first stage to try to independently diagnose and draw any conclusion about the malfunction. If there are no repair skills, you need to contact the repair service, since repairs require not only knowledge, but also special equipment.
It all depends on the quality of the circuit elements, so well-known brands producing DVB T2 tuners that use a higher quality element base are more preferable.
The easiest way to diagnose a breakdown is when the indicator (light on the panel) does not light up. This clearly indicates a malfunction of the power supply.
If the light is blinking, this can indicate both a malfunction of the PSU and the chassis (this is the main board with a tuner and processor) of the set-top box, as well as a firmware failure.
In the case when the device spontaneously, repeatedly reboots and does not turn on, all the same elements of the set-top box can be to blame. You can read about such repairs. If the display reads “ON” and the indicator is green, and the set-top box does not turn on, then this may also indicate a malfunction of the circuit.
As noted above, in some cases it is rather difficult to separate what exactly is the cause of the malfunction of the firmware or the electronic part of the circuit without additional measurements. But if the tuner does not turn on after the firmware, then the conclusion is unambiguous, it is she who is faulty.
Here you need to warn that you need to be careful when updating, follow the instructions and install exactly the firmware that is required for your device.
With such a malfunction, you need to contact the service, although not every center undertakes such repairs.
On many cheap models of set-top boxes, there are no control buttons on the front panel, and this is a significant minus, since if the remote control malfunctions, you lose the ability to control the tuner at all. This has already been written on the site in an article about choosing a prefix.
Therefore, if the remote control from the digital set-top box does not work, only buying a new one or a master will help to identify it. Unfortunately remotes for tuners are still rare and quite expensive.
It happens that the tuner does not turn on from a long distance, both the tuner and the remote control itself (which is rare) can be guilty here. You can try replacing the batteries, but if it doesn't help, buy a new one. If in this case there is a negative result, then the prefix is \u200b\u200bto blame.
Once again, without special skills, it is difficult to solder parts on your own, which can cause great harm to the board.
The exact causes of the breakdown can only be identified after diagnosis. In addition, this will make sure that all other elements are working and will not fail in the near future. When making an application, it is recommended to indicate a visible malfunction of the TV tuner.
Our workshop "TVF" has been operating for a long time and serves many customers who leave a lot of positive feedback. For a long time of work, we were able to accumulate invaluable experience in the repair of receivers and form a professional team.
To carry out the repair of digital television set-top boxes, you need professional tools. In our work, our masters use only high-quality consumables and spare parts. All services are guaranteed.
