Set-top box (receiver) for TV
is an electronic device designed to convert a high-frequency signal coming from a television antenna into a low-frequency signal for a TV or monitor that is not capable of receiving a digital signal of the DVB-T2 standard directly.
The number of set-top boxes due to the transition to digital broadcasting in Russia has increased significantly, and like any electronic device, it can break down at any time. But, despite the variety of models, the operating principle and circuit design of all consoles are the same and they differ only in the presence of additional functions.
The set-top box is a minicomputer, and at first glance it seems beyond repair, but usually radio elements fail, which can be successfully replaced by a home technician.
In what cases is repair advisable?
Some breakdowns can be fixed quickly at home, without even resorting to a soldering iron. But I would like to immediately note the fact that the receiver is an affordable and cheap device. Sometimes the cost of repairs can exceed the cost of an analogue, which makes such repairs impractical.
It is not recommended to repair a digital receiver if it is a complex universal equipment. Usually they are stuffed with a couple of decoders to support several signal types, a bunch of inputs and outputs. If your receiver is just such a case, it’s easier to take it to a television repair shop.
Useful: Which set-top box to buy for digital television
FIRMWARE
As noted above, in some cases it is quite difficult to separate whether the firmware or the electronic part of the circuit is causing the malfunction without additional measurements. But if the tuner does not turn on after flashing the firmware, then the conclusion is clear: it is the one that 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.
If such a malfunction occurs, you need to contact a service center, although not every center undertakes such repairs.
What can go wrong and how to fix it
The DVB-T2 receiver consists of the following key elements:
- Inputs: RF IN and RF OUT connectors, HDMI port, LAN port for connecting to a network (if available).
- “Tulips” for sound and image output.
- A decoder for converting binary code into a signal.
- Voltage converter 220V to 5V, which is needed for the board to operate.
- Memory chip for storing firmware and containing all basic settings for TV.
If any of the above fails, you can try to repair the receiver. It is too difficult to repair the remaining elements of the board at home and in most cases it is not advisable.
Nutrition
If digital television malfunctions, you should always start diagnosing by checking the power supply (specifically, whether the current supply is working properly). Depending on the data received, further “receiver treatment” will occur. When power is applied:
- The indicator lights up statically and a startup sound is heard. The food works properly.
- The indicator is on, but there is no sound. Perhaps the sound on the processor has stopped. This fact is verified by calling multimedia. What values are shown on the CPU pins can be found in the device manual.
- The indicator lights up. This means that it is not working properly, or there is no current supply to the board.
Connect another lamp in parallel with the LED. If it lights up when power is applied, the LED is faulty. If it doesn’t light either, the reason is a faulty power supply.
Another cause of power problems is a malfunction of the board itself. In this case, a complete replacement of the device is recommended.
Repairing a DVB-T2 digital set-top box using a multimeter
If you have a multimeter, you can repair the set-top box faster and identify other faulty elements.
Checking the switching power supply
The top cover is removed and the set-top box is connected to the network. Next, the multimeter is switched to the mode of changing the constant voltage and its value is measured at the cathode of the Schottky rectifier diode relative to the common wire. It should be 5 V. The voltage can also be measured at the terminals of the capacitor, indicated by the number 1.
If the voltage is less than 4.8 V or absent, then the reason may be a malfunction of capacitors 1, 2, 6, the Schottky diode of the power supply or voltage converters.
To determine which half is faulty, you need to remove the cathode terminal of the Schottky diode (usually there is a marking in the form of a ring on the diode body near the cathode) from the board and test it with a multimeter.
If the diode is working properly, solder any electrolytic capacitor with a plus to its soldered terminal, and its second terminal to the common wire of the board. It is not recommended to turn on switching power supplies without a load, so you need to solder a resistor with a resistance of 50-100 Ohms in parallel with the capacitor.
Turn on the set-top box and measure the voltage on the capacitor. If it is equal to 5 V, then C1 or one of the voltage converters is faulty. C1 is soldered off and connected instead of the additional one. If voltage appears, one of the secondary converters is definitely faulty.
If voltage does not appear after the steps described above, then the power supply is faulty. In this case, you can still check capacitors 3, 2 and 6.
If the power supply cannot be repaired, then you can replace it with an external one, for example, an adapter for charging cell phones, which usually output 5 V. It is necessary, observing the polarity, to solder the positive wire of the adapter to the point of the soldered Schottky diode, and the negative wire to the common wire. I repaired my slow cooker in a similar way. The adapter must provide a current of at least 0.5 A.
Where to get spare parts for repairs
If you are comfortable with a soldering iron, and the practice of taking measurements with a multimeter is in your blood, start diagnosing the damaged receiver. If you find that your digital television set-top box has stopped working and you need to replace some spare parts, the best place to buy is the radio market.
Usually you can buy there:
- Small parts (LEDs, connectors);
- Buttons;
- Faulty donor and so on.
You can also go through secondary market advertisements on the Internet. The electronics sections are teeming with a variety of DVB-T2 set-top boxes.
How to identify a malfunction
Above we looked at many reasons and situations related to tuner malfunction. But the main question remains - how to understand that it is the digital set-top box that is not working. The main symptom is the absence of a red indicator light after plugging into a power outlet or the presence of dim light from the indicator.
In addition, a sign of a malfunction may be a sudden disappearance of the image after a certain time (overheating of the processor or power supply), as well as the absence of any image. If no recovery actions produce results, you must contact specialists.
Additional Tips
For diagnostics and minor repairs, the standard gentleman's kit for an electronics engineer is a screwdriver, a multimeter and a soldering iron. Carry out diagnostics and repairs if this is not a difficult process for you. It is not recommended to do this:
- When the warranty period for the device has not expired. Simply replace or repair the set-top box under warranty.
- If an expensive model fails. Typically, such set-top boxes have complex boards with many elements closely connected to each other. Without professional equipment and knowledge, it is better not to engage in self-repair, but to take it to a service center.
Repair of TV set-top boxes and receivers
Our Company repairs absolutely all receivers, tuners and set-top boxes for digital satellite television, we will definitely try to help you! In a set for watching satellite television, the receiver is the main and expensive unit. Tuner repair or repair of satellite receivers may be required both for models that have been used for some time and for completely new ones. Whatever the cause of the breakdown, the Nikom Service service center will diagnose your device and bring it back to life thanks to the many years of experience of our specialists, the availability of professional equipment, and the use of only original components.
Major failures of TV tuners and receivers:
Most often, the need to repair a TV tuner arises due to a breakdown of the built-in or external power supply. Replacing an external unit is not difficult, but it is still better to entrust all work with the unit integrated into the board to a specialist. Often, during the repair of decoders, it is necessary to replace capacitors or varistors that have become unusable, which fail after approximately 2-3 years of operation of the device. It happens that one or more microcircuits burn out on the board itself due to unstable voltage in the electrical network or a short circuit. Also, repair of a T2 tuner or other repeater will be necessary both in the presence of oxides on the board and capacitors, as well as in the event of failure of diode assemblies. Over time or as a result of breakdown, certain elements fail, but in the vast majority of cases the device itself can be restored. Our specialists from the Nikom Service service center will help you perform the necessary repair work on tuners in Moscow.
Repair of satellite tuners:
Repair of satellite tuners is often required due to breakdowns or malfunction of a special chip that controls and powers the converter directly on the satellite dish.
Channel decoders may also malfunction. Due to operation of the equipment in adverse weather conditions, the satellite tuner may also need to be repaired. After all, a lightning strike to an antenna often disables the entire set of equipment, including the receiver. A failure in the software located on a non-volatile flash card may lead to the need to repair receivers. However, its certain isolation does not guarantee the absence of failures, and a complete re-flashing of the device may be required. This procedure for repairing T2 tuners and other types of similar devices requires a professional approach, the presence of certain knowledge, skills and equipment. Each model requires its own version of the Software. By the way, the reason for repairing the tuner can be a breakdown of the memory chip itself.
It is worth noting that you should look for faults not only in the device itself, but also in the remote control. Remote controls are much more likely to be dropped, which can damage the quartz resonator. Also, due to low-quality components or their wear, T2 or any other signal repeater may be subject to repair. To definitely find out the cause of a device failure, you need a complete diagnosis, and for this you need special equipment. Most users of consumer electronics, after their failure, tend to buy new ones, assuming that the new equipment will work for a long time and will never break. But often with the development of the range of equipment and the increase in the number of manufacturers, the quality of new equipment leaves much to be desired. Many modern electronics manufacturers are trying to cut costs and optimize production, so the quality of materials and software often suffers.
Repairing a satellite receiver is always cheaper than buying a new one!
1) when repairing equipment, you pay a third or even a quarter of the cost of a new one 2) repaired equipment lasts a long time, because weak elements have already been replaced 3) owners often get used to their equipment, there is no need to learn a new one 4) new equipment has become much more expensive (2 times) recently 5) you always have time to buy a new one, repair the old one - it’s still good 
Bring your tuner in for repair, we will definitely try to help you! We will give your equipment a second life!
REMOTE CONTROLLER
Many cheap models of set-top boxes do not have control buttons on the front panel, and this is a significant disadvantage since if the remote control malfunctions, you will be unable to control the tuner at all. This has already been written about on the website in an article about choosing a console.
Therefore, if the remote control for a digital set-top box does not work, only purchasing a new one or a repairman will help identify it. Unfortunately, remote controls for tuners are still rare and quite expensive.
It happens that the tuner does not turn on from a long distance; here, both the tuner and the remote control itself may be to blame (which is rare). You can try replacing the batteries, but if that doesn’t help, buy a new one. If in this case there is a negative result, then the prefix is to blame.
Once again, without special skills, it is difficult to solder the parts yourself, which can cause great harm to the board.
