I have two TVs in my house and they both work through Cadena dvb-t2 set-top boxes, and it turned out that at about the same time they both stopped working. Repairing such a set-top box costs approximately from 600 to 800 rubles, a new one costs from 1200, which turns out to be both expensive. It was decided to try to fix it myself, to do this, by 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 broken console:
- when you turn on the set-top box, the red indicator lights up and the set-top box no longer responds to anything.

Set-top box repair process

First of all, we disassemble the console and carefully examine its insides, special attention should be paid to the 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 unsolder the capacitor, look at the parameters and look for a suitable one. In this case, 10 volts and 1000 microfarads, as well as 105 degrees Celsius, are required. But in my case, there was only 10v1000mf and 95Hz available, and it is a little smaller in size, but as practice has shown, it works great.

Now we solder the new air conditioner in place of the old one and, as you can see in the photo, everything is fine. (marked in blue).

We check the attachment for functionality and put the case back.

What to do if the digital set-top box does not work?

If your DVB-T2 digital set-top box for receiving terrestrial digital TV has stopped working, then in some cases you can solve the problem yourself. In this article we will describe the most common problems that arise when using digital set-top boxes. You will also be able to determine whether viewing problems are a defect in the set-top box itself or whether it is an issue with the antenna or TV.

The set-top box does not turn on

This is one of the most common failures of digital broadcast set-top boxes. It manifests itself, as a rule, in two variants: the receiver shows no signs of life at all, or the red standby indicator is on, but the set-top box does not go into operating mode. Most receivers start working immediately after being plugged in and do not require turning on from 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 technology and digital set-top boxes are no exception. The power supply may fail completely - in this case, not a single indicator on the set-top box lights up at all and the device does not react in any way to being connected to a 220V network. But it often happens that the power supply produces too low voltage or current. In this case, the tuner “tries to turn on” by showing 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 it’s easy to solve this problem yourself. Power supplies for set-top boxes are usually standard and interchangeable, even across different models and manufacturers. You just need to make sure that the new power supply produces a voltage of 5V and has the same plug at the end of the wire as the old one. You can buy one in specialized stores that sell 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 resolved.

It is more difficult if the power supply is built into the console. A characteristic feature of the internal power supply is a regular plug at the end of the wire. In this case, the power cord is not disconnected from the set-top box itself, as is the case with the external version. In this case, it is best to contact a service center for repairs.

The image freezes shortly after turning on the console

This defect is quite rare, but if it is detected, repairing the receiver is most often impractical. A clear sign of such a malfunction: the appearance of image distortion and “freezing” of the picture, which appears 5-20 minutes after turning on the digital tuner, after which the problem does not disappear. Similar symptoms also occur when the signal from the antenna is weak, but in the latter case, image distortion does not have a clear connection with the operating time of the DVB-T2 receiver.

The problem could be the same power supply or overheating of the processor. If the power supply is external, you can try connecting another power supply. If not, then the problem is in the processor itself and repairing the product in this case is impractical.

Repair manual for digital TV set-top boxes Reflect Digaital

Capacitors:

1 – Problems with the image on the AV output (no image, noise in the picture), sound clicking.
8 – Does not start – hangs on boot; The splash screen appears, and then the blue screen again. In this case, the capacitance, when measured, can correspond to the nominal value (low ESR of the capacitor).
9 – Doesn’t turn on – no image at all
13 – seems to slow down too
14 – the picture slows down, the image blurs.
15 is the same as 14, but 14 is more important.
“does not pick up channels” - quartz between C13 – C15

Capacitors in the power supply:


These two capacities affect the performance of the power supply. The power supply either does not work at all (output voltage 0V) or produces a low voltage of 1.7V.
Container 2 swells - you can see the insides coming out from below.

Voltage measurements:


1. PSU output – 5V
2. Output AMS1117 – 1.8 V, if there is no such value – go to point 3
3. There should be 3.3V, if not, then the problem is in the capacitor nearby or in the AS11D itself
4. There should be 1.34 V here, but even if there is that much, the problem is still most likely in the capacitor - it’s better to change it. In this case, nodes 2 and 3 show normal voltage values. This is the case when the receiver starts to load and cannot completely do it - the problem is in the capacitor of node 4. We cannot exclude AS11D in this node, but the probability of its malfunction is very small, compared to the probability of a bad capacitance.
THE BIGGEST NUMBER OF PROBLEMS ARE CONNECTED WITH TANK 8 AND 9 (SEE 1 PHOTO) IF THEY ARE NOT EVEN THE PROBLEM, THEN WE CHANGE THEM AS A PREVENTION.

Since the late 90s of the last century, audio-video technology has evolved greatly. From VCRs and DVD players, CD and MP3 recorders, to omnivorous media players that allowed you to read media files from a USB flash drive. Such devices at one time cost 3-4 thousand.

Now every DVB-T2 receiver can do this. The receivers are quite cheap - from 900 rubles, and in addition to reading media files from a flash drive, they allow you to watch television for free in digital quality, even if only 20 channels. And everything would be fine if the Chinese, in pursuit of cheap devices, did not put low-quality parts there. I have had cases where, in a receiver with a built-in power supply, after 2 years of operation, a small electrolytic capacitor had .

Small electrolytic capacitor

And accordingly, the receiver did not turn on, after measuring the equivalent series resistance with an ESR meter, and replacing the three-ruble capacitor, everything returned to normal and the receiver turned on. But this, as they say, was just luck. Much more often, DC-DC converters burn out in receivers. Sometimes, fortunately for the user who decides to independently repair the set-top box, stabilizers with 3 legs are installed instead; replacement is not difficult, but sometimes the boards have unreliable five-legged converters, and we will analyze this case. There are 3 of them there - small microcircuits in the SOT-23-5 package.

Chip Converter - drawing

They produce, respectively, 3.3 volts, necessary to power the RAM chip, 1.8 volts and 1.2 volts, necessary to power the processor.

Converter chip dimensions

It is easy to determine where the output of the microcircuit is, even without having a datasheet for this microcircuit; the output of the converter can be connected by a track to the inductor necessary for the operation of the converter. You can familiarize yourself with one of the typical converter circuits by looking at the figure below:

What if your set-top box refused to turn on, you opened it and, after ringing, found two or more terminals in a short circuit or low resistance? Such converters, due to the fact that their wiring is sometimes individual and incompatible with other types of converters, it is necessary to replace them strictly with exactly the same ones, or, in extreme cases, with complete analogues taken from the datasheets.

Converter chip pinout

The connection diagram, component ratings, output current, and, of course, the output voltage must completely match. I received one of these set-top boxes for repairs with the 3.3 volt converter power input punched to ground. A quick search in radio stores in our city showed that we have neither such a microcircuit nor complete analogues anywhere.

The fact is that for design on Arduino and microcontrollers, special small-sized boards of converters and stabilizers are produced in China, immediately with the necessary kit soldered on the board for their operation. These are AMS1117 stabilizer chips familiar to many electronics engineers.

AMS1117 stabilizer chips

These microcircuits are produced both adjustable, which in this case is unnecessary for us, and with a fixed output voltage, but we are interested in voltages of 1.2, 1.8, 3.3 volts. For all these voltages there are ready-made converter boards based on these stabilizers. How can you distinguish converter boards if, for example, you bought them earlier and forgot what voltage they were for?

On the case of the microcircuits, in addition to the model name, for stabilizers for a fixed voltage, the voltage that will be at the output of the converter is written, that is, the same 1.2, 1.8, 3.3 V we need. How to place these converters in the receiver case? They won’t take up much space, I wouldn’t think twice, I soldered the MGTF to three of the contacts on the converter board, there are 4 in total: input plus power, output plus power, and two contacts, a common ground for input and output.

I think it’s clear why we use three out of four contacts. How can we check ourselves whether we have found the correct pinout of the microcircuit, if the Chinese datasheet found, for example, raises doubts? Call the output indicated by the datasheet Vin, often if the set-top box comes with an external power supply, it is directly connected to the power socket. Also, between the ground and the power input, an electrolytic capacitor is often installed on the board, 220 uF x10 or 16 volts.

Capacitor 220 x 25 volts

The plus of the capacitor is connected to the power input of the converter microcircuit. What if you don’t know what output voltage this converter was for, that is, what voltage do you need to buy a converter for? You can try, after dismantling the burnt microcircuit and cleaning the contacts on the board from solder, apply power to the receiver and measure the supply voltage on the two remaining converters. And determine the voltage at the output of the remaining microcircuit by elimination. Solder this burnt-out converter using a soldering gun, or by applying a drop of solder, Rose or Wood alloy to all contacts, and warming them up quickly alternately with a 25-watt soldering iron.

If you are sure that the converter has burned out and are not afraid of burning it with the high temperature of the tip, during dismantling, you can apply a little ordinary POS-61 solder to all contacts and alternately heat the 40-watt terminals with a soldering iron, trying to move the microcircuit. If, after desoldering, it turns out that the short circuit was “underfoot” on the board, and not in the microcircuit, to finally make sure of this, you need to clean the contacts of the old soldered converter from solder using a dismantling braid, applying alcohol-rosin flux to the contacts with a brush (SKF).

Alcohol rosin flux SKF

Then we simply place the braid on top of the contacts and heat the leads on top of the braid with a soldering iron. Our solder will transfer to the clean braid. For better absorption, the tip of the braid can even be dipped in alcohol-rosin flux. As the solder is absorbed, the tip of the braid should be cut off and the procedure repeated from the beginning. The same should be done with the contacts on the board remaining after the soldered converter.

Dismantling braid

There, as usual, we will be left with “snot” from the solder applied during dismantling - they must be removed. Then you can solder the MGTF wire connected to the contacts of the converter, finding from the datasheet for this chip where we have the power input, where the output is, and where the ground is. It will be possible to check, as I wrote above, the contact connected to the ground by the power supply minus, we can call by touching either the polygon on the board, or if you are a beginner and are not sure of the correctness of the connection - the metal case of the USB connector.

Ethyl alcohol photo

After everything has been soldered, do not rush to connect the set-top box to the network, wash off traces of flux with alcohol, especially if you never know, you used a low-active flux, which in this case is a prerequisite for long-term operation of the device. Then look under a strong magnifying glass or take a photo with a phone with a good camera and make sure that you haven’t put “sniff” on the adjacent contacts, because they are located quite close to each other.

Multimeter in audio mode

To be completely sure that there is no short circuit, or if you couldn’t find a strong magnifying glass, test all adjacent contacts relative to each other for short circuits with a multimeter in audio testing mode. All these procedures with replacing the converter make sense only in one case - if, after checking the datasheet, you did not find a short circuit of the power input pins to the power output, since in this case your processor or RAM chip has already burned out due to the supply of an excessive supply voltage.

Which, of course, is sad, since then it will be impossible to repair it either at home, or even in a good workshop, due to the laboriousness of the repair and its high cost - higher than the cost of a new set-top box, it will not make sense.

Conclusion about the work done

Any more or less trained radio amateur can easily cope with this repair, and due to the low cost of the board for replacing the converter, it can be recommended as a means of albeit a “collective farm”, but very budget solution, in the event that a thrifty radio amateur does not have extra funds for buying a new console. Or you simply have a desire to prove to yourself that sometimes it is quite possible to carry out repairs of complex digital equipment on your own. Happy repairs everyone! AKV.

I decided to give my parents a gift - to organize digital TV at home, since regular terrestrial (analog) TV was not very well received at a distance of 5 km from the transmitting tower. I spent a long time reading forums and choosing, visited the store - it turns out that the receivers that come on sale are sold out very quickly, I had to order through the store’s network (it arrived the next day). As a result, the device was selected and purchased Oriel 821 (DVB-T2). Its characteristics and specifications according to the manufacturer:
General characteristics

Type digital TV tuner
External version
Connection type: stand-alone
No video capture
No FM tuner

Video characteristics

Support HD 720p, 1080i, 1080p
Output video format 4:3, 16:9
Digital standards DVB-T, DVB-T2

Inputs and outputs

Audio outputs, HDMI, component
No firewire

Other features and functionality

Teletext available
There is a recording timer
There is a delayed viewing mode
USB 2.0 with recording support;
Coaxial digital audio output.

It turns out that for a small price (the device cost me 1,400 rubles), we get not only a digital receiver, but also a media player from a USB drive.

With a 32 GB drive - it works great, reads all the movies that I downloaded - 2-5 GB without any freezes, everything is fast and clear, I checked it on my 32-inch TV (parents of course don’t need this, they have a CRT TV, but it still became interesting).

The 21st century is making itself felt, the device is universal and you can watch a lot of things. I am pleased with the good and convenient control panel, the presence of buttons on the front panel, a bright informative display that shows the activation and channel number, as well as the time when necessary, there is an LED.

You can connect the device to almost any modern TV, since the back panel has a rich selection of connectors.

During operation, the device gets quite hot, which is probably due to the compactness of the entire device inside a small case, so it is advisable to install it away from heat sources and ensure good air circulation.

An antenna is required for the device to operate. The choice fell on ROLSEN 160 - its characteristics from the manufacturer’s website:

UHF/VHF/FM signal reception
Frequency range VHF 87.5-230MHz, UHF 470-862MHz
Adjusting the signal level
Variable tilt angle
Maximum gain VHF 30dB, UHF 36dB
Output level 100dB?V
Impedance 75 Ohm
Noise figure< 3dB
HDTV, DVB-T, DAB/FM signal reception
Power supply DC 6V/100mA.

Power is supplied via the power supply that comes with the antenna, but you can also use the supply voltage supplied via the TV cable by selecting the desired item in the receiver menu.

Description of the antenna from the manufacturer's website: is a worthy functional replacement for bulky outdoor antennas and a modern stylish gadget that will complement the interior of your apartment. The design of the RDA-160 is specially designed to allow it to be placed in any, even the most prominent place. It looks modern, stylish and organic in any home interior.

The devices provide high-quality reception of both analogue and digital television signals, as well as radio signals (FM range).

Indoor antennas with an amplifier provide a high-quality signal over long distances (including in urban environments). They can be placed away from windows.

For ease of settings and better image quality RDA-160 are equipped with a regulator with which you can set the required signal reception level.

I was able to receive all the digital channels broadcast in the city (10 pieces + 3 radio channels) after I set everything up and figured it out. Everything is in Russian: instructions, menus, and descriptions, so it’s quite a good choice. I was with you redmoon .