What to do if the digital set-top box does not work? A set-top box for digital television is a repair that is not possible for a professional Dvb t2 dc100 1hd electrical circuit.

Since there are no freely available schemes for them and apparently there will not be, manufacturers answer with silence or formal replies about certified centers that are licensed to repair a particular brand. 1. RECEIVER DOES NOT TURN ON; The LED blinks or is dimly lit, or does not light at all - We supply 5 volts from an external source (with an output current of at least 1.5 amperes) to the PSU output capacitor, observing the polarity, see if the receiver starts up, if so, then we repair the PSU. Most often, the PSU output capacitor needs to be replaced, we put a new 1000 uF 16 V, although more often they cost 1000 uF 10 V 2. There are 5 volts, the receiver does not start - we check the secondary power converters (five-footed with inductances nearby), we measure on inductances 3.3 1 ,8 1.15 volts, if not, we change the microcircuit Information on "five-legged" can be found on sites such as monitor, etc. P. (firmware has flown) - we flash the flash memory chip 25Q32 4. DOES NOT CATCH CHANNELS - reset to factory settings, re-search, change the quartz resonator in the tuner (if available), after making sure that the antenna is working. If it doesn’t help, most likely the problem is in the tuner, demodulator or processor microcircuit, repair is impractical, especially for non-professionals, for scrap ... DO NOT Rush TO CHANGE THE FIRMWARE, in this case you can get unnecessary problems on your head, without experience this often leads to a programmer . 5. NO COLOR ON THE ANALOGUE OUTPUT - change the quartz near the processor. 6. The image jumps and twitches, the color is distorted - we change the capacitor located at the rear wall near the analog outputs. 7. There is no signal through the analog output, but there is through hdmi, the cord is in order, the socket is also - most often associated with burnout of the analog signal outputs from the processor in the absence of buffer protective elements of the circuit. in the presence of buffer elements (more often installed via sound channels) - check their serviceability. If there are none, then either viewing via HDMI, or junk, well, or replacing the processor ... Do not connect the set-top box to the TV when it is on! 8. The receiver turns off by itself - look in the menu in the advanced settings for the item responsible for the sleep timer, or shutdown when idle, it can be called differently! 9. When you try to update the firmware from the air, the receiver freezes - leave it on for half an hour, the receiver, not finding the update, will reboot and continue to work in normal mode. 10. The receiver reboots when you try to search for channels or insert a USB drive into it - most likely, the matter is in the "five-legged" secondary converters and the quality of their strapping, a good voltmeter and oscilloscope are desirable.

Reflect Digaital digital TV set-top box repair manual

Capacitors:

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

Capacitors in the power supply:


These two capacitances affect the performance of the power supply. The PSU either does not work at all (the output voltage is 0V) or gives a low voltage of 1.7V.
Tank 2 swells - you can see or the insides come out from below.

Voltage measurements:


1. PSU output - 5v
2. AMS1117 output - 1.8 V, if there is no such value - go to point 3
3. It 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, but even if there is so much, the problem is still, most likely, in the capacitor - it is better to change it. In this case, nodes 2 and 3 show normal stress values. This is the case when the receiver starts to boot and cannot finally do it - the problem is in the capacitor of node 4. AS11D in this node is also not excluded, but the probability of its failure is very small compared to the probability of a bad capacitance.
THE BIGGEST NUMBER OF FAULTS IS ASSOCIATED WITH TANKS 8 AND 9 (SEE 1 PHOTO) IF EVEN THE PROBLEM IS NOT IN THEM, THEN WE CHANGE THEM AS A PREVENTION.

The most common malfunction of digital television set-top boxes is the failure of the power supply. In such an unpleasant case, it is very good if the set-top box model was with an external adapter, buy a new one and look further! And if not! And the power supply was built into the console itself? Then you have to repair or buy a new one. But perhaps there is an easy way out!

Hello dear readers! In this article, I want to share one simple repair that anyone who knows how to hold a screwdriver and a soldering iron can do! Moreover, it is not necessary to master these tools masterfully.

I'm also not going to tell you anything overly complicated from the field of electronics repair, this is the lot of professionals. On the contrary, I will try to describe everything in such a way that even a non-specialist could cope and eliminate this malfunction.

I’ll make a reservation right away that this method is not suitable for all models of set-top boxes, but for many, since they are often made according to a very similar scheme for this case. Everything will be on a specific example of a set-top box from D-Color, namely the DC1401HD model. So by understanding this "high technology" you can repair your digital TV set-top box yourself.

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Do-it-yourself console repair

What is a sign that it is the power supply that has failed in the set-top box, and not something else? If the set-top box connected to the outlet does not show any signs of life, neither the digital indicator nor the LED on the front panel is lit, then with a probability of 99% the reason is in it, in the power supply.

If at the same time the warranty period has already expired, then you can safely do the disassembly. As experienced craftsmen say, “An autopsy will show” I think you will deal with this part of the work without a detailed description, just be careful, usually two screws on the back wall, sometimes also on the sides, allow you to release and open the top cover. Plastic latches on the sides and bottom hold the front panel, and the board itself is also fixed with screws to the bottom of the case and in the area of ​​​​the connectors on the back of the case.

So, the set-top box is disassembled, the power cord is also removed from the connector, it will no longer be needed. On the bottom of the case, traces of the “fire” are visible, which was left behind by the burnt power supply.

P.S. The power supply here is not a separate unit, as you might think from the name, but a section of the board on which radio elements are located that provide the necessary supply voltage to the set-top box.

What is the transformation

I will outline the general picture, and for those who are already a little versed in radio engineering, this will already be enough to catch the basis of the idea and repeat. So, the power circuits of this set-top box give out only one voltage - 5 volts. Since this circuit burned out and repair may not be feasible (in terms of the cost of radio components and repairs), that is, a simple solution. Replace the internal power supply with an external one. It's not very difficult!

In the photo above, the section of the PSU that has failed is highlighted with a yellow frame. The board has already been washed, so no traces of burning are visible. By the way - Among repairmen, the expression "Burned out" does not always mean literal burning with charring and other similar manifestations, it only means that the radio components are out of order.

For our repair, you will need to purchase an external power supply with an output voltage of 5 volts and capable of delivering a current of 1.5 or better 2 amperes. Now you can buy a lot of these and not expensive, or maybe you have a similar one, for example, an unused charger from a tablet or smartphone.

When a suitable adapter is available, it remains to find the desired point on the set-top box board and, observing the polarity, apply voltage to it from an external power supply. Everything! It remains to lay and secure the wire, or you can organize a detachable connection, as you like. I think the basics are clear, let's get down to the details.

A little acquaintance with the power supply circuit of the set-top box

Just a little background for those who are not in the subject, so that you can figure it out. Pay attention to the photo. Click to enlarge.

In short, the power supply consists of:

• Primary "Hot" part - Hot it is called because it is dangerous, connected with the mains voltage of 220 volts. Please note that even after unplugging from the outlet, for some time, there is a charge that can bring brr.. 😯 unpleasant sensations if you climb there. But in our case, you don’t need to climb there and we won’t connect it to the outlet either.
• Secondary part - It is safe there, there is a galvanic isolation from the mains. In the above example, at the points indicated in the photo, a voltage of only 5 volts comes out of the rectifier diode.

Let's get down to business

In the purchased, external power supply (at least 1.5 amperes, 5 Volts.), we bite off the plug, strip the ends of the wires and determine the polarity, solder them: Positive to the output of the diode, on the side where the strip is drawn on it, and negative to the common bus - the case of the USB port will be a convenient place for this. If you don’t know how to determine the polarity, even without a device, see additional materials at the end of the article.

We connect a new power supply to the network, remove it from standby mode, check what happened.

All OK! It remains to lay and secure the wire so as not to accidentally pull it out, put everything together and use it. In the end it will look like this.

If you need ideas on how to fix the wire to the body of the set-top box? How to determine the polarity without a device? Or how to solder a wire to the underside of the board? — Then these additional materials are further down the text.

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 PSU 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 is 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.

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.

Attachment repair process

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).