In detail: do-it-yourself repair of satellite tuners from a real master for the site my.housecope.com.
Let's consider some of the nuances of the repair in more detail. If the receiver works, but not correctly, then at the beginning of the repair, first of all, you should check (or reinstall again) all the necessary software settings of the equipment. If this does not help, we proceed to check the antenna-feeder path - we check the antenna settings (whether it has moved, is there any damage or deformation). Next, we check the converter and the lead-in cable.
The converter can be checked using Satfinder or another receiver - if there is a problem in it, you will have to spend money on buying a new one (although some, especially inquisitive home-builders, manage to cut the internal silumin case of the converter and get to its insides). I would especially like to draw your attention to the choice of an antenna cable - the use of a low-quality (China or Poland) antenna cable of the RG-6U type can lead to very serious consequences.
This cable does not stand up to any criticism - the outer insulation can be torn off by hand, a violation of the insulation at least in one place leads to the fact that the inner sheath of the cable is filled with water! The use of bimetal as a material for the central core leads to corrosion in the first season. As a result of external factors, the cable may fail in a week (there have been cases!) After installation. Professionals in the field of satellite reception will advise you to use a cable from the Italian company Cavel, which is much more expensive than a proven cable from domestic manufacturers, also suitable for use.
The most common malfunction of a satellite receiver is a malfunction of the power supply, as the most unreliable part of any electronic equipment. The power supply generates voltages to power the internal circuitry of the receiver as well as to power the external LNBs and the drive (if installed). We start repairing the power supply unit by checking the fuses and protective breaking resistors. Burning out of these parts does not necessarily indicate a malfunction of the circuit - it may have happened as a result of a surge in the AC mains, or these parts originally had a manufacturing defect. If the malfunction was not eliminated, we begin to "dig" further. To do this, consider the principle of operation of a pulsed power supply unit on a block diagram.
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The equipment of European manufacturers in this regard is certainly out of competition (in comparison with Chinese) - the simplest receiver shown in the picture (with the cover removed) from the German company Golden Interstar has been working without repair in my dacha for many years. Consider all the above criteria for choosing equipment and you will not have to repair it!
During operation satellite receivers Globo, Bigsat, Allsat, Yumatu, Lumax, Digital, Boston and others like them, one malfunction inherent in all of them was noticed:
the tuner does not start, the front panel LED is on, and the digital display is off or flickering weakly. The reason for this behavior of the tuners was a malfunction of the power supplies in the + 3.3V circuits, much less often in the + 5V circuits.
In more than 90%, the reason was poor quality capacitors (C15) of the power supply in 3.3 volt circuits.
It is important to remember that the stabilization of the group of voltages of the entire power supply is carried out precisely along the + 3.3V circuit, and it is in it that the optocoupler LED (PC817) is installed.
Defective capacitors often swell and become spherical at the end. A swollen condenser can be identified visually.
At the initial stage of drying of the capacitor (C15), the voltage of + 3.3V is normal (the feedback is still able to compensate for the decrease in the capacitance of the capacitor), (but the rest of the voltages will be higher than normal). The voltages in the + 5V, + 12V and + 22V circuits (in case of malfunctions in the + 3.3V circuit) will be overestimated. (The stabilization circuit seeks to maintain the voltage in the + 3.3V circuit in the norm, simultaneously increasing the voltage in all secondary voltage circuits)
After replacing faulty elements, all voltages return to normal both at idle and under load.
On the oscillogram “voltage after diode D8” (there should be a straight horizontal line at the level of +3.3 V);
Replacing faulty containers is usually enough to restore the tuner's functionality. Motherboards of this type of equipment have a fairly high reliability.
Note: Once, in addition to replacing capacitors, it was necessary to replace the rectifier diode (D8) in the +3.3 V circuit. In some models of tuners, the power supply circuit has a different numbering of elements.
In some cases, due to overvoltage in the network, 2 diodes in the bridge on the high-voltage side and a fuse burned out. Diodes burn in pairs. Burnt diodes are short-circuited, so they only pull the fuse with them, the rest of the circuit usually remains intact.
- - when the supply voltage (310 V) appears on the capacitor C1 and pin 5 of the microcircuit through the internal current limiting circuit, the built-in key, pin 2 of the microcircuit, the capacitor C8 is charged to a voltage of 12 V. Then the key breaks the described circuit;
- - the PWM generator starts up and the circuit is already powered by the circuit: additional transformer winding, R5, D6, capacitor C8.
- - when the supply voltage (310 V) appears on the capacitor C1 through the resistors R1, R2, the capacitor C8 is charged, supplying the supply voltage to pin 3 of the microcircuit.
- - the PWM generator starts up and the circuit is already powered by the circuit: additional transformer winding, R5, D6, capacitor C8.
Part of the stabilization circuit located on the low voltage side of the UPS.
- DC battery charge, battery voltage rises to 14.4 V (2.4 V per cell)
- Charging the battery with a constant voltage of 14.4 V (while the charge current gradually decreases and at 100% charge is close to 0)
YKF25225-2 is a three-point capacitive generator. The active element of the generator is transistor Q1.
I installed the program from the disk that came with the microscope. I didn't like her.
Launched the video player program, selected the video signal source WEB-camera. The microscope connected with no problem.
Home >> Electronics >> Repair of power supplies for satellite tuners
Satellite TV is not the last in the entertainment industry. And this is facilitated by the inexpensive price of equipment and an extensive list of channels. But all the joy can descend to "no" if the satellite TV receiver does not turn on.
All is good, but there is one unpleasant moment. Chinese receivers often fail. The main reason for equipment failure is a breakdown of the power supply. This happens due to thunderstorms, voltage surges, and simply poor-quality components of this unit. In contrast, other receiver modules practically do not break. It is about this common breakdown that we will talk about and find out how to repair the receiver's power supply with our own hands.
This article will provide simple and practical ways to identify a faulty part in a tuner power supply. Although the methods are simple, their use in most cases allows you to repair the power supply of a satellite TV receiver with your own hands.
So, if your satellite TV receiver of the model: Gione, Cosmo Sat and the like has stopped working, then do not rush to worry, perhaps everything is not so bad. Try to find the cause yourself without the help of specialists.
What might you need? Multimeter, dial tone, soldering iron and a little patience.
We remove the cover of the device, and we see a free-standing module. This is a switching power supply. To start troubleshooting, remove it by unscrewing the screws and disconnecting the connector on the system board. Now the board is in front of us.
The first thing to do with the board is to visually determine if there are damaged (swollen) capacitors and other circuit elements. Often it is for this reason that the satellite TV receiver does not turn on.
If no damage is visible, then it is necessary to check the integrity of the cord and fuse. We put a dial on the ends of the fuse, and by the reaction of the device we determine its integrity.
If the fuse is good, that's good. And if not, then you should not rush to change it, since the same thing can happen to it as to the first one. It is better to solder a cartridge with an incandescent lamp in its place. A lamp with a power of 60 watts and a voltage of 220 volts.
Now, if in the circuit, when turned on, there is a short circuit, then the lamp will simply light up at full heat, without causing any harm to the circuit. If the lamp does not light up when turned on, we take a multimeter and measure the voltage across a large capacitor of 47 μF * 400 volts.
The multimeter must be set to the "DC voltage measurement" mode. At the contacts of the capacitor during normal operation, there should be a voltage of about 300 volts. If there is none, then we are calling along the chain - from the fuse to the diode bridge. In the case of the presence of an alternating voltage at the input of the bridge, everything indicates a breakdown of the diodes, and this is also one of the frequent breakdowns in which the satellite TV receiver does not turn on. To determine which diode is out of order, it is necessary to solder one end of each.
Then, throwing a dial on each diode alternately, and swapping the ends, we determine their integrity. The working diode must pass current in one direction. If the diode rings in two positions in the same way, then it is broken. Most often, a pair of diodes fails. Therefore, if possible, it is better to change all four at once, since after such breakdowns, even those that remain workers change their parameters. As a result, partial replacement of diodes can be considered as defective repair of the receiver's power supply. And this means that there is a high probability that at one fine moment you may again face a situation when it is necessary to eliminate this malfunction, as a result of which the satellite television receiver stopped working.
The diodes have been replaced, now we turn it on again and measure the constant voltage across the same capacitor. It should be, as mentioned above, about 300 volts. If so, then the next step in the diagnosis is to measure the alternating voltage on one of the primary windings of the transformer. How to do this can be seen in the photo below.
The device should show about 150 volts, and the voltage should seem to "float", that is, change. If this does not happen, then most likely the microcircuit is out of order. You can replace the microcircuit and repeat the measurements again.
When the device shows the presence of a pulsating AC voltage on the primary winding, it is necessary to immediately measure the DC voltage at the output of the unit.
To do this, put the multimeter in the "constant voltage measurement" mode and connect the negative (black) probe to the second slot on the connector. This is a common (negative) contact.With the other end of the device, we alternately measure the voltage at the slots of the connector.
If you turn the plug with the slots towards you, and measure from left to right, then the voltages should be as follows:
If there is no voltage, then we do the same operation with the diodes of the secondary circuit, as described above. Having identified the faulty one, we replace it. Note the larger diode. It is labeled SR-360 and the like. He most often fails. Replacing it, you can solve the problem when the satellite TV receiver does not turn on. Again we measure the voltages at the terminals.
If this method did not give anything, then most likely the microcircuit in the primary circuit, which plays the role of a high-frequency alternating voltage generator, "flew out". But, as practice shows, this rarely happens.
That's all that I wanted to tell you about the repair of the power supply unit of the satellite TV receiver. Successful renovation.
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Hello, today we will try to fix the Tricolor receiver. Many faced such a problem when the warranty (usually 12 months) expired and the receiver suddenly failed. A new one is expensive, and in most cases the repair will not be difficult and will cost a penny, if you are even a little friends with a soldering iron, the main and most common faults are easy to fix yourself. Let's consider such a repair on the example of another receiver from the Tricolor company GS-8300 N. I must say, the device is not of the best quality, and the money that Tricolor takes for it, of course, is not worth it. But, nevertheless, the number of subscribers is large and not all of them work for a long time and regularly.
The main and most common malfunction of all receivers is a malfunction in the power supply and voltage conversion circuit. Also, the modulator often fails due to a short circuit in the coaxial cable from the LNB, although the latest models have good protection against short circuits in the cable, when triggered, the voltage supply to the converter simply stops until the short circuit is eliminated.
And so, our receiver does not show any signs of life, the indicators on the front panel display do not light up, and no twitching of the power plug from the outlet and turning on the toggle switch does not help us (at least that was the case with the device, an example of which is given in this article) ... The first thing we do is pull out the plug from the network and remove the top cover, we need to get to the electronic filling of the device. And here it is important to remember one thing, namely, about the warranty seal, which of course we will break if we remove the cover. Therefore, once again make sure that the warranty period has definitely expired, and under warranty no one will repair it for you. If the warranty is still valid, I advise you to take the receiver to a service center and entrust this matter to a specialist.
Receiver inside:
The electrolytic or oxide capacitor at the input often dries up and fails, which is also a malfunction, not everyone can find such a breakdown either, you need to have at least an initial level of a radio amateur. Usually, defective capacitors are swollen, yellowish, or have a small brown speck on the board at the base of the legs. Also, the serviceability of a capacitor can be determined by comparing its nominal and measured capacitance.
The receiver uses direct current, which is rectified from the AC mains using a diode bridge. Diode bridge problems also happen. It is very simple to check diodes, the main function of a semiconductor diode is to pass current in one direction, and not in the other. In my case, the transistor of the primary winding of the transformer turned out to be faulty, it is not difficult to find it, it usually has a radiator to remove heat. I determined the malfunction of the transistor by measuring the voltage at its emitter, it was absent there, the primary winding was not powered, respectively, everything else is de-energized.The transistor cost me 28.5 rubles. Replacing it with a soldering iron, I fixed the malfunction and the receiver is back in working order. I must say such a breakdown is quite a rare occurrence, usually it all ends with a fuse.
A very common malfunction is a firmware crash. The firmware often crashes, this is usually evidenced by the complete hang of the receiver. In this case, "flashing" will help. I will tell you about one more reason for the malfunction, which may arise due to poor-quality installation. Water in the cable. If the outer insulation of the cable is broken, then water from atmospheric precipitation can get inside, it easily enters the receiver like a hose, sometimes flooding all of its insides. The condition of the cable must be monitored throughout the entire service life of the device.
In this article, we will fix the most common failure in a satellite receiver, namely, we will repair the power supply of this device. Why a power supply? Yes, because in 95% of cases of failure of the receiver, the power supply is the culprit. The receiver may not turn on at all, it may turn on "halfway" (for example: the red indicator is on, and the green one, despite our efforts when pressing a certain button, does not turn on and there are many more signs), or some function may not work. And the reason for all these misunderstandings, in most cases, can be the power supply. We will repair the SVEC receiver, but functionally, on most of these devices, the power supplies differ only in the shape and location of the radioelements. The principle of repairing receivers is almost always the same.
So, let's begin. To begin with, of course, you need to disassemble our "unit". We unscrew the screws or bolts on the sides of the cover and remove it. We are presented with the following picture:
Now we will visually inspect the unit and the board for the apparent reasons for the breakdown (this can be "swelling" of capacitors, burnout of the board or individual elements, etc.). If no apparent reason is found, then we look at the fuse. Even if it is not visually visible that the fuse has "blown", it is better, nevertheless, to check its integrity with a device. If the fuse is not working, do not rush to change it and try to turn on the receiver. Usually they just do not "burn out", on the contrary, for the most part, with overvoltage in the network, they remain unharmed, and something else must fail. This is how modern technology works. In general, we need to remove the power supply (in the figure it is marked with a blue arrow) from the receiver in order to check other items.
First of all, you need to check the power capacitor: there may be a residual charge in it. If there is a charge in the capacitor, it is imperative to discharge it, otherwise, when checking other radioelements, we can not only "burn" the device, but also get a good electric shock, albeit not fatal, but still unpleasant.
After that, we proceed to check the main transistor, which stands on the radiator. If we discard all professional terms, then we simply "ring" him for a "short circuit". These transistors are constantly failing, they are designated like this: D13009K. The literal values can be different, but the numerical values must be the same. This transistor is found in many receivers, but not all. In others, there are similar ones or there may be microcircuits. This is not the point, it is important that in most cases, it is the power transistors or microcircuits that fail.
On our power supply, after checking this transistor, a short circuit was found between its contacts. It follows from this that the transistor is "burnt out".
Now we need to unsolder it and check the rest of the radioelements. I will explain the check in a simple way: you need to check all the transistors and diodes (zener diodes) for a "short circuit".
All parts marked with arrows in the picture must be checked for "short circuit". After such a check, I found a "burnt out" diode, which is powered by 5V.We also need to remove it, so that, like the transistor, we can replace it with a usable one.
Next, we solder the new transistor and diode into place. Then you can check our power supply. We do it like this: insert it into the receiver and connect only the power cord and the power button to it. We DO NOT connect the loop with wires that goes to the board with processors. We will check by the output voltages, the value of which is indicated on the power supply, near the "socket" where the loop is inserted.
We measure the voltages at the output of the power supply and, if they coincide with the values on the board, you can connect a loop.
Everything. Now we fasten all the bolts that secure the power supply to the receiver and close our device with a lid. Ready.
Of course, the most common and not difficult type of breakdown is described here. There may be more serious reasons for the failure of this device. Then, without the intervention of a specialist, it is impossible to do, but without doing anything, it is impossible to learn something.
