The receiver's power supply voltage is too low. You can use an oscilloscope and check what type of current we have at the output

Facebook

Failure of the power supply is one of the most common failures satellite receivers. As a rule, this occurs due to loss of capacitance of capacitors due to long term operation, or if damper elements and diode bridges are damaged due to a sudden voltage drop.

The symptoms of a breakdown are quite simple: the receiver either does not turn on at all, or after turning on the device screen begins to blink and nothing else happens. Repairing satellite receivers comes down to replacing damaged elements and does not take much time. In the most difficult case, the problem is solved by completely replacing the power supply.

Cryptomodule failure

A rarer, but rather simple case is the breakdown of the cryptomodule responsible for decrypting the encrypted signal. In this case, the receiver works normally, but a message appears on the TV screen indicating that the signal is encrypted (depending on the model, this message can be displayed in both Russian and English languages). Repair of satellite receivers in in this case is also quite simple: replacing the crypto module with a working one will help correct the situation.

Tuner malfunction

Failure of the tuner is accompanied by scattering or complete disappearance of the image, as well as periodic or constant loss of sound. This symptomatology is nonspecific, and may also be a consequence of damage to the antenna socket or cable, problems with satellite converter, and even a banal weakening of the signal due to external factors. Therefore, repair of satellite receivers in such cases should be carried out only after a thorough diagnosis.

Malfunction of the system (motherboard) board

This category of faults is very diverse, and in most cases, in order to unambiguously identify the cause of the failure, it is necessary to carry out full diagnostics. Many symptoms are ambiguous and may result from incorrect setting peripheral equipment, cable damage, and other factors.

For example, if the receiver goes into continuous booting, or all the symbols on its display light up at the same time, and the device itself refuses to work, this may be the result of a failure software. Repairing satellite receivers comes down to a simple flashing (that is, reprogramming the device). At the same time, this symptom may be a consequence of a failure of the receiver's BIOS, and require replacement of the defective chip.

Hello, today we will try to fix the Tricolor receiver. Many people have encountered this problem when the warranty (usually 12 months) has expired and the receiver suddenly breaks down. A new one is expensive, and in most cases, repairs will not be difficult and will cost pennies, if you are even a little familiar with a soldering iron, the main and most common faults are easy to fix yourself. Let's consider such a repair using the example of another receiver from the Tricolor company GS-8300 N. I must say, the device is not the most best quality, and the money he takes for it, of course, is not worth it. But, nevertheless, the number of subscribers is large and not everyone has everything working for a long time and properly.

The main and most common malfunction of all receivers is a malfunction in the power supply circuit and voltage conversion. Also, the modulator often fails due to a short circuit in the circuit, although the latest models have good protection from a short circuit 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 amount of juggling the power plug from the socket and turning the toggle switch on or off helps us (according to at least, this was the case with the device, an example of which is given in this article). The first thing we do is unplug the plug from the network and remove top cover, we need to get to the electronic filling of the device. And here it is important to remember one thing, namely the warranty seal, which we will certainly break if we remove the cover. Therefore, make sure once again that guarantee period It’s 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.

Opening the lid, we see printed circuit boards with many components connected to each other by wire buses. Below are photos describing some of the devices on the board. First of all, we are interested in the power board; it is not difficult to distinguish it by the transformer installed on it and the supply network wire. And the first thing we pay attention to is the fuse. It is usually installed at the beginning of the chain. The fuse will not necessarily have the shape you are familiar with (a glass capsule with a thin conductor inside), for example, in my case the fuse is enclosed in a small plastic box, and in order to get directly to the fuse itself, the cover of this box must be removed. This is done very simply, for example with tweezers. Having reached the fuse, we check it with a tester or multimeter for a break. If the fuse burns out, which by the way happens very often, we go to a radio store, buy the same one, change it and that’s it. If this is not the case, we check the parts further along the chain. Often the transformer itself fails; we can detect such a malfunction by measuring the voltage on the secondary winding. I must say that not everyone can replace the transformer, if so, then it is better to take the receiver to a workshop, but if you are confident in your abilities, then go ahead, for example, it will not be difficult for me.

Receiver inside:

The electrolytic or oxide capacitor located at the input often dries out and fails, which is also a malfunction; not everyone can find such a breakdown either, you need to have at least First level radio amateur. Typically, faulty capacitors are swollen, have a yellowish appearance, or have a small brown spot on the board at the base of the legs. Also, the health of a capacitor can be determined by comparing its nominal and measured capacity.

The receiver uses direct current, which is rectified from the AC network using a diode bridge. Problems with the diode bridge also happen. Diodes are very easy to check; 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 usually has a radiator for heat removal. I determined the malfunction of the transistor by measuring the voltage at its emitter, it was absent there, the primary winding was not powered, and therefore everything else was de-energized. The transistor cost me 28.5 rubles. Replacing it with a soldering iron, I fixed the fault and the receiver is in working order again. I must say that such a breakdown is quite a rare occurrence; usually everything ends on the fuse.

A very common problem is a firmware crash. The firmware often crashes, which is usually evidenced by the receiver completely freezing. In this case it will help. I’ll tell you about another reason for the malfunction, which may arise due to poor-quality installation. Water in the cable. If the external insulation of the cable is broken, then water from precipitation can get inside; it easily gets into the receiver like a hose, sometimes flooding all its insides. The condition of the cable must be monitored throughout the entire service life of the device.

This article is dedicated to satellite receivers , or rather repairs their power supply.

Satellite receiver power supply repair

Breaking satellite receiver power supply – one of the most common causes of device malfunction. This is due to the fact that the receiver is constantly connected to the network, as a result of which rapid wear of various parts becomes inevitable.

Diagnosing a power supply failure is quite simple. The receiver either shows no signs of life at all, or blinks one indicator, but does not function. It is not uncommon to see a flashing display. Depending on the model and type of failure, the symptoms may vary, but in any case, it is better to start diagnosing the device with the power supply.

Visual inspection

Before starting work, the receiver must be disconnected from the network. Then you need to disassemble the device case and clean the board from dust (perhaps this is the problem). It is not necessary to immediately take up a multimeter and an oscilloscope (especially if you simply don’t have them). The most common failure can be diagnosed with the naked eye: a faulty capacitor.

A failed capacitor, as a rule, is characterized by a swollen top part. In some cases, the capacitor may leak, which, again, is easily detected by external inspection. Having noticed this, you need to immediately unsolder the capacitor and solder in, observing the polarity, a new one with similar parameters.

It is also easy to identify a blown fuse. It should also be replaced with a similar one, because without it, in principle, no voltage is supplied to the power supply. If after the described procedures the receiver still does not work, you need to take measurements.

General measurements

First you need to measure all the output voltages from the power supply. As a rule, their values are marked on the board next to the corresponding contacts. If all voltages correspond to the declared ones, then, obviously, the power supply is in order, and the problem lies further. If the values differ, then the fault is still in the power supply.

You can use an oscilloscope and check what type of current we have at the output. If the voltage is constant, then most likely the problem is in the smoothing capacitor. If the variable is in the diode bridge. Important! The described measurements must be made with the receiver connected to the network!

Spot measurements

You can do without an oscilloscope by simply “calling” all capacitors and diodes with a multimeter. A faulty capacitor does not necessarily look swollen; it may not differ in any way from a normal, working one. Accordingly, its malfunction can be detected only by measuring the internal resistance.

Also, the fault may lie in the high-voltage part of the circuit. As a rule, these are diodes. You need to “ring” each one and, if necessary, resolder the diode bridge. Even if only one diode has burned out, all four should be replaced. It is possible that the diodes “burn out,” temporarily remaining operational, but fail in the near future. In addition, you should check the resistance of all resistors.

Other cases

In rare cases, it may happen that the throttle fails. This is one of the most problematic parts. Finding a new throttle will most likely not work. You will have to use the service of a “donor” if possible. Fortunately, such breakdowns do not happen very often - during strong power surges in the network.

The PWM controller may also burn out. This is the last thing you should sin on if everything else has already been replaced or was working. Can be replaced, finding a new one is not difficult.

In this article we will repair with our own hands "tricolor" receiver. Often a problem arises that the warranty period has expired and the receiver suddenly breaks down. Buy new receiver expensive, taking it to a service center means depriving yourself of watching satellite TV. But in many cases, a device breakdown can be corrected independently, without spending much effort or a lot of money. Money. If you know how to solder, then it is easier to figure out the problems yourself and fix them.

We will use a television receiver as an example. It is worth noting that the quality of the receiver leaves much to be desired, since it costs a decent amount. However, many subscribers use this particular receiver, and not everyone has it working properly.

The main and most common problem with most receivers is malfunctions in the power supply system and voltage conversion. Besides, short circuit V coaxial cable from the LNB often causes the modulator to break down. Only in latest models They began to use good protection, which, when shorted, stops the supply of voltage to the converter until this short circuit is eliminated.

So, a problem arose: the receiver does not turn on and shows no signs of life at all, and the indicators on the front panel do not light up. We tried to pull the plug out of the socket, turn the toggle switch on/off, but it didn’t help.
Then let's figure it out further. First, be sure to unplug the plug from the socket and remove the top cover using a screwdriver. We need to look at the electronic components of the device. It is important to remember here that when removing the cover we will definitely break the warranty seal.
Therefore, if the warranty period has not yet expired, it is better not to try it yourself, otherwise you will not be able to repair your receiver under warranty later.
But if the warranty has expired and you have no one to rely on, then go ahead and break the seal.

Removing the cover, you will see printed circuit boards with various components. They are connected to each other by wire buses. The photo shows some devices with descriptions. We need to find the power board. It has a transformer and an inlet for the power cord, so it’s not difficult to find. The first thing you should pay attention to is the fuse, which is usually installed at the beginning of the circuit. The fuse can take different forms, such as a glass capsule with a conductor or a small plastic box in which the fuse is placed. In the second case, you must first remove the lid of the box (you can use tweezers or tweezers) to get to the fuse itself. Next you need to check the fuse with a tester or multimeter for breakage. If it blows, which often happens, then go to a radio store, buy the same fuse and just change it. If everything is fine with the fuse, then we check further along the circuit.

Another element that often breaks is the transformer itself. Such a fault is detected by measuring the voltage on the secondary winding. It is worth noting that not everyone can replace a transformer. If you are not sure that you can change it yourself, then it is better to take your receiver to a repairman, and if this does not seem difficult for you, then go for it.

Another malfunction is the failure of the electrolytic or oxide capacitor at the input due to drying out. To detect this breakdown, you need to have at least a little understanding of radio mechanics. A faulty capacitor is usually yellowish in color; there may also be a small brown spot on the board at the base of its legs. You can also compare the rated and measured capacitance of the capacitor to determine its health.
The diode bridge in the receiver converts alternating mains current into direct current.

The diode bridge may also break. This is easy to check, since semiconductor diode has one main function: to pass current in one direction, but not in the other.

In the case we are considering, the breakdown occurred with the transistor of the primary winding of the transformer. It has a heatsink to dissipate heat, so it's quite easy to find. The malfunction was discovered as follows: we measured the voltage at the emitter of the transistor, it was not there, the primary winding was not powered, which means that all other parts were de-energized. The cost of the transistor is about 30 rubles. To replace it we need a soldering iron. We fix the problem, and – “Hurray! It’s working!” – the receiver is ok again. Note that the transistor does not break down often; most receivers fail due to a fuse.

Let's look at another very common malfunction - a firmware crash. This happens quite often. A sign of a firmware failure is a complete freeze of the receiver. Then we just need a receiver.

The cause of receiver failure can also be poor-quality, unprofessional installation. If the external insulation of the cable is broken, then rainwater or snow can easily penetrate inside the cable and, like a hose, seep into the receiver, flooding all its internal contents. Therefore, you need to monitor the cable to see if there are any kinks or insulation damage.

For those who don't understand anything about internal structure satellite receivers, or who have no time to deal with this at all, do not despair if the device breaks down. No one has canceled service centers yet. You can go there with your problem and specialists will help you solve it.

They fail for various reasons - a voltage drop, wear and tear of the device itself due to intensive use, and the failure of certain elements. This also includes breakdowns caused by owners who decided to figure out the problem themselves without having special skills, for example, they incorrectly replaced the firmware in a satellite or cable receiver.

The power supply is perhaps the most broken part of the receiver. The power supply may break due to a poor-quality power supply network or low-quality radio components (especially on cheap Chinese equipment).

Dust and dirt can also cause receiver to breakdown, creating an incorrect thermal regime.

IN service center repairs and maintenance of various satellite equipment. Moreover, repairs are carried out by specialists and using professional equipment. Almost any faulty part can be replaced with a new one. The timing of repairs will depend on the availability of parts at the service center. If any part is missing, it will be ordered from suppliers, which will take some time. But in large serious centers, usually, parts are always available.

Let's consider another situation: the receiver failed after a power surge. After opening the lid, it was discovered that the following parts had burned out:

network capacity C5 - 47µFx400V
Q1 - CS2N60F
R8, R11, R13 – each 3 Ohm (size 1206)
R9 - 47 Ohm (1206)
U1 – type not defined

We found a page on the Internet with a table on identification and selection of analogues (for example, http://remont-aud.net/ic_power/), using it we look at what we have and what we don’t. Let's replace the last part with SG6848 to minimize interference with the factory circuit.

We dismantle the faulty parts (circled in red in the photo):

R8, R11, R13 - 3 Ohm (1206)
R3, R6 (one of them is possible) - 1 MOm (1206)
C3 - 68nF
R25 - 3.6 kOm (0805)
R26 - 10 kOm (0805)

Installing new parts:

instead of U1 - SG6848
instead of R8, R11, R13 - one resistor 1.8 Ohm x 0.5W
instead of C3 there is a 100 kOm resistor (1206)
instead of R26 there is a 33 kOm resistor
instead of R25, we select a resistor in the range of 10-12 kOm, controlling the voltage 3V3 at the cathode VD8, we will settle on a nominal value of 11 kOm, U = 3.36V (at 10 kOm U = 3.28 V, at 12 kOm U = 3.41 V)
instead of the burned-out Q1 - SSS4N60B (TO-220F housing).

Video review: repair of the Tricolor GS8300 receiver (no signal)

———————

From June 28, 2011, all subscribers using the GS-8300, GS-8300M and GS-8300N receivers need to update the software via satellite to version 1.0.157.

When testing the voltage coming from the power supply, it turned out that a voltage of 1.8 V is present in the power circuit of these buffer stages (lower in the image above).

To understand what it is responsible for in the circuit of these cascades, we had to printed circuit board draw a diagram of these buffer stages.

It is assembled on two transistors. Accordingly, an input signal is supplied to the input. At the output we must receive the signal that is directly fed to the video output and to the “RGB” outputs of the SCART connector.

This 1.8 V voltage is used to power this stage. But for this cascade this is a very low voltage. Because the swing of the output video signal is typically 1 V. Plus, the voltage drop at the “collector-emitter” junction is approximately 0.7 V. That is, we are already approaching the extreme value of the supply voltage.

It is unlikely that the circuit should be powered by such a low voltage. For normal operation For such a cascade, its supply voltage should be from 3 to 5 V.

Next step. Using the number on the board itself (at the top of the board) of the power supply, we find its circuit.

From it you can find out what voltage should be at this pin. This receiver has a power supply model “FP06M024”.

Based on the circuit data, the output voltages for our power supply are +5 V, +30 V, +22 V, +3.3 V and + 12 V. As we can see, there is no 1.8 V voltage in the output voltages of this power supply.

If we look at the diagram of the power supply itself, the line on which we have 1.8 V should actually have 5 V.

Next, we will understand how this voltage is formed. We see that in this power supply, stabilization is carried out along the 3.3 V line. From here the signal is taken for the master divider of the U3 TL431 microcircuit. This is our controlled zener diode, which directly controls the optocoupler and due to this, the output voltage is stabilized.

12 V – stabilization is carried out using a linear stabilizer 1117 at 12 V.

22 V – not strictly stabilized. Stabilization of this voltage occurs due to the inductive coupling of the 3.3 V and 22 V windings. That is, when our voltage drops, it will drop equally on both the 3.3 V line and the other lines.

But, the 3.3 V line is connected to the optocoupler control circuit, therefore, if there is stabilization along the 3.3 V line, then there will automatically be stabilization for other voltages.

Same for 30V voltage.

And the 5 V voltage is stabilized by a separate stabilizer, which is assembled on field effect transistor U5 and the same chip as in the circuit feedback, controlled by a zener diode TL431.

This zener diode changes its resistance between the anode and cathode so that we maintain a voltage of 2.5 V at control pin 1.

Here we have a resistive divider. The resistance ratings are the same. Therefore, if the output is 5 V, then at the division point there will be half of this voltage.

Accordingly, if output voltage If you need to make more than 5 V, then the resistance of the upper resistor needs to be increased.

If it is necessary to obtain a voltage less than 5 V, the resistance of the upper resistor must be reduced.