Methods for repairing car amplifiers. Amplifier repair at home. Based on the characteristic of the fault, it was obvious that the audio power amplifier was faulty.

Hello dear readers of my site!

In this article we will repair active speaker Chinese production.

This equipment is different in appearance, but inside, in most cases, is far from original.

So, an active speaker system came in for repair.

The problem was this: one channel worked without complaints, but the other made hoarse sounds.

Well, the first action of the master before diagnosing the device is its disassembly, which was done. This acoustics is disassembled quite simply - the back wall and corners are unscrewed. After parsing, the column looked like this:

Based on the characteristics of the malfunction, it was obvious that the audio power amplifier .

Audio amplifier power was disconnected and, together with the back wall, moved to the repair table for more convenient diagnosis.

Nothing was found on visual inspection. Then it was decided to check the radioelements. The input and output capacitors, diodes and transistors were checked - nothing suspicious was found. Now it's the turn of checking the key transistors.

The audio amplifier sound power was assembled on four key transistors D718.

The transistors had to be soldered out to make an accurate check.

Transistor D718 - NPN, 8A, 120V, 80W.

After checking all four elements, it was revealed that one of them had a blown B-E (base-emitter) junction.

Well, the cause of the hoarseness of one of the channels was determined. Now it remains only to replace the failed transistor with a known good one.

Yes, this would be the easiest solution to the problem, but ... Well, in general, the same transistors were not available. Then an analogue was selected that was suitable in terms of parameters and it turned out to be the KT819BM transistor.

In terms of parameters, this radio component fit perfectly, but not at all in size.

Then I found a radiator suitable for this transistor, fixed the transistor itself on it, and fixed this whole structure on the wall of our column. Since the KT819BM transistor is in contact with the radiator by the collector, this radiator was fixed so that it did not touch the radiator on which the D718 transistors were fixed, since this radiator was defined in the circuit as a case.

Then, with the help of wiring, the contacts of the replaced transistor were soldered to the board. When performing this action, the location of the terminals of both transistors (base to base, collector to collector and emitter to emitter) was taken into account.

Now it remained to attach the cables disconnected during disassembly to the board sound amplifier and make a trial run and check the performance of our speaker amplifier , which was done.

Here I will share my modest experience in the field of repairing car amplifiers. I hope the information will be useful to novice radio mechanics in their difficult task of restoring audio equipment, as well as to motorists who are familiar with electronics and who want to fix their amplifier on their own.

To begin with, I would like to talk about how to turn on a car amplifier without a car radio and at home. Read more about this. This will be needed when repairing the car amplifier.

If you do not have a sufficiently powerful power supply at hand, then any one for a voltage of 12V and a current of 1 - 3 amperes will do. But here it is worth understanding that we need it only in order to turn on and adjust the amplifier. We will not operate it at full power, so the current consumption will be minimal.

I also strongly recommend reading or taking note of the material on the design of the car amplifier converter. This information is very important.

Well, now, examples of repairs from real practice. Basically, they relate to one of the main blocks of any car amplifier - a voltage converter, or in other words - an inverter.

Repair of car amplifiers CALCELL.

1. Fault: auto amplifier goes into protection. The red LED PRT (Protect) is lit on the front panel. After a couple of turns on, the amplifier stopped showing signs of life at all - the PRT LED stopped glowing.

The cause of the malfunction was the 2N4403 transistor in the circuit of the TL494CN microcircuit (converter). One of his crossings was broken. In addition, the 10Ω resistor (Ohm) burned out. In the photo, R7 is him. While the resistor "endured" - the amplifier turned on, but went into protection. As it burned out, the amplifier stopped turning on at all.

Bipolar pinout P-N-P transistor 2N4403.

Why did the amplifier go into protection? The fact is that this transistor is part of the on / off circuit. Because of breakdown P-N transistor transition, the amplifier did not turn on and went into protection.

There was no suitable replacement for the PNP transistor 2N4403 at hand. Therefore, a risky attempt was made to take the same transistor from the preliminary stage of one of the amplifier channels. Thankfully they were there. Yes, think about it, I decided, well, I’ll pull out the transistor from there, solder it to replace the faulty one, check the amplifier. Oh yes, he did. But after a few seconds after switching on, I smelled a burning smell. It turned out that due to the lack of 1 small transistor, the powerful complementary transistors of the UMZCH output stage began to heat up terribly. Fortunately, the transistors survived. Therefore, I do not advise so "cunning".

The replacement of the transistor was complicated by the fact that it was smeared with some kind of rubber glue, with which kegs of electrolytes were glued to the board.

2. The CALCELL POP 80.4 amplifier does not turn on. Protective fuses blown.

The device came "dead", apparently after an incorrect connection. After a quick inspection of the parts without soldering, it turned out that the 11V zener diode was broken in the "strapping" of the TL494CN PWM controller chip. A breakdown of the TL494CN chip itself was also found. When measuring the resistance between pin 12 (+ power, Vcc) and 7 (- food, GND) the multimeter showed - "0". Apparently, the power supply voltage of the amplifier was greatly overestimated.

After replacing the TL494CN chip and the zener diode with 11V, an attempt was made to turn on the amplifier. But, after turning on, the red PRT LED lit up for a few seconds (as it should), and then complete silence .... The power supply from which the amplifier was powered went into protection due to overcurrent.

It turned out that one of the two groups of MOSFET transistors on the converter board is very hot. Transistors of the other group are cold. After checking 3 STP75NF75 transistors that were warming up, it turned out that they were broken (Source - Drain). The 2N4403 transistor was also broken, which is a buffer for this converter arm. You can familiarize yourself with the diagram of a typical converter (inverter) of an auto amplifier in more detail.

After replacing the 2N4403 buffer transistor and three STP75NF75 MOSFETs (marked as P75NF75), the car amplifier began to work properly.

3. Amplifier CALCELL POP 80.4. When the amplifier is turned on, the red LED lights up. PROTECT and after a few seconds it goes out. The amplifier does not turn on - there is no indication.

This happens when the converter goes into protection due to high current consumption or short circuit in load. The load in this case is all four amplifiers, filter block and preamplifiers.

The most likely reason for the protection trip is the failure of the output transistors. The CALCELL POP 80.4 amplifier uses powerful bipolar transistors. You can evaluate their serviceability using this method, and soldering transistors is not at all necessary. As a rule, the breakdown of the transistor junction is easily determined, the multimeter starts beeping disgustingly with a buzzer - a signal that there is zero resistance between the transistor terminals.

It is worth considering that with such a quick test, the parts associated with the tested transistor (low-power transistors, etc.) can affect the readings. Therefore, if there is any doubt, we solder and check the transistor separately. It is not uncommon that it is precisely the elements associated with our transistor that are pierced, and not the transistor itself. In some amplifiers, for example, such as the SUPRA SBD-A4240, MOSFETs are used as output transistors. MOSFET transistors can be checked with a universal tester, since a conventional multimeter is not always suitable for such purposes.

Let's go back to our amplifier. For the sake of clarity, I will refer to circuit diagram of this amplifier - CALCELL POP 80.4 auto amplifier circuit. When checking the output transistors of one of them, the Base - Collector (B-C) transition "rang" as broken. On the diagram, it is designated as Q312 ( 2SA1694). To check the performance of the amplifier, I soldered bad transistor and its complementary pair - transistor 2SC4467 (Q311). I turned on the amplifier, but it again went into protection. It means there is something burning somewhere. In addition, low-power transistors Q309 were very hot ( MPSA06) and Q310 ( MPSA56). The check showed that both junctions of the Q309 (MPSA06) transistor were broken.

Since there was no complementary pair 2SC4467 / 2SA1694 on sale, I decided to replace more powerful counterparts- couple 2SA1943/2SC5200 manufactured by TOSHIBA. Here they are. They are heavy to the touch and inspire confidence.

After installing the new 2SA1943/2SC5200 transistors, it turned out that they are too large and because of this, the board does not fit into the case.

I had to bite out a small part of the printed circuit board so that they retracted into the case and fit snugly to the surface.

After replacing the amplifier began to work properly.

During the electrical run, I noticed that even without a load, low-power transistors in the preamps heat up quite noticeably. When playing music with rich bass, the heating increases. The amplifier worked for two subwoofers (one per bridge).

It is possible that prolonged operation at maximum power led to overheating and failure of the low-power transistor MPSA06 (Q309), and this, in turn, led to a breakdown transition B-K powerful transistor 2SA1694 (Q312) in the output stage of the amplifier.

4. Non-standard case. The CALCELL amplifier just bought in the store was brought in for repair. According to the owner, after connecting the power, smoke came out of the vents of the amplifier.

After opening and inspecting the printed circuit board, it turned out that there were traces of solder paste and solder balls on the terminals of one of the MOSFET transistors of the converter. Here is a photo.

Apparently, a current went through the remnants of the solder paste when turned on. Because of this, the rosin in the paste heated up and began to evaporate in the form of a white haze. After that, the amplifier did not turn on due to the solder bridge formed during the solder paste reflow. It's no secret that cheap electronics made in China don't pass presale checks. Hence such "blunders".

Repair of car amplifier Lanzar VIBE 221.

Diagnosis: amplifier won't turn on. No LED indication. Judging by appearance printed circuit board, the amplifier was tried to be repaired, and even the key MOSFET transistors in one of the converter arms were replaced. Instead of native IRFZ44N, STP55N06 were installed. But the amplifier ordered a long life. Also in the gate circuit of the MOSFETs were "burnt", but serviceable 100 ohm resistors. When checking the buffer transistors 2SA1023, which "rock" the IRFZ44N mosfets, it turned out that they were in good order.

After replacing the TL494CN SHI controller chip, the amplifier started working. Just in case, buffer transistors 2SA1023 and diodes 1N4148 were replaced in the base-emitter circuit of these transistors.

Car Amplifier Repair Mystery.

Problem: Amplifier turns on but no sound. car amplifier Mystery 1.300 a typical representative of the so-called monoblocks. That is, it is a monophonic amplifier. The sound power declared by the manufacturer is 300W. Such amplifiers are usually used to drive a powerful low-frequency speaker, that is, a subwoofer or subwoofer.

After opening and inspecting the printed circuit board, it turned out that several transistors (2SB1367 and 2SD2058) were poorly soldered, there was soldering degradation and excessive heating of the soldering points. The transistors appear to be part of the 15V regulators in the secondary power circuits. These stabilizers serve to power operational amplifiers and amplifier filters. In another way, this node can be called preamplifier. It is to him that we connect the very "tulips" through which an audio signal is sent from the car radio. Naturally, if there is no power to the preamplifier, then there will be no sound.

Why did it happen? The fact is that overheated transistors do not have a heatsink, their body is plastic. They stick to their own conclusions. There is no additional attachment. Due to overheating and constant shaking (after all, it was installed in the car), the soldering collapsed and the contact was broken. Therefore, the stabilizers stopped working. A little more and the transistors would simply fall out of the mounting holes!

After restoring the soldering of the transistors, the amplifier was fully operational, but the noticeable heating of the transistors suggested that after a while there would be a repetition.

It was decided to install heating transistors on a homemade radiator to reduce heat. Also update the pin soldering and make it more reliable. Here's what came out of it.

At the same time, adjacent transistors were planted on the radiator, which heated up less - to stiffen the structure. Since the transistors are in a plastic case and do not have a metal flange, I also applied heat-conducting paste KPT-19 to the place of thermal contact with the radiator.

Among other things, on the printed circuit board of the monoblock there was a clearly "inflated" electrolytic capacitor at 3300 µF * 63V in the secondary rectifier. In the power supply - inverter, 2 electrolytic capacitors are usually placed, because food amplifying stages bipolar, in the region of ± 28 - 37 volts. The adjacent electrolyte looked better and was not "bloated".

It was decided, just in case, to replace the electrolyte that was swollen with a new one at 4700 µF * 63V (this was in stock). During the electrical run of the car amplifier, it turned out that the replaced electrolytic capacitor was slightly heated. It turned out that it is heated by powerful resistors located nearby. For reference, the neighboring electrolyte does not have such resistors nearby. This is an obvious oversight. As you know, heating has a bad effect on electrolytic capacitors, since the electrolyte dries out faster and their capacity decreases.

Fusion FP-804 car amplifier repair.

Fault: amplifier does not turn on. There is no indication. After opening the cause, it was not necessary to look for a long time. All of the HFP50N06 MOSFETs (original STP50N06) burned out in the converter, as well as several 47 ohm resistors in the gate circuit of some of these transistors. Also knocked out buffer transistors 2SA1266.

Instead of the burned out HFP50N06 transistors, IRFZ48N were installed, replaced with new 2SA1266 buffer transistors, burned-out 47 Ohm resistors, and also, just in case, the TL494CN SHI controller chip.

The device turned on and began to work properly. But my joy was short-lived. Three days later, the owner of the amplifier called me and said that there was a weak monotonous whistle in the rear speakers. The whistling was only heard when the engine was running.

The first thought that came to mind was noise from the generator that enters the audio path of the amplifier. This happens with hastily made wiring and close proximity of the supply and signal (interconnect) circuits. But the wiring and interconnect cables were of high quality, which I was convinced of. A day later, they brought me an already "dead" Fusion FP-804 amplifier with a familiar diagnosis: it does not turn on.

The most interesting thing was that the power indicator "Power" barely noticeable. But I did not pay attention to this. After the autopsy, it turned out that all the same MOSFETs were knocked out again. So this amplifier turned out to be in my pile of scrap - they gave it away for parts.

After some time, I decided to restore this amplifier, and I wanted to figure out what is the reason for the general burnout of rather expensive mosfets in the converter. I bought new transistors to replace the faulty ones, installed and ...

At the first start, I witnessed an enchanting show. Immediately after switching on, a growing whistle was heard - a slow start of the converter, and then I saw sparks jumping from the center of the toroidal transformer.

Here it is - a malfunction! Breakdown of the windings in the transformer. If I hesitated and didn’t turn it off, I would completely burn out this batch of MOSFETs.

After that, it became clear why the green LED was dimly lit. "Power" with 12V power connected. The current entered the secondary circuit through a breakdown between the transformer windings and slightly "highlighted" the power indication LED. This is the first time I've encountered such a problem. The only way out is to rewind the toroidal transformer.

Schematic diagram of the auto amplifier Fusion FP-804 (aka Blaupunkt GTA-480).

SUPRA car amplifier repair.

Car amplifier SUPRA SBD-A4240.

Fault: Turns on normally - " green LED". But when a signal is applied to the inputs, there is no sound in any channel. The amplifier is silent.

This error is not typical. For a better explanation of the troubleshooting technique, I will refer to the circuit of this amplifier. Diagram of car amplifier Supra SBD-A4240 (opens in a new window).

Measurements of the supply voltage in the secondary circuits did not give anything - everything is normal. After a cursory check, a broken 7.5V zener diode was found (indicated as ZD4 in the diagram).

A broken zener diode led to the disconnection of the signal circuits of all amplifiers, since it is installed in the input signal blocking circuit (Q3, Q101, Q201, Q301, Q401, ZD3, ZD4).

This circuit blocks the signal audio frequency to the preamplifier inputs. "Blocking" of the signal occurs for a short time, immediately after turning on the amplifier. This is done in order to avoid a "click" in the speakers.

Since there was no 7.5V zener diode available, a 5.6V zener diode was installed instead of the broken one (this led to slight signal distortion, later I installed a 7.5V zener diode). After that, 3 channels began to work with slight distortions, and 1 channel gave out strong distortions with signs of self-excitation of the amplifier. When touching the entrance with tweezers sound signal("tulips") in the speaker, a periodic "gurgling" was heard.

Suspicion fell on the block of input filters, the one that is implemented on operational amplifiers- KIA4558 microcircuits (in the diagram U1-A And U2-A). Therefore, in order to determine where the malfunction lies, the signal circuit was broken, going from the output of the input filter block to the input of the preamplifier. This is done simply - one terminal of the electrolytic capacitor is soldered (in the diagram it is C108).

Next, touch with tweezers the output of the resistor R115 or the output of the base of the transistor Q103. Thus, we apply a "signal-to-noise" to the input of the preamplifier. Moreover, if the amplifier is working, then in the speakers we will hear a characteristic hum. But in this case, along with the hum in the dynamics, I again heard the nasty "gurgling". It became clear that the problem should be looked for in the preamplifier, and not in the input filter block.

The search for a faulty element in the preamplifier was complicated by the fact that it was made on low-power transistors (in the Q102 - Q116 circuit), of which there are quite a few. Checking these transistors without desoldering from the board (for breakdowns of transitions) did not give a result. Therefore, it was decided to solder all the preamplifier transistors and check them more carefully.

This also did not give a result, although it was possible to detect two 2N5551 transistors, which caused distrust. I checked them with a universal tester, and every other time they were defined as broken. I had to replace them with new ones. All other transistors turned out to be serviceable, as were other elements of the circuit: diodes (D3 - D5) and capacitors. BUT! I didn't check the resistors.

During an external examination, I noticed that on the case of one of the resistors (in the R124 diagram - 47 Ohms) there is a barely noticeable burnout. When checking, it turned out that the resistor was open.

Since the resistor R124 is installed in the emitter circuit of the transistor Q106 (2N5551), its breakage led to incorrect operation of the amplifier and the same “gurgling”. After replacing the faulty resistor, the amplifier began to work properly. It was also replaced by a new transistor Q106. As already mentioned, when checking a pair of transistors 2N5551 came under suspicion. Perhaps one of them is the transistor Q106, in the circuit of which the resistor R124 burned out.

Another malfunction of the same amplifier.

The car amplifier already familiar to us was brought in for repair SUPRA SBD-A4240 (V1M07) with "torn out" electrolytes in the secondary circuits of the converter. To my question: "How did this happen?" - the owner replied that the amplifier was in the car that had an accident. As a result, the amplifier worked properly, but there was a terrible background in the speakers - impulse noise from the converter did its job. In place of native capacitors, new ones were installed with a capacity of 2200 uF * 35V. The background is gone.

If possible, then, of course, it is better to install electrolytes with a larger capacity (2200 - 4700 microfarads).

There are times when it is quite difficult to find a large capacity electrolytic capacitor. No problem! You can make a composite capacitor from several, the capacity of which is small. Read about how to connect capacitors correctly.

Other little things.

All active elements - transistors, both field and powerful complementary pairs of transistors are installed on the radiator through an insulating mica gasket. Heat transfer paste is used to improve heat transfer.

In some cases it is necessary to dismantle printed circuit board from the amplifier case, which is also a radiator. Naturally, heat-conducting paste is smeared, soils everything around, dust and dirt stick to it. Therefore, you have to remove it from the radiator and transistor cases, clean the insulating mica gaskets from it. The job is not pleasant.

After the repair, everything needs to be restored as it was. Have heat conductive paste handy KPT-8 or KPT-19. It is better to apply the paste on both sides, both on the metal substrate of the transistor and on the radiator. In this case, the mica will be in the middle and covered on both sides with a layer of thermal paste. I do not advise applying a lot of paste, the main thing is that an even, thin layer of paste forms on the surface.

I also advise you to buy mica on occasion. For example, I bought a mica plate 10 * 5 cm in size and about 1 mm thick. Mica can be easily "flaked" with a sharp knife blade. Get a few insulating gaskets from mica. They can be used to replace broken, damaged, lost insulation pads. Mica is easily cut with a knife into slices of suitable size.

Where can I get repair parts?

When repairing a car amplifier, parts are often required to replace faulty ones. It happens that you can't find them. Where can I buy? You can buy radio components via the Internet. For example, I ordered on AliExpress. It is not always possible to find what you need in our online stores.

An audio frequency amplifier is a device where the signal passes through cascades connected in series. Troubleshooting is carried out according to sufficient simple algorithm, so the question of how to repair a sound amplifier with your own hands is not too difficult. The only condition is the availability of measuring equipment. A conventional tester can detect some defects, and the presence of such measuring equipment as an oscilloscope and an audio frequency generator will allow you to repair the device efficiently and quickly.

How to fix a sound amplifier

Troubleshooting in low frequency amplification systems must be done in sequence. This will avoid mistakes and waste of time. Sound amplifier repair begins with an external inspection. In this case, you can easily notice broken wires, broken conductors or mechanical damage to individual elements. Because all the details sound system, falling under the influence of too high currents, change, inspection will reveal defects associated with electrical damage in various circuits. On fixed resistors, the paint burns completely, and the printed tracks on the board are often violated. Defective electrolytic capacitors are easy to detect by swelling in the upper part of the cylindrical body. Usually, such damage to radio components is not the cause, but the result of another malfunction, therefore, after removing visible defects, the device is not recommended to be turned on, but all stages should be checked sequentially. The first thing to do is to ring the speaker system and check for an open circuit between the amplifier output and the speakers.

power unit

Checking the audio frequency device must begin with the power supply. Most nodes use simple circuits transformer power supplies and only in some designs pulse voltage converters are used. If the defect in the audio frequency system is unknown, then before checking, the power supply should be disconnected from the main circuit. This can be done by cutting the printed tracks. Checking the power supply begins with measuring the output constant voltage. If it is too high, you need to check the control transistor and zener diodes.

If there is no voltage, the diode "bridge" is checked and the presence AC voltage on the secondary winding of the power transformer. The tester should check the electrolytic capacitors of the filter. A bipolar power supply is tested in a similar way, since electrical circuits"+" and "-" are usually the same. If there are faulty parts, they should be replaced and the DC output voltage checked.

Amplifying path

The next step is to check the output stage. A common malfunction is the breakdown of the terminal powerful transistors. If the device failed during operation, you need to touch the case or radiators of the output semiconductor devices with your finger. A strong heating of the radiator indicates that the transistor is broken. Using the tester, you can easily check the base-emitter and base-collector junctions. If there is any doubt, it is better to remove the transistors from the board. In order to qualitatively repair the sound amplifier, one tester is not enough. To work, you need a low-frequency generator and an oscilloscope.

If the power supply and output transistors are working, you need to look for defects in the pre-terminal and preliminary stages. To do this, the signal from the generator with a frequency of 800 Hz-1 kHz and an amplitude of 100 mV must be successively fed to the cascades of the audio frequency unit and control the passage of the signal through the acoustic system. When repairing structures of high output power, instead of speakers, you need to use a load dummy, and control the signal with an oscilloscope.

Structures assembled on specialized integrated circuits, do not have discrete elements. The board may contain power filter capacitors and input capacitance. In this case, any diagnosis does not make sense. If the supply voltage of the device is normal and there are no breaks in the input and output circuits, then the microcircuit will have to be changed. In automotive systems, printed wiring defects are common faults. Such violations are found in Chinese manufacturers. Poor-quality soldering from shaking and vibration is broken, and the car's low-frequency unit fails.

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Instruction

Find out the cause of the malfunction of the music center. The most frequent and obvious breakdowns can be associated with a violation of its parameters or the absence of sound as such. Check the speakers (speakers) with a tester for voltage.

Use a workable speaker from another technique to make sure that the reason for the loss of sound lies not in the very center. If, after connecting working speakers, there is still no sound, there is a problem in the music device itself.

Disassemble the body of the music center. To do this, unscrew all the fixing screws with a Phillips screwdriver and remove the rear protective cover of the device. So you get to the main board and you can inspect it.

Inspect the connection of the input connector and copper contact tracks on the main board of the music center. Use a soldering iron to restore the soldering in those places where it is damaged. To do this, it is better to use low-temperature solders that melt at 100 degrees, or conductive glue in general, so as not to violate the integrity of the small parts of the board.

Play the music center in all possible modes (radio, cassettes, MP3 player) and check for violations. If in all modes the sound is reproduced with the same noise, then the matter is in the output amplification path. Breakdown in the power amplifier. To fix it, replace the damaged amplifier chip with a working one.

After troubleshooting, carefully inspect the main board again. It may have poorly soldered places, swollen capacitors, darkened tracks and other defects that may soon make themselves felt. Replace all "suspicious" parts. Thus, you will prevent another breakdown of your music center and extend the life of your equipment.

Sources:

• Music center FIRSTaustria TCD
• Music center repair

Sometimes the music center does not have an MP3 function, but the pocket player does. But the player, unlike the music center, is not able to sound loud. To correct this shortcoming, it is necessary to connect the player and the center to each other.

Instruction

First, check your music system for front panel RCA input jacks labeled AUX or PHONO. Don't confuse them with headphone or microphone jacks - not only are they made to a different standard, they're designed for a different one.

If you did not find such sockets, then carefully, so as not to tear off any cables, turn the music center with the back wall towards you. You will surely find such nests there. Do not confuse them with other jacks, which can also be made according to the RCA standard.

Now take your unwanted headphones. Cut off the sound emitters from them. Purchase two RCA type plugs. Strip the wires that went to the sounder. One of the pairs consists of a colorless (or yellow) and red (or orange) conductors, and in the other, instead of a red or orange wire, there is a blue or green one. Connect all colorless or yellow wires to the ring contacts of the plugs, and the red (orange) and blue (green) wires to the pins.

Connect the cable to the player and the music center. On the latter, select the mode called AUX or PHONO. If it has several inputs, they may be labeled AUX1, AUX2 and the like. When searching for an input, set both the player and the center to a low volume. In the future, set the volume on the player so that the center preamplifier is not overloaded, and then adjust from the center side.

To prevent the player's battery from being discharged, connect the device to a special power supply that emulates a USB port. You can also use a powered USB hub that is connected to the unit, but not to the computer. Remember that if the player is not powered by a battery, but by a battery, charging the latter in any way is not allowed. Using the music center in conjunction with the player does not exclude the possibility of switching it, if necessary, to other modes.

Some novice radio amateurs are not eager to take on the repair of fairly complex electronic devices, such as CD or MP3 players, computers or stereos. In fact, most of the malfunctions of the same music center are quite simple to fix, with minimal knowledge in the field of electronics and little experience in handling equipment.

You will need

• - soldering iron;
• - solder;
• - flux;
• - headphones;
• - good speaker.

Instruction

Determine what kind of problem you need to fix. It is quite difficult to cover all the problems of music centers. Most often, you have to deal with the absence of sound or a violation of its parameters (timbre, signal amplification, frequency characteristics).

Start the search for the cause of the sound malfunction by checking the speakers (speakers). Connect another speaker (speaker) with a resistance of 4-8 ohms for testing. You can use a workable speaker from an old TV or tape recorder. Typically, the load resistance value is indicated on the back of the device case next to the corresponding connector.

If, after connecting a working speaker, sound appears or its quality is restored, the malfunction should be sought in the speakers. Otherwise, you will have to look in the internal circuits of the music center.

If wheezing is heard during playback, and the sound either appears or disappears, look for the cause of the malfunction in a broken connection between the input connector and the contact copper tracks on the main board of the player. Restore soldering in places where it is broken.

Check the operation of the music center in all modes: in the mode of the receiver, cassette deck, MP3 player. If the sound disturbance occurs in all three cases, the breakdown is most likely related to the output amplification path, namely the audio power amplifier. To finally make sure of this, connect the headphones to the “Phone” jack, remembering to turn down the volume. The absence of sound in this case indicates the failure of the specified amplifier. Replace the amplifier chip with a good one.

Even if the above steps resolve the problem, inspect the PCB for bad solder spots, "bulging" electrolytic capacitors, dark traces, and other defective wiring. Replace the identified defective elements. Such prevention will prevent larger malfunctions during the further operation of the music center.

Firmware programs are periodically released separately for each model of equipment. Update software necessary in cases of malfunctions or obsolescence of the previous firmware version.