DIY Mystery Amplifier Repair

Hello. My transistors q213 and q212 are heating up and at the same time the amplifier works in defense. Their legs do not ring among themselves. And the rest is all whole. What could this be? Thank you (photo is not mine)

Sucks :( I have the same problem.

Maybe someone will come in handy, I repaired teachers yesterday with the same problem of heating q213 and q212. The whole thing turned out to be in non-propa q207. After inspection, I found several more elements all over the board, which are about to fall off. So check the quality of the soldering

Mystery 2.80 did not use the car for half a year after the sale of the car, now, when connected, there is no full zero indication. After disassembly, an inspection for physical damage of any clues, I checked the diodes and transistors are not broken. TL494 replaced everything as it was - silence. Maybe TL494 is not working because soldered from the burnt out bp pc.
On board 12v available

Hello, tell me please, I have Mystery mk2.80 and the Q7 transistor is constantly on. What can be wrong?

What could be the problem? I noticed that the body of the diode d01 at the power input cracked and cracked. I'll try to change it tomorrow. although the diode only rings in one direction.

Hello, please tell me. I bought such an amplifier for a sub, but it periodically turns off on bumps or with strong bass. Moreover, the green indicator on it is on, the red one does not light up, and the sub is somehow working, but barely ... as if it is 100 times weaker. you can only feel if you put your hand on the speaker of the sub, that there are some vibrations ... I disassembled the amp, visually everything is intact, nothing is soldered ...

Something has fallen off somewhere, maybe the regulator is not soldered ... Such a malfunction is difficult to find) Solder all the contacts on the amplifier, most likely it will help ...

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The entire renovation took approximately 40 minutes. For questions in VK: Link to last repair:

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Repair of a car low frequency power amplifier (ULF). Causes of malfunctions. Analysis of blocks, circuitry.

Replacing transistors B688 and D718 is clearly not worth special attention, however:

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A car player, the main purpose of which is initially high-quality reproduction of music records from a tape cassette, CD-disk or flash card during a trip or a long wait (in traffic jams), very often upset its users with the following breakdowns:

• lack of sound;
• poor sound quality. wheezing, squeaking and so on;
• refusal to play records from cd, mp3-disks.

How to disassemble?

That is, for the most part, in violation of their direct duties. We will tell you in more detail what to do if sound disappeared on your car radio (Mystery, Pioneer).

The display lights up and gives information that the CD (flash drive) is being read, but there is no sound. Often this situation occurs with the following breakdowns:

• disruption of power supply circuits;
• failure of the speakers (speakers) of the car;
• amplifier malfunction;
• violation of contacts (solder) of the device;
• closure of the electrical circuit;
• the use of a powerful acoustic system that exceeds the technical capabilities of the radio.

The first, the main method that should be used in the event that your sound-reproducing equipment has lost sound is to ask for help from a specialist: to conduct a diagnostic examination of the device itself and its components in order to determine the cause of the breakdown and eliminate it in a specially designed technical center. You should not start doing self-repair if your device is under warranty service. Very often, the masters working on this profile, upon detecting external interference with the player, simply remove it from the warranty. This means that you will pay separately from your own pocket for equipment repairs.

In the case (second method), when the warranty period has already expired or it did not exist at all, you have the knowledge (initial), the necessary instruments and tools, confidence in your abilities, you should try to restore the device to work with your own hands.

Do-it-yourself repair of the Mystery radio tape recorder in case of suspicion of electrical circuit failure is carried out according to the following scheme.

With a multimeter, nickname the sections of the circuit in contact with the car radio for detecting a malfunction. As a rule, this can be a burnt out capacitor. We replace it with a new one. In the event that such a breakdown does not occur for the first time, we replace the capacitor with a more powerful part in terms of capacity.

Failure of both speakers is a rare occurrence. This usually happens to one of them. But then the sound does not disappear at all, but only worsens. If, nevertheless, both speakers are silent at the same time, using a tester, look for the cause in a broken contact with poor insulation, a short circuit, a malfunction of the power circuits or an amplifier breakdown is possible.

To repair the radio with your own hands, if the sound does not turn on, and more specifically, to replace the amplifier, you will need the following tools:

• soldering iron;
• solder;
• Screwdriver Set;
• tweezers;
• pliers;
• new amplifier board.

After preparing the named tools, we proceed to work in the following order:

• We disconnect the radio tape recorder from the on-board power supply after removing the device from the receiving socket.
• Remove the bottom and side covers of the device, the front panel.
• We release access to the replaceable amplifier board.
• With a preheated soldering iron, we soften the solder of the board.
• We very carefully straighten the bent ends of the latches holding the electronic board with pliers.
• We remove the board.
• Protecting the nearby parts and microcircuits with foil, carefully solder the worn-out board and remove it.
• We prepare the seat for the new part by removing the remnants of the solder and degreasing the seat with ethyl alcohol.
• We install a new board, if necessary, align its mounting legs with tweezers.
• We fix the part by soldering the legs.
• We check the correctness of the work performed with a multimeter for new damage, possible with careless handling with a soldering iron.
• We collect and install the car radio in its usual place.

Replacing the amplifier (board) is the most difficult and expensive DIY car player repair with complete or partial sound disappearance. The same faults as a violation of the integrity of the solders and a short circuit of the electrical circuit are detected easily and quickly, and are corrected with a multimeter and a soldering iron.

As for the loss of sound after you install a more powerful speaker system in your car that exceeds the technical capabilities of the radio, simply adjust their parameters necessary for high-quality and full-fledged playback of sound files.

We consider it our duty to remind once again that any actions to repair the acoustics of a personal car (with the exception of frankly minor malfunctions) are best left to professionals, despite the high cost of this kind of work.If you make mistakes during the repair with your own hands, you can be left not only without sound, but generally render the entire audio system unusable. Therefore, before starting, carefully study all the available information on fixing a breakdown, as well as photo and video materials related to this issue.

Sun 6 Jul 2014

Views: 20 987 Category: Power amplifiers

It's no secret that to get high-quality sound and powerful bass in a car, you definitely need a power amplifier. Today, fortunately, on the market you can find car amplifiers for every taste, it all depends on your specific needs. An amplifier for 200-400 watts is enough to power the standard car acoustics, but among us there are true connoisseurs of sound pressure, audiophiles and music lovers who will not be surprised by a couple of hundred watts of sound power.

It is for such people that class D amplifiers were invented - digital audio amplifiers that have high efficiency, compact dimensions and many other advantages.

Unfortunately, a car amplifier sometimes breaks down, in some cases repairs are more expensive than the initial cost of the amplifier itself, so it is very desirable to consider or try to repair it yourself, because sometimes a blown fuse can be the cause of a breakdown. Having at hand a simple and cheap multimeter with a diode continuity mode, you can find most of the defects that are very often observed in many car amplifiers.

Any car amplifier consists of three main parts - a voltage converter, a power amplifier block and a filter block (crossover).

A voltage converter or inverter is the most vulnerable part in any amplifier - 90% of the problems are associated with this particular node. The converter essentially powers the entire amplifier including the filter bank.

Exclusively all voltage converters are made according to a standard push-pull circuit using a PWM controller, most often on a TL494. Then everything is standard - driver, power transistors, transformer, rectifier and filter unit. In some (cheap) amplifiers, inverter circuits of an unregulated type are implemented - in a word, there is no control of the output voltage, of course this is quite bad, but it is not at all a necessary process if the amplifier is not sensitive to the supply voltage and is a cheap model.

Converter transistors - they are the ones that fail most often. In cheap Chinese amplifiers, transistors are strangely marked, even if you cannot find similar transistors, you just need to know one thing - the keys can always be replaced with IRFZ40 / IRFZ44 / IRFZ46 / IRFZ48 or more powerful IRF3205, the choice of keys is actually quite large, I just listed the most available options. In general, N-channel high-power field-effect transistors are used exclusively in all inverters of automobile low-frequency transistors - up to the brutal IRF1404.

Initially, we check the board by eye - sometimes visible defects can be observed (burned out resistor, broken tracks on the back of the board, etc.)

Before replacing the transistors, you must first check the power fuse, the diode on the plus and minus buses (when the power is reversed, it also burns out), and only after you have made sure that everything is ok with these parts, we replace the keys.

For a more professional repair, an oscilloscope is indispensable. Initially, you need to check the presence of rectangular pulses at the 9th and 10th output of the generator microcircuit, if any, then the microcircuit is working. Then we check for the presence of the same pulses after the driver - on the gates of the field switches. If there are no pulses, then most likely the problem is in the driver, if they are, then without hesitation we replace the field-effect transistors.

It is extremely rare that there is a problem with the power amplifier, the converter burns out first, keeping the amplifiers. In the converter, other breakdowns are possible, although very rarely.There is a problem with the input and output capacitors or the diode rectifier, which rectifies the high frequency AC voltage from the transformer.

definitely well done, but five minutes extra!

I took care of it all absolutely until the short man in a trance.

amplifier from the microcircuit the current is not milked the microcircuit changed the change is not present what to do?

5.40, how did you determine that mikruha died?

REACTIONS SPEAKS ZERO. FUCK @ FUCK! FUSE REMOVED!

you said that the KA 455S microcircuit burned out, in fact it is the KIA4558 operational amplifier which is responsible for protection. but you didn’t make a video how you changed it.

The Mystery MR 2.75 amplifier went into defense immediately after being turned on, and even a cursory glance at the board was enough to see the possible reason for this behavior. As usual, we will conduct an initial inspection and diagnostics of the amplifier, fix what was repaired in it before us.

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They brought an active mystery subwoofer, and after opening it, a horrifying picture appeared in my eyes in the form of a board, a good part of which is covered with the remnants of a torn capacitor. Other faulty elements were also identified, and even such a setup as an incompletely closed transistor.

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Repair video for another car amplifier. The essence of the problem is that when turned on, the fuse in the MYSTERY Jadoo MJ 2.120 amplifier blows. After a visual inspection, the cause of the malfunction was immediately identified and eliminated, but it was not completely eliminated. However, this did not affect the work. almost a year has passed, and the amplifier still pleases the owner.

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Quite an interesting repair of the Mystery MA-4.250V2 amplifier. The amplifier goes into protection immediately after switching on, but the current consumption does not increase. It can be assumed that everything is in order with the power unit, and the problem is somewhere in terms of control. But checking the radio components shows that they are all in good working order, and only a more careful examination and checking the transistor with a tester showed which part does not behave very correctly. I will show you how to diagnose a malfunction in a car amplifier converter, how to fix it. How to check the operation of PWM on the TL494 with a multimeter and an oscilloscope, how to disable the built-in protection of the TL494.
We will also check if the power amplifier can be repaired using a cheap Chinese toy oscilloscope DSO150. And also a pulse converter for TL494 in a car amplifier.

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Good afternoon to all radio amateurs. Help connect the transformer. The subwoofer from the computer has broken. Sound on your computer through a subwoofer and 2 speakers. The subwoofer stopped working (there is an amplifier in it). I gave it to a friend to make it out. He rang the bell and said that the transformer had flown. I bought it via the Internet, as they said, an analogue. But a friend according to the scheme cannot understand anything how to connect it. All the more so (complete zero in this science). I only understood how to connect 220V, well, it's not difficult. Help me to understand. I attach a photo of my native and Russian counterparts with a diagram. Please help. Thank you in advance for your help.

It looks like there really is a 2-polarity voltage.
This is where this transformer is used,
Total power 63W

the photo shows that the winding wires (two blue and black) from the transformer go to the diodes connected 2 in parallel.

These are two alternating voltages with a midpoint rectified by diodes (2 in parallel), which are connected to the windings either by anodes or cathodes to obtain a 2-pole voltage, at the output there are two electrolytes for each arm.

TPP258 will do, but only with a total power of more than 25-30W there will be a voltage drop. There will be no maximum power.
But for a room, 20-25W is enough for neighbors to hear both from below and from above.

Active subwoofer Mystery

How to connect a Mystery active subwoofer, this article will be able to suggest.The main advantage of this technique is its price.
In addition, this sub can be easily connected to the radio, and then placed in the car. By the way, usually such a speaker is placed directly under the car seat.
The connection diagram of the Mystery active subwoofer implies reproduction of frequencies in the range of 30-200 Hz.

How to connect a subwoofer active mystery

The most important advantages of this active subwoofer are the following features:

• It is equipped with a built-in amplifier for even higher sound levels.
• Such a device is very compact in size.

Note. Due to this, it can be easily placed, as mentioned above, directly under the car seat.

• Thanks to the quality characteristics of this speaker, it is possible to reproduce sound with clear low frequencies. At the same time, due to this, the frequency of the sound will be slightly increased, which is why it will be clearer.
• The speaker costs very little - only 2500 rubles. But despite the price, it is very reliable.
• On the territory of the Russian Federation, its sale began in 2012. That is why it will not be difficult to acquire such a device, since now it is quite common.
• And although the device has a very compact size, the sound quality can be called very good. That is, a subwoofer (see How to Make a Subwoofer: Good Tips) has excellent sound output.

How to connect an active mystery subwoofer

• Has a stylish design (although this is not so important, because it still has to be "hidden" under the seat). However, due to this, it can be easily positioned near the rear window.
  But he, in no way, will affect the overall style of the car. The body is made of aluminum and is very durable. As a matter of fact, one can be convinced of this only once having seen this speaker.

Note. The speaker can easily withstand even the most severe mechanical shocks. And this is a fairly common phenomenon, since the device is concentrated directly under the seat of the car.

• The remote control of any system perfectly adjusts the volume of the sub. Also on its body there are several additional adjustments that facilitate the work of the subwoofer itself.

Remote control, which is placed directly on the steering wheel

• The sub has an overload and power on indicator, due to which the user will always be able to understand whether the device has already booted up, or whether it is necessary to wait a little longer.
• Fits in any car as the speaker is versatile.
• It is easy to connect, but it requires special knowledge.

Note. You can get them after reading our instructions.

There are few disadvantages of this device.
But still they are:

• Connecting a subwoofer is specific, so you have to tinker with it a lot.

Note. You should not purchase this subwoofer based on its cost alone. This technique is perfect for those who are first-time self-installing a subwoofer. Will fit into a car that does not require too high acoustic parameters.

Mystery subwoofers have the following main characteristics:

• The speaker is small - only 1 x 200 mm.
• It can reach power up to 200 W, but this is its maximum value.
• The diffuser has a diagonal of 8 inches, which is due to the fact that it is made of Kevlar and Nomex.

• Equipped with a magnet weighing 425 grams. Actually, this is the reason for the overall weight of the device.
• The voice coil is 1.5 inches in size. It is made of aluminum material.
• The cutoff frequency can well be adjusted. Its values ​​range from 40 to 160 Hz.
• Can reproduce frequencies in the range of 30-200 Hz.
• It is possible to adjust the bass level using the remote control.

Note. The bass can vary from weaker to stronger. However, not every song requires too high bass.

• The body is cast, made of aluminum.This provides it with great strength. In addition, this is due to its low cost.

Mystery subwoofer active how to connect

Connection can be made in several main ways. Moreover, each of them is original.

Mystery active subwoofer connection diagram

In this case, the connection itself is carried out by connecting the line input of a special amplifier (see How to connect an amplifier and a subwoofer to a car radio: your own master) to the input of the subwoofer. This input is called “stereo”. Once connected, inside the amplifier, these signals are either mixed or transferred to 2 different amplifiers.

Note. If the amplifier has only one connector, then the receiver is connected with a cable to the line inputs located on the subwoofer. In this case, you have to follow the instructions that are usually found in the kit.