Do-it-yourself Kenwood car radio repair does not turn on

Aradio is a very common electronic device. With rare exceptions, this undoubtedly useful device is not present in the car. The evolution of car radios is the video recorder and the car CD / MP3 player. But despite changing the recording medium in a car player, these devices are still referred to by the familiar word. car radio... It has been well established since the massive use of car cassette players.

Danny the section of the site is devoted to the issues of repairing car radios with your own hands. It's no secret that car players of various modifications and manufacturers break down.

Non the pages This section will not be a simple listing of specific malfunctions of certain car radio models, but methods of repair and restoration of these devices will be revealed. The presentation will be conducted without interrupting practice, with examples of repairing specific models of car turntables.

Introduction article. It describes the necessary devices that will be required in the process of repairing car radios.

How to connect a car radio or car CD / MP3 receiver to a computer power supply (PSU)? Anyone who wants to "power" a car radio from a 220V network faces this question. This makes sense if you plan to repair the car radio or upgrade it to a stationary music center.

Here you will learn about typical car player malfunctions and their causes.

What is a complex malfunction and how can error codes help in car radio repair? A real example of troubleshooting a complex malfunction of the Pioneer DEH-P3500MP car CD receiver.

When repairing disc car radios, it is often necessary to disassemble the CD mechanism. Shown in detail is the method of disassembling the CD mechanism, which is widespread among modern car CD / MP3 players.

CD drives for car receivers of different brands differ in their design. This means that you need to be able to disassemble CD mechanisms of different types. Here you will learn how to disassemble the CD drive of the Kenwood car radio without errors.

An article that tells about one of the typical malfunctions of car CD / MP3-receivers - there is no display backlight. How to fix this breakdown will be discussed.

Here we talk about an atypical breakdown of the Mystery MCD-778MP car CD / MP3 receiver. A real example of repair using an oscilloscope.

The volume control of the car radio does not work? The knob may be the cause of the problem. The rotary encoder is very often used in digital equipment to adjust various functions and control the device. Is it really necessary to replace the rotary encoder if it does not work correctly? How to restore the correct operation of the knob and avoid replacing it is described in this article.

In the practice of repairing car players and CD-receivers, there are cases when a schematic diagram, information on the pinout of the connector or a table for decoding error codes is needed. This information is contained in the service manual for a specific car radio model. You can download the service manual for some models of popular car radios by clicking on the link above.

Which brand of car radio should you choose? Read this article and this question will disappear forever.

Find out about the device of SD / MP3 car receivers. Among all kinds of modifications of car radios, so-called flash car radios have found their place under the sun.This article examines the device and the elemental composition of car SD / MP3-receivers without a disk using the Velas V-201U model as an example.

Warnings: 1

Posts: 2056

Warnings: 1

Posts: 2056

the whole problem is that there is no diagram, can anyone ease my problem. special thanks to hazik for good advice. with gratitude I will listen to further advice, including from other participants

the whole problem is that there is no circuit. can anyone ease my problem. special thanks to haziku for good advice. with gratitude I will listen to further advice, including from other participants

Warnings: 1

Posts: 2056

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, use a tester to 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.

The car radio, like any other device or mechanism in the car, can fail. As practice shows, the repair of car radios is usually carried out in the event of improper operation of the device or in the event of malfunctions not related to use. In this article, we suggest that you familiarize yourself with the main causes and methods of eliminating audio system breakdowns.

It's no secret that over time, the mechanical elements of a multimedia system tend to wear out. So, if the system does not turn on or off, it is necessary to either repair or replace it.

But first, let's figure out the main reasons why the radio tape recorder does not work:

1. Dirty device. If the radio tape recorder stops working, this may be due to contamination of the mechanisms - dirt or dust can accumulate between them, especially if the system is used in harsh conditions. As a rule, optical or mechanical components break in this case. One of the signs of contamination is a disc that is stuck and cannot play properly.
2. Also, mechanical failures can be the reason. This type of failure is usually associated with the power circuit. If the connection of the head unit was made incorrectly initially, or the electrical circuit is characterized by sharp drops, then there is nothing to be surprised at. The first symptom of problems with the power circuit is the lack of screen backlighting or the inability to start the radio.

Car audio system board

Before removing the radio from the car and starting to repair it, read the list of faults specific to audio systems. Getting and repairing the car radio from the car is not such a problem, but before you pull it out, you need to know exactly what to repair.

1. Perhaps the problem is the lack of power at +5. If you decide to get the device and repair it yourself, first of all you need to pay attention to diagnostics of the second contact of the CN701 connector. It should have a voltage in positive territory of 14 volts, this voltage should be transmitted to the collectors of the transistors. If there is no voltage, repairing car radios consists in replacing transistors or a zener diode.
2. There is no power activation signal. Before repairing car radios, you need to check the voltage of + 4.8 volts at the fortieth contact of the IZ901 controller. You should also check for a pulse on the third contact of the controller.

Dialing a multimedia system with a multimeter

Repair of car radios on your own or by a specialist is required if there is no sound volume or when the volume is increased and the tracks are played, the sound fills.

There may be several options:

Why does the radio tape recorder not read a USB flash drive or disc after starting the engine? The disk is stuck, stutters, the system does not see the USB flash drive?

The reasons may be as follows:

1. The radio tape recorder does not read the USB flash drive, does not see the disc, or the disc stutters or is stuck after starting the engine. Perhaps the device simply does not understand the recording format. Repair of radio tape recorders in this case is not required, you just need to burn the disc in a different format.
2. If the system does not see the disc when starting the engine, the disc is stuck, stutters or heats up, this may be due to contamination of the optical lens. As mentioned above, problems in the operation of buttons and the device as a whole after starting the engine can be associated with dirt. In this case, the problem is solved by using a special cleaning disc. The operation of such a disk is carried out in accordance with the requirements specified in the instructions. You can self-clean the system by blowing the elements or cleaning with a cotton swab.
3. Another reason may be the lack of laser current; you can get rid of such a malfunction by adjusting it.
4. Inoperability of loops and wires. Perhaps, during the operation of the car, the screws inside the structure simply loosened, or it could be a leakage of resistors.

Buttons do not work - there are several reasons. First, it may be mechanical damage to the buttons. To restore the functionality of the buttons, you need to disassemble the front panel and check the condition of the contacts. Perhaps the contacts from the buttons simply leave and they need to be re-soldered. If the button is inoperative, then it will have to be changed.

Secondly, the problem with the buttons may be due to a software malfunction. The malfunction is solved by rebooting the audio system and returning its functionality to the factory configuration. All settings will be erased from memory. After returning to factory settings, the device must be turned off for a few minutes.

If the radio tape recorder heats up and turns off arbitrarily, there may be several reasons:

1. The system heats up and shuts down as a result of poor power supply. Lack of power will cause the radio to turn off arbitrarily, or this is due to power failures. When the radio tape recorder heats up and turns off, you need to check the power cable - it may just come off or break, then it will have to be changed.
2. The device heats up due to poor ventilation and turns off when overheated. If the system heats up, this indicates insufficient ventilation. Such a malfunction is relevant for Pioneer radio tape recorders and, as car owners of such systems assure, there is nothing to worry about. But if the system heats up constantly and turns off at the same time, you need to think about additional ventilation.
3. Sometimes the device turns off due to software glitch. You can try to solve such a malfunction by resetting the radio to factory settings.

Kenwood Corporation has been producing high quality products for motorists for several years. Founded in Japan in 1946, it has grown to become one of the leading manufacturers of audio equipment. Stylish design, clear sound, dominance of high frequencies, long service life and ease of use are the result of the use of the latest technologies in the development of Kenwood car radios. There are two types of Kenwood car radios: CD / MP3 and CD / DVD 2 DIN car radios, which in turn are divided into different models. But, unfortunately, even the highest quality equipment, for one reason or another, may require repair.Highly qualified specialists of our service center will eliminate any problems, and your car radio will function well. You can trust repair of car radios Kenwood our service center.

1. The car radio does not turn on - since car radios with electronic control are especially sensitive to any voltage surges, the power supply may be damaged. In this case, it needs to be repaired;
2. No sound - there is no sound if the power supply, speakers, output stage or preamplifier fail;
3. The car radio does not read DVD or MP3 CDs - this problem arises when the mechanic or the laser head needs to be repaired. Mostly laser heads fail as a result of dust and driving on very bad roads. Another reason for unstable disc reading is a malfunction of the shock absorbers and the motor that rotates the disc;
4. Decks cannot be opened or cassettes cannot be played - this problem concerns older models. In this situation, the defect is associated with a break or slipping of the belts of the tape drive mechanism. Cleaning and replacement of some of the mechanical parts that are responsible for the movement of the cassette tape are required
5. Backlight is off or unstable - the reason is damage to LEDs, bulbs or power failure of the control unit
6. Disks are not unloaded or loaded - such a nuisance occurs if there are defects in the operation of the loading motor, control and power circuits, or if the sensors fail.

Repair of car radios Kenwood (Kenwood) is made very high quality and in the shortest possible time. We employ only professional specialists. After completing the repair, you will receive all the necessary recommendations for the correct and careful operation of the equipment in order to avoid breakdowns in the future. In addition, we issue a guarantee of the quality of the work performed.

The price for the repair of Kenwood car radios will depend on the type of malfunction and on the model of the device. For example, repairing standard car radios starts at 2,000 rubles, and cassette ones - from 900 rubles.

We do the diagnostics free of charge, the rest of the work, starting with dismantling and ending with the installation of the repaired device, is paid for. Our service center has all the necessary spare parts to replace any items that cannot be repaired. In order to find out how much it may cost you to repair your car radio, you can call us and get a full consultation.

It is very easy to use the services of our service center:

• Call by phone in Moscow (495) 771-52-79 and describe your problem. Our experts will help determine the most likely cause of the breakdown and the approximate cost of repair, or
• You can come to our service center and bring the device to free diagnostics... If the defect is not clear, we will accept the device and print you a receipt. After diagnostics, we inform you about the exact reason and cost of the repair.
• Ask a question using the feedback form on the site. We will answer you by phone, if you specify in the request, or by e-mail.
• If the cost is acceptable - we repair. You take the finished device, check it - pay for the repair, get a guarantee.
• If the cost turns out to be high - you take the device “without repair” without paying anything.
• Courier service - the courier will deliver your device to the service center and bring the repaired one back. Check the possibility of using this service with a consultant by phone in Moscow (495) 771-52-79.

When replacing BA3917 with BA3918 in a PIONEER vehicle, conclusions 10-10, 9-11 (AM / FM).

13.) CLARION ARX-3470 Fault: The FM receiver does not automatically pick up even-numbered stations. Solution to the problem: put a 2K resistor on R824. After installing the resistor, it is necessary to discharge the capacitor for the power supply of the car radio (it is enough to short-circuit the positive and frame wires between each other). Otherwise, the receiver will tune as before until the capacitor itself is discharged.

14.) TOYOTA CROWN 93.The standard amplifier is in the trunk - 4 powerful outputs + a subwoofer. All 4 outputs suddenly failed, only gurgling sounds, the subwoofer continues to work. There is a preamplifier board in the amplifier - the painfully familiar capacitors in the red shell 100mkf10v are immediately striking - they flow godlessly! The electrolyte eats through the tracks. In Toyota radio tape recorders, 99 percent of electronics failures are associated with these capacitors - change without hesitation!

15.) CD-changer CDC-M3. German. He worked in tandem with his fellow countryman BLaupunkt Paris RM104 with a data adapter. Started to fail when reading a disc with the effect of driving over bumps, even in the garage. Cleaning the optics didn't help. After investigations, rubbing of the laser head plume on the bottom of the case was found. It can be seen that there, in their homeland, the train once freed itself from the adhesive tape fastening it, but then they forgot to return the tape back. Eh! Germans. You would have our problems, and yours for us!
The loop, of course, was restored by stripping and soldering with MGTF wire, fortunately, it does not work for bending in this place.

16.) ALPINE CDA-7873R. Does not read CD. Doesn't even try to start. Knowing the owner, he asked how it happened.
It turns out that he was driving around a hedgehog running across the road in his BMW. At a speed of more than 150 km / h. Well, in a ditch.
BMW died, but the radio and the owner remained almost intact. Only CD does not read (for some reason))). I checked the broach of the laser, bent something, adjusted it, but found nothing else. It turned out that BMW took a terrible blow mainly on the bottom. Aha! This means that the plate has crouched on the axis of the disk rotation drive. Raised to the desired height. And everything is ok. This ALPINE is tenacious.

17.) DAEWOO AKF-7331, AKF-9255XV and many other models where Asians like to place the tuner KCF-201VA, KCF-203, KCF-205. FM band does not work. Or it works only after warming up. Or just frozen (in the garage in winter), and when the car warms up, it goes down. In any case, you can try to strongly warm up the tuner case at the soldering point of the case bus on the top cover with a 40-watt soldering iron for 15 to 30 seconds. You will receive FM reception. But not for long. From 0.5 - 5 days in winter and up to a month in summer. And do not look for non-propane, although there are always enough of them there and of course they also need to be eliminated. If you calm down on this, wait for guests with a complaint after a while. The reason is in the communication coil, or rather in the ill-fated implanted capacitor in this coil. This has already been written in the secrets of repairing TVs No. 509 - in some detail.

18.) GRUNDIG SCD5290 RDS (GR0945) Processor with mask E59B. The radio tape recorder is constantly trying to start up with an illumination of the scoreboard. At the same time, there is no information on the board. Altering the EEPROM in the processor did not give any results. The defect disappeared when cooled from the chlodon cylinder of the radio board. The malfunction turned out to be in a capacity of 100.0x10 volts. It stands under the LED mechanism close to the radiator of the voltage stabilizer.

19.) In Chinese-made radio and audio players, crackling and wheezing often appear in the volume control. Replacement is hard to find. The defect can be eliminated by screwing on the rivets that connect the potentiometer leads to the carbon track.

20.) Opel SC202 I got a typical glitch: when the relay is turned on, it pops and falls off. The relay is powered by BAW70 SMD diodes. One of them is supplied with 12 volts across 10 ohms (SMD). A break in this resistor leads to such a defect - the weak link

21.) FREIBURG CR43 BP2475, CR42 BP1475 In both radios, a processor with a mask 8 925 900 474 is used. When turned on without a card, it turns on as expected with a CARD request. But if you insert a native card, it additionally displays on the FM display and freezes. It is required to change the EEPROM in the MC68HC05B6 processor.

22.) FREIBURG CR43 BP2475, CR42 BP1475 Both radios use a processor with mask 8 925 900 474. When turned on, only the display backlight is available. It is required to change the EEPROM in the MC68HC05B6 processor.

23.) BMW REVERSE RDS (BP3836) P / N 7 643 836 341. Processor XC86515CFN 8 925 901 009 (68HC05B6). The radio turns on without asking for a code. The receiver is configurable and works without problems. We insert the cassette, the engine starts, but the head does not fit. We take out the cassette, and the engine continues to rotate until you reset the power from the radio. Reason: The processor EEPROM firmware has flown. It is required to change the processor.

24.) BLAUPUNKT SC202 (C) Made in Malaysia GM0202 7 642 852 521. Processor ZC408800CFN 8 925 900 612 mask 1C14H. Defect: the code is entered, the radio turns on, the receiver works, but the mechanic does not work! The EEPROM firmware in the processor has flown.It is required to overwrite the EEPROM of the processor.

25.) MERSEDES BENZ SPECIAL (BE 1350) Processor: SAB 80C535-N T40 / 85 (342) BIOS: NM27C512QE (250); LABEL: 1350 35/94 Memory: 85C82 I / SM smd. Some buttons do not work. Rather, only 3 and 4 work, so the native code cannot be entered. We redo the firmware and set the code for example 33333. Enter it. The radio turned on immediately without confirmation. Receiver tuning turns on and does not stop. The problem is in the oxides under the buttons themselves. With a tester at large limits, we measure the resistance on all buttons and look for a leak. In my case, the oxide is under the two buttons. Two cases in 2 months.

26.) PANASONIC CQ-DP33EU. Laser. On the UPD75112GF processor. Conversion from American mode (search step 0.2 MHz) to European. Solder the 47kOhm chip resistor in place with the R625 mark (to the 16th leg of the processor). You will get a step of 0.1MHz.
For more “careful” ones, the option of a step of 0.05 MHz is offered. The same resistor, but on the adjacent pad under the nickname R626 (to the 17th leg of the processor).

27.) Reconstruction of car radios from the American standard (tuning step 0.2 MHz FM and 10 kHz AM):

Pioneer KEH-2600 (percent PD4502A) - move the R603 4.7kOhm resistor to an empty pad under R601. And if you come across a "Jap" (76 MHz - 89 MHz) - then you have a similar resistor soldered to R605 or R506, or both together. For us, only R601 is useful, delete the rest.

SONY XR-C5300R (RX, RV), XR-C5400R (RX, RV), XR-C5200R, XR-C4200R and others with percent. series MN101C09—- MN101C12—- (variants are possible, the last 3-4 characters in the number are unimportant). The 6th leg of the processor (DST SEL) is removed from the ground by desoldering the chip resistor R532 with a nominal value of 100 kOhm and suspended at +5 volts.

28.) SONY XR - C 35 0 restructuring of the grid from the American standard (tuning step 0.2 MHz FM and 10 kHz AM) Processor MPD 17708 GC - its 22nd leg (DSTSEL) at a voltage of about 2.5 V our grid, at a voltage of 3.5 in Japanese grid, at voltage 0 or 5 in American grid.

29.) Sony XR-C453 RDS The power was not connected properly. After replacing the UMZCH NA13157, the radio tape recorder started working, all the button commands from the panel were executed, but the indicator on the removable panel did not light up (the indicator backlight lamps were on) and the button backlight LEDs did not light up (the LEDs are mounted in the button body). When checking, in the socket, 2 punctured SMD zener diodes at 6.2V D903 and D905 (on the case designation 6-2) were found, they stand at the input of the connector. After replacing the zener diodes, the socket worked normally.

30.) LG TCC9310 Reverse works either in one direction or in both directions. The defect is typical for this model (4 cases). When you click on the corner of the board with the optocoupler, the triggering becomes less frequent. Cleaning the optics and gear does not help. I stuck foil from a different CVL to each gear segment. Working. Looks like the optocouplers are of poor quality. Next time I'll try to change them. If someone went the other way, write.

31.) I would like to share the secret of tuning the frequency of the receiver without loss of sensitivity. As you know, there are 2 main methods of frequency tuning. This is, with the help of a converter and switching of the broadcast grid by the processor with the tuning of the tuner. But there is also a third method, which I have tested in several car radios. As you know, the processor in car radios constantly monitors the frequency of the FM local oscillator and with the tuning voltage maintains the local oscillator frequency with great accuracy. And for this you cannot simply switch the broadcasting grid or change the local oscillator frequency in the tuner. In general, the method is this, we take a 2-band tuner from the car radio and solder it in parallel with the "native" one, except for the local oscillator output to the processor, cut off the output from the "native" one, solder it from the installed one, and you're done. It is very convenient in Japanese car radios where you cannot switch the broadcasting grid.

32.) To convert the JVC KS-RT515 car radio to the European standard, it is necessary to solder the diode, which is located closest to the processor on the board. In the figure, it is indicated as D1, if you solder D2, the radio tape recorder will operate in the range from 74 to 90 MHz, and if you solder D3, it will only scroll through odd stations.

33.) DENON DCT-A100. Laser pickup problem. The original head is successfully replaced by SANYO SF-C93AQ at the price of $ 15.

34.) PROLOGY KX-2000R Fault: the cassette does not spin, the speed of rotation of the drive is floating... Wrong value of resistor R317. Replace with 4.7 kOhm or install an additional 1.3 kOhm in parallel.

35.) PROLOGY CMD-100, CMD-120 Fault: does not read MP3 discs, does not read MP3 discs with a high bit rate (over 192). Wrong value of resistor R224 and R225. Replace resistor R224 by 150 kOhm, resistor R225 by 18 kOhm (15 kOhm) on the CD control board.

36.) PROLOGY MX-7010 Fault: the cassette does not spin, the radio wheezes. Defective transistor Q203. Replace Q203 (2SC3203).

37.) PROLOGY ZX-9050, ZX-9090 Fault: does not load discs. The presence of a disc in the radio is not detected. The discs are loading, but the disc does not spin up. Defect of one of the capacitors (C25, C26, C56) on the CD control board, the voltage at the VREF point when loading the disc is 0 Volts. Replacing C25, C26, C56 on the CD control board with new ones. Denomination - 0.1 uF.

38.) PROLOGY ZX-9050, ZX-9090 Fault: does not read MP3 discs. Crash when reading MP3 discs with heating... Defective capacitor C3 (very rarely C4) on the CD control board. Substitution C3 - 820 pF, C4 - 940 pF.

39.) PROLOGY ZX-9050, ZX-9090 Fault: does not read discs (Er2), the disc spins up with jerks, the laser lens is trying to adjust. Defective laser. RF0 level is below 0.7-0.9 replacement of the laser with a new one.

40.) PROLOGY ZX-9050, ZX-9090 Fault: sound disappears with heating when playing CDMP3 on both or one channel. Defective capacitor C15 or C14. Replacing C14 (C15) with a new one - 0.1uF.

41.) AIWA CT-FX727M, came with a malfunction - there is no sound. I checked the amplifier separately - it works fine. Adjusts the sound of the TDA7313, working over I2C with a processor. The signal came to her, but there was no way out. The replacement gave nothing. The study revealed that at pin 27, the I2C amplitude is only 0.8V. The problem was in the resistors R926 and R927 (22k ​​each), one of them was open circuit, going from + 5V to the I2C bus

42.) SDA 4331-2 is in MB COMAND 2.5 This microcircuit breaks down on the VDD2 power supply (21 legs are broken to GND).
A certain percentage of microcircuits can be “cured”. We solder the microcircuit and supply power to 21 and 24 legs (briefly 1-2 seconds), about 8-9 volts (observing the polarity) from a power source designed for a current of 2 Amperes. If the burn is successful, the above pins are called by the device as a diode.

This week we had a car radio Kenwood KDC-4051 in our service. The device refused to work, or rather it hung up, reacted poorly to buttons and did not allow functions to be controlled. The client asked our technicians to repair the device, since the presence of USB and pleasant sound completely satisfied the owner. Oddly enough, but quite often old devices sound nicer than newer counterparts. Therefore, if there is USB in the radio, then you should definitely try to make repairs.

After carrying out the diagnostics, our experts came to the conclusion that the radio tape recorder is trite short-circuited along one of the control circuits. Some controls and protective zener diodes will need to be replaced. Sometimes this malfunction occurs due to charging the phone from the radio. Not all car radios support phone charging!

After agreeing on the cost, the car radio was repaired. The device is now operating normally.

The client was satisfied with the efficiency and cost of the repair. Now there is no need to buy a new car radio.

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Hello everyone. I bought a radio tape recorder KENWOOD KDC-BT92SD, put everything played normally, it worked. Car bmw e46 320 2000. The car was parked for a couple of days and the radio was not included. the panel did not work. I dropped it through the reset and it worked. And so every time. A couple of days and does not work. And if you arrived, for example, in the afternoon and the next morning it turns on. I have already brought a plus and minus from another place. From the cigarette lighter. And everything is the same. Who can help?

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Throw good wires with a cross section of 2 × 2.5 in the corrugation for the minus of the radio and for the yellow plus directly to the battery terminals. Put a fuse at the positive terminal, 15 amperes.
Put the red plus on the “acc” contact of the ignition switch - it should not be connected to the yellow one.
Of course, all connections must be of the highest quality, both in terms of electrical conduction and in terms of protection from external influences.
When you do all this, the problem should go away. Then write if everything is in order.

Car radios from China are highly sought after electronic devices used by Russian drivers. Such devices are inexpensive, and the benefits are enormous.
In this regard, the repair of Chinese pioneer car radios is very relevant and the ability to do it yourself will become a truly excellent talent. In this article, we will learn how to repair a car radio with our own hands.
China has always been famous for its electronic technology and the number of manufactured products that have flooded the world markets. So there will be practically no problems with parts on the car radio.
Recently, car radios have experienced an unprecedented heyday and technological surge. Appliances such as videotapes and MP3 players have evolved.
Despite the change in media, we still call all devices a car radio, and this name has been firmly established since the days of using cassette equipment.
Unfortunately, Chinese Pioneer car radios are paying the price for their immense popularity by frequent appearances in repair shops. And it's not just the quality of the products, which, frankly, is inferior to the Japanese and European models, but in harsh operating conditions.
Constant vibration, dust, voltage instability - all this leads to equipment failure.

It is not difficult to carry out repairs at home, but you need to acquire several necessary components, so to speak, the necessary equipment.

First of all, the pioneer car radio needs to be supplied with power, because it does not have a built-in unit, as in music centers.
It is not recommended to use a battery for this purpose. We need a network power supply, which will become the most acceptable option.
Power supply requirements:

• The power supply must provide an output voltage of 12-13 V.
• The power supply must withstand a load of 10 amperes.

Note. Naturally, you can use a power supply with a lower load current, because a 10A standard radio tape recorder consumes at a very high volume, and during repairs, you do not need to increase the sound so much.

• You can also use a homemade power supply, but it must have a powerful transformer.
• You can use a PC power supply that has an AT or ATX format (such a switching power supply for a personal computer has several outputs with a voltage of 12V and 5V, and it is these voltages that will be needed for repairs).

A digital multimeter is a standard measuring instrument that a novice repairer should have. Such a multimeter will allow you to measure not only voltage, but current and resistance.
In addition, modern multimeters have other additional features. This is a kind of "eye" of the electronics engineer, allowing him to evaluate what is happening in the electronic circuit.

The standard set of electronic tools includes:

Malfunctions can be different and below are the most common "ailments" and how to treat them.

• In the first place in the list of typical malfunctions of Chinese Pioneer car radios, it is the inability to read CDs and malfunctions during playback. The reason lies, as a rule, in the CD-mechanism itself, where there are a large number of electromechanical and mechanical components.

• If the malfunction is mechanical, then the tiny electric motor in the CD drive is replaced.

Note. It also happens that the engine in the CD drive does not have obvious damaged mechanisms, but gives out understated revs. In this case, it will be much more difficult to find the faulty element.

It is an equally common reason for poor performance of the car radio.There is nothing surprising in this, because almost all car radios are operated in harsh conditions when the optics and mechanics are contaminated. If dust gets into the device, playback malfunctions, the car radio freezes or the disc does not load.
Solution:

• The CD drive is disassembled and the lens of the laser reader is cleaned. This is usually enough so that the deposited dust does not interfere with the laser beam focusing on the surface of the disk.

Note. During the repair process, do not forget about checking the operation of the car radio with different disc formats.

Another common reason. This problem appears when the supply voltage is incorrectly connected, or when voltage surges are observed in the vehicle's on-board network. In this case, the car sound system may not turn on at all, or the sound or display backlight may disappear.
Solution:

• The protective fuse is checked.
• The protective diode is checked.
• The printed circuit board is inspected for burned tracks and capacitors.
• The microcircuits are examined for damage to the case: chips, cracks, etc.

• UMCHZ - this is what this microcircuit is called, which is a component of an audio frequency power amplifier. Failure of the UMZCH, as a rule, is associated with incorrect connection of the speakers, or with a short circuit in the circuit. As a result, one of the amplification channels does not work, which affects the sound in one of the speakers.

Attention. When connecting the car radio, the power must be connected last, before making sure that everything is done correctly and the connections correspond to the manual.

• Failure of the UMZCH can also be associated with overvoltage. It is noteworthy that the supply voltage of this microcircuit is not stabilized by anything and tends to fluctuate within a certain permissible interval.

• The microcircuit is simply replaced with a new one.

• In its pure form, mechanical failure that occurs due to vibrations or shaking of the soldering. Over time, the connectors for connecting the car radio are destroyed, and on Chinese models they are generally made poorly.
  As a result, normal electrical contact is disrupted.
• Spontaneous shutdown of the car radio, loss of sound or its absence - this is only an incomplete list of violations that occur during soldering degradation.

• The quality of the soldering of the car radio connector is checked.

• With this malfunction, the car radio does not respond to user commands when buttons are pressed.
• The car radio may start to "glitch".

China car radio with a menu in Russian

• The removable panel is disassembled. The ohmmeter checks the operation of all buttons.

It is also a common cause of car radio malfunction. A knob is a volume control that either deteriorates over time (Chinese ones quickly fail) or gets dirty.
Solution:

• Simple cleaning of internal contacts from dirt and oxidation, after disassembling the knob. The regulator itself must be properly dismantled from the car radio using a special desoldering tool.
  You also need to disassemble without using unnecessary force.

Note. The rotary encoder is cleaned with a special spray that is easy to apply to surfaces and evaporates quickly.

• If it does not help, the knob is replaced with a new one.

• A common breakdown that most often affects Chinese car radio models. In the disc playback mode, the car radio does not show a malfunction, but during loading / unloading - problems.
  In a word, those nodes that are controlled by the driver itself do not work. At the same time, the driver microcircuit heats up a lot, reaching as much as 80 degrees Celsius.

Universal car radios from China

• We replace the driver by dismantling the faulty hot-air soldering iron. The installation of the new driver is carried out with a low-power soldering iron with a narrow tip for 25-40 watts.

The above were the most common malfunctions of Chinese-made car radios and instructions for repairing do-it-yourself car radios. In the process of repair, it will be useful to use photo and video materials.
The price of parts for Chinese car radios is very cheap, so there will be no large repair costs.