Repair and diagnostics of electronic circuits. Repair methods for electronic cigarettes. What kind of damage can you fix yourself?

Most often, people are interested in electronics in order to be able to repair any device. Only a small part of hobbyists engage in independent development. Although theoretical knowledge gives a general understanding of the operating principle of components, for repairs it is much more important to know the methods for checking them. We will tell you how to find a fault in an electronic circuit with your own hands, eyes and a simple tool.

Basic troubleshooting methods

Before carrying out repairs, it is important to determine what the problem is - this process is called diagnostics. So, we can distinguish two stages of checking electronic devices:

1. Checking the functionality of the device. It does not always happen that the device is completely “dead”; you need to check whether the device turns on at all, or turns on and turns off immediately, or some specific buttons or functions do not work.

For example, when repairing LCD monitors, a problem such as backlight failure occurs. In this case, the monitor may either not turn on at all and its indicator blinks, or the indicator indicates the on state, but there is no image. In this case, if you shine a flashlight on the screen, you can see that the image is still there and the monitor seems to be working, but it is dark - and this is just one example when a preliminary check simplifies diagnostics.

Most problems with an electrical appliance can be identified externally. These can be either simply burnt components - diodes, resistors, transistors and capacitors, or soldering defects or mechanical damage to the elements and the printed circuit board itself.

3. Measurements. If the board and parts look normal, then you should proceed to measurements. They are carried out mainly using a multimeter and an oscilloscope. In some cases, specialized devices are used, such as frequency counters, logic analyzers, etc.

So, the generalized troubleshooting algorithm is:

Board inspection;

Determination of excessive heating of electronic components of the board;

Measurements and testing with a multimeter;

Using an oscilloscope and other instruments;

Replacement of a failed part or unit.

Visual inspection should be carried out from general to specific. Or in simple words - inspect the general appearance of the electronic device, immediately checking the integrity of the cables and power wires. Their cover should be smooth and intact, without kinks or sharp bends, there should be no bumps or other unevenness on the shell.

After you have verified the integrity of the device, you need to disassemble it and get to the printed circuit board. Inspection of the internals should begin with checking the integrity of the cables and wires of other interconnects. It is important not to tear them during disassembly, since cables often go from the boards to the key blocks and displays mounted on the case.

After this, inspect for traces of heat or soot on the board and damaged components. Let's look at what faulty electronic components look like. For example, the housings of faulty transistors and burnt-out diodes burst or crack.

A crack or small dot appears on integrated circuits. In some cases, both burn out, leaving burning marks on the board as a result. Pay attention to whether there is a characteristic smell of burnt insulation. This way you can localize from which element or area of the board this smell comes from. You can see below how to identify burnt transistors and microcircuits.

Resistors usually burn out or darken, less often the resistive layer breaks and the part looks serviceable.

How to identify burnt capacitors? They basically “short” between the plates and, if they are in the power circuit, then the board tracks or the capacitor body are damaged. If the circuit was low-current, a broken capacitor will simply short-circuit it without visible traces of the flow of large currents. Capacitor housings crack less often.

While electrolytic capacitors can be identified by a deformed housing cover or traces of electrolyte leaking down. There are two diagonal grooves on the cap of the capacitor; they are needed to prevent the housing from being torn apart in an emergency. In this case, the lid swells or cracks. Less often squeezes out the bottom.

With SMD components the situation is somewhat more complicated. They are often extremely difficult to examine for integrity. There is one method for finding a short circuit in a board with SMD - this is thermal paper, such paper is used in a cash register, so you can use any receipt. Printing on it occurs due to heat. This means that when you apply power to the board, the shorted part will overheat and be printed on the paper. You can see the troubleshooting technique using thermal paper in the video:

But you need to remember about electrical safety and not resort to this diagnostic method if you are not sure whether there is dangerous voltage there. This can be done safely and accurately.

To detect a thermal short, in most cases you will need a lab power supply or other current-limiting power source. If you are diagnosing 220V circuits, you can use a test lamp; if there is a short circuit, the lamp will light up at full intensity. In fact, it will act as a current-limiting resistor.

During a visual inspection, it is important to determine the condition of the contacts of all detachable connections. They must be clean, without oxides, with a characteristic copper or silver luster. If the contacts are not too heavily oxidized, they can be cleaned with a paper eraser or the wooden side of a match.

In more advanced cases, they need to be tinned, this way you can restore the contact surface with tin. The worst option is when there is nothing to clean or tin, then you need to either change the entire board, or solder conductors to the board tracks and connect them through them.

Also carefully inspect the traces of the printed circuit board; they can burn out, crack when the board is bent, peel off and oxidize. They are restored either with a drop of tin or a piece of wire; when the tracks are located too tightly - they are replaced with a piece of wire - a thin winding wire or twisted pair wire will do, soldering them to the beginning and end of the printed track.

To summarize, learn 5 tips for external electronics diagnostics:

1. Most faults can be found during external inspection;

2. Carefully check the quality of soldering and the presence of microcracks;

3. Pay special attention to power circuits;

4. Swollen electrolytic capacitors in most cases are the cause of both complete inoperability and the inoperability of some individual functions;

5. A part that appears to be in good working order is not always so.

If an external examination does not bring results, then you should. If the device shows no signs of life and:

Its fuse has blown, so we use a multimeter to test the circuit and find where we have a short circuit. The ring mode in most multimeters is combined with the diode test mode (in the figure below);

If the fuse is working, check with a voltmeter whether the supply voltage is reaching the board.

If the voltage does not come, then the problem is most likely in the cable; this can be determined by ringing the cable from the plug to the point of connection to the printed circuit board.

Do not plug the power supply directly into the network unless you are sure that you have corrected all problems. Connect in series the incandescent light bulb that we mentioned in the middle of the article.

After you have verified that the diode bridge is working properly, you should check whether voltage is present. If not, then look for a break on the board; if it does, then the method for checking it is shown in the video below:

Further diagnostics of the electronic device board consists of step-by-step measurement of the parameters of each component and comparing them with nominal values. The task is greatly simplified if you have a diagram of the device being repaired.

If you have an oscilloscope, diagnostics will be greatly simplified, since checking PWM signals at the controller output and at the bases or gates of transistors is normally only possible in this way. How to use an oscilloscope is described in the article and a number of other articles on our website from the thematic section.

Conclusion

Electronics repair is not only knowledge of the operating principle of the elements, but also intuition, experience and luck. The main thing to remember when making repairs is safety precautions - do not touch the power supply board if voltage is applied to it. Discharge the filter capacitors of the power supplies, since their terminals can carry voltages of up to 300 volts. And also when diagnosing circuits with integrated circuits, it is better to immediately look for the technical documentation for them, it can be found by searching for “datasheet name of the microcircuit”.

Determine the malfunction of parts, both installed on the board and in their “pure” form. Select analogues for replacement, learn by what basic criteria this is done, and determine the interchangeability of parts.

In practice, you will learn typical connection diagrams with examples of connection in the circuit of a real device. As an example, we will look at the circuits of the most common devices: power supply, laptops, monitors, chargers, etc. As a result, you will be able to repair them yourself at the component level.

The study of various electronic components found in almost all household and industrial electronic devices without exception. Construction of circuits based on them, from elementary simple to more complex, with the construction of timing diagrams and a detailed study of ongoing processes

Studying the operation of operational amplifiers, comparators, logic elements. Small circuits are also assembled based on almost all of the listed elements, with the study of their operation, measurement of basic parameters or examination of circuits using an oscilloscope.

Study of the basic principles of operation of measuring instruments designed to measure resistance voltage current, visual examination of electrical signals (oscilloscope)

Topologies for constructing circuits and examples of real circuits based on one or another topology will be considered. The features of these schemes and areas of application are described. Let's look at several basic typical circuits for constructing pulsed power supplies; we will talk about the features and areas of application of a particular circuit. Next, students will be offered real circuits (sheets with different power supply circuits were distributed) and they will have to independently determine the topology of this circuit. It is the determination of the topology of the circuit that 80% determines the success of further repairs, which in 99% of cases will have to be carried out without having a diagram of the specific power supply being repaired.

All listeners will be asked to examine several dozen electronic components of various designs; by power, by the method of marking (alphanumeric or color) and it tells what and how it is designated, what it is (diode, resistor, transistor, etc.) and what it is used for. What other design options exist and where are they installed, depending on the characteristics. We train repair technicians to help you identify the fault in any electronic circuit.

Practical training in troubleshooting electronic devices. You can bring something that doesn’t work from home, and here we repair it collectively or in groups. For practical classes, people bring circuit boards from washing machines, hoverboards, power supplies and other equipment for repair.

During the learning process, we give students various questions or problems that have non-standard solutions, so that they not only memorize how this or that element works, but can also think independently and apply the acquired knowledge in practice.

As a rule, we meet the wishes of students and, according to their choice, place the main emphasis when studying circuits in the direction of computers, household appliances or telephones.

The course is suitable for anyone who plans to understand the repair of any electronics. Household appliances, industrial and any other that operate under electronic control.

The courses will be interesting both for people with zero experience and for those who are already involved in equipment repair. To begin with, you can come to our center and see with your own eyes how the courses are conducted. You will be able to chat with the teacher and learn more about the course. We accept people of any age.

On any Monday you can come and try the electronics course absolutely free.

After completing the entire course, you will have the skills to repair any electronics. All our students can ask for advice or help at any time, and we will be happy to help. Bonus! all our students sign up for a common group on Watsapp, where you can consult and share experiences. You will also have a discount on our other courses and, of course, a certificate of completion of electronics repair courses.

We train experienced and certified craftsmen who are fully prepared for the job. The experience and knowledge gained during the training will give you confidence in your abilities to open your own workshop for repairing modern electronics.

R section Workshop compiled for beginner radio amateurs who want not only to assemble and make homemade products, but also to independently repair household electronics.

Z here You will find repair articles ranging from devices such as CD/MP3 players to household compact fluorescent lamps. You will learn how to properly disassemble/assemble a CD deck of a car player and how to restore the functionality of a portable audio speaker. The main points of the repair are also discussed and high-quality photographs are provided for clarity.

N and pages This section contains information on how to repair a DVD player and stereo system. We talk about such typical malfunctions of modern color TVs, such as the appearance of colored spots on the kinescope screen. There are also articles about modern portable technology - MP3 players, portable sound speakers and small-sized LCD TVs.

D la For a more complete assimilation of information, high-quality photographs of the repaired devices and their components are provided. In some cases, schematic diagrams, photographs of radio components and their pinouts are provided. All information provided is based solely on personal experience in repairing consumer electronics.

To go to the article you are interested in, click the link or miniature picture icon located next to the brief description of the material.

Happy renovation!

Television equipment repair

What should you do if your LCD TV has lost its firmware and won’t turn on? We reflash SPI Flash memory 25 series. A detailed manual for beginner radio mechanics and electronics engineers.

On Erisson TVs, a common fault is the 2SB764 transistor in the vertical scanning circuits. However, the fault appears again even after replacing the faulty transistor with a new one. The cause of the malfunction is a “bug”, an error in the design of the device. The article discusses in detail an example of eliminating this defect when repairing Erisson TVs models 1401 and 2102.

The article discusses the repair of a portable LCD TV Prology HDTV-909S. Malfunction - the TV does not turn on. During the repair of the portable TV, the 2SA2039 transistor was replaced with a domestic analogue, which did not in any way affect the performance of the Prology LCD TV.

Repair of equipment with a laser optical drive

The main part of any disk device is the laser drive. A little knowledge about repairing and eliminating the causes of failures of these devices will not hurt, especially for novice radio mechanics!

Basic malfunctions of DVD players and methods for eliminating them (No disk and Error). The most vulnerable parts of DVD players are the laser reader, spindle drive, driver and main processor. Recommendations for repairing and replacing faulty parts and components of DVD players.

How to quickly replace the optical laser unit in a DVD? A simple step-by-step technique will relieve novice radio mechanics from the painstaking work of disassembling a DVD drive and replacing the laser in it.

When repairing car CD/MP3 players, it is sometimes necessary to clean the lens of the optical laser unit and replace the spindle motor in the CD drive. How to properly and quickly disassemble/assemble a CD drive? The article discusses a step-by-step method for disassembling a CD drive; many photographs are provided for clarity.

Is your portable CD/MP3 player having trouble playing disc recordings? Learn how to troubleshoot your CD/MP3 player when playing a disc. An example from real-life repair practice, plus some tips on how to troubleshoot a portable CD/MP3 player.

Repair of sound-reproducing equipment

With this article we will begin our acquaintance with the device, circuitry, as well as the “components” of a car amplifier. Despite the apparent differences, all car amplifiers have a similar design and circuitry. The material presented in the article will help novice radio mechanics understand the structure of any car amplifier.

This article describes the design and repair of the SVEN IHOO MT5.1R speaker system. The information will be of interest to all those who are interested in independently repairing sound reinforcement equipment. An example of a real malfunction and repair methods. Attached is an archive with a schematic diagram of the device.

Despite the complexity of the circuitry of modern music centers, their malfunctions are quite typical. The practice of repair is shown using the example of troubleshooting a Samsung MAX-VS720 music center - hoarse and quiet sound. Find out now!

Simple repair of the Xcube player. The most common malfunctions of miniature MP-3 players are mechanical breakdowns associated with intensive use of these popular devices.

Once they brought me a JBL Charge 3 Bluetooth speaker for repair, but it turned out to be not it... An example of repairing a cheap copy of one of the popular wireless speaker systems.

Recently, portable speaker systems, in English terminology - Portable Speakers, have become widespread. Portable speaker systems are especially in demand among young people. Portable speaker systems are small in size, have good sound reproduction quality, and are self-powered. What is the “electronic content” of these devices?

In repair practice, there are often cases when repairing a device is impossible due to the impossibility of replacing any electronic component. In such cases, you have to look for the most suitable replacement for the faulty part. The article discusses the repair of a portable speaker system. Instead of the faulty PAM8403 chip, the TDA2822 chip was quite successfully integrated.

According to the statistics of car radio malfunctions, in first place are breakdowns associated with the power circuits of these devices. A simple repair of the Mystery MCD-795MPU car radio is considered - the protective fuse has burned out, the radio does not turn on. This repair technique is useful when repairing any car radios: cassette, disk, diskless (with USB).

Repair of various household radio electronics

This article describes the design and repair of an electric thermos kettle. The design and purpose of specific parts and electronic components are examined in detail.

This article discusses the concept of a thermopot. The main electrical components, as well as electronic components that are used in thermopots from different companies, are examined in detail. The information will certainly be useful to all those who want to repair a faulty thermos kettle themselves.

Instead of ordinary household incandescent lamps, compact energy-saving lamps come, which can be installed in a standard E27 (E14) base. Despite the fact that energy-saving lamps are more durable than conventional incandescent lamps, they also fail. The cost of energy-saving lamps is quite high and their repair is justified at least for personal purposes. Especially when you consider the fact that in most cases the lamp itself is working, but the high-frequency converter fails, which is easy to repair.

SMD installation is one of the most difficult to repair, especially in the absence of special equipment and necessary spare parts. Each radio mechanic solves the problem of replacing SMD components for himself. Here is one example...

Electrical safety during maintenance and repair of radio-electronic equipment

When repairing electrical installations, electronic devices and electrical wiring, you must follow simple electrical safety rules. The article briefly describes some of the techniques and rules that radio amateurs and electricians use in everyday practice.

Electrical equipment of vehicles

This article is devoted to the electrics and electrical equipment of an ordinary Chinese scooter. Almost all elements of the electrical circuit of the scooter, their purpose and features are described. The information will be of interest to all owners of Chinese scooters who are not familiar with the electrical equipment of the scooter, but want to know more about it.

A malfunction of the scooter relay-controller leads to undesirable consequences: the lighting lamps burn out, the battery fails, over time the battery charge decreases and you have to start the scooter with a kickstarter. You can check the relay regulator on a scooter using a multimeter. Read about how to do this here.

Power supply repair

The second part is a continuation of the first part and examines the composition and operation of the circuit management and control welding inverter.

5 parts are devoted to the circuitry of PC power supplies. Each of them talks about one of the electronic components of a switching power supply (UPS). Schematic diagrams are provided, as well as circuit solutions used in a specific circuit and possible malfunctions are described.

This series of articles will help those novice radio amateurs who want to learn how to repair, upgrade and independently analyze the circuitry of real power supplies. And although diagrams of electronic components of AT form factor UPSs are given as examples, the information provided will help you understand the principle of operation of a computer UPS and further understand the design of more complex ATX format UPSs.

Most floor scales are made according to the same principle, so they experience the same breakdowns. To learn how to repair electronic floor scales, you will need to study several important nuances.

Device of electronic floor scales

The product consists of several elements. As a rule, experts distinguish the following parts of it:

display;
frame;
printed circuit board with various microcircuits;
strain gauges.

You need to start diagnosing a device by looking for simple problems.

The device is made of tempered glass, which rarely fails due to the high strength of the case

The process of operating a bathroom scale involves constant pressure on its surface. After this, the load will be evenly distributed across the sensors. Metal strain gauges can fail due to the passage of time. If one of them sends the wrong value, .

If the scales do not work, then repairing the scales yourself is a difficult procedure. To fix most problems, you need to use a special tool. You also need to have skills, for example, to cope with replacing and soldering a new contact.

To diagnose a breakdown, you will need to check each element of the product. If the scales are completely turned off and do not turn on, you need to disassemble them and check the integrity of all wires. If they show incorrect data, then you need to look for a problem among the strain gauges.
Elimination of the most common breakdowns
For successful repair you will need to follow a simple algorithm of actions. If a person wants to know how to repair an electronic floor scale, he should read the step-by-step repair instructions.
Sensor repair
If the scales break down due to sensors, first of all you will need to establish the type of problem (sensor bending, wire breakage, complete breakdown). If the malfunction is related to the curvature of the structure, it will need to be straightened. Most often, one of the strain gauges fails. In this case, you will need to perform the following steps.
Check the functionality of the sensors. To do this, you need to press your hands on each of them. Even with slight pressure on only 1 sensor, the scale should turn on.
Disassemble the scales and carefully examine the wiring.
If there is a break (near the board or the sensor itself), it will need to be repaired. To do this you will need to use a soldering iron.
In some cases, the break is hidden behind the adhesive base. It is necessary to carefully open it and check the reliability of the connection.

Wires connected to the strain gauge
If the sensor is completely broken, it is replaced. Finding and buying a suitable spare part on your own is quite problematic. When looking for a new load cell, you need to pay attention to its compatibility with the device. It is better to purchase it in specialized stores. When purchasing, you must use the help of consultants. The new sensor will need to be secured in the mounting location, and the wires will also need to be soldered to it.
Repairing the cable
Loop repair is usually required when the numbers on the display are not fully displayed. A cable is a set of wires that connects the display and the board inside the device. To assess the condition of this element and carry out repairs, perform the following steps:
Complete disassembly of the case. Checking the integrity of the loop.
If the numbers are not fully displayed, this means that the cable is coming off.
Elements that move away from the board are securely soldered.

Fuzzy display of numbers on the display (example in the picture) may be due to its breakdown or poor-quality wire connection
You can use a special conductive glue to press the cable and all contacts to the board. After this, the problem should disappear. All gluing or soldering work must be carried out with great care. There is a possibility of damage to the board due to careless actions.
Device calibration
In some cases, the malfunction is due to incorrect sensor settings. Incorrect data may appear on the display if for some reason calibration has not been performed. Modern scales are automatically calibrated every time they are placed in a new location.

Reader malfunctions occur for various reasons. This could be a simple freeze caused by an error when opening a large file. In such cases, the e-reader stops responding to touches on the sensor and button presses. And if you cannot reboot it by pressing the RESET button and holding it for 10-20 seconds, there is only one way out - disassembly and repair.

Typically, e-reader owners are afraid to disassemble their devices themselves and turn to service centers to carry out qualified e-reader repairs. However, in this case, self-repair is possible and even desirable, because it will help save not only money, but also time. The main thing is not to worry. Disassembling the e-book is quite simple. First you need to prepare everything you need. In addition to observant eyes and “even” hands, you will need very few tools: a small knife, maybe a kitchen knife; miniature Phillips screwdriver (can be replaced with a nail file or the tip of a stationery knife); Tweezers with sharp stems are also desirable.

Prepare your work area. The table should be cleaned and well lit. When disassembling, it is advisable to place the device itself on a soft cloth or large napkin. To prevent screws and other small parts from getting lost, it is better to immediately put them in a small box or bowl.

Important! Before starting repairs, be sure to ensure that the memory card is removed from the device. A card left behind during disassembly usually breaks, often damaging the slot as well.

Place the book in front of you on a flat surface, after laying down a napkin or piece of soft cloth.
The case is held on by latches along the entire perimeter, so at the first stage of disassembly you need a sharp tool to open them. This can be done with a kitchen knife, inserting it into the groove and moving with little force.
As soon as you reach the place where the latch is located, it will open with a characteristic sound. Be careful, applying too much force may break the latches or leave untidy nicks in the plastic.
Having found and opened the first latch, open all the latches around the perimeter of the case in the same way.
Place the disconnected panel aside immediately.
Unscrew the two miniature bolts at the bottom of the book. Movements should be confident, but not sharp, so as not to damage the splines. Make sure that the screwdriver (file, blade) is tightly fixed in the slot, then begin to slowly turn it counterclockwise, trying to feel the moment the bolt moves from its place. The bolts located at the corners of the screen do not need to be touched.
To remove the entire platform from the body, simply pull it down so that it comes out of the fixing grooves. Be very careful at this stage - the white plates with the side buttons may be glued to the body. If this turns out to be the case, pry them off with a utility knife, being careful not to damage the cables.
Also set the second panel aside and turn the board over to gain access to the battery.
Peel off the adhesive tape and disconnect the power connector from the board (you cannot pull on the wiring; it is advisable to pry the plug itself by the “ears” with tweezers).
Wait 5-10 seconds, then reconnect the battery and press the power button (it’s easy to identify by aligning the board with the case).
If the blue light comes on, it means the problem has been fixed. Now all that remains is to assemble the book. If the light does not light up, the device will require more complex diagnostics, which require professional equipment and skills.

Now the book should be assembled. If you followed the instructions described above during disassembly, this will not be difficult.

Place the adhesive tape back on the battery connector.
Insert the display board into the lower case panel, making sure that the fixing elements fit into the grooves and the side buttons into their stops. Also pay attention to the power button - the plastic pusher should fit onto its lever.
Fasten the two screws holding the platform to the rear of the case.
Install the front panel and ensure that all latches around the perimeter are closed.