How to identify the wrong one. SHRUS malfunction - diagnostics, how to determine the breakdown by characteristic signs

Electronics accompanies modern man everywhere: at work, at home, in the car. Working in production, and no matter in what particular area, you often have to repair something electronic. Let's agree to call this "something" a "device". This is such an abstract collective image. Today we’ll talk about all kinds of repair wisdom, having mastered which, you can repair almost any electronic “device”, regardless of its design, principle of operation and scope.

Where to begin

There is little wisdom in resoldering a part, but finding a defective element is the main task in repair. You should start by determining the type of malfunction, since it depends on where to start the repair.

There are three such types:
1. the device does not work at all - the indicators do not light up, nothing moves, nothing buzzes, there are no responses to the control;
2. any part of the device does not work, that is, part of its functions is not performed, but although glimpses of life in it are still visible;
3. The device mostly works properly, but sometimes it makes so-called failures. It is impossible to call such a device broken yet, but still something prevents it from working normally. Repair in this case just consists in finding this interference. It is believed that this is the most difficult repair.
Let's look at examples of repairing each of the three types of faults.

Repair of the first category
Let's start with the simplest - a breakdown of the first type, this is when the device is completely dead. Anyone will guess that you need to start with nutrition. All devices living in their own world of machines necessarily consume energy in one form or another. And if our device does not move at all, then the probability of the absence of this very energy is very high. A small digression. When looking for a fault in our device, we will often talk about “probability”. Repair always begins with the process of determining possible points of influence on the malfunction of the device and estimating the probability of involvement of each such point in this particular defect, with the subsequent transformation of this probability into a fact. At the same time, the most complete knowledge of the device device, its operation algorithm, the physical laws on which the device is based, the ability to think logically and, of course, , his majesty experience. One of the most effective repair methods is the so-called elimination method. From the entire list of all blocks and assemblies suspected of involvement in the defect of the device, with varying degrees of probability, it is necessary to consistently exclude the innocent.

It is necessary to start the search, respectively, from those blocks, the probability of which may be the culprits of this malfunction is the highest. Hence, it turns out that the more precisely this very degree of probability is determined, the less time will be spent on repairs. In modern "devices" internal nodes are strongly integrated with each other, and there are a lot of connections. Therefore, the number of points of influence is often extremely large. But your experience is also growing, and over time you will identify the "pest" with a maximum of two or three attempts.

For example, there is an assumption that with a high probability block “X” is to blame for the illness of the device. Then you need to conduct a series of checks, measurements, experiments that would confirm or disprove this assumption. If after such experiments even the slightest doubt remains that the block was not involved in the “criminal” influence on the device, then this block cannot be completely excluded from the number of suspects. It is necessary to look for such a way to check the suspect's alibi in order to be 100% sure of his innocence. This is very important in the elimination method. And the most reliable way to check the suspect is to replace the unit with a known good one.

Let's get back to our "patient", in whom we assumed a power failure. Where to start in this case? And as in all other cases - with a complete external and internal examination of the "patient". Never neglect this procedure, even when you are sure that you know the exact location of the breakdown. Inspect the device always completely and very carefully, slowly. Often, during the inspection, you can find defects that do not directly affect the problem you are looking for, but which can cause a breakdown in the future. Look for burnt electrical components, swollen capacitors, and other suspicious looking items.

If the external and internal examination did not bring any results, then pick up a multimeter and get to work. I hope there is no need to remind about checking the presence of mains voltage and fuses. But let's talk a little about power supplies. First of all, check the high-energy elements of the power supply (PSU): output transistors, thyristors, diodes, power microcircuits. Then you can start to sin on the remaining semiconductors, electrolytic capacitors and, last but not least, on the rest of the passive electrical elements. In general, the value of the probability of failure of an element depends on its energy saturation. The more energy an electrical element uses for its functioning, the more likely it is to break.

If mechanical components are worn out by friction, then electrical ones are worn out by current. The greater the current, the greater the heating of the element, and heating / cooling wears out any materials no worse than friction. Temperature fluctuations lead to deformation of the material of electrical elements at the micro level due to thermal expansion. Such variable temperature loads are the main cause of the so-called material fatigue effect during the operation of electrical elements. This must be taken into account when determining the order in which elements are checked.

Do not forget to check the PSU for output voltage ripples, or any other interference on the power buses. Although infrequently, such defects can also cause the device to fail. Check whether the power actually reaches all consumers. Maybe due to problems in the connector / cable / wire, this “food” does not reach them? The PSU will be serviceable, but there is still no energy in the device blocks.

It also happens that a malfunction lurks in the load itself - a short circuit (short circuit) is not uncommon there. At the same time, in some “economical” PSUs there is no current protection and, accordingly, there is no such indication. Therefore, the version of the short circuit in the load should also be checked.

Now the failure of the second type. Although here too everything should start with the same external-internal examination, there is a much greater variety of aspects to which attention should be paid. - The most important thing is to have time to remember (write down) the whole picture of the state of the sound, light, digital indication of the device, error codes on the monitor, display, the position of alarms, flags, blinkers at the time of the accident. Moreover, it is obligatory before its reset, acknowledgment, power off! It is very important! Missing some important information means you will certainly increase the time spent on repairs. Examine all the available indications - both emergency and working, and remember all the readings. Open the control cabinets and memorize (write down) the state of the internal indication, if any. Shake the boards installed on the motherboard, cables, blocks in the device case. Maybe the problem will go away. And be sure to clean the radiators.

Sometimes it makes sense to check the voltage on some suspicious indicator, especially if it is an incandescent lamp. Carefully read the readings of the monitor (display), if available. Decipher the error codes. Look at the tables of input and output signals at the time of the accident, write down their status. If the device has the function of recording the processes occurring with it, do not forget to read and analyze such an event log.

Feel free to sniff the device. Is there a characteristic smell of burnt insulation? Pay special attention to products made of carbolite and other reactive plastics. Infrequently, but it happens that they break through, and this breakdown is sometimes very hard to see, especially if the insulator is black. Due to their reactive properties, these plastics do not warp when heated, which also makes it difficult to detect broken insulation.

Look for darkened insulation of relay windings, starters, electric motors. Are there any darkened resistors and other electrical radio elements that have changed their normal color and shape.

Are there any bulging or "shooting" capacitors.

Check if there is water, dirt, foreign objects in the device.

See if the connector is skewed, or if the block/board is not fully inserted into its place. Try removing and reinserting them.

Perhaps some switch on the device is in the wrong position. The button is stuck, or the moving contacts at the switch have become in an intermediate, not fixed position. Perhaps the contact has disappeared in some toggle switch, switch, potentiometer. Touch them all (when the device is de-energized), move it, turn it on. It won't be redundant.

Check the mechanical parts of the executive bodies for jamming - turn the rotors of electric motors, stepper motors. Move other mechanisms as needed. Compare the effort applied in this case with other similar working devices, if of course there is such a possibility.

Inspect the inside of the device while it is running - you may see strong sparking in the contacts of relays, starters, switches, which will indicate an excessively high current in this circuit. And this is a good clue for troubleshooting. Often the fault of such a breakdown is a defect in a sensor. These intermediaries between the outside world and the device they serve are usually placed far beyond the edge of the device body itself. And at the same time, they usually work in a more aggressive environment than the internal parts of the device, which, one way or another, are protected from external influences. Therefore, all sensors require increased attention to themselves. Check their performance and do not be too lazy to clean them from contamination. Limit switches, various blocking contacts and other sensors with galvanic contacts are high priority suspects. And in general, any "dry contact" i.e. not soldered, should become an element of close attention.

And another point - if the device has already served for a long time, then you should pay attention to the elements that are most susceptible to any wear or change in their parameters over time. For example: mechanical components and parts; elements exposed during operation to increased heat or other aggressive effects; electrolytic capacitors, some types of which tend to lose capacity over time due to the drying of the electrolyte; all contact connections; instrument controls.

Almost all types of "dry" contacts lose their reliability over time. Special attention should be paid to silver plated contacts. If the device has worked for a long time without maintenance, I recommend that before starting an in-depth troubleshooting, do preventive maintenance of the contacts - brighten them with an ordinary eraser and wipe them with alcohol. Attention! Never use abrasive pads to clean silver or gold plated contacts. This is certain death to the connector. The coating with silver or gold is always done in a very thin layer, and it is very easy to erase it with an abrasive to copper. It is useful to carry out the self-cleaning procedure for the contacts of the female part of the connector, in the professional slang of “mother”: connect and disconnect the connector several times, the springy contacts are slightly cleaned of friction. I also advise, when working with any contact connections, do not touch them with your hands - oil stains from fingers negatively affect the reliability of electrical contact. Cleanliness is the key to reliable operation of the contact.

The first thing is to check the operation of any blocking, protection at the beginning of the repair. (In any normal technical documentation for the device there is a chapter with a detailed description of the interlocks used in it.)

After inspecting and checking the power, think offhand - what is most likely broken in the device, and check these versions. Immediately into the jungle of the device is not worth climbing. First, check all the peripherals, especially the serviceability of the executive bodies - perhaps it was not the device itself that broke, but some mechanism controlled by it. In general, it is recommended to study, albeit not to the subtleties, the entire production process, in which the ward device is a participant. When the obvious versions are exhausted - then sit down at your desktop, make some tea, lay out the diagrams and other documentation for the device and “give birth” to new ideas. Think about what else could cause this disease of the device.

After some time, you should "be born" a certain number of new versions. Here I recommend not to rush to run to check them. Sit down somewhere in a calm atmosphere and think over these versions in terms of the magnitude of the probability of each of them. Train yourself in assessing such probabilities, and when you gain experience in such selection, you will begin to make repairs much faster.

The most effective and reliable way to test a suspected unit, a device node for operability, as already mentioned, is to replace it with a known good one. Do not forget to carefully check the blocks for their complete identity. If you connect the unit under test to a device that is working properly, then, if possible, make sure - check the unit for excessive output voltages, a short circuit in the power supply and in the power section, and other possible malfunctions that can damage the working device. The reverse also happens: you connect a donor working board to a broken device, check what you wanted, and when you return it back, it turns out to be inoperative. This does not happen often, but still keep this point in mind.

If in this way it was possible to find a faulty unit, then the so-called “signature analysis” will help to further localize the troubleshooting to a specific electrical element. This is the name of the method in which the repairman conducts an intellectual analysis of all the signals with which the tested node “lives”. Connect the block, node, board under study to the device using special extension adapters (these are usually supplied with the device) so that there is free access to all electrical elements. Lay out the circuit, measuring instruments nearby and turn on the power. Now check the signals at the control points on the board with the voltages, waveforms on the diagram (in the documentation). If the scheme and documentation do not shine with such details, strain your brains here. A good knowledge of circuitry will be very useful here.

If there are any doubts, then you can “hang” a serviceable exemplary board from a working device on the adapter and compare the signals. Check with the circuit (with documentation) all possible signals, voltages, waveforms. If a deviation of any signal from the norm is found, do not rush to conclude that this particular electrical element is malfunctioning. It may not be the cause, but just a consequence of another abnormal signal that forced this element to issue a false signal. During repairs, try to narrow the search circle, to localize the malfunction as much as possible. When working with a suspect node / block, come up with such tests and measurements for it that would exclude (or confirm) the involvement of this node / block in this malfunction for sure! Think seven times when you exclude a block from the number of unreliable ones. All doubts in this case must be dispelled by clear evidence.

Always make experiments meaningfully, the “scientific poke” method is not our method. Say, let me stick this wire here and see what happens. Never be like such "repairers". The consequences of any experiment must necessarily be thought out and carry useful information. Senseless experiments are a waste of time, and besides, something else can be broken. Develop the ability to think logically, strive to see clear cause-and-effect relationships in the operation of the device. Even the operation of a broken device has its own logic, there is an explanation for everything. You will be able to understand and explain the non-standard behavior of the device - you will find its defect. In the matter of repair, it is very important to clearly imagine the algorithm of the device. If you have gaps in this area, read the documentation, ask everyone who knows at least something about the issue of interest. And do not be afraid to ask, contrary to popular belief, this does not diminish authority in the eyes of colleagues, but on the contrary, smart people will always appreciate it positively. It is absolutely unnecessary to memorize the scheme of the device; paper was invented for this. But the algorithm of its work must be known "by heart". And now you have been “shaking” the device for many days. We studied it so that it seems there is nowhere further. And already repeatedly tortured all suspected blocks / nodes. Even the seemingly most fantastic options have been tried, but the malfunction has not been found. You are already starting to get a little nervous, maybe even panic. Congratulations! You have reached the apogee in this repair. And here only ... rest will help! You're just tired, you need to take a break from work. You have, as experienced people say, "the eye is washed out." So stop working and completely turn off your attention from the ward device. You can do something else, or do nothing at all. But you need to forget about the device. But when you rest, you yourself will feel the desire to continue the battle. And as often happens, after such a break, you suddenly see such a simple solution to the problem that you will be surprised beyond words!

But with a malfunction of the third type, everything is much more complicated. Since failures in the operation of the device are usually random in nature, it often takes a lot of time to catch the moment of manifestation of a failure. The features of the external examination in this case are to combine the search for a possible cause of the failure with the implementation of preventive maintenance. Here is a list of some possible causes of failures as a guideline.

Bad contact (first of all!). Clean the connectors all at once in the entire device and carefully inspect the contacts.

Overheating (as well as hypothermia) of the entire device, caused by an increased (lower) ambient temperature, or caused by prolonged operation with a high load.

Dust on boards, nodes, blocks.

Contaminated cooling radiators. Overheating of the semiconductor elements they cool can also cause failures.

Interference in the power supply. If the power filter is missing or out of order, or its filtering properties are not enough for the given operating conditions of the device, then failures in its operation will be frequent guests. Try to link failures with the inclusion of any load in the same mains supply from which the device is powered, and thereby find the culprit of the interference. Perhaps it is in the neighboring device that the surge protector is faulty, or some other malfunction in it, and not in the device being repaired. If possible, power the device for some time from an uninterruptible power supply with a good built-in surge protector. Failures will disappear - look for a problem on the network.

And here, as in the previous case, the most effective way of repair is the method of replacing blocks with known good ones. When changing blocks and nodes between the same devices, carefully monitor their complete identity. Pay attention to the presence of personal settings in them - various potentiometers, customized inductance circuits, switches, jumpers, jumpers, software inserts, ROM with different firmware versions. If they are, then make the decision to replace, having considered all possible problems that may arise due to the danger of disrupting the operation of the unit/assembly and the device as a whole, due to the difference in such settings. If, nevertheless, there is an urgent need for such a replacement, then reconfigure the blocks with the obligatory recording of the previous state - it will come in handy when returning.

It happens that all the boards, blocks, nodes that make up the device are replaced, but the defect remains. So, it is logical to assume that the malfunction has settled in the remaining periphery in the wiring harnesses, the wiring has come off inside any connector, there may be a defect in the backplane. Sometimes a jammed connector contact is to blame, for example, in a box for boards. When working with microprocessor systems, multiple runs of test programs sometimes help. They can be looped or configured for a large number of cycles. Moreover, it is better if they are specialized test ones, and not workers. These programs are able to fix the failure and all the information accompanying it. If you know how, write such a test program yourself, with a focus on a specific failure.

It happens that the periodicity of the manifestation of a failure has a certain pattern. If the failure can be linked in time to the execution of any particular process in the device, then you are in luck. This is a very good clue for analysis. Therefore, always carefully observe device failures, note all the circumstances under which they occur, and try to associate them with the performance of any function of the device. Prolonged observation of the failing device in this case may provide a clue to the mystery of the failure. If you find the dependence of the appearance of a failure on, for example, overheating, increase / decrease in supply voltage, on vibration exposure, this will give some idea of ​​the nature of the malfunction. And then - "let the seeker find it."

The method of control replacement almost always brings positive results. But in the block found in this way there can be many microcircuits and other elements. This means that it is possible to restore the operation of the unit by replacing only one, inexpensive part. How in this case to localize the search further? Here, too, not everything is lost, there are several interesting tricks. Signature analysis is almost impossible to catch a failure. Therefore, let's try to use some non-standard methods. It is necessary to provoke the block to failure under a certain local impact on it, and at the same time it is necessary that the moment of manifestation of the failure can be tied to a specific part of the block. Hang the block on the adapter / extension cord and start torturing him. If you suspect a microcrack in the board, you can try to fix the board on some rigid base and deform only small parts of its area (corners, edges) and bend them in different planes. And at the same time observe the operation of the device - catch a failure. You can try to knock the handle of a screwdriver on parts of the board. We decided on the area of ​​\u200b\u200bthe board - take the lens and carefully look for a crack. Infrequently, but sometimes it is still possible to detect a defect, and, by the way, a microcrack is not always the culprit. Soldering defects are much more common. Therefore, it is recommended not only to bend the board itself, but also to move all its electrical elements, carefully observing their soldered connection. If there are few suspicious elements, you can simply solder everything at once, so that in the future there will be no more problems with this block.

But if any semiconductor element of the board is suspected to be the cause of the failure, it will not be easy to find it. But here, too, you can say something, there is such a somewhat radical way to provoke a failure: in working condition, heat each electrical element in turn with a soldering iron and monitor the behavior of the device. The soldering iron must be applied to the metal parts of the electrical elements through a thin plate of mica. Warm up to about 100-120 degrees, although sometimes more is required. In this case, of course, there is a certain degree of probability to additionally spoil some “innocent” element on the board, but it is up to you to decide whether it is worth the risk in this case. You can try the opposite, cool with an ice cube. Not often either, but still you can try in this way, as we say, "pick out the bug." If it's really hot, and if possible, of course, then change all the semiconductors on the board in a row. The order of replacement is in descending order of energy saturation. Change blocks of several pieces, periodically checking the operability of the block for failures. Try to properly solder all the electrical elements on the board, sometimes only this procedure alone returns the device to a healthy life. In general, with a malfunction of this type, a complete recovery of the device can never be guaranteed. It often happens that during troubleshooting you accidentally moved some element that had a weak contact. At the same time, the malfunction disappeared, but most likely this contact will again manifest itself over time. Repairing a rarely occurring failure is a thankless task, it takes a lot of time and effort, and there is no guarantee that the device will be repaired without fail. Therefore, many craftsmen often refuse to take on the repair of such capricious devices, and, frankly, I don’t blame them for this.

Car electrical faults are very common and occupy one of the leading places in the list of breakdowns. They can be conditionally divided into malfunctions of current sources (batteries, generators) and malfunctions of consumers (optics, ignition, climate, etc.). Main The vehicle's power sources are batteries and alternators.. A malfunction of each of them leads to a general malfunction of the car and its operation in abnormal modes, or even to immobilization of the car.

In the electrical equipment of a car, the battery and the alternator work in unbreakable tandem. If one fails, after a while the other will fail. For example, it leads to an increase in the charging current of the generator. And this entails a malfunction of the rectifier (diode bridge). In turn, when coming from the generator, the charging current may increase, which will inevitably lead to a systematic recharge of the battery, electrolyte “boiling away” and rapid destruction.

Common generator malfunctions:

• wear or damage to the pulley;
• wear of collector brushes;
• collector wear (slip rings);
• damage to the voltage regulator;
• short circuit of the turns of the stator winding;
• wear or destruction of the bearing;
• damage to the rectifier (diode bridge);
• damage to the wires of the charging circuit.

Common battery problems:

• short circuit of battery electrodes/plates;
• mechanical or chemical damage to the battery plates;
• violation of the tightness of battery cans - cracks in the battery case as a result of impacts or improper installation;
• chemical. The main causes of these malfunctions are:
• gross violations of the rules of operation;
• expiration of the service life of the product;
• various manufacturing defects.

Of course, the design of the generator is more complicated than the battery. It is quite reasonable that there are many times more generator malfunctions, and their diagnosis is much more difficult.

It is very useful for the driver to know main causes of generator malfunctions, ways to eliminate them, as well as preventive measures to prevent breakdowns.

All generators are divided into generators variable And direct current. Modern passenger vehicles are equipped with alternators with a built-in diode bridge (rectifier). The latter is necessary to convert current into direct current, on which the car's electrical consumers operate. The rectifier, as a rule, is located in the cover or housing of the generator and is one with the latter.

All electrical appliances of the car are designed for a strictly defined range of operating currents by voltage. As a rule, operating voltages are in the range of 13.8–14.7 V. Due to the fact that the generator is “tied” with a belt to the engine crankshaft, from different revolutions and vehicle speeds, it will work differently. It is for smoothing and regulating the output current that the relay-voltage regulator is intended, which plays the role of a stabilizer and prevents both surges and dips in the operating voltage. Modern generators are equipped with built-in integrated voltage regulators, colloquially referred to as "chocolate" or "pill".

It is already clear that any generator is a rather complex unit, extremely important for any car.

Types of generator malfunctions

Due to the fact that any generator is an electromechanical device, there will be two types of malfunctions, respectively - mechanical And electrical.

The former include the destruction of fasteners, housing, disruption of bearings, clamping springs, belt drive, and other failures not related to the electrical part.

Electrical faults include winding breaks, diode bridge faults, brush burnout/wear, inter-turn short circuits, breakdowns, rotor beats, relay-regulator faults.

Often, symptoms indicating a characteristic faulty generator may also appear as a result of completely different problems. As an example, a bad contact in the alternator excitation circuit fuse socket will indicate a malfunction of the alternator. The same suspicion may arise due to burnt contacts in the ignition lock housing. Also, the constant burning of the generator malfunction indicator lamp can be caused by a relay failure, the blinking of this lamp that turns on may indicate a malfunction of the generator.

The main symptoms of a malfunction of the oscillator:

• When the engine is running, the low battery warning lamp flashes (or stays on).
• Discharging or recharging (boiling away) of the battery.
• Dim car headlights, rattling or quiet sound signal when the engine is running.
• A significant change in the brightness of the headlights with an increase in the number of revolutions. This may be permissible with an increase in speed (resetting) from idle, but the headlights, having lit up brightly, should not increase their brightness further, remaining at the same intensity.
• Extraneous sounds (howling, squeaking) coming from the generator.

The tension and general condition of the drive belt must be checked regularly. Cracks and delaminations require immediate replacement.

Generator repair kits

To eliminate these malfunctions of the generator, it will be necessary to carry out repairs. When you start searching for a generator repair kit on the Internet, you should prepare for disappointment - the kits offered, as a rule, contain washers, bolts and nuts. And sometimes you can return the generator to working capacity only by replacing - brushes, a diode bridge, a regulator ... Therefore, a brave man who decides to repair makes an individual repair kit from those parts that fit his generator. It looks something like the table below, using the example of a pair of generators for the VAZ 2110 and Ford Focus 2.

Generator VAZ 2110 - KZATE 9402.3701-03 for 80 A. It is used on VAZ 2110-2112 and their modifications after 05.2004, as well as on VAZ-2170 Lada Priora and modifications

Generator Renault Logan - Bosch 0 986 041 850 for 98 A. Used on Renault: Megane, Scenic, Laguna, Sandero, Clio, Grand Scenic, Kangoo, and Dacia: Logan.

Troubleshooting

On modern cars, the use of the "old-fashioned" method by dropping the battery from the battery terminal can also lead to serious damage to many of the car's electronic systems. Significant voltage drops on the vehicle's on-board network can disable almost all on-board electronics. That is why modern generators are always checked only by measuring the voltage in the network or diagnosing the most removed node on a special stand. First, the voltage at the battery terminals is measured, the engine starts and readings are taken already with the engine running. Before starting, the voltage should be about 12 V, after starting - from 13.8 to 14.7 V. A deviation to a large side indicates that you are “recharging”, which implies a malfunction of the relay-regulator, to a smaller one - that no current is flowing. The absence of charging current indicates generator malfunction or chains.

Causes of breakdowns

Common causes of generator malfunctions It's just wear and tear and corrosion. Almost all mechanical failures, whether it be worn brushes or collapsed bearings, are the result of long operation. Modern generators are equipped with sealed (non-maintained) bearings that simply need to be replaced after a certain period or mileage of the car. The same applies to the electrical part - often the components must be replaced entirely.

Also, the reasons may be:

• low quality of manufacturing components;
• violation of the rules of operation or work outside the limits of normal modes;
• external factors (salt, liquids, heat, road chemicals, dirt).

Self test generator

The easiest way is to check the fuse. If it is serviceable, and its location. The free rotation of the rotor is checked, the integrity of the belt, wires, housing. If nothing raised suspicions, brushes and slip rings are checked. During operation, the brushes inevitably wear out, they can jam, warp, and the slip ring grooves become clogged with graphite dust. A clear sign of this is excessive sparking.

There are frequent cases of complete wear or breakage of both bearings and stator failure.

The most common mechanical problem in a generator is bearing wear. A sign of this malfunction is a howl or whistle during operation of the unit. Of course, the bearings must be replaced immediately after inspecting the seats. Weakening can also cause weak generator performance. One of the signs may be a high-pitched whistle from under the hood when the car is accelerating or accelerating.

To check the excitation winding of the rotor for short-circuited turns or breaks, you need to connect a multimeter switched to resistance measurement mode to both contact rings of the generator. Normal resistance is from 1.8 to 5 ohms. The reading below indicates the presence of a short circuit in the turns; above - a direct break in the winding.

To check the stator winding for "breakdown to ground", they must be disconnected from the rectifier unit. With the resistance readings given by the multimeter having an infinitely large value, there is no doubt that the stator windings are not in contact with the housing ("ground").

A multimeter is used to test the diodes in the rectifier unit (after completely disconnecting from the stator windings). The test mode is "diode test". The positive probe is connected to the plus or minus of the rectifier, and the negative probe is connected to the phase output. After that, the probes are interchanged. If at the same time the readings of the multimeter are very different from the previous ones, the diode is working, if they do not differ, it is faulty. Another sign indicating the imminent "death" of the diode bridge of the generator is the oxidation of the contacts, and the reason for this is overheating of the radiator.

Repair and Troubleshooting

All mechanical problems are eliminated by replacing faulty components and parts(brushes, belt, bearings, etc.) for new or serviceable ones. On older models of generators, slip rings are often required to be machined. Drive belts are replaced due to wear, maximum stretch or the end of their service life. Damaged rotor or stator windings, they are currently being replaced with new ones as an assembly. Rewinding, although it is found among the services of car repairmen, is less and less common - it is expensive and impractical.

And that's all electrical problems with a generator decide by checking like others circuit elements(in particular the battery), so and directly its details and output voltage. One of the most common problems car owners face is overcharge, or vice versa, generator low voltage. Checking and replacing the voltage regulator or diode bridge will help eliminate the first malfunction, and it will be a little more difficult to deal with the issuance of low voltage. There can be several reasons why the generator produces low voltage:

1. increased load on the onboard network by consumers;
2. breakdown of one of the diodes on the diode bridge;
3. failure of the voltage regulator;
4. V-ribbed belt slippage (due to low tension)
5. poor ground wire contact on the generator;
6. short circuit;
7. squandered battery.

Regular automatic transmission diagnostics will help to avoid serious malfunctions and, in the event of the first signs of a breakdown, solve the problem at an early stage of its development.

Diagnosis of automatic transmission independently

What to look for before buying a car with automatic transmission?

Driving a car with an automatic transmission is very comfortable and convenient. But the cost of a new car with such a transmission is somewhat higher than the equivalent on the "mechanics". Therefore, often motorists turn to buying a used car. In this situation, you need to be very careful and know how to check automatic transmission before buying a car. Here are some tips to remember and stop buying if:

• previously a car with automatic transmission was under a taxi;
• the gearbox has already been repaired;
• the car was restored after the accident;
• the car has a towbar (towing contributes to the wear of the automatic transmission).

If you do not want to buy a pig in a poke, we recommend that you conduct a thorough automatic box computer diagnostics in a specialized car service.

Reasons for the breakdown of the automatic transmission

The failure of an automatic transmission can be caused by various reasons that can be combined into several related items:

Malfunction of the control cable due to incorrect adjustment or souring;

Breakdown of hydraulics or mechanical part of the system;

Wear of friction discs;

Or freewheels;

Malfunction of electronics (for example, control unit);

Violation of the general automatic transmission settings.

If the transmission began to function with deviations, there were suspicions of its breakdown, then urgent automatic box check. The sooner the cause is identified, the less expensive the repair will be.

Transmission diagnostics. How to check automatic transmission?

We tried to collect in one article all the diagnostic procedures that will help you figure out what exactly failed in the automatic transmission. We advise you to search for a breakdown of the “machine” in the following sequence:

• checking the level and condition of the oil;
• visual check of the throttle valve control cable;
• stall test check on a braked car;
• car diagnostics in motion;
• oil pressure check.

Checking the level and condition of the oil

Before proceeding with this procedure, let's take a closer look at . In fact, there is nothing difficult in this. We start the car engine and switchselector box to position "P" (parking). While the car is idling, check the oil. We take out the dipstick, wipe it and insert it back. After that, take out the dipstick again and look at what level the oil is. Now you need to wipe the probe with white paper. There should be no traces of metal shavings or other extraneous microelements on the paper sheet. If the oil has darkened (ideally it should be red), then it has not been changed for a long time. On some modern models of cars with automatic transmission, the indicated probe is missing. In such a situation, you can check the level and condition of the oil only in a car service.

Checking the level and condition of fluid in the automatic transmission | Video

Checking the adjusting cable

next step automatic transmission diagnostics is to check the throttle valve control cable or, as it is also called, the adjusting cable. During the operation of the gearbox, the adjusting cable wears out, which leads to disruption of the entire transmission. In particular, the need for cable adjustment is indicated by premature gear shifting at high or low speeds. As a result, the wear of the main components of the box increases, and fuel consumption also increases. The cable may need to be lubricated or tightened if it is loose.

How to check the automatic transmission on a stationary car

This procedure is recommended to be carried out in the presence of a qualified specialist. The so-called Stall Test is carried out on a fully braked car, with the engine running at maximum power. As a result of this test, it is possible to evaluate the braking properties of friction discs, the quality of the torque converter and the engine as a whole.

Before checking, you must make sure that the car is safely braked. Set the automatic transmission selector to the "P" position, and also apply the main and auxiliary brakes. In addition, fix the wheels with any stops. When carrying out the check, there should be no people in front and behind the car.

This test will not take long. For automatic transmission checks you need to do the following:

1. switch the automatic transmission selector to the "D" mode;
2. depress the throttle pedal as much as possible;
3. fix the maximum engine speed;
4. move the gearshift lever to "neutral" (position "N") and let the engine idle for at least one minute, this will cool it down.

If during this procedure unusual extraneous noises appear in the operation of the engine, then the check must be urgently stopped.

After that, it is necessary to compare the obtained indicators with the values ​​​​set by the manufacturer. If the number of revolutions exceeds the manufacturer's figures, then the problem is probably low pressure in the main line. If, on the contrary, the number of revolutions does not reach the recommended value, then, most likely, the clutch of the free movement of the torque converter reactor has become unusable.

How to check the automatic transmission in the movement of the car

Road testing is one of the most important automatic transmission diagnostic tools. During this test, the following transmission performance indicators are checked:

Timeliness of gear shifting;

No jerks when driving;

The presence of third-party noise or vibration under the hood;

Correct operation of the box in various driving modes;

Timely response of the box, no slippage.

If, as a result of this check, slipping of the car or an unforeseen increase in engine speed when shifting gears was detected, then, most likely, the friction discs or a problem in the freewheel have become unusable.

Checking the oil pressure in the automatic transmission

Automatic transmission diagnostics completed by checking the oil pressure. This procedure must be carried out in strict accordance with the requirements of the vehicle operation manual. This is due to the fact that the process of this diagnosis is different for each.

After checking, it is necessary to compare the obtained indicators with the values ​​\u200b\u200bspecified by the manufacturer. If there are deviations from the recommended indicators, then we can talk about the presence of malfunctions in the operation of the transmission hydraulic system. The definition of a problem area depends on the experience and knowledge of the basics of the operation of this automatic transmission model. If there is no such knowledge, then you should contact the professionals in a specialized service center.

In progress automatic transmission diagnostics Don't be in a hurry as you may miss important details. It is also necessary to pay attention to the little things, they will help to understand a possible problem in more detail. Self-diagnosis of the automatic transmission box does not cause great difficulties. Any novice driver can handle this. However, if you want to be completely confident in the automatic transmission, you need to contact the service station.

Pressure test - Video

PC Troubleshooting- a few useful tips that will allow you to properly diagnose and repair computers yourself at home.

• You can carry out diagnostics very efficiently, without resorting to the services of professionals for money. Each computer failure manifests itself in different ways, and sometimes it is not so easy to identify it.

For example, the mouse does not respond when you click on Start, and all attempts to turn off the computer are in vain. Or at startup, some important functions remain unavailable, the browser does not work, there is no Internet or a blue screen, and so on.

One way or another, you first need to try to figure out the causes of the malfunction yourself. Check elementary functions, visually inspect the motherboard for swollen capacitors, whether all parts of the system unit are tightly inserted, whether it is possible to enter BIOS, and so on.

See my PC diagnostic services —

If something does not work out, go to another diagnostic procedure, and return to the one that did not work out later. This will help you more accurately understand what exactly is not working and, if necessary, tell the master on arrival in more detail about the malfunction, so that he understands where to start considering the problem.

1.Does not respond to the power button on the system unit.

• The computer simply does not turn on, there are no signs of performance. In this situation, it is necessary check all batteries, the entire chain, from the power supply to the motherboard.

Check all cables and loops, inspect the power supply for a burnt smell. And it is important to check the button on the power supply, which supplies and disconnects electrical current to the power supply.

Maybe it's just turned off (this happens sometimes). If a visual inspection did not reveal any obvious defects, then we proceed to inspect the motherboard. The connectors that power the motherboard and processor are usually checked. If the plugs are disconnected or torn off, they must be carefully connected to the desired sockets and connectors.

• If this diagnostic did not give tangible results, then you should disconnect all plugs from the motherboard. Then you need to bridge the contacts on the system board that are responsible for starting with a screwdriver, usually this is power sw.

If computer restarted after shutdown, then this means that Possibly a faulty power button on the hull. To get out of the situation, you can do this. For example, on your case there is a second button - Reset (reboot).

You can assign the start of the computer to this button. We connect the Reset sw connectors to the Power sw connectors. Now you can use the Reset button to turn on the computer. Since we are talking about this button, I want to remind you that during normal computer operation, using this button is highly discouraged, as this harms the hard drive.

• You can check the power supply is the case or not. To do this, you guessed it, you just need to connect another power supply. If everything worked, then the problem was in the PSU.

If the above measures did not help, this may indicate motherboard failure. In this case, PC diagnostics and repair on their own will not help. It is necessary to diagnose the system board in a service center or replace it.

2.No image appears on your computer monitor.

If no image is displayed on the monitor, but it is clear from the operation of the LEDs on the motherboard and the operation of the fans that the computer is working, then you should deal with the devices responsible for displaying the image on the monitor.

• In this situation, you need to check the monitor itself for performance. Connect it to another working device.

Very often, when the video signal stops coming to the monitor, the system reports this with the appropriate signals. In this case, you must have decoding BIOS signals for your motherboard.

This symptom also appears if there is a short inside the Reset button itself.

• Also, the absence of a picture on the monitor is also due to wrong bios settings. To do this, you need to reset the settings to factory settings. This can be done with a jumper or in the BIOS itself. The motherboard usually has a Clear Cmos jumper. You just need to close and return it to its normal position. You can also remove the battery for 1-2 minutes.

• Sometimes it happens that the image disappears due to non-working RAM. You need to try to start the computer alternately with one or the other bar (if there are 2 of them). If there is only one bar, then you need to try to insert another bar of the same type and try to start with it.

• A faulty video card can be identified by its replacement for another. If everything works with another card, then the problem was in it.

• Sometimes the image is not displayed on the monitor due to the processor. This happens sometimes too. So you can still try as an option replace processor.

Now you know how to PC troubleshooting. If you have done all of the above and the picture still does not appear, then most likely there are problems with the computer's motherboard. More detailed diagnostics only in the conditions of the service center.

» How to identify malfunctions of the chassis of the car

The operation of the car in conditions of poor quality roads often causes wear and tear of many parts and components. It is the running gear that has the hardest time - it takes on all the “blows” of the domestic road. The suspension performs the most important tasks in the operation of the car. It distributes dynamic loads, improves traction, absorbs vibrations and noise, and adapts the running gear to various road surfaces.

Violation of the integrity and performance of even one small element entails a disruption in the operation of the entire chassis, which, in most cases, leads motorists to the service. In the worst case, safe driving can be endangered due to loss of vehicle control, and this already creates a serious risk of getting into a traffic accident.

There are many reasons that can cause such problems, and it is very important to notice signs of undercarriage malfunctions in time.

• The vehicle deviates to the left or right from a straight line

Cause: wheel alignment violations, air pressure difference in tires, strong difference in wheel wear, difference in tread height.

If after diagnosing and troubleshooting the problem of vehicle withdrawal has not disappeared, then a complete check of the chassis is necessary to identify the real causes of the malfunction. They can be: deformation of the front suspension arm, difference in stiffness of the springs of the struts, violation of the parallelism of the bridges, incomplete releasing of the wheel,

• When turning and braking, the car sways

Reason: failure or malfunction of shock absorbers or springs, wear of the stabilizer bar bushings, weakening or breakage of springs and suspension parts.

• Increased vibration while driving

Cause: Incorrect tire pressure, damaged springs, incorrect wheel balance, loose wheel nuts, disc damage (or deformation).

• Noise and rattle

Cause: the shock absorber is out of order, wear of the ball bearings, wear of the silent blocks of the levers, damage to the lever strut, failure of the steering rack elements.

• Knock shock absorbers

Cause: the body geometry is broken, the shock absorber leaked, the suspension arm was deformed, the brake system malfunctioned, the alignment was incorrect, the shock absorber support was worn out.

• Squeaks when braking while cornering

Reason: malfunction of shock absorbers, damage to the bushings of the anti-roll bar.

• Frequent "punching" of the suspension

Reason: Tires or wheels are deformed, shock absorbers are faulty, suspension arms are deformed.

• Wheel tire wear uneven or increased

Cause: Loose piston fastening, malfunction of shock absorber parts.

• Fluid leakage from suspension struts

Reason: there is too much fluid in the shock absorber, the stem seal is defective, the formation of nicks on the stem.

Alas, no driver is immune from damage to the chassis of the car. Only careful driving in traffic conditions on a good road will help to avoid trouble. The second condition is difficult to meet, given the seasonal damage to the pavement, so the best option is to prevent damage than their costly repair in a car service.

The chassis, like other elements of the car, needs care and timely inspection. The main thing in this matter is regularity, because the safe functioning of the entire car depends on regular diagnostics. A small deviation from the norm in work often leads to serious problems, and therefore it is not worth waiting until the trouble turns into a risk.

To do this, each car owner should know what points the inspection of the parts of the chassis of the car includes:

• — check threaded connections (if necessary, they are tightened)
• - lubrication of parts of the front and rear suspensions according to the lubrication scheme for this vehicle
• - check the amount of fluid in the shock absorbers (if necessary, add fluid)
• - control of bearing adjustment
• — check the front wheels, if necessary — their adjustment and balancing
• - measuring the pressure in the tires of the wheels (carried out using a tire pressure gauge)
• - the obligation to check the integrity and serviceability of the frame itself
• - once every 30 thousand kilometers, replace the stabilizer rods and bushings
• - it will not be superfluous to drive onto the overpass, since the suspension check from below will be more productive. You should also check if oil or other technical fluids are leaking anywhere.

A timely inspection, although it will take a certain amount of your time, will never become superfluous. In this way, you can prevent unpleasant surprises or sending the car to a car service. Good luck on the roads!

Knock in the front suspension - suspension device and repair
Suspension MacPherson (McPherson) - device and scheme of work Rear suspension diagram - types and arrangement Peugeot 206 rear beam - repair Wheel balancing - we fight for the health of your car
Ball joint - purpose and design, causes of failure, diagnostics