Let's figure out what is needed and how to repair a car generator. Malfunctions in the device arise for many reasons. In addition, if this happened on the road, then a breakdown of this kind causes a lot of trouble. The fact is that all the load goes to the battery, therefore, it discharges quite quickly.
Generator circuit and principle of operation
If you do not go deep into details, the device works quite simply. Due to the copper winding on the rotor, a rotating magnetic field is created. At the same time, there is a pulley on the rotor shaft, as well as a fan impeller. When the key is turned in the ignition switch , a current is supplied to the copper winding located on the rotor, as a result of which a magnetic field is formed on the winding. Consequently, the rotor is driven along with the engine crankshaft. When certain speeds are reached, the winding is fed not from the battery, but directly from the generator, that is, it passes from the excitation mode to self-excitation.
Since we get an alternating voltage, a rectifier unit is installed, which converts it to direct. It is worth noting that the generator circuit is quite simple, so everyone can understand it. While driving, it receives electric current and a battery from the generator. You can monitor the generator’s performance using a special sensor on the vehicle’s instrument panel.
How to understand that the electric current generator is faulty?
There are a huge number of ways to find out if the device is working normally or not. The simplest of them is to look at the battery charge level of the started engine. If the arrow tends up (to a full charge), then the generator works, but if it is in the red zone, this indicates that all the electrical systems of the car are powered directly from the battery, which is not good.
Also, a malfunction of the generator in fact may be absent, this happens in cases where the sensor itself is faulty. The same applies to the lamp on the dashboard, which may fail. A prerequisite for failure can be increased noise, whistling while the engine is running, and much more. In most cases, the fault is insufficient care for this unit.
Since the device is located in front of the engine, it is quite easy to get to it. Therefore, it should not be difficult to periodically lubricate friction surfaces, tension / loosen the belt on the pulleys, and also, if necessary, replace it.
Self-diagnosis of the generator
If you don’t want to go to a car service, you can check the device yourself. As an example, take the so-called “classic” VAZ-2107 with a typical generator. The first step is to start the engine, and then observe the headlights. If it is stable for several minutes, then there are no malfunctions of the VAZ-2107 generator. If it is dull, then most likely the fault is the weakening of the pulley nut or insufficient or excessive belt tension. If you apply a force on the belt equal to 10 kilograms / force (kgf), then the total deflection should be no more than 10-15 millimeters.
If the obtained value was more or less, then you need to tighten or, accordingly, weaken the tension. Also, the malfunction can be determined by an incomprehensible noise in the engine compartment. This happens due to the fact that the vibration of the pulley nut is weakened due to vibrations, as a result of which it starts to work more noisily and less efficiently. And now in more detail about the main problems.
Control devices do not work
As noted at the very beginning of the article, when the key is turned in the ignition switch, the indicator lamp of the generator should light up. If this does not happen, then you need to look for a problem. Do not immediately climb under the hood and dismantle the device, because often this is not a malfunction of the generator, and the problem can be solved much easier. It is necessary to check the fuse in the mounting block under the 19th number, if it is blown, then replace it, and the control devices will work.
Another problem is an open circuit, because of which voltage may not be supplied from the ignition switch to the mounting block or from the block to the instrument panel. All this is easily eliminated. First of all, you need to check the wire "0", and then "TP". One is responsible for supplying current from the block to the panel, the second from the ignition switch to the block.
The control lamp does not light, the battery is low
Of course, an indicator is used on the instrument panel, which can simply burn out, and you do not need to look for anything more. Sometimes just replacing the lamp is enough. There are also malfunctions of the car generator in the form of insufficient pressing of the lamp holder to the printed circuit board, as a result of which there are malfunctions on the dashboard.
As we know, sooner or later everything fails, even with the most careful care. This also applies to the generator. The brushes of the device wear out pretty quickly, as a result of which there are problems with work. In this case, they simply need to be changed. Exactly the same situation with the oxidative processes of the metal, which no one has yet to cancel.
Contact rings undergo oxidation, and therefore fail. To fix the problem, you must first change the brush holder, and then thoroughly wipe the oxidized rings with a rag or napkin; for greater effect, use gasoline or acetone. Worst of all, if positive diodes are closed, because in this case you need to completely replace the mounting block.
Generator malfunction: battery discharge, unstable lamp burning
Almost every driver experienced a bothersome whistle from under the hood by his own example. The fault is the alternator belt, which slips due to wear and tear or insufficient tension. If you encounter such a problem, then the usual adjustment or replacement of the belt is enough, its cost is low, about 100-200 rubles.
It cannot be said that the main malfunctions of the generator are damage to the diodes of the rectifier unit and the rotor winding. Both in the first and in the second case, this entails not the best consequences. The problem is eliminated by replacing the rectifier unit or, if possible, diodes.
Short circuits in the stator also happen. In most cases, this damage cannot be repaired, and if restoration work is possible, then a new stator is much cheaper and easier to buy. A short circuit to the so-called “mass” may occur, in which case the part must be changed.
Noise threshold increase, battery recharge
First, let's talk about why the generator starts to work noisier. The fact is that during operation, the bearings work out their life, which is measured in hours. Therefore, after a certain number of hours they fail. These places begin to work unstable, there is a backlash, knocks, etc. Therefore, the noise level increases.
Of course, it is extremely difficult to foresee such causes of the generator malfunction, however, you need to be able to understand that the bearing is out of order and it is time to change it. When the so-called “howl” of the generator appears, this indicates, at least, the presence of an inter-turn circuit in the stator. It is fraught with consequences and loosening the pulley nut of the generator, it must be tightened tightly.
Some more troubleshooting
There are also generator malfunctions such as overcharging the battery, this can be tracked by the arrow of the voltmeter on the dashboard. The reason for this may be an exclusively faulty voltage regulator, which does not cope with its immediate purpose. It can be repaired or replaced.
Everywhere there is a weak point, this also applies to our case. Such a malfunction of the generator, such as oxidation of wires, is more than common. Fortunately, it’s enough to have sandpaper or a brush for metal, which removes oxide. By the way, the presence of oxidative processes can cause a complete failure of the generator, due to deterioration of contacts.
Do not forget that bearings need lubrication, this will increase their service life. When axial play appears on the armature shaft, this only means that it is time to change the bearing. Do not give preference to unknown manufacturers. It is better to buy a bearing from a well-known company, even if it will be more expensive, but its resource is an order of magnitude greater. In general, there is a special stand on which you can determine the general condition of the device. It displays the generator circuit, open circuits and much more.
Important points
It cannot be said that a periodic check of the device’s operability is the key to trouble-free operation. Of course, no one is immune from short circuits, but it is possible and even necessary to check the belt tension, the condition of brushes and rings.
Under no circumstances should you work with the generator while the engine is running, as it is hazardous to health, because we are dealing with high revolutions of the crankshaft and fan. As already noted above, the generator circuit is extremely simple, so if necessary it will not be difficult to study it. This will allow not only to understand how the device works, but also to independently carry out most of the repair work.
Conclusion
If we are dealing with "classics", then there are quite often problems with wires. They must be re-soldered and cleaned. The same applies to the generator belt, which due to intense wear can break. By the way, its rupture during the movement of a car is fraught with the fact that there will be a strong blow. As a rule, the hood gets the most, there are cases when, due to a strong blow, paint bounced off the front side of the hood.
It will be useful to carry a spare belt with you. This will eliminate some malfunctions of the VAZ-2107 generator directly on the road. You also need to have the necessary tools with you, that is, a flat and Phillips screwdriver, a set of keys, etc. That, perhaps, is all that can be said about what are the signs of a generator malfunction and how to eliminate them.