Do-it-yourself generator auto repair

I have already talked about the design of electric current generators, which are similar to synchronous motors, only differ from them in a collector, so the process of troubleshooting and repairing electric current generators is in many ways similar to them.

In this article I will tell you in detail using the example of do-it-yourself repair of a car generator, because it is the repair that most people most often face. The principle of repairing a generator with your own hands as part of a power plant will be similar. Only a voltage rectifier will not be built into its case and the output voltage adjustment will work differently.

Cars use a three-phase alternator alternating current, but as is known in the on-board network, a constant voltage of 12 volts. To obtain direct current, a rectifier consisting of 6 diodes is used, and a voltage regulator is provided to keep the voltage of 12 volts within acceptable limits.

The generator is quite simple. Voltage is applied to the rotor through graphite brushes and slip rings to excite it. It is driven by a pulley through a belt drive. The rotor rotates in bearings. The electrical voltage is generated in the stator windings and converted to DC using six power semiconductor diodes, three of which are connected to the positive terminal of the generator, and the other three are connected to the negative terminal and "vehicle ground".

• If on the dashboard of the car after cranking does not go out indicator lamp, this indicates that the generator is not working and does not give current. But sometimes the cause of the alarm may be a bad contact of the connector, wires, or a malfunction of the relay.
• Discharging the battery. But keep in mind that sometimes the battery is discharged and does not have time to be charged by a working generator when moving over short distances and with the car's lights and electrical appliances turned on as much as possible.
• Generator at engine speed 2000-2500 produces a voltage below the allowable limit of 13.2 Volts.
• If the generator generates voltage above the allowable limit in 14-14.8 Volt (depending on the model), then this indicates a faulty voltage regulator, which leads to disastrous overcharging for the battery.

Before removing the alternator for repair, check:

1. Tensioning the drive belt and rotating the pulley, tightening its nut.
2. Connecting the battery and alternator to the car body.
3. The integrity of the fuses.
4. Bearing play. It is checked in the same way as for electric motors according to this instruction.

1. Before removal and disassembly power unit, if there is generator noise during operation, try disconnecting the wires. If the noise has disappeared, then this indicates a short circuit or an interturn circuit of the stator windings, or a short circuit to ground. Repair is not advisable, it will be cheaper to replace the generator with a new one. If the noise remains, then this indicates wear on the bearings. They need to be replaced.
2. Most often Worn brushes are the cause of the failure.. Check and replace them.
3. Poor contact between brushes and slip rings. Check for a bad spring pressure. It can be stretched or replaced if necessary. Inspect the slip rings for signs of burning or dirt. For cleaning, use the finest sandpaper, and for dirt, use a rag. In case of severe wear of the slip ring, the rotor must be replaced.
4. Rotor winding damage can be checked with a multimeter. The windings should ring between each other for a short circuit or show a resistance of a small value. If the windings are intact, then it is necessary to ring for the absence of an electrical connection between them and the case. A defective rotor cannot be repaired and must be replaced.
5. Stator winding damage checked in a similar way. Between the terminals, the multimeter should show a short circuit or resistance of a very small value. And there should be no electrical contact between the winding and the generator housing. A defective stator must be replaced.
6. Check all diodes in the rectifier. They should conduct electric current only in one direction, in the opposite direction (the positive and negative probes are interchangeable) - the resistance is quite high. In the example in the picture, it is necessary to check each diode between points numbered 1 and numbered 2.

Recommend additionally get acquainted with the instructions for repairing synchronous electric motors with their own hands, because they have troubleshooting carried out in almost the same way as for generators.

Hello dear car enthusiasts! Today I will tell you how to repair the generator with your own hands. You may have already encountered such a problem when the battery discharge indicator suddenly turned on on the dashboard, which means that charging has disappeared on your car, and you don’t have long to go, the battery will last for a maximum of 1-2 hours.

Do not rush to throw away the generator. Try to fix it first. The most common alternator failure is brush wear.

To check the brush assembly, you need to remove the rear plastic cover by bending three plastic clips arranged in a circle.

Remove the cover, unscrew the two screws and remove the voltage regulator.

Check the wear of the brushes, if the residual length of the brushes is less than five millimeters, feel free to buy a new voltage regulator in the store. Sometimes it happens that the generator does not charge or recharge the battery, this is also a malfunction of the voltage regulator. The normal voltage of the generator is from 13.5 to 14.5 volts, depending on the engine speed and the load on the generator.

The next generator malfunction is a breakdown of the diode bridge. To test the diodes, you need to remove the diode bridge. We unscrew the bolts that hold the diode bridge.

Bend the wires to the side.

Remove the diode bridge. How to test a diode bridge. Read here: How to test a diode bridge?

After removing the diode bridge, be sure to check the stator windings. We do this, turn on the multimeter in the dialing mode and check all three stator windings for an open circuit. All windings must ring among themselves.

Next, we check the short to ground. We connect one probe of the multimeter to ground, and connect the second one in turn to the terminals of the windings. There should be no short to ground.

Similarly, we check the armature winding.

We check the anchor, there is no short to ground.

Now I will show how to disassemble the generator to replace the bearings. We unscrew the four screws connecting the two halves of the generator together.

Loosen the nut and remove the pulley.

Using a screwdriver, carefully split the generator into two parts so as not to damage the aluminum covers.

Replace defective bearings with new ones. Assemble the generator in reverse order.

Friends, I wish you good luck! See you in new articles!

Mon 19 Oct 2015

Views: 10 620 Category: Auto electrics

Hello! Today I will show you how I repaired my generator, which, perhaps, someone else would have thrown in a landfill. When I was driving home yesterday, it was all inclusive - light, stove and music. At some point, the on-board computer squeaked and the battery light on the panel lit up. I immediately brought the voltage of the on-board network to the BC and was surprised - it was 11.4 volts. I immediately turned everything off and slowly drove home.

After turning off the engine, the computer showed 8 volts. Having removed and disassembled the generator, it was revealed that one of the copper-graphite brushes of the relay-regulator simply fell off the wire. This one costs 510 rubles, but I thought it would be better to fix it myself.
This is how it looks.

Rummaging through the warehouse, new brushes from the drill were found.

They differed in width and thickness, but the length was the same. Compare:

After a little grinding on the grinder, they became almost identical, only the color was different.

Then I soldered a thin copper wire to the brush pigtail, so that with its help in the future I would not have any problems with how to tighten this very pigtail into the brush contact hole.

After the brush contact of the relay-regulator was cleaned, there were still remnants of the old braid.

And he tinned the whole thing using tin and soldering acid.

Then I put a spring on that same wire.

And I put it in the contact hole of the relay-regulator brush.

Then I saw that the contact bushings of the generator rotor were rubbed with brushes, so much so that plastic was already visible in the grooves, that is, either the contact bushings or the rotor needed to be changed.

Well, it looks like a repaired generator.

I installed it back in the car, started it and see 14.1 volts. Of course, I could not take a steam bath and buy all this, incl. and a new generator. But why? Repairs were spent 0 rubles and a minimum of effort. I hope this is useful to someone. Good luck!

A car generator is a unit that is used to provide electricity to all energy consumers in a car. The failure of the generator set will lead to the fact that all equipment will be powered by the battery, and this will subsequently cause it to quickly discharge. In what cases is it necessary to repair generators, and what malfunctions are typical for this device? You will find answers below.

Why does the engine stall when the generator is loaded, what may be the problems of current leakage, what should be the voltage, why does the device not work and how to repair the breakdown? Repairing malfunctions of car generators with your own hands is a rather complicated matter, therefore, for starters, it recommends that you familiarize yourself with the main breakdowns of the device. Mechanical failures include damage to the mounting brackets, unit housing, wear of the pulley and bearings, pressure springs, etc. There can be many reasons for the damage, but in any case, they have nothing to do with the electrical component.

If the car engine does not start and you think that it is the generator that has broken down, then it will be useful for you to learn about the main signs of malfunctions in the operation of the unit:

1. The low battery indicator appeared on the dashboard with the engine running. The lamp may flash or remain on continuously.
2. In case of incorrect operation of the device, when the unit is subjected to a higher load than that for which it is designed, the battery comes into operation to support the power supply to the equipment. This can cause the electrolyte in the battery to boil off.
3. The next symptom - when you turn on the headlights, you can see how the optics began to burn more dimly. If you press the gas pedal, which will lead to an increase in the speed of the power unit, then the brightness of the optics will be restored to the required level.
4. The device howls, hums, or whistles. If during the operation of the unit extraneous sounds began to appear, this indicates a malfunction in its operation, which may be different. Also, the generator gets very hot.
5. The car engine stalls from time to time for no apparent reason. A malfunction of this kind may indicate that there is a lack of voltage in the on-board network, which is necessary to power electrical equipment. If at the same time the battery is fully charged, then most likely the reason lies precisely in the generator.

Now consider the possible causes of problems that may require the removal, disassembly and repair of the vehicle's generator set:

1. Pulley damage or wear. If we are talking about serious malfunctions and significant damage to the pulley, then it will be easier to replace it. In some cases, repair and restoration is allowed, but it is best to change the device.
2. Damage or natural wear of slip rings that can be damaged.
3. Malfunctions in the operation of the regulatory device. The voltage regulator is designed to equalize the working value in the electrical network of the car, its failure will lead to power surges in the network.
4. Breakdown of the diode bridge of the unit. When the diodes fail, the first symptom of a breakdown is the absence or too weak spark on the candles, and the battery capacity can also be reduced.
5. Closing the turns of the stator winding. Sometimes rewinding the winding solves the problem, but it is often easier to simply replace it.
6. Bearing wear. With wear and tear of the bearing elements, additional noise will appear in the operation of the unit.
7. Damage to the power supply circuit.

How to disassemble and how to repair the device? Below are some basic troubleshooting tips.

These tips are relevant if you know the main causes and signs of breakdowns:

Sometimes self-repair of the unit is impractical, so car owners have to change the device. Consider the replacement procedure using the example of the Lada Kalina car.

To successfully complete the replacement, prepare the following tool:

• wrenches for 8, 13 and 19, for greater convenience, use ring and open-end wrenches;
• ratchets with heads of similar sizes;
• extension cord with a crank (the author of the video is the AndRamons channel).

The replacement procedure must be carried out taking into account the recommendations and requirements of the manufacturer, which are indicated in the service manual. Before proceeding with the replacement, be sure to study the manual.

So, how to remove and replace the unit yourself:

Timely repair and maintenance of the unit are the main aspects that will increase the service life of the device.

What nuances should be considered:

A visual lesson with a detailed description of all aspects on the principle of operation of the unit is shown in the video below (the video was published by Mikhail Nesterov).

car alternator - an electrical installation that converts the mechanical energy of the engine into electrical current. The car generator in the engine compartment of the car performs the function of charging the battery, and also feeds the electrical equipment of the running engine. It is no secret that without the proper operation of this device, the normal operation of the engine is impossible. I propose to understand the design of the generator, as well as consider some possible breakdowns and options for their elimination.

The device itself belongs to the category of electrical equipment, which has a rather complex design. The failure of the generator will lead to the lack of charging of the battery, as well as the failure of the car's engine. Buying a new generator or repairing a generator at a service center is not cheap and will most likely cost you a pretty penny.

However, if you are not from the “timid dozen”, but you have a soldering iron at your disposal, and you know how to use it purely by chance, then it makes sense to try to repair a car generator with your own hands.

I propose, for starters, to analyze the main "diseases" that often occur in the generator:

1. The device stopped charging.

2. The device outputs too little voltage.

3. Alternator is overcharging.

4. During charging, the indicator light on the instrument panel flashes.

5. During the operation of the device, some extraneous noise is heard.

The next step will be to determine the nature of some problems and determine the "root of evil".

If the generator has stopped providing normal charging to the battery, this may mean the following:

1. The fuse has blown, or just moved away a little (contacts).

2. Critical brush wear, either the brushes are broken or jammed.

3. Damaged regulator relay.

4. The winding may have shorted or the rotor or stator circuit may have been broken.

Regarding the first three cases, most likely, it will be necessary to replace the defective parts. However, if you have all the signs of the latter, then you have to pretty tricky.

There are several options for solving the problem.

You can simply buy a normal winding for the stator, or send a failed one for repair and replace it. If the winding breaks, it is necessary to repair the rotor. Often, a winding break occurs in slip rings (this can also be a desoldering of one end of the winding). In this case, you will need to unwind the coils of the damaged section to the point of rupture. The wire must be long enough to be soldered to the slip ring. Next, you need to unsolder the broken tip of the winding from the contact ring and then a serviceable end is made from the same winding (broken off back, postings).

It is possible that there was a desoldering of the end of the winding, which is located on the rotor. If so, then you just need to solder it back. If there is a need to clean the slip rings, do it. If there is a deep defect, it is removed with a file.

At the same time, as they say, you can eliminate another "headache" - the noise of the generator. If the problem is relevant, you should visually inspect the bearing, which is located on the rotor and, if necessary, replace it. However, if the bearing has no play, then it must be carefully removed and washed, for example, in gasoline, and then lubricated. Lubrication should be approximately 30% of the volume of the bearing itself. After that, install the bearing in place.

Battery overcharge or weak charge.

If you have this kind of problem, you will need to look for a solution in the battery relay, if necessary, replace it. As a variant of the occurrence of this breakdown, one can also consider a breakdown of the diode, which is located in the diode bridge.

The signal lamp lights up when the current is good.

Most likely, the reason is the breakdown of one or several diodes at once, which are responsible for the power circuit passing through this lamp. Search for these diodes should be on the same diode bridge. Unscrew the three nuts on the generator using a 7 wrench and remove the stator winding mount, release the nut on the generator output mount with the “+” sign and remove the diode bridge. By following this procedure, you can replace the winding on the stator.

That's actually all. I hope my article will help you repair a car generator with your own hands. Remember that taking on such work, you need to have at least some knowledge in the field of electrical engineering.

A car generator is a device that takes the mechanical energy of the engine and converts it into electric current, thus providing the rest of the car with electricity. The generator provides battery charging and power supply to the car engine. Therefore, the “engine-generator” connection should not be interrupted, because an idle generator is a battery that does not receive a charge and, accordingly, the main organ of the car is not working.
Replacing the generator will entail significant financial costs. Therefore, if you have at hand all the necessary tools and knowledge of the devices of the engine compartment of the car, then you can fix the breakdown yourself (read about what to do if the car does not start - the starter turns, read in our other article).

So the generator is broken. What malfunctions can cause the failure of this device? Consider them:

1. The generator produces current at a very low voltage.
2. The generator does not produce electricity at all.
3. The failure of the device is displayed on the dashboard in the form of a flashing light bulb.
4. The generator is charging in excess of the optimum rate.
5. The operation of the generator is accompanied by extraneous noise.

Before you start repairing the generator with your own hands, it is necessary to check its technical condition and disassemble the unit into parts. Before disassembling the generator, check the condition of the belt and its tension, and make sure that the alternator belt is not expected to be replaced in the near future (read more about how the timing belt is replaced on the VAZ 2109). The check consists in pressing a finger on the middle of this part of the generator. If the belt is in good condition, then it should not fall more than half a centimeter when pressed. It is worth noting that the new belt should not sag by more than 2 mm. If the belt is not worn out, but the tension is weak, then the deficiency can be corrected by tightening the alternator belt. Also scroll the tension roller of the generator, if it scrolls with difficulty and creaks, then it will need to be lubricated with oil, or a new roller should be put in its place.

The technical condition of the generator can be checked using the following measuring instruments:

The rotor speed is measured using a tachometer (usually located next to the speedometer on the instrument panel). During normal operation of the generator, the indicators of this device should not be less than 2000 rpm., The norm is 5000 rpm.

Consider the reasons that can cause a generator to break down. So, if the generator does not generate a charge, then the following phenomena may be the reasons for this:

1. Blown fuse or contacts.
2. Broken or worn alternator brushes.
3. The regulator relay has failed.
4. Due to the short circuit of the winding, an open occurred in the stator or rotor circuit.

In order to fix the first three malfunctions from the list, you just need to replace the worn parts of the generator, having previously, of course, disassembled it.

1. First of all, remove the brush holder together with the voltage regulator, carefully unscrewing all the fasteners.
2. Remove the tension bolts and then the cover with the stator.
3. Remove the cover from the stator, having previously disconnected the phase windings from the output wires on the rectifier unit.
4. Next, remove the pulley from the shaft and the front cover of the generator using a special puller.

The assembly of the generator is carried out in the reverse order.

In the event of a winding short circuit, you will need more serious action than a simple replacement of the part. So, a broken winding can either be repaired or replaced with new wires. Often the winding breaks near the slip rings. In addition, a breakdown can occur due to the desoldering of any of the ends of the winding. Such a malfunction can be repaired by unwinding the turn in the gap area back from the rotor winding. Next, the broken end of the winding must be removed (soldered) from the slip ring and the previously unwound wire is soldered there. Desoldering is very easy to fix by resoldering the wiring.

A damaged relay indicates a weak or too strong charge of the generator, which must be replaced when repairing the generator.

If checking the generator voltage showed that the device is working, but at the same time the indicator flashes on the instrument panel, then most likely one of the diodes that are responsible for powering the light bulb in the indicator has failed. These diodes are located in the generator itself, and the replacement is carried out after disassembling the device.

Noises unusual for the generator may indicate wear on the rotor bearing. If during inspection it is found that the alternator bearing is worn, it will need to be replaced. If the incomprehensible sounds of the generator are associated with the lack of play in the bearing, then it can simply be filled with oil, after washing it in gasoline.Extraneous sounds will then disappear.

Thus, you can even repair the generator on your own in your garage (as well as overhaul the engine, in fact). When checking and replacing parts of the device, follow safety precautions and be careful, because the electrical system should not be damaged.