Repair the generator

To repair the generator alone is difficult and impractical as to determine its serviceability and its compliance with the characteristics required special stand.

Therefore repairing generator is better to entrust to those skilled in the workshop of the company ?�Volkswagen?�, where you can also replace the generator of the exchange fund. Such a generator is up to 50% cheaper than a new.

However, before replacing the generator, it is possible to carry out some verification work.

Checking the voltage regulator on the car

To check the voltage regulator, it is necessary to have a DC voltmeter with a scale up to 15 - 30 in accuracy class not worse than 1.0.

Check voltage regulator mounted on the car, spend in the following order:

- Start the engine and let it run for about 15 minutes at medium speed;

- Using a voltmeter, measure the voltage between "30" and "weight" of the generator;

- Voltage should be between 13.3 - 14.6 V.

In the event that there is a systematic undercharging or overcharging the battery and the regulated voltage does not fit in the specified range, the voltage regulator must be replaced. In addition, check the condition of the carbon brushes.

Checking the carbon brushes

Although this work can be carried out during a generator, it is still recommended to remove the generator from the car.

Check the state of the carbon brushes spend in the following order:

- Unscrew guard and remove it;

- Unscrew the two screws on the voltage regulator;

- Carefully remove the body of the generator voltage regulator assembly with the brush holder and brushes of the generator;

- Check the condition of the contact portion of the carbon brushes. Check the mobility of the brushes in the brush guides, if necessary, clean the brush holder by trichlorethylene;

- Measure the length of the "a" (Fig. 9.4) protruding from the brush holder carbon brushes. If their height is less than 5 mm, the brush should be replaced.

The new carbon brush has a length of 12 mm, thus, it is possible to know how much to grind off the carbon brushes. Replacing old carbon brushes with new means replacing the entire voltage regulator assembly with the brushes and brush holder, as the carbon brushes are soldered to the brush holder. However, you can optionally soldered electrical connection to the new carbon brush.

Check rotor

The winding of the generator is checked for breakage and short circuit. Connect the tester (ohmmeter mode) to the slip rings of the rotor (Fig. 9.5). The tester should display the coil resistance of 2.8 - 3.0 ohms.

If the tester shows more resistance, then wipe with a cloth soaked in trichlorethylene slip rings and strip of glass cloth. If the contact ring groove formed deeper than 1.5 mm, it is necessary to resharpen the ring on the lathe. If the tester indicates an open (resistance "infinite"), primarily examine the joints of the field winding with slip rings. Often, they are the causes of breakage of a chain drive. Carefully Solder these powerful connections (not less than 100 W) soldering or replace the rotor.

Sometimes slip rings are turned relative to the rotor, which also leads to the edge of the field circuit. Replace the rotor or glue cranks ring to the shaft using an epoxy adhesive.

The reason for termination of the excitation circuit may also disconnect the wires from the brush. In this case, replace the rotor or drill into the brush end of the recess diameter, large diameter wires, fill cavity with glue mixed with sawdust from a faulty graphite brushes, insert the wire.

Short circuit in the field coil is checked by adding one probe of the tester (ohmmeter mode) to the slip ring rotor and the other - to the rotor (Fig. 9.6).

If the arrow is rejected, try to find and repair the short. Most often, it happens at the joints of the excitation winding slipring - under the influence of centrifugal forces wire terminates and is connected to the rotor shaft of the generator. If you can not remove the short circuit in the field winding - replace the entire rotor.

Note that the field winding can be checked without removing the generator from the car. To contact rings can be accessed if you remove the protective cover, and a voltage regulator with a brush holder.,

Checking the stator

Generator stator winding also check for an open or short circuit. To check for open circuit tester (ohmmeter mode) is connected alternately to the ends of the two phases of the stator. If the indicators do not correspond to 0.1 - 0.11 ohms, the circuit has audited winding cliff. If the place of the cliff found Solder joint continuity of a powerful soldering iron (at least 100 W), cover it with varnish and dry at a high temperature.

When checking the stator windings for an open look at the testimony of the tester when it is connected between the terminal phase. With all the connections tester his testimony should be the same. If the tester will show a different resistance, it means that in the stator winding has interturn circuit. This coil should be replaced.

The most common short-circuit fault location can be determined by visual inspection - traces of overheating wiring. Short-circuiting the stator windings of the housing is defined by connecting a probe tester (ohmmeter mode) to one of the winding, and a second probe - to the stator housing. If the needle deviates tester - so verifiable winding earthed. If you find a place you can not short-circuit - replace the entire stator.