Generator — Checking and Repairing (VAZ-2107)

Checking the generator 372.3701

To complete the work you will need a multimeter.

1. Remove the generator from the car (see "Generator - removal and installation").

2. Using a rag, clean the outer surface of the generator from dirt.

3. By connecting the positive probe of the ohmmeter to terminal "30" and the negative probe to the generator body, we check the generator diodes for "breakdown".



If the ohmmeter shows a resistance close to zero, one or more diodes have broken down or the stator winding has short-circuited to the housing.

4. Connect the positive probe of the ohmmeter to terminal "30" and the negative probe to one of the rectifier block mounting bolts and check the positive diodes.



If the ohmmeter shows a resistance close to zero, then one or more diodes have broken down.



5. Having connected the positive probe of the ohmmeter to one of the bolts of the rectifier unit, and the negative one to the generator body, we check the negative diodes of the generator for "breakdown". If the ohmmeter shows a resistance close to zero, then one or more diodes have broken down.



6. To check the capacitor, remove it from the generator (see "Repair" below). When connecting the ohmmeter probes to the capacitor terminals, the resistance should decrease and then gradually increase.

7. To check the regulator, remove it from the generator (see "Repair" below). When pressing on the brushes, they should move freely in the grooves and be spring-loaded. The protrusion of the brushes in a free state from the brush holder should be at least 5 mm, otherwise replace the regulator.

8. Connect the "B" terminal of the voltage regulator to the positive terminal of the battery, and the negative terminal (shown by arrow A) - with "mass". We measure the voltage on the contacts of the brush assembly with a voltmeter.



If there is no voltage, then the regulator is faulty.


9. By connecting one contact of the ohmmeter to the housing and the other to the rotor slip ring, we check for a short circuit between the rotor winding and the generator housing.



If the ohmmeter shows a resistance close to zero, then a short circuit has occurred.

A faulty rotor, stator, capacitor or voltage regulator must be replaced. If one diode is faulty, replace the rectifier unit as a whole.

Generator repair 372.3701

To perform the work you will need: a two- or three-jaw puller, a mandrel for pressing out the front bearing, a mandrel for pressing in the rear bearing.

1. Using a screwdriver to hold the rotor from turning, use a 19 mm socket wrench to unscrew the nut securing the pulley and fan impeller.



2. Remove the pulley parts, fan impeller, segment key and limit washers from the shaft.



3. To remove the voltage regulator, disconnect the wire connector from it.



4. Using a Phillips screwdriver, unscrew the two screws securing the voltage regulator.



5. Remove the voltage regulator assembly with the brush unit from the generator housing.



6. Using a 10 mm socket wrench, unscrew the four nuts securing the generator covers and remove the connecting bolts.



7. Lean the front cover of the generator onto a wooden block and press it off the stator using light blows on the shaft.



8. Remove the generator cover and spacer sleeve.



9. Check the technical condition of the front bearing. Holding the cover, rock and turn the inner ring of the bearing in both directions. The bearing rotation should be smooth, the axial play should be insignificant. Replace the faulty bearing.

10. When replacing the front bearing, use an 8 mm socket or open-end wrench to unscrew the four nuts. If the nuts do not unscrew, grind down the punched ends of the bolts.

Attention! After installing the bolts and tightening the nuts, the ends of the bolts must be punched. If the length of the bolts is not enough to punch them, then replace the bolts.

11. Remove the bolts and remove the inner and outer bearing mounting washers.



12. Using a mandrel of suitable diameter, press out the bearing.



13. Support the edges of the rear cover of the generator (for example, on two wooden blocks), we knock out the rotor using a soft metal punch.



14. Check the technical condition of the rear bearing. The bearing should roll smoothly, the axial play should be insignificant. There should be no noise when the outer ring rotates quickly. Replace the faulty bearing.

15. If it is necessary to replace the bearing, use a puller to press it off the rotor shaft.



16. Using an 8 mm socket wrench with an extension, unscrew the three nuts securing the rectifier unit and the stator winding terminals.



17. After removing two bolts, remove the stator from the cover.



The insulation of the stator winding wires must be free of signs of overheating.

18. Using a 10 mm deep-head socket wrench, unscrew the terminal nut "30" and remove the insulating washer A.



19. Remove the rectifier block.



21. Using a Phillips screwdriver, unscrew the screw securing the capacitor and remove it. Remove the third bolt (B) securing the rectifier unit from the hole in the cover.

Generator assembly 372.3701

1. Clean the generator parts from dirt and dust, blow with compressed air, metal parts (except bearings) wash with white spirit or kerosene.

2. Using a mandrel that matches the diameter of the inner ring, press the new bearing onto the rotor axis with light blows.



3. Check the bearing mounting holes in the covers. The holes should not be deformed, there should be no burrs on their surfaces. If necessary, use a file or scraper to restore the chamfer of the hole edges. Replace cracked covers.

4. The misalignment of the holes in the generator cover lugs should be no more than 0.4 mm. When assembling, for the mutual orientation of the covers, use a fastening bolt and a buffer sleeve.

5. The generator is assembled in the reverse order.

Disassembling the generator 9412.3701

1. Remove the generator from the car (see "Generator - removal and installation").

2. After pressing three spring clamps, remove the protective cover of the rectifier unit.



3. Using a Phillips screwdriver, unscrew the two screws securing the voltage regulator.



4. Disconnect the wire connector from the voltage regulator terminal and remove the regulator.



5. Using an 8 mm open-end wrench, unscrew the three bolts (1) connecting the stator winding terminals to the rectifier unit, and another bolt (2) securing the rectifier unit (remember how the isolating and thrust washers are installed).



6. Carefully bend the stator winding terminal wires to the side.



7. Using a Phillips screwdriver, unscrew the screw securing the capacitor.



8. Remove the rectifier unit together with the capacitor. Use a 10 mm socket wrench to unscrew the two nuts of the contact bolt. Remove the distance and insulating bushings from the bolt, take the bolt out of the rectifier unit and remove the capacitor tip from the contact bolt.



9. Using a marker, mark the relative positions of the front and rear covers of the generator (to simplify assembly).



10. Using an 8 mm socket wrench, unscrew the four bolts holding the front and rear covers of the generator.



11. Using a slotted screwdriver, carefully move the generator covers apart.



12. Disconnect the back cover together with the stator from the front cover.

Recommendation. To determine the technical condition of the rear bearing, rock it from side to side and vigorously rotate its outer ring. The bearing should not have significant play, and the ring should rotate freely without jamming or extraneous noise. A faulty bearing must be replaced.

13. Using a marker, make a mark on the stator (to indicate its position relative to the back cover).



14. Remove the stator from the rear cover of the generator.

Recommendation. To determine the technical condition of the front bearing, hold the pulley with your hand, swing it from side to side and rotate the front cover. If the bearing is jammed, has significant play, or makes noise when the cover is rotated vigorously, it must be replaced.

Advice. The manufacturer recommends replacing the front rotor bearing together with the front generator cover, as it is rolled into the cover. However, given that the cost of the bearing is significantly lower than the cost of a new front cover and, especially, the generator assembly, it is advisable to press out and replace the faulty bearing.

15. If it is necessary to replace the front generator bearing, use a 24 mm socket wrench to loosen the pulley mounting nut while holding the pulley with sliding pliers.

16. Remove the pulley with spring (3) and flat (2) washers, and the spacer sleeve (1) from the rotor shaft.



17. Screw the pulley mounting nut onto the rotor shaft thread (flush with end). Using a rubber-headed hammer, press the rotor out of the front bearing on the nut.



18. If it is necessary to replace the front generator bearing, install the front cover in a vice (the jaws of the vice should be fitted with soft metal pads).

19. Having selected suitable mandrels from the cup puller set (see "Tools, accessories and operating materials"), we press the bearing out of the seat in the front cover.



20. If it is necessary to replace the rear generator bearing, secure the rotor in a vice with soft pads on the jaws. Using a universal puller (see "Tools, accessories and operating materials") we press the rear bearing from the rotor shaft.

Generator check 9412.3701

1. Check the stator windings: a) by applying the ohmmeter probes to the rotor slip rings, check the excitation winding for breakage. The resistance of a serviceable excitation winding should be 5-10 Ohm;



b) by connecting the ohmmeter probes to any contact ring and to the rotor, we check the excitation winding for short circuit to ground. If the rotor winding is in good condition, the ohmmeter should show infinite resistance.



2. Check the stator windings:

a) alternately connecting the ohmmeter probes to the stator winding terminals, we check the winding for a break. If there is no break, the ohmmeter will show low electrical resistance (about 10 Ohm);



b) by connecting the ohmmeter probes to any terminal of the winding and to the stator, we check the stator winding for the absence of a short circuit to ground.

If there is no short circuit, the ohmmeter should show infinite resistance.



3. Check the rectifier unit:

Note: A healthy semiconductor diode conducts electric current in only one direction. A diode is faulty if it does not conduct current or conducts current in both directions.

a) connect the positive lead of the ohmmeter (in diode test mode) to the common bus of the auxiliary diodes (1), and the probe of the negative terminal to the terminal of the diode being tested (2). A serviceable diode should not pass current (resistance tends to infinity);



b) swap the tester probes. If the diode is working properly, the ohmmeter should show resistance (several hundred ohms). We check the other two auxiliary diodes in the same way;



c) connect the probe of the negative terminal of the ohmmeter to the plate of the rectifier block, into which the diode being tested is pressed, and the probe of the positive terminal to the terminal of the diode. A serviceable diode should not pass current (resistance tends to infinity);



d) swap the tester probes. If the diode is working properly, the ohmmeter should show a resistance of several hundred ohms).



We check other power diodes in the same way.

4. Check the voltage regulator:

a) inspect the voltage regulator brushes, make sure they move. If the brushes are broken or badly worn (protrude from the brush holder by no more than 5 mm), or they are jammed in the brush holder - the voltage regulator needs to be replaced;

b) to check the voltage regulator, we assemble the simplest circuit (see below). We connect the negative terminal of the power source to the regulator's "ground" with a wire, and the positive terminal to its terminal. We connect the test lamp to the brushes of the voltage regulator.

Warning! When connecting the wires supplying voltage to the voltage regulator, strictly observe the polarity. Incorrect connection of the wires will disable the voltage regulator.

We use a voltmeter to control the voltage supplied to the voltage regulator;



c) turn on the power supply and apply 13 V to the voltage regulator. The control lamp should light up, indicating that with such voltage in the vehicle's on-board network, the excitation current will flow to the generator rotor winding;



d) gradually increase the voltage until the control lamp goes out. The voltage at which the control lamp goes out should be 14.5-14.7 V.

d) Reduce the supplied voltage until the control lamp lights up again. The voltage at which the control lamp lights up should not be lower than 13.2 V.

5. Checking the capacitor:

Note. The capacity of a capacitor can only be measured with a special device. You can verify the capacitor's fault using an ohmmeter with a measurement limit of at least 1000 kOhm.

We connect an ohmmeter to the terminals of the capacitor and observe its readings. If the capacitor is not "broken", then when connecting the terminals of the device to it, the ohmmeter will initially show a small resistance, then this resistance will quickly increase until it stabilizes. A similar change in the ohmmeter readings should be repeated when changing the polarity of the device.

A faulty rotor, stator, capacitor or voltage regulator must be replaced. If one or more diodes in the rectifier unit are faulty, the entire unit must be replaced.

Generator assembly 9412.3701

Warning! Before pressing in the front generator bearing, it is necessary to check the bearing seat and, if necessary, use a knife or scraper to restore the chamfer where the edges of the hole have remained dented. When pressing the front bearing into the cover, the force must be transmitted only to the outer ring of the bearing.

1. Having selected suitable mandrels from the cup puller set (see "Tools, accessories and operating materials"), press the new front bearing into the seat in the front cover until it stops.

Warning: When performing the following operation, use only light hammer blows. Strong blows may crack the cover, which is made of fragile aluminum alloy.

2. Using a steel punch of suitable diameter and a hammer, restore the bearing crimp in the cover.

Warning! Before installing the rear generator bearing, make sure that the rotor shaft is securely clamped in a vice. Place a wooden block of suitable size under the rotor shaft to avoid damaging the front impeller during pressing. To avoid damaging the bearing, only strike its inner ring.

3. Using a piece of pipe of a suitable diameter (you can use a 19mm deep socket) we press the new bearing onto the rotor shaft until it stops.



Further assembly of the generator is performed in the reverse order of disassembly. In this case, we align the marks applied to the covers and the generator stator. Finally, tighten the tie bolts evenly, crosswise, in several steps of half a turn. Having tightened the bolts, we make sure that the rotor rotates easily (the rotor task may be due to the skewing of the covers). Before tightening the stator winding mounting bolts, make sure that insulating washers are installed under their heads.

Warning: When installing the voltage regulator, do not apply lateral force to the brushes.