Control checks of the generator of the VAZ-21214 car (VAZ-21213)

Testing the generator on the bench

Testing on a stand allows you to determine the generator's serviceability and whether its characteristics correspond to the nominal ones. The tested generator's brushes should be well ground to the collector's contact rings, and the rings themselves should be clean.

Install the generator on the stand and make connections as shown in Fig. 9-7. Turn on the stand's electric motor, use rheostat 4 to set the generator output voltage to 13 V and bring the rotor speed to 6000 min⁻¹. Let the generator run in this mode for at least 10 minutes, and then measure the output current. For a serviceable generator, it should be at least 80 A.





If the measured value of the return current is significantly less, this indicates faults in the stator and rotor windings or damage to the valves. In this case, a thorough check of the windings and valves is necessary to determine the location of the fault .
The generator output voltage is checked at a rotor speed of 5000 min⁻¹. Using rheostat 4, set the output current to 15 A and measure the generator output voltage, which should be 13.2-14.7 V at an ambient air and generator temperature of (25±10)°C.

If the voltage does not fit within the specified limits, then replace the brush holder with a voltage regulator with a new one, known to be in good working order, and repeat the check. If the voltage is normal, then the old voltage regulator is damaged and must be replaced. And if the voltage still does not fit within the above limits, then it is necessary to check the windings and valves of the generator.

Checking the generator with an electronic oscilloscope

The oscilloscope allows you to accurately and quickly check the generator's serviceability and determine the nature of the damage based on the shape of the rectified voltage curve.

To check, assemble the circuit according to Fig. 9-8. Disconnect the common terminal wire of the three additional diodes from the "D+" plug of the voltage regulator and take measures to ensure that the tip of the disconnected wire does not short-circuit with the "ground" of the generator. Connect the wire from the storage battery to the "D+" plug of the regulator through switch 1. Thus, the excitation winding will be powered only from the storage battery.




Turn on the stand's electric motor and increase the rotor speed to 1500-2000 min⁻¹. Using switch 6, disconnect the battery from the "B+" terminal of the generator and use rheostat 4 to set the output current to 10 A.

Check the voltage on the "B+" terminal of the generator using an oscilloscope. If the valves and stator winding are in good condition, the rectified voltage curve has a sawtooth shape with uniform teeth (fig. 9-9, I). If there is a break in the stator winding or a break or short circuit in the rectifier block valves, the shape of the curve changes dramatically: the uniformity of the teeth is disrupted and deep depressions appear (fig. 9-9, II and III).



Having checked the shape of the voltage curve at the "B+" terminal of the generator and having made sure that it has a normal appearance, check the voltage at the "D" plug of the generator with the wire disconnected from the "D+" plug of the voltage regulator. The "D" plug is the common terminal of three additional diodes that supply power to the excitation winding when the generator is running. The shape of the voltage curve here should also have a correct sawtooth shape. An incorrect shape of the curve indicates damage to the additional diodes.

Checking the rotor excitation winding

The excitation winding can be checked without removing the generator from the car, by removing only the protective casing and the voltage regulator together with the brush holder. If necessary, clean the contact rings with sandpaper, and use an ohmmeter or test lamp to check whether there is a break in the excitation winding and whether it is shorted to ground.

Stator check

The stator is checked separately, after removing the rectifier unit.

First of all, check with an ohmmeter or with a test lamp and a battery to see if there are any breaks in the stator winding and if its turns are shorted to ground.

The insulation of the winding wires must be free of traces of overheating, which occurs during a short circuit in the rectifier block valves. Replace the stator with such a damaged winding.

Finally, after disassembling the generator, it is necessary to check with a special defectoscope whether there are any short-circuited turns in the stator winding.

Checking the rectifier block valves

The original can be seen on the website: VAZBOOK.RU

A working valve only passes current in one direction. A faulty valve may not pass current at all (chain break), or pass current in both directions (short circuit).

If one of the rectifier valves is damaged, the entire rectifier unit must be replaced.

A short circuit of the rectifier block valves can be checked without removing the generator from the car, after disconnecting the wires from the battery and generator and removing the casing from the rear cover of the generator. The wire from the "D+" terminal of the voltage regulator is also disconnected. You can check with an ohmmeter or a lamp (1-5W, 12V) and the battery, as shown in Fig. 9-10.

Note: In order to simplify the fastening of the rectifier parts, three valves (with a red mark) create a "plus" of the rectifier block on the case. These valves are "positive" and they are pressed into one plate of the rectifier block, connected to the "B+" terminal of the generator. The other three valves ("negative" with a black mark) have a "minus" of the rectifier block on the case. They are pressed into another plate of the rectifier block, connected to the "ground".

First check if there is a short circuit in both the "positive" and "negative" valves. To do this, connect the "plus" of the battery through the lamp to the "B+" terminal of the generator, and the "minus" to the generator body (fig. 9-10, I). If the lamp is on, then the "negative" and "positive" valves are short-circuited.

To check for a short circuit in the "positive" valves, connect the "plus" of the battery through a lamp to the "B+" terminal of the generator, and the "minus" to one of the phase terminals of the stator winding (fig. 9-10, II). The lamp lighting up will indicate a short circuit in one or more "positive" valves.

A short circuit of the "negative" valves can be checked by connecting the "plus" of the battery through a lamp to one of the phase terminals of the stator winding, and the "minus" to the generator body (fig. 9-10, III). The lamp burning means a short circuit in one or more "negative" valves. It should be remembered that in this case the lamp burning may also be a consequence of the stator winding turns shorting to the generator housing. However, such a malfunction occurs much less frequently than a short circuit of the valves.

A break in the valves without disassembling the generator can be detected either with an oscilloscope or by testing the generator on a bench by a significant decrease (by 20-30%) in the value of the output current compared to the nominal value. If the windings, additional diodes and the voltage regulator of the generator are in good order, and there is no short circuit in the valves, then the reason for the decrease in the output current is a break in the valves.

Checking additional diodes

A short circuit of additional diodes can be checked without removing and disassembling the generator using the diagram shown in Fig. 9-11. Just as for checking the rectifier block valves, it is necessary to disconnect the wires from the battery and the generator, remove the generator protective cover and disconnect the wire from the "D+" terminal of the voltage regulator.



"Plus" of the battery through the lamp (1-3W, 12V) connect to the "D" terminal of the generator, and the "minus" to one of the phase terminals of the stator winding.

If the lamp lights up, then one of the additional diodes has a short circuit. The damaged diode can only be found by removing the rectifier block and checking each diode separately.

A break in the additional diodes can be detected with an oscilloscope by the distortion of the voltage curve on the "D" plug, as well as by the low voltage (below 14 V) on the "D" plug at the average rotation frequency of the generator rotor.

Checking the voltage regulator

The operation of the voltage regulator consists of continuously and automatically changing the excitation current of the generator so that the generator voltage is maintained within specified limits when the rotation speed and load current of the generator change.

Checking on a car. To check, you need a DC voltmeter with a scale of up to 15-30 V and an accuracy class of at least 1.0.

After 15 minutes of engine operation at medium speed with the headlights on, measure the voltage between the "B+" terminal and the generator "ground". The voltage should be within 13.2-14.7 V.

If systematic undercharging or overcharging of the battery is observed and the regulated voltage does not fall within the specified limits, the voltage regulator must be replaced.

Checking the removed regulator. The regulator assembled with the brush holder, removed from the generator, is checked according to the diagram shown in Fig. 9-12.



Between the brushes, turn on a 1-3 W, 12 V lamp. Connect a power source with a voltage of 12 V to the terminals "D+" and "ground" of the regulator, and then with a voltage of 15-16 V.

If the regulator is working properly, then in the first case the lamp should light up, and in the second case it should go out.

If the lamp lights up in both cases, then there is a breakdown in the regulator, and if it does not light up in both cases, then either there is a break in the regulator, or there is no contact between the brushes and the terminals of the voltage regulator. The latter can be checked by connecting the wires from the lamp not to the brushes, but directly to the terminals "D+" and "DF" of the voltage regulator.

Checking the capacitor

The capacitor serves to protect the vehicle's electronic equipment and reduce interference with radio reception.

Damage to the capacitor or weakening of its fastening on the generator (deterioration of contact with the "ground") is detected by an increase in interference to radio reception when the engine is running.

The condition of the capacitor can be approximately checked with a megohmmeter or tester (on the scale 1-10 MOhm). If there is no break in the capacitor, then at the moment of connecting the device probes to the terminals of the capacitor, the arrow should move towards decreasing resistance, and then gradually return back.

The capacitor capacity, measured with a special device, should be 2.2 μF ±20%.