Vehicle check
To check, you must have a DC voltmeter with a scale of up to 15-30 V, an accuracy class of at least 1.0.
After 15 minutes of engine operation at medium speeds with the headlights on, measure the voltage between the terminal «30» and generator housing. The voltage should be in the range of 13.6-14.6 V.
In the event that a systematic undercharging or overcharging of the battery is observed and the regulated voltage does not fit within the above limits, the voltage regulator must be replaced.
Checking the removed regulator
The voltage regulator removed from the generator is checked according to the circuit shown in fig. 131. It is better to check it assembled with a brush holder, since in this case you can immediately detect breaks in the brush leads and poor contact between the leads of the voltage regulator and the brush holder.
Pic. 131. Scheme for testing the voltage regulator: 1 - battery; 2 - voltage regulator; 3 - control lamp
Between the brushes include a lamp with a power of 1-3 W, 12 V. To the conclusions «B», «IN» and a power supply is first connected to the regulator ground with a voltage of 12 V, and then 15-16 V. If the regulator is working, then in the first case the lamp should be on, and in the second it should not.
If the lamp is on in both cases, then there is a breakdown in the regulator, and if it does not light in both cases, then either there is an open in the regulator or there is no contact between the brushes and the outputs of the voltage regulator.
Capacitor check
The capacitor serves to protect the electronic equipment of the car from voltage pulses in the ignition system, as well as to reduce radio interference. Capacitor damaged or loose on alternator (deterioration of contact with the body) detected by an increase in radio interference when the engine is running.
Approximately the health of the capacitor can be checked with a megger or tester (on a scale of 1-10 MΩ). If there is no break in the capacitor, then at the moment the probes of the device are connected to the terminals of the capacitor, the arrow should deviate in the direction of decreasing resistance, and then gradually return back. Capacitor capacitance 2.2uF±20%.