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 terminal "30" and the generator "ground". The voltage should be within 13.6-14.6 V.
If there is systematic undercharging or overcharging of the battery and the regulated voltage does not fall within the specified limits, the voltage regulator must be replaced.
Checking the removed regulator
The regulator removed from the generator is checked according to the diagram shown in Fig. 7-10. It is better to check the regulator used before 1996 together with the brush holder, since in this case it is possible to immediately detect breaks in the brush terminals and poor contact between the terminals of the voltage regulator and the brush holder.
Between the brushes, connect a 1-3 W, 12 V lamp to terminals "B", "B" (if there is one) and connect a power source with a voltage of 12 V to the "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 (for generators manufactured before 1996.).