as shown in figure 4-5. The alternator develops ac voltage in the stator windings and is rectified to a dc voltage that appears across the generator "BAT" terminal and the ground screw in the slip ring end frame.

When you service or repair a regulator, follow the manufacturer's service instructions for that specific make and model of regulator. You are not to guess about how to repair or adjust regulators.

TROUBLESHOOTING THE CHARGING SYSTEM WITH A VOLTAMPERE TESTER

There are two types of vehicle charging systems in use today. One system is equipped with a dc generator,

Figure 4-5. - Charging circuit (transistorized regulator).

Figure 4-6.-A circuit.

and the other is equipped with an ac generator or alternator. Both systems are tested in much the same manner.

Field circuits are commonly classified as A and B circuits. The A circuit or externally grounded field, as shown in figure 4-6, is connected to the armature terminal of the generator and is grounded outside the generator by the regulator contacts. In the B circuit shown in figure 4-7, the ground is reached internally, and the supply to the field is obtained via the armature circuit of the regulator. Most alternators and some dc generators are B circuits.

A dc generator depends upon its relatively permanent field pole piece magnetism for initial generator output. The polarity of this magnetic field determines the output polarity of the generator. A mismatched electrical system will cause early component failure. A generator with no magnetic field can produce no output. Therefore, each time a generator is repaired, installed, inoperative for a period of time, or disconnected, it must be polarized. To polarize a generator, you must pass an electric current through the field winding in the proper direction before the system is started.

To polarize an A CIRCUIT GENERATOR at the generator, ground the field and momentarily apply battery voltage to the armature terminal. To polarize at the regulator, momentarily apply a jumper lead from the armature terminal to the battery terminal. To polarize B

Figure 4-7.-B circuit.