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Figure 44.-Typical wiring diagram (transistor regulator). | Up
Construction Mechanic Advanced - Construction methods and practices | Next
Alternator Test |
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.
4-4
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