Two-Unit Vibrating-Contact Regulator
When the alternator charging circuit is serviced, the
following precautions must be observed.
Set up the voltampere tester (VAT) as shown in
Ensure that the polarity of the system being
figure 6-40. With the engine off, remove the cable from
serviced is known so that the battery is connected
the battery's positive post. Then, connect a switching
properly. Reversed battery polarity will damage
device to the battery post, which will allow the circuit to
rectifiers and regulators.
be opened between the battery and the battery terminal
When using booster batteries for starting a
of the alternator. Connect the positive cable of the
battery (coming from the alternator) to the opposite
vehicle, ensure they are connected properly to the
side of the switching device. Connect the voltmeter's
vehicle battery. That is, connect the positive cable from
positive lead to the battery terminal of the alternator,
the vehicle battery to the positive terminal on the
and the negative lead to a good ground. Connect the
booster battery, then connect the negative cable from
negative lead of the ammeter to the battery cable on the
the vehicle to the negative terminal of the booster
switching device, and the positive lead of the ammeter
battery. Failure to do this will result in damage to the
to the battery's positive post.
rectifiers and regulators.
Adjust engine speed to 1,500 rpm and operate for at
Unless the system includes a load relay,
least 15 minutes to stabilize system temperature. Cycle
grounding the alternator output terminal will damage
the system by bringing the engine back to idle,
the alternator and/or circuits. This is true even when the
stopping, and restarting the engine. Adjust speed to
system is not in operation, because no circuit breaker is
2,500 rpm and rotate the load control knob of the VAT
used and the battery is connected to the alternator
to the VARIABLE LOAD position until the ammeter
output terminal at all times. The field or load relay acts
indicates about 15 amperes. The indication provided by
as a circuit breaker in that it is controlled by the ignition
the voltmeter is the voltage setting of the series (lower)
contacts of the regulator. Make a note of the setting.
Ensure that you do not short the adjusting tool to
Rotate the load control knob to the 1/4-OHM
the regulator base when making adjustments to the
POSITION and again check the voltmeter. The
voltage regulator. To do so may result in damage to the
indication on the voltmeter is the voltage setting of the
regulator. The tool should be insulated by taping or by
shorting (upper) contacts of the regulator. Then, refer to
fitting with a plastic sleeve.
the manufacturer's specifications to determine if the
When a vehicle battery is charged with a fast
readings are within limits. Bring the load control knob
charger, ensure the vehicle battery cables are
back to DIRECT and the engine back to idle.
disconnected unless the fast charger is equipped with a
If adjustments are necessary, they are made by
special alternator protector, in which case the vehicle
changing spring tension, by adjustment screws, or by
battery cables need not be disconnected. Also, the fast
bending spring attachment bars.
charger should never be used to start a vehicle, as
damage to rectifiers will result.
Ensure the alternator belt is adjusted to the
The semitransistorized regulator is tested and
adjusted in the same way as the vibrating contact
To prevent damage to the system, the ignition
regulator just described.
switch should be OFF and the battery ground cable
disconnected before making any test connections.
Fully Transistorized Regulator
The vehicle battery must be fully charged or a
With the VAT connected as shown in figure 6-40,
fully charged battery should be installed for accurate
adjust engine rpm to 1,500 and operate for at least 15
minutes to stabilize system temperature. Rotate the
Do not attempt to polarize an alternator. Any
load control knob to the DIRECT position. The
voltmeter will indicate the setting of the voltage
attempt to do so will damage the alternator and the
regulator. Refer to the manufacturer's specifications to
determine if this reading is within limits.