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8-28
ALTERNATOR AND REGULATOR
Bypassing the alternator field coil will cause the
alternator output voltage and the battery line voltage
to drop. This reduction in voltage will reduce the mag-
netic pull of the regulator voltage coil, to the extent
that it cannot hold the armature contact against the
stationery lower contact.
The armature moves into a "no contact'' position
between the upper and lower stationary contacts. This
momentarily allows the field current to flow through
resistors number one and number two, and through
the rotor field coil to ground. At high engine speed
and low electrical load operation, the armature oscil-
lates between the "no contact" position, and contact
with the lower stationary contact, to limit the battery
line voltage.
TESTING THE ARMATURE SYSTEM
(On
the Vehicle Using the Sun Volt
Ampere Tester Model
VAT-20D
and
Sun Battery Post Adapter)
For the sake of uniformity, one type of equipment
is shown. Follow the instructions of the equipment
manufacturers on comparable equipment when
making the following tests:
Preliminary Checks
(1)
Test the Battery Condition.
Perform reliable
battery tests to deternline the condition and state of
charge of the battery. If the battery is defective or
not fully charged, install a fully charged battery for
test purposes.
(2)
Test alternator belt condition and tension.
Re-
place the alternator drive belt if necessary and make
sure that there is adequate tension on the belt.
(3)
Inspect the condition of wires and their connec-
tions.
Before performing the test on the system, cor-
rect any problem with the wiring, such as loose con-
64 x 472
Fig. 7-7ester
l e a d Connections
V
64x473A
Fig. 8-Field
Circuit Resistance and
Field Current Draw Test
nections, corroded connections, burned wiring har-
ness, etc.
Tester Controls
and
Switches
(1) Set Polarity Switch to the NEGATIVE position.
(2)
Set tester control knob to the DIRECT position.
(3)
Set voltage switch to the
2
VOLT position.
(4)
Set
field
control to the OPEN position.
Tester Lead Connections
(Fig.
7 )
(1) Disconnect the positive battery cable from the
battery post and install the BATTERY
POST
ADAPT-
ER between the cable and post.
(2)
Connect the "BAT" lead of the tester to the
stud on the adapter.
(3)
Connect the "REG' lead of the tester to the
binding post on the adapter.
(4)
Connect the "GRD" lead of the tester to a good
ground on the vehicle.
(5)
Connect the negative lead of the voltmeter to
the
field
terminal of the regulator.
(6)
Connect the positive lead of the voltmeter to
the battery end of the positive battery cable.
NOTE:
The
Battery
Post
Adapter
BY-PASS
SWITCH must be open for all charging system
tests. It is closed only for starting the engine.
Field Circuit Resistance Test
(Fig. 81
(1)
Disconnect the slipon connector from either
end of the ignition ballast resistor.
(2)
Turn the ignition switch on.
(3)
With vehicle doors closed and all accessories
turned off, observe the Voltmeter reading. The volt-
age should not exceed
.55
volt. A reading in excess of
.55
volt indicates high resistance in the field circuit
between the battery and the voltage regulator field
terminal.
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