4---5
CONDITIONS: Start---run---stop switch (SRS) in
RUN position and engine stopped (after proper hook---
up is made and test leads connected). No electrical loads.
a. With jumper not attached. Check for battery
voltage at terminal A and for 1.5 to 3.0 volts at terminal B.
see Figure 4---6.
b. Add jumper JU1 between terminals A and B. Start
engine and run with no load. If the test lamp now goes off,
and charging voltage is present at terminal A (more than
battery voltage), the diode---trio is open. Alternator
should be removed for repair. If the voltmeter indication
is not in this range, remove the jumper and proceed to the
regulator test
(test no. 2).
Test No. 2 --- Open Regulator Test
CONDITIONS: Engine stopped (start---run---stop
switch in the RUN position) and voltmeter set---up as
shown in Figure 4---7.
NOTE
Before performing test, removal of back cover is
required. To remove, disconnect wires from
terminals extending through back cover.
Remove back cover (two screws) and reconnect
all wires.
a. With jumper not attached, check for battery voltage
at terminals A and B. Test lamp will be off.
b. Add jumper JU1 between field and ground (see
Figure 4---7). If 1.5 to 3.0 volts is present at terminal B
and the test lamp is on, the regulator is open. Alternator
should be removed for repair.
B
A
D+
AC TAP
(TACH.)
POS + OUTPUT
(B+)
FIELD
GROUND
INTEGRAL
REGULATOR
EXCITE
JU1
BATTERY
VOLTS
BLK
RED
STEP TEST POINT
INDICATION
1
2
3
A (B+)
B (REG)
BATTERY
VOLTAGE
B (D+)
SENSE TO
BATTERY
BATTERY VOLTAGE
WITH TEST LAMP OFF
JUMPERATTACHED.
1.5 TO 3.0 VOLTS.
TEST LAMP ON
d
12vdc
TEST LAMP
d
+
TOGGLE
SWITCH
BATTERY
* JUMPER NOT ATTACHED
** REMOTE BATTERY SENSE ONLY
*
*
**
(TO OIL PRESSURE
SWITCH OR
TOGGLE SWITCH )
Figure 4---7. Open Regulator Test
Test No. 3. Alternator Output Test
CONDITIONS: Engine running (after voltmeter is
connected as shown in Figure 4---8).
VOLTS
AC TAP
(TACH.)
POS+
OUTPUT
(B+)
BATTERY
GROUND
INTEGRAL
REGULATOR
EXCITE
BLK
RED
POS + OUTPUT
13.8 TO 14.8V
D+
(TO OIL PRESSURE SWITCH
OR TOGGLE SWITCH)
SENSE TO
BATTERY
d
12vdc
TEST LAMP
d
+
TOGGLE
SWITCH
BATTERY
** REMOTE BATTERY SENSE ONLY
**
Figure 4---8. Alternator Output Test
a. Start unit and run engine with load. With the unit
operating (placing a load on charging circuit) check for
nominal system output voltage of between 13.8 --- 14.8
volts for a properly operating charging system. (Voltages
may vary a few tenths of a volt, higher or lower, due to
ambient temperature variations.)
b. If the alternator output voltage does not fall within
the proper range, the alternator should be removed for
further inspection and tests. (Refer to Motorola manu-
al.)
4.4.5Alternator Brush Test Procedure
NOTE
Before performing test, removal of back cover is
required. To remove, disconnect wires from
terminals extending through back cover.
Remove two screws securing back cover to rear
housing and remove cover.
a. Removing Brush Set
a. Remove two locknuts securing brush holder and
remove brush assembly.
b. Check brush assembly for cracked, chipped or oil
soaked brushes. Remaining brush length should be at
least 3/16 inch (4.76 mm) long.
c. Check slip rings for carbon build---up.
d. Using a 12 vdc test lamp or ohmmeter, test brush
assembly for continuity and insulation (see Figure 4---9).
Replace brush assembly if necessary.
b. Brush Continuity Check
Using a 12 vdc test lamp or ohmmeter, test brush
assembly for continuity and insulation as shown. Remove
brush assembly if necessary.
CONTINUITY CHECK
Continuity
A to B
OK
Continuity
C to D
OK
No Circuit
A to C
OK
No Circuit
A to D
OK
No Circuit
B to C
OK
No Circuit
B to D
OK