Carrier 69GN15-114 Operation And Service Manual page 22

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.
TOGGLE 12vdc
SWITCH TEST LAMP
+
d d
BATTERY
B
GROUND
INTEGRAL
REGULATOR
EXCITE
(TO OIL PRESSURE
SWITCH OR
TOGGLE SWITCH )
VOLTS
BLK
RED
STEP TEST POINT
*
1 A (B+)
*
2 B (REG)
3 B (D+)
* JUMPER NOT ATTACHED
** REMOTE BATTERY SENSE ONLY
Figure 4---7. Open Regulator Test
AC TAP
(TACH.)
D+
POS + OUTPUT
(B+)
A
FIELD
JU1
SENSE TO
BATTERY
BATTERY
INDICATION
BATTERY
VOLTAGE
BATTERY VOLTAGE
WITH TEST LAMP OFF
JUMPERATTACHED.
1.5 TO 3.0 VOLTS.
TEST LAMP ON
Test No. 3. Alternator Output Test
CONDITIONS: Engine running (after voltmeter is
connected as shown in Figure 4---8).
TOGGLE
SWITCH
+
d d
BATTERY
GROUND
INTEGRAL
REGULATOR
EXCITE
(TO OIL PRESSURE SWITCH
OR TOGGLE SWITCH)
BLK
VOLTS
POS + OUTPUT
RED 13.8 TO 14.8V
** 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.)
4.4.5 Alternator Brush Test Procedure
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
Continuity
No Circuit
No Circuit
No Circuit
No Circuit
4---5
12vdc
TEST LAMP
AC TAP
(TACH.)
POS+
D+
OUTPUT
(B+)
SENSE TO
BATTERY
BATTERY
NOTE
A to B OK
C to D OK
A to C OK
A to D OK
B to C OK
B to D OK
**