Alternator Test

TM 5-4110-217-14

each cable, wire and terminal.

NOTE

(3) Remove screw (1) and lockwasher (2)

Remove carbon pile immediately after

from alternator (10).

engine is stopped to avoid discharging

(4) Remove nut (4) and adjusting bracket (3).

battery when alternator Is not operating

(5) Swing up alternator and detach bolt (9).

The alternator system Is functioning

(6) Remove screw (5), lockwasher (6) and nut

properly if the output current is 25

(7) to release alternator (10) from unit.

amperes at alternator temperature of

(7) If alternator is to be replaced, remove nut

75F

(14), lockwasher (15) and pulley (13).

g. Cleaning and Inspection.

(7) If the current output is below normal and

(1) Clean alternator with a clean lint-free

the output terminal voltage exceeds 13 volts, replace

cloth.

alternator and/or regulator or refer to direct sup- port unit

(2) Inspect alternator for dents, cracks, chips

for further testing.

or other damage. Replace if defective or refer to direct

(8) If output is below the minimum rated or

support unit for repairs.

the output terminal voltage is below 12 volts, proceed to

h. Installation.

"Alternator Test".

(1) Install pulley (13) on alternator (10) using

e. Alternator Test. This test excludes the

nut (14) and lockwasher (15).

regulator from the alternator system, thereby isolating the

(2) Place alternator in unit as in original

problem to either the regulator or alternator.

configuration and secure with screw (5), lockwasher (6)

(1) With engine off, connect carbon pile load

and nut (7).

across battery (carbon pile in "OFF" position) and place

(3) Place alternator drive belt (9) on pulley.

0-5 ampere meter in series with output terminal and ( + )

(4) Assemble

adjusting

bracket(3)

battery (positive meter to positive battery).

mounting bracket (8) with nut (4).

(2) Remove regulator screws. Place a folded

(5) Fasten adjusting bracket (3) to alternator

wiping cloth over the isolation diode to prevent the

(10) with screw (1) and lockwasher (2). Adjust belt to

regulator body from touching the sink on the output

proper tension before tightening (para 3-13B; figure 3-6).

terminal stud.

(6) Connect cable from alternator voltage

(3) Disconnect regulator field wire from brush

regulator and all other wires as in original configuration.

terminal.

(4) Connect field rheostat with knob set to

maximum resistance, between the positive output

3-47.

Voltage Regulator.

terminal and the brush terminal.

The voltage regulator (fig. 3-19) is an all-electronic,

(5) Connect voltmeter between the brush

transistorized device. No mechanical contacts or relays

terminal ()and the negative output terminal of alternator.

are used to perform the voltage regulation of the

alternator system. The electronic circuitry should never

(6) Slowly reduce resistance of rheostat. If

require adjustment and the solid state active elements

rheostat resistance can be fully eliminated with the test

used have proved reliable enough to warrant a sealed

ammeter indicating 3.0 amperes or less, the rotor (field)

unit. The system is temperature compensated to permit

circuit is correct.

the ideal charging rate at all temperature.

(7) With rheostat eliminated, note reading on

a. Test. The regulator should be checked with an

voltmeter and test ammeter. Slowly apply carbon pile

alternator that is functioning properly (para 3-46).

load to the battery until voltmeter indicates reference

(1) Connect a 60 amp ammeter and a carbon

voltage of 10.0 volts. The field current should be 1.95-

2.55 amperes at 70-80F.

pile load per paragraph 3-46, 1; 2; and 3.

(2) Connect a DC voltmeter (16 volt range)

(8) A slight variation in current may be noted

with an accuracy of 0.1 volts to output terminal and

if the rotor is moved during test, indicating slip rings and

negative ( - ) battery terminal.

brushes require cleaning.

(3) Start engine, increase load with carbon

(9) Return cabon pile to "OFF" immediately

pile, if necessary, to obtain 10 amperes to output current.

after test to avoid discharging battery.

Operate for 15 minutes to stabilize temperature.

(10) Reconnect regulator and field wire.

(4) Output terminal voltage must be 14.4 0.4

Removal (fig. 3-19).

volt at regulator ambient temperature of 75 5F.

(1) Disconnect negative (-) battery cable (5,

fig. 3-20) from battery.

Measure ambient temperature of regulator by placing a

(2) Disconnect cable from alternator to

reliable thermometer 1 inch away from regulator case.

voltage regulator and all other wires. Carefully label

Change 1 3-27