11-7. CHECKING ALTERNATOR SYSTEM. An ammeter is used which enables an independent output check
of the alternator, as well as the electrical output-input of the battery. Should the alternator show no output on the
ammeter, check the circuit breakers of the alternator. If a further check of the ammeter shows no output from the
alternator, check the alternator system. (Refer to appropriate alternator and starter schematic.).
a. Ascertain that the ammeter is operating properly.
b. Disconnect the battery lead (+) at the alternator.
c. Disconnect field leads at the alternator.
d. Ascertain that all electrical units are off and the battery is fully charged.
e. Turn on the master switch.
f. To check the alternator output circuit, connect a voltmeter or 12 volt test light to the battery lead and to
ground. If a reading of approximately 12 volts registers on the voltmeter or the test light lights,the battery circuit
is operational.
g. Should there be no indication of voltage, trace back through the output circuit until voltage is indicated.
(Refer to appropriate alternator and starter schematic.) A component that allows no voltage to pass through it
should be replaced.
h. Check the field circuit by the following procedure:
1. On lead connected to (F-l) terminal, connect a voltmeter to the field lead and to Ground. If the
voltmeter indicates any voltage, the circuit is operational.
i. If voltage is indicated at both the battery lead and field lead, the alternator should be checked for possible
malfunction. (Refer to Paragraph 11-9.)
11-8. SERVICE PROCEDURES. Since the alternator and regulator are designed for use on only one polarity
system, the following procedures must be observed when working on the charging circuit. Failure to observe
these service procedures will result in serious damage to the electrical equipment.
a. When installing a battery, always make sure the ground polarity of the battery and the ground polarity of
the alternator are the same.
b. When connecting a booster battery, make certain to connect the negative battery terminals together and the
positive battery terminals together.
c. When connecting a charger to the battery, connect the charger positive lead to the battery positive terminal
and the charger negative lead to the battery negative terminal.
d. Never operate the alternator on an open circuit. Make absolutely certain all connections in the circuit are
secure.
e. Do not short across or ground any of the terminals on the alternator or regulator.
f. Do not attempt to polarize the alternator.
11-9. OVERHAUL OF ALTERNATORS. When repairing the alternator, complete disassembly may not be
required. In some cases it will only be necessary to perform those operations which are required to effect the
repair. However, in this section, the complete overhaul is covered step by step to provide detailed information on
each operation. In actual service practice these operations may be used as required.
11-10. DISASSEMBLY OF ALTERNATORS.
a. Remove the two Number 10-24 screws holding the brush holder assembly in the slip ring end head.
Remove the brush and holder assembly from the end head.
b. Remove the safety wire from the through bolts. Hold the pulley with a strap wrench and remove the
pulley nut. The pulley must be removed with a puller. Remove the fan, wodruff key and spacer from the shaft.
c. Remove the four through bolts and tap the drive end head lightly to separate the drive end head and rotor
as a unit from the stator and slip ring end head.
PIPER AIRCRAFT
PA-28-161 CADET
AIRPLANE MAINTENANCE MANUAL
Issued: FEBRUARY. 28, 1989
ELECTRICAL SYSTEM
2D1