Piper COMANCHE PA-24-180 Service Manual page 567

PIPER COMANCHE SERVICE MANUAL
f The drle end head supports a sealed. prelubricated ball bearing in which the drive end of the rotor
shaft rotates
9-61c. Checking Alternator System. The ammeter is equipped to check the electrical output-input of the
battery. Should the alternator show no output on the ammeter. check the alternator output and field thermo
circuit protectors. and ammeter line fuses. If a further check of the ammeter shows no output from the
alternator. check the alternator system. (Refer to Figure 9-27b.)
a. Ascertain that the ammeter is operating properly
b. Disconnect the battery lead (1+ at the alternator
c. Disconnect the field leads (Fl and F2) 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 Should there be no indication of voltage. trace back through the output circuit
until voltage is indicated. '
fer to Figure 9-27b ) A component that allows no voltage to pass through it
should be replaced
g
To check the field circuit. connect a voltmeter or 12 volt test light to each field lead and to ground.
and separately check as follows
I
A check of the FI circuit will give a ariable voltage. if any voltage is indicated on the voltmeter
or if any filament glow is indicated on the test light. the circuit is operational
2 The check of the F2 circuit should give a reading of approximately 12 volts or the test lamp
should glow normally for an operational circuit
3 Both the main and auxiliary field circuits may be checked in a like manner
4 If indication shows a possible malfunction of the voltage regulator and before installing a new
regulator. refer to Paragraph 9-61m For the overvoltage control. refer to Paragraph 9-61s
h
If voltage is indicated at both the battery lead and field lead. the alternator should be checked for
possible malfunction. refer to Paragraph 9-61i
9-61d Adjustments. The only adjustments necessary to maintain the alternator system is the adjustment ol
the voltage control on the \oltage regulator A voltage of 14.2 volts.is maintained All other control adjust.
ments are made at time of installaton and need not be reset
IMPORTANT
Since the alternator and regulator are designed for use on only one
polarity system. the following precautions must be observed when
working on the charging unit. Failure to observe these precautions
will result in serious damage to the electrical equipment
a
When installing a batter!. alway s make absolutely sure the ground polarity of the battery and th(
ground polarity of the alternator are the same.
b When connecting a booster battery. make certain to connect the negative batter! terminals togethe
and the positive battern 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 open circuit. Make absolutely certain all connections in the circui
are secure
ISSUED: 8/18/72
3B21
ELECTRICAL SYSTEN
3B21