Piper Comanche PA-24 Service Manual page 697

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PIPER COMANCHE SERVICE MANUAL
f The dri"e end head supports a sealed. pre lubricated ball bearing in which the drive end of the rotor
shaft rotates
9-6Ic. 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. I Refer to F'gure 9-27b.)
a. Ascertain that the ammeter is operating properly
b. Disconnect the battery lead 1+) at the alternator
c. Disconnect the field leads IFI 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, oltage IS !Odicated. ,'fer to Figure 9-27b ) A component that allows no ,oltage to pass through it
should be replaced.
g To check the field circuit. connect a \oltmeter or 12 volt test light to each field lead and to ground.
and separately check as follows
I A check of the F I circuit will gl\ e a ,ariable voltage. if any voltage is indicated on the, oltmeter
or if any filament glow is indicated on the test light. the circuit is operational
2 The check of the F2 circuit should gi\e a reading of approximately 12 \olts or the test lamp
should glow normally for an operational circuit
:I Both the main and auxiliar, field circuits may be checked in a like manner
4 If indication shows a possible malfunction of the \oltage regulator and before installing a new
regulator. refer to Paragraph 9'('lm For the overvoltage control. refer to Paragraph 9-615
h If \oltage is indicated at both the battery lead and field lead. the alternator should be checkcd for
po,,,ble malfunction. refer to Paragraph 9-l>li
9-old Adjustment •. The only adjustments necessary to maintain the alternator system is the adjustment
01 ,
the ,oltage control on the \oltage regulator A \oltage of 14.2 volts.is maintained All other control adjust·
ments are made at time of installation and need not be reset
IMPORTAl\T
Since the alternator and regulator are designed for use on onlv one
polarit' 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 battery. always make absolutely sure the ground polarit\' of the battery and thl
ground polarity of the alternator are the same.
b When connecting a booster battery. make cenain to connect the negati"e battery terminals togethe'
and the positi\'e battei)· terminals together.
c. When connecting a charger to the battery. connect the charger positive lead to the battery positiVI
terminal and the charger negative lead to the battery negati" terminal.
d "ever operate the alternator on open circuit. Make absolutely cenain all connections in the circui
are secure
ISSl:ED: 8/18/72
3B21
ELECTRICAL SYSTEI\<