Piper COMANCHE PA-24-180 Service Manual page 578

g. The lternmor should be in good condiion and capable of producing full ornput. and the
alternator driv belt mus be adjused dgt
enough to prevent slippage. Refer o pagraph 9-91 for
methods of checing belt tamons.
h. The battery must be in good condition and should be fully charged.
i. The voltmeter and ammeter should be of the best quality and should be accurate.
j. A carbon-pile connected across the battery may be used to load the charging circuit while
testing the regulator.
9-61q. Testing Regulator.
a. The procedure for testing the regulator, whether on the airplane or on the test bench,
remains the same. Connect test meters as shown in Figure 9-27q.
b. All circuit connections should be clean and tight. This includes the test instrument con-
nections which must not come loose or open the charging circuit at any time while the system
is operating.
c. The voltmeter will not indicate the true regulator setting until the regulator has been
operating in the charging system or on the test bench for at least one minute, at a charge rate of
from 10 to 15-amperes.
d. Connect the voltmeter and the ammeter as shown in Figure 9-27q. Start the engine and
adjust its speed to obtain 3,000 to 4,000 alternator RPM. Turn on accessories as needed to es-
tablish 10 to 15-ampere electncal load, or use a carbon-pile across the battery to obtain this
charge rate.
e. After one minute operating time, check the regulator operating voltage as indicated by the
voltmeter. Refer to Alternator Service Test Specifications, paragraph 9-611., for the correct oper-
ating voltage. The operating voltage is shown for the ambient temperature in which the regulator
is operating.
[. If the voltmeter reading indicates that the operating voltage is not within limits, lift the
plastc plug from top of regulator and adjust the voltage to the desired value. Replace the plug
^
after adjustment. Before condemning the regulator. recheck the alternator and the battery; making
sure that they are in good condition. Recheck
all circuit connections and all wiring for un-
wanted resistance (voltage drop test). Recheck
the voltmeter for accuracy and repeat the
entire operating test.
9-61r. Adjutlng Regulator.
a. Adiustment: These units have an ex-
an adjustment spread ranging from 13.0-volts
to L1.0 volts. Output is increased byturning the
adjustment clockwise.
i
b. OperatingVoltage: The regulatorshould
be adjusted to 14.2-volts when controlling a
^
load of 10 to 1S-amps after one minute oper-
n
'"
atnon. These units are not affected by ambient
temperatures. The voltmeter must be connected
from the "I' or switch terminal to ground.
FIGURE 9-27q. TESTING REGULATOR
ELECTRICAL SYSTEM
3C8
PIPER COMANCHE SERVICE MANUAL