Adjusting Regulator (Lamar) - Piper Navajo Chieftain PA-31-350 Service Manual

NAVAJO CHIEFTAIN SERVICE MANUAL
e.
After five minutes operating time, check the regulator operating voltage as indicated by the
voltmeter. Refer to Table XI-I Alternator Test Specifications, for correct operating voltage. The operating
voltage is shown for ambient temperature in which the regulator is operating.
f.
If the voltmeter reading indicates that the operating voltage is not within limits, carefully insert a
small screwdriver (Phillips O) in the voltage adjustment access hole on top of the regulator and adjust
voltage adjustment slowly to obtain desired value. 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 unwanted resistance (voltage drop test). Recheck the voltmeter for accuracy and repeat the entire
operating test.
g.
Balance circuit operation is confirmed by closing the press-to-test switch momentarily and
observing that the alternator output current increases abruptly to a higher level. Upon release of this switch,
the alternator output will be restored to its previous level, except that minor differences may be noted
which are due to battery charge conditions.
11-24. ADJUSTING REGULATOR (Lamar).
a.
These regulators are normally used in parallel alternator systems of multi-engine aircraft. Their
final adjustment should be made in actual operation in the aircraft system with test equipment connected
as shown in Figure 11-20. The balance adjustment is made while operating only one engine, either left or
right. The engine to be operated must be selected so as to permit the technician a completely safe access to
both of the regulators, so that they may be adjusted while the engine is operating without danger. We shall
designate the engine selected to be operated as "RIGHT" and the inoperative engine as "LEFT" for
purposes of discussion.
b.
Lift the wire from the 'TAR" terminal of either regulator and insulate the free end so it will not
contact other circuits or ground during the adjustment procedure. Breaking the circuit disables the
balancing circuit in both regulators.
c.
Turn off the "LEFT" alternator field switch. All the "RIGHT" alternator switches are to be on.
d.
Operate the "RIGHT" engine and alternator system with a load of 15 to 30 amperes, and an
engine RPM of 1500 for at least five minutes. If required, carefully set the "RIGHT" regulator voltage
adjustment to the correct voltage value as measured with the precision voltmeter connected to the regulator
terminals. Replace the snap plug in the "RIGHT" regulator adjustment access hole.
CAUTION
Do not make any further adjustment of the "RIGHT" regulator.
NOTE
Several operations of connecting and disconnecting the "PAR"
circuit wire are required by the following steps. For convenience, a
switch or a dependable clip connection may be used to accomplish
this. No danger of damage exists if this circuit touches any other
circuit or ground, however, erroneous results will be obtained if
such occurs.
Reissued: 9/23/80
ELECTRICAL SYSTEM
3D7