Adjusting Regulator (Lamar); Adjusting Regulator (Prestolite) - Piper Navajo PA-31 Service Manual

PIPER NAVAJO SERVICE MANUAL
10 to 15-ampere load value. Note that the battery charge current is indicated by the
ammeter. Therefore, the current value may change downward at the beginning of a test run.
This will be especially true if the battery was used for engine starting.
e. After five minutes operating time, check the regulator operating voltage as indicated
by the voltmeter. Refer to Alternator Service Test Specifications as outlined in Paragraph
11-36 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.
11-50. ADJUSTING REGULATOR (PRESTOLITE).
a. Adjustment:
These units have an external adjustment located under the plastic plug
on top of the regulator. The regulator has an adjustment spread ranging from 26.0-volts to
30.0-volts. Output is increased by turning the adjustment clockwise.
b. Operating Voltage: The regulator should be adjusted to 28.4-volts when controlling
a load of 10 to 15-amps after one minute operation. These units are not affected by ambient
temperatures. The voltmeter must be connected from the "I" or switch terminal to ground.
c. Caution Notes:
1. Use only with insulated (ungrounded) field alternators.
2. Regulator base must have a good ground connection.
3. Do not connect ground power to aircraft until voltage regulator "I" terminal has
been disconnected from electrical system.
4. Do not (even momentarily)
connect the two voltage regulator terminals
together.
5. Do not connect battery into system with polarity reversed.
6. Do not force the voltage adjustment screw.
7. This is a sealed unit and not repairable. Replace with a new unit.
11-51. 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 11-36. 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.
Reissued: 10/12/79
ELECTRICAL SYSTEM
4C11