Piper COMANCHE PA-24-180 Service Manual page 547

PIPER COMANCHE SERVICE MANUAL
9-31. Regulator Checks And Adjustments.
ADJUSTING SCREW
TURN TO ADJUST SETTING)
9-32. Voltage Regulator. Two checks and
(TURN TO
adjustments are
required on the voltage regu-
lator, air gap and voltage setting.
a. Air Gap - To check air gap, push ar-
mature down until the contact points are just
touching and then measure air gap (Figure
9-5). Adjust by loosening the contact mounting
screws and raising or lowering contact bracket
as required. Be sure the points are lined up
and tighten screws after adjustment.
9-33. Voltage Setting. There are two ways
to check the voltage setting-the fixed re-
sistance method and the variable resistance
method (refer to figures 9-7 and 9-8).
FIGURE 9-6. ADJUSTING VOLTAGE Fixed Resistance Method-
REGULATOR SETTING
a. Connect a fixed resistance between
the battery terminal and ground as shown in
Figure 9-7 after disconnecting the battery lead from the battery terminal of the regulator. The re-
sistance must be 1 1/2 ohms for 12-volt units. It must be capable of carying 10 amperes without
any change of resistance with temperature changes.
b. Connect a voltmeter from regulator "BAT" terminal to ground.
c. Place the thermometer within 1/4 inch of regulato cover to measure regulator ambient tem-
perature.
d. Operate generator at specified speed for 15 minutes with regulator cover in place to bring
the voltage regulator to operatig temperature.
REGULATOR
REGULATOR
CONNECT TO
VARIABLE
GROUND
RESISTANCE
GEN
j
FIGURE 9-7. CHECKING VOLTAGE
CONNECT TO
GROUND
TO BATTERY
VOLTMETER GENERATOR RESISTANCE AMMETER VOLTMETER GENERATOR
FIGURE 9-7. CHECKING VOLTAGE
FIGURE 9-8. CHECKING VOLTAGE
SETTING, FIXED RESISTANCE METHOD
SETTING, VARIABLE RESISTANCE METHOD
ELECTRICAL SYSTEM
ISSUED: 8/18/72
3B1