Piper CHEROKEE WARRIOR PA-28-151 1995 Maintenance Manual page 426

PIPER CHEROKEE WARRIOR SERV I C E M A N U A L
2. Light Bulb Connections. (Refer to Figure 11-47.)
A. Connect one bulb lead to blue wire (field) at regulator harness connector or wire.
B. Connect other bulb lead to regulator ground wire (black).
3. In the regulation check procedure, increase voltage to regulator and monitor both the voltmeter
and bulb.
4. As the regulation point of a properly functioning control unit is approached, the bulb will blink
off and on. At regulation, the bulb will be ON continuously.
5. If regulator does not regulate to 28 Volts, it is out of calibration, and must be replaced.
c. If regulator checks good, check airplane for:
1. Poor or loose connections.
2. Poor ground on regulator housing.
3. Shorted alternator windings.
4. A grounded wire.
d. After completing test, connect regulator into circuit
11-63. OVERVOLTAGE RELAY
The PA-28-151, Warrior, s/n's 28-7415001 and up, and the PA-278-16, s/n' 28-7716001 through s/n's
28-8416028, were originally equipped with Wico overvoltage relays. These relays are no longer available, and
have been replaced by Lamar overvoltage relays. Refer to Piper's Alternator Control Service Replacement
Kit No. 764 928.
11-64. CHECKING WICO 14 VOLT OVERVOLTAGE RELAY (Refer to Figure 11-45)
To test the relay, use of a good quality, accurate voltmeter, with a scale of at least 20 volts and a
s u i table power supply, with an output of at least 20 volts. Sufficient batteries, with a voltage divider to regulate
voltage, may be used as a power supply. Connect the test equipment as follows:
a. B+ is connected to "BAT" terminal of the overvoltage control.
b. B- is connected to the frame of the overvoltage control.
c. Be sure both connections are secure and connected to a clean, bright surface.
d. Connect the positive lead of the voltmeter to the "BAT" terminal of the overvoltage control.
e. Connect the negative lead of the voltmeter to the frame of the overvoltage control.
f. The overvoltage control is set to operate between 16.2 to 17.3 volts. Increase power supply voltage
until an audible click is heard when the relay operates.
g. If the relay does not operate between 16.2 to 17.3 volts the overvoltage relay is out of specification
and must be replaced.
11-65. REMOVAL OF WICO 14 VOLT OVERVOLTAGE RELAY.
a. The overvoltage relay is located on the left side of the airplane just below the instrument panel.
Gain access from beneath the instrument panel
b. Remove the two electrical leads attached with screws.
Ensure that the master switch is off before performing any
work on the overvoltage relay.
Revised: February 28, 1995
NOTE
2F19
Island Enterprises
ELECTRICAL SYSTEM