Piper Arrow IV Turbo Maintenance Manual page 209

TESTING OF ROTOR.
1. Check for a "grounded" field coil by connecting an ohmmeter from each slip ring to the rotor shaft.
The ohmmeter should read infinite. If the reading is zero or higher, the rotor is grounded.
2. To check for an "open" field coil, connect an ohmmeter to the slip rings.
A. The ohmmeter should read between l.5 and 2.0 ohms on rotor coils at room ambient conditions.
B. The ohmmeter should read between 2.5 and 3.0 ohms on rotor coils that have been operated on the
aircraft at higher engine compartment temperatures.
C. Readings above 3.5 ohms indicate high resistance rotor coils and further testing or replacement may be
required.
3. To check for a "shorted" field coil, connect an ohmmeter to the two slip rings. If the reading is below
1.5 ohms, the field coil is shorted.
SLIP RINGS.
The slip rings are considered to be part of the rotor assembly and are not serviced as a separate item.
ASSEMBLY OF ALTERNATOR.
1. Position the grease retainer on the rotor shaft and press retainer on shaft with installer tool C-3921.
The plastic retainer is properly positioned when the inner bore of the installer tool bottoms on the rotor shaft.
(Refer to Figure 24-18.)
Figure 24-16. Testing Rotor for Ground
EFFECTIVITY:
CHRYSLER ALTERNATOR
PIPER AIRCRAFT
PA-28RT-201 / 201T
MAINTENANCE MANUAL
Figure 24-17. Testing Rotor for Opens or Shorts
1I17
24-32-14
Page 24-22
Revised: July 13, 1983