Piper PA-32R-301T SARATOGA S, Maintenance Manual

Page: 220 / 956

D.C. GENERATION (cont.)
(b) Inspection and Testing of Components (cont.)
3 Stator: The stator can be tested for open or grounded windings with a 12-volt test bulb,
described in the rectifier section, or an ohmmeter, in the following manner. Separate
the stator from the slip ring end head just far enough to insert a fold of rags or blocks of
wood. In other words, insulate the stator from the end head. To test for grounded windings,
touch one test bulb or ohmmeter probe to the auxiliary terminal or any stator lead, and
the other test bulb or ohmmeter probe to the stator frame. If the test bulb lights, or the
ohmmeter indicates continuity, the stator is grounded. To test for open windings, connect
one test probe to the auxiliary terminal or the stator winding center connection and touch
each of the three stator leads. The test bulb must light, or the ohmmeter must show
continuity. Due to the low resistance in the stator windings, shorted windings are almost
impossible to locate. However, shorted stator windings will usually cause the alternator
to “growl” or be noisy during operation and will usually show some signs of overheating.
If all other electrical checks are normal and alternator fails to supply its rated output,
the stator should be replaced to determine whether or not it is the faulty component.
4 Bearings and Seals: Whenever the alternator is overhauled, new bearings and oil or
grease seals are recommended, even though the bearings and seals appear to be in good
condition. A faulty seal can cause an alternator to fail within a very short period of time.
(c) Assembly of Alternator
1 Press the ball bearing into the drive end head using a flat block approximately two inch
square so that the pressure is exerted on the outer race of the bearing. Install the retainer
plate. With the snap ring and retainer cup in place on the rotor shaft, use a tool that fits
over the shaft and against the inner bearing race, and press until the inner bearing race is
against the snap ring retainer cup. (Refer to Figure 11.)
— CAUTION —
Use an arbor press, do not hammer. Connect stator leads to the
rectifiers. When soldering these connections, use pliers as a
heat dam on lead between solder joint and rectifier. Too much
heat will damage rectifiers.
2 Carefully install the rectifiers in the slip ring end head or rectifier mounting plate by
supporting the unit and using the special tools illustrated in Figure 12.
3 Reassemble the rectifier mounting plate studs and insulators, making sure they are in the
correct order. (Refer to Figure 13.)
4 After the slip ring end head is completely assembled, the stator and rectifier leads must
be secured to the rectifier mounting plate with epoxy. Make sure the stator leads are
positioned so that they do not interfere with the rotor.
PIPER AIRCRAFT
PA-32-R-301/301T
MAINTENANCE MANUAL
24-30-00
Page 24-15
Reissued: July 1, 1993
1K15