c. Touch one test lamp probe to one of the slip rings and remaining test probe to rotor shaft. Lamp
should not light. A lighted test lamp indicates a grounded rotor assembly and requires rotor
replacement. If test lamp does not light, a ground condition exists in insulated brush assembly.
Brush assembly has either been improperly assembled or was damaged and has short circuited to
ground. Inspect brush holder and insulated washer and replace if damaged.
d. The stack of parts attaching insulated brush holder assembly to end shield must always be installed
in sequence: Insulated brush holder, field terminal, insulating washer, lockwasher and attaching
screw.
INSPECTION
l. Inspect condition of alternator components. Pay special attention to slip rings. Check for indications of
burning, wear, or presence of oil.
2. Inspect brushes for signs of sticking in holder or shield and wear.
3. Inspect bearing surface of rotor shaft and roller bearings at rectifier end.
a. Rotate rotor in drive end shield to feel for roughness in bearing.
b. Inspect grease retainer, if so equipped.
c. Inspect rectifier leads at connections for good solder joint and condition of insulation.
d. Ensure that rectifier/stator lead is pushed down into slots which are cast in end shield and
cemented with MoPar cement number 22993l4.
TESTING OF RECTIFIER ASSEMBLIES
There are two methods of testing rectifiers. These are test lamp method and method using a Rectifier
Tester Tool No. C-3829. The rectifer tester tool method is preferred, as it provides a quick, simple and accurate
test of alternator rectifiers without necessity of disconnecting stator phase leads (figure 24-7), however, both
methods are described in this chapter.
—CAUTION—
The plastic cases surrounding rectifiers are for protection against
corrosion and must not be broken. When performing tests,
always touch test probe to metal strap nearest rectifier.
TESTING OF POSITIVE RECTIFIERS USING C-3829 TESTER (figure 24-5)
1. Place rectifier end shield and stator assembly on insulated surface.
2. Plug tester C-3829 power source lead into a 110-volt ac power supply.
3. Connect test lead alligator clip to alternator BAT terminal.
24 - 32 - 00
Page - 24 - 14
Reissued: August 1, 1986
1I13
PIPER AIRCRAFT
PA-28-236
MAINTENANCE MANUAL
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