TM 55-1930-209-14&P-21
(10) Remove two remaining screws and remove brush holder and regulator.
WARNING
Notice two insulators located over top of brush clips. These two screws have special insulating
sleeves over screw body above threads. Third mounting screw may or may not have an insulating
sleeve. If not, this screw must NOT be interchanged with either one of other two screws. A
ground may result. This would cause no output or uncontrolled alternator output. Regulators
may vary in appearance, but are interchangeable in these alternators.
(11) Remove rectifier and capacitor as necessary.
(12) Remove three retainer plate screws and lockwashers and ball bearing retainer plate from driven end
frame. Press ball bearing grease slinger from driven end frame.
(13) Press slip ring end grease cup and bearing and lip grease seal out of frame, from the outside inward.
5-26 Alternator and voltage regulator inspection and repair
a.
Rotor Field Winding. Check for open circuit by connecting an ohmmeter between slip rings. Infinite
resistance requires replacement of rotor. Use ohmmeter to check for grounded winding by connecting between slip rings
and shaft. Check for high-or-low-resistance of winding (burnout or shorted turns) by noting resistance reading, and
compare it with specification values in this manual.
b.
Diode Trio. Connect a 1 1/2-volt ohmmeter, set on lowest range, between single connector and one of three
other connectors. Note reading, then reverse ohmmeter connections and again note reading. If both readings are same,
replace diode. Repeat this step for each of other two connectors of trio, using same criteria.
NOTE
The rectifier bridge has a grounded heat sink and an insulated heat sink connected to output
terminal.
c.
Rectifier Bridge. Connect a low-voltage ohmmeter between ungrounded heat sink and one of three
terminals. Perform same tests to same criteria as in preceding (diode trio) check.
d.
Stator. Connect a low-voltage ohmmeter successively between pairs of stator leads. If any of three readings
are high, windings are open. Then take reading between any stator lead and frame; a low reading means winding is
grounded.
e.
Voltage Regulator. Special test equipment must be used to determine if a regulator is defective.
5-22
