TM 5-3895-359-14&P
successively connected between each pair of stator
Rectifier Bridge Check
leads, the windings are open (Fig. 12).
Note that the rectifier bridge has a grounded heat sink
and an insulated heat sink connected to the output
terminal.
To check the rectifier bridge, connect the ohmmeter to
the grounded heat sink and one of the three terminals
Fig. 12 - Testing Stator.
NOTE
Ohmmeter or test light checks for opens can
be made only on "Y" stators, visually
identified by three stator leads crimped
together.
Fig. 11 - Testing Rectifier Bridge.
Delta windings cannot be checked for opens with an
IMPORTANT
ohmmeter or test light. Usually laboratory equipment is
Connect ohmmeter pressing down very
required to check Delta windings.
A short circuit in the stator windings is difficult to locate
firmly onto flat metal connector, then
without laboratory test equipment due to the low
reverse the lead connections to the
resistance of the windings.
However, if all other
grounded heat sink and same terminal. If
electrical checks are normal and the generator fails to
both readings are the same, replace the
supply rated output, a shorted stator winding or an open
rectifier bridge. A good rectifier bridge will
Delta winding is indicated. Also, a shorted stator can
give one high and one low reading. Repeat
cause the indicator lamp to be on with the engine at low
this same test between the grounded heat
speed. Check the regulator in next section before
sink and the other two terminals, and
replacing stator.
between the insulated heat sink and each of
the three terminals. This makes a total of six
Brush Holder and Regulator Replacement
checks, with two readings taken for each
check.
To determine if the regulator is defective, an
approved regulator tester must be used.
The ohmmeter check of the rectifier bridge, and of the
diode trio as previously covered, is a valid and accurate
After removing the three attaching nuts, the stator, and
check. DO NOT replace either unit unless at least one
diode trio screw (Fig. 11), the brush holder and
pair of readings is the same.
regulator may be replaced by removing the two
CAUTION
remaining screws. Note the two insulators located over
Do not use high voltage to check
the top of the brush clips in Fig. 9, and that these two
these units, such as a 110-volt test
screws have special insulating sleeves over the screw
lamp.
body above the threads. The third mounting screw may
To replace the rectifier bridge, remove the attaching
or may not have an insulating sleeve. If not, this screw
screws and disconnect the capacitor lead.
must not be interchanged with either one of the other
Stator Check
two screws, as a ground may result, causing no output
The stator windings may be checked with a 110-volt test
or uncontrolled generator output. Regulators may vary in
lamp or an ohmmeter. If the lamp lights, or if the meter
appearance but are completely interchangeable in these
reading is low when connected from any stator lead to
generators.
the frame, the windings are grounded. If the lamp fails
to light, or if the meter reading is high when
10-8-7
