TM-9-2320-280-34
TRUCK, UTILITY: M998 SERIES
TECHNICAL MANUAL; DIRECT SUPPORT AND GENERAL SUPPORT MAINTENANCE
JANUARY 1996
TM-9-2320-280-34 - Page 341 of 1258
TM 9-2320-280-34
6 - 1 8 . 3 6
Change 1
c. Static Testing
d. Cleaning
6±-±3±
.±3±
. 100 AMPERE DUAL VOLTAGE ALT±E±R±N±ATOR (12447109) TESTING AND REPAIR (Cont'd)
NOT E
Refer to disassembly for component removal, if necessary.
1.
Perform Stator Test:
(a) Remove six nuts and phase leads from diodes in front housing.
(b) Set multimeter to XI scale and zero multimeter.
(c) Connect multimeter leads between each successive pair of stator phase leads P1-P2, P2-P3, and
P1-P3. Multimeter should read less than 1 ohm. If multimeter reads infinity (
∞
), the stator is
open; replace alternator.
(d) Set multimeter to X10 scale and zero multimeter.
(e) Connect multimeter leads between each phase lead, P1, P2, and P3 and the ground terminal on
outside of front housing. Multimeter should read infinity (
∞
). If multimeter reads zero, the stator
is grounded; replace alternator.
(f) Repeat step (e) to check phase leads P4, P5, and P6.
2.
Perform Field Coil Test:
(a) Remove two nuts and field coil leads (F+, F-) from diodes in front housing.
(b) Set multimeter to XI scale and zero multimeter.
(c) Connect multimeter leads to the two field leads and measure the resistance. Multimeter should
read less than 3 ohms. If multimeter reads more than 3 ohms, the field coil is open; replace
alternator.
(d) Set multimeter to X10K scale and zero multimeter.
(e) Connect one multimeter lead to a field lead and the other to the ground stud on front housing.
Multimeter should read infinity (
∞
). If multimeter reads less than 100K ohms, the field coil is
grounded. Replace alternator.
3.
Perform Positive Diode Test:
(a) Set multimeter to X100 scale and zero multimeter.
(b) Connect one ohmmeter lead to the B+ output stud and the other lead to each of the six diode
terminals S. Multimeter should read either less than 600 ohms or infinity (
∞
) for all six diode
terminals. Reverse multimeter leads. Multimeter should read nearly alike for all six, but
opposite the first set of readings. If readings are not opposite, the diode rectifier assembly is
open. Replace alternator.
4.
Perform Negative Diode Test:
(a) Set multimeter to X100 scale and zero multimeter.
(b) Connect one multimeter lead to the ground terminal and the other lead to each of the six diode
terminals S. Multimeter should read either less than 600 ohms or infinity (
∞
) for all six diode
terminals. Reverse multimeter leads. Multimeter should read nearly alike for all six, but
opposite the first set of readings. If readings are not opposite, the diode rectifier assembly is
open. Replace alternator.
Clean all alternator components in accordance with para. 2-13.
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