Westerbeke 8.0KW-60Hz Service Manual page 54

MANDO ALTERNATOR SERVICE
B~RING
DRIVER
FRONT
BEARING
BEARING LOCKING
SCREWS
FRONT BEARING
HOUSING
16. Remove the rectifier assembly by removing the Phillips
screw and lifting out the assembly.
RECTIFIER ASSEMBLY
RECTIFIER REMOVAL
CLEAN AND TEST ALTERNATOR COMPONENTS
1.
Inspect and test the brush/regulator assembly. The
brush set may be reused if the brushes are 114 in.
(6 mm) or longer. The brushes must not be oil soaked,
cracked or grooved.
Test for continuity between 1 and 2, and 3 and 4 using
a test lamp or an ohmmeter. These checks will indicate
a good brush/regulator assembly; replace the complete
assembly, if necessary.
TESTING BRUSH ASSEMBLY
2. Inspect and test the diode-trio assembly:
a. Using a commercial diode tester, a 12-volt DC test
lamp or an ohmmeter, check the resistance between
each' of the three diode terminals and the indicator
light stud.
light stud
DIODE TERMINAL
DIODE TRIO ASSEMBLY
b. Reverse the tester leads and repeat the resistance
checks.
c. A very low resistance should be indicated in one
direction and a very high resistance should be indi-
cated in the other direction if the diodes are normal.
d, If any diode appears to be defective, replace the
complete assembly. Do not attempt to replace an
individual diode.
3. Test the diode-rectifier bridge as follows:
a. Using a commercial diode tester, check for
continuity from each of three terminals to the
ouput terminal.
TERMINAL
OUTPUT
I
RECTIFIER
DIODES
b. Reverse "the tester leads and repeat Step a.
c. Continuity should exist in only one direction and
all diodes should check alike.
d. Perform the same continuity checks between the
three terminals and strap ground terminal. This
should show continuity in only one direction
through the diodes and all diodes should check
alike.
e. If any diode appears to be defective, replace the
rectifier assembly.
Engines
&
Generators
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