Mando Alternator Service - Westerbeke 11.5KW-60Hz Service Manual

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MANDO ALTERNATOR SERVICE
TESTING THE EXCITER LEAD
5. If no reading is obtained, an open exists in the
alternator-excitation.1ead or in the excitation circuit of
the regulator. Disconnect the lead from exc tenninal R.
Connect the positive voltmeter lead to the excitation
lead and the negative voltmeter lead to ground terminal
E. If the voltmeter now indicates an approximate battery
voltage, the voltage regulator is defective and must be
replaced. If no voltage is indicated, check the excitation
circuit for loose or dirty connections or damaged wiring.
TEST VOLTAGE REGULATOR
Perfonn this test to determine if the voltage regulator is
operating correctly, using a 0 - 20 volt DC voltmeter.
NOTE:
The battery must be fully charged to obtain a proper
voltage reading in this test.
If
necessary, charge the battery
with a battery chargeror allow the engine to run a sufficient
length of time to fully charge the battery before taking a
reading.
1. Connect the positive
(+)
voltmeter lead to the positive
battery terminal and the negative (-) voltmeter lead to
the negative tenninal.
2. Start the engine and run it at fast idle until the engine
reaches its nonnal operating temperature. Adjust the
engine speed to 1500 - 2000 rpm and observe the
voltmeter for the highest reading. The reading should
be between 13.7 and 14.7 volts.
3. If the reading is high, check for a loose or dirty
alternator ground lead connection. If the connection is
good, the voltage regulator is faulty and must be
replaced. Be sure to disconnect the battery cables before
attempting to remove the alternator.
4. If the reading is low:
a. Stop the engine and remove the alternatot wiring
connections.
b. Remove the Phillips cover screw from the regulator
cover (see illustration).
c. Remove the nut from the output terminal and the
nut from the sensing terminal, and remove Jumper
(A).
d. Remove another nut from the sensing tenninal, and
the nut from the excitation terminal.
e. Remove the regulator cover.
f. Temporarily re-install Jumper (A) and all associated
nuts. Leave Jumper (B) installed.
g. Remove the plastic plug from the side of the
regulator.
h. Connect a jumper betweeu the top brush lead
and the ground.
JUMPER A
COVER
SENSING
TERMINAL
,r-__
OUTPUT
TERMINAL
GROUND
\
\ \
\
CONNECT ...
JUMPER WIRE \
\
\
REGULATOR
PLASTIC PLUG
i. Repeat stepS 1 and 2.
B
LEAO
FROM BRUSH
NOTE:
Do not let the voltage exceed
16
volts.
j. If a voltmeter reading of 14.5 volts or above is
now obtained, the voltage regulator is faulty and
must be replaced. If the voltmeter reading is below
14.5 volts, inspect the brushes and slip rings for
wear, dirt or damage. If the brushes and slip rings
are good, the alternator is fault internally.
Disassemble the alternator and test the components,
as outlined in this section.
Engines
&
Generators
. 65