ALTERNATORS
TESTING/TROUBLESHOOTING
TESTING
THE
EXCITATION
CIRCUIT
1. Connect
the
positive (+) multimeter probe
to
the
excit~tion
terminal R
on
the
alternator
and
the negative
(-) lead
to
ground.
2.
Turn the battery switch to the
on
position
and
note
the multimeter reading.
The
reading should be
1.3
to
2.5
volts
(see
illustration).
TESTING
THE
EXCiTATION
J~IRCUJT
(IGNITION
UIVl'-~il
3.
If
the reading is hetween
.75
and
1.1
volts,
the
rotor
field
circuit probably
is
shorted
or
wpunded.
4.
If
the reading
is
between
6.0
and 7.0 volts, the rotor
field
circuit probably
is
open.
.
5.
If
no reading is obtained,
an
open
eXists
in
the
alternator-excitation lead
or
in the excitation circuit of
the regulator. Disconnect
the
lead
from
exe.
terminal
R.
Connect the'positive multimeter probe
to
the
excitation
lead
and
the negative multimeter probe to ground.
If
the
multimeter
now
indicates
an
approximate battery
voltage, the voltage regulator is defective
and
must
be
replaced. If
no
voltageJs indicated, check the
excitation circuit for
loose
or
dirty connectlons or.
damaged
wiring.
TERMINAL
R
.
TESTING
THE
EXCITATION
CIRCUIT
(IGNITION
ON)
(+)
CHECKING
THE
SERVICE
BATTERY
Check
the
voltage
of the
service
battery.
lhis
battery
shOuld
have
.voltage between
13
and
14
volts
when
the
engine
is
running.
If
not,
there
is a
pro.b1em
in
the
service
battery
charging
circuit.
Troubleshoot.the
service
battery
eharging
circuit
·by
checking
the
wiring
and
connections,
the
solenoid,
isolator,
battery
switch,
and
the
battery
itself.
When
the
problem
has
been
solved
and
before
the
alternator
.
is
back
in
operation,
take
the
time
to
tighten·
and
clean
the
terminal
studs.
Also
clean
the
connecting
terminals
from
the
wiring
harness.
ALTERNATOR
REPAIR
If
tests
indicate a
failed
alternator,
it
will
need
to
be
disas-
sembled
and
repaired.
Any
good
alternator
service
shop
can
do
the
job.
NIiTE:
WESTERBEKE'S
service
Manual
has
detailed
instructions
for
the
disa"sembly
and
repair
of
their
staridard
alternators.
·
BATTERY
CARE
The
minimum
recommended
capacity
of
the
battery
used
in
·
the
engine's
12
volt
DC
control
circuit
is
600
- 900
C;old
Cranking
Amps
(CCA).
·
Review
the
manufacturer's
recommendations
lind
thel).
establish
a systematic
maintenance
schedule
for·yout
engine's starting batteries
and
house
batteries.
•
Mouitor
your voltmeter for
proper
charging
during
engine
operation.
•
Check
the
electrolyte
level
and
specific
gravity
with
a
hydrometer.
•
Use
ouly
distilled water
to
bring
electrolytes
to
a
proper
level.
•.
Make
certain that
battery
cable
connections
are
clean
and
tight
to
the
battery
posts
(and
to
your
engine).
•
Keep
your batteries
clean
and
free
of
corrosion.
A
CAUTION:
Before
starting
the
engine
make
certain
that
everyone
is
clear
of
moving
parts!
Keep
away
from
sheaves
and
belts
during
test
procedures.
A
CAUTION:
To
avoid
damage
to
the
battery
charging
circuit,
never
shut
off
the
engine
battery
switch
when
the
engine
Is
running!
~
WESTERBEICE
Engines & Generators
27
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