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Electrical
ALTERNATOR
Precautumay
Service NotllS
The
following
precautions should be taken when serviCing
IS
carned
out
on
vehIcles wIth alternator
charging
systems
1
Reversed
battery
connections
will
damage
the
dIode
rectifIers
Ensure
that the
battery
negatIve
terminal
IS
connected
to
earth
2
Never
earth
the
main
alternator
cable
when
It
IS
disconnected
at
the alternator If thiS cable
IS
earthed With
the
IgnitIon
SWItched
on
the
voltage regulator
and the
assocIated wlrtng may be
damaged
3
Earthing
the
main
cable
or
the terminal of the alternator
WIll
damage
the alternator and
or
the alternator
CIrcUIt
even
when the
IgnitIon
SWItch
IS
SWItched off
Since
no
CirCUIt
breakers
are
used
4
Do
not
run
the alternator WIth the
battery
dIsconnected
and the field
WindIngs
energlsed
otherwIse the control
u
nit
WIll be
damaged
5
Do
not
attempt
to
polartse
the
alternator
It
IS
not
necessary
Any
attempt
to
do
so
may result
In
damage
to
the alternator
regulator
or
associated
CirCUItS
6
DIsconnect
the
battery
cables
before
uSIng
a
battery
charger
to
prevent damage
to
the rectIfIer diodes A boost
charger
to assIst
starting
the engine
cannot
be used WIthout
first
dIsconnectIng
the control
unit
voltage regulator
The
control
Unit
can
be
Isolated
by
disconnecting
the
connecting
wire
to
the alternator
7
Never
use
an
ohmmeter
of
the type
Incorporating
a
hand l r tven
generator
for
checking
the dIode rectIfIers
or
transIstor
8
Belt
tensIOn
to
aVOid
bearing damage
when
adJustIng
belt
tenSion
apply leverage
only
on
the alternator drtve end
bracket
not
on
any other part of the alternator
9
If
arc
welding
IS
carried
out on
the
car
disconnect the
alternator and control
Unit to
prevent
pOSSIble
damage
It
IS
also
Important
to
Inform any
welding speclahst
of thIS
fact
as
It
IS
poSSIble
that he Will
not
know that thIS
car
IS
fItted With
an
alternator
chargrng
system
10
The
battery
must
never
be connected
or
dIsconnected
while the engine
IS
running
or
damage
may
occur
to the
regulator
seml
conduct o r
devIces
ALTERNATOR
Removal
Disconnect the
battery
earth cable and dIsconnect the
Wires
from
the
alternator
Remove the bolt securtng the fan belt
tensIoning
strut
ana
hft away
the
fan
belt
Remove the
alternator
retaIning
bolts
and
lift the alternator from the
mounting
bracket
ALTERNATOR
Dlsmanthng
Fig
M l
Remove
the
through
bolts and
remove
the
diode
end
hOUSing
from the drive
end
housing by
tapping
the front bracket
hghtly
Equipment
with
a
hammer
The
parts separate
as
shown
In
Fig
M 2
Hold
the drIVe end
rotor
carefully
In a
VIce
and
remove
the
pulley
nut
the
pulley
the fan
arid
tha spacer from the rotor shaft
Fig
M 3
and
M 4
Tap
out
the rotor from the drive
end
bracket
uSing
a
hide mallet
F Ig M 5
Remove the
beartng
retainer
and press
out
the
beartng
from the
beartng
hOUSing
The
bearing
from the
rotor
IS
removed
by
means
of
a
two
arm
puller
of conventlonal
deSign FIg
M 6
Remove the
stator
from the dIode end
hOUSing by
unsoldering
3
negatIVe
diodes black
fIgures
for
negative
diodes red
fIgures
for
pOSitIve
dIodes
In
FIg
M6
from the cOIl lead
WIres
but take
care not to
overheat the diodes
as
thIS WIll lead
to
Irrepalrable
damage
Then
unscrew
and
remove
the
brush
cover
and
unsolder the
N
termlnai
as
shown
In
Fig
M 8
Lift
ff the
stator
Remove the heat Sink and the brush holder from the
rear cover
as
shown
In
Fig
M 9
Dismantle the brush holder and unsolder
the lead
wires
F
black whIte
and
E
black
and also the
brush holder
wires
A dIsmantled
View can
be
seen
In
Fig
M l0
If the diodes need
replaCIng
they
should be
pressed
out of the
heat Sink and
replaced
USing
a
SUItable press tool Do
not
drtve
out
the
damaged
dIode
as
the other stIli
servIceable
dIodes may
be
damaged through
the
Impact
and shock
ALTERNATOR
Inspection
Rotor
USing
an
ohmmeter
check the
rotor
COIl for open
or
short
CirCUItS
Connect the
Instrument to
the
shp
rings of the
rotor
and check the indicatIon
on
the ohmmeter No
reading
indicates
a
dIsconnected field
co
When the
readIng
IS
approx
447
ohms
at
room
temperature
the connectIon
IS In
order
Next
cbeck
the
rotor
between
shp
rtng and
rotor core
If there
IS
a
readIng
on
the ohmmeter
the
rotor
assembly
should be
replaced
as
In
thiS
case
the fIeld COIl
or
the
shp
nng
must
be
connected
to
earth
FIg
M 11 shows the
testIng
of the fIeld coil
for
conductIVIty top
and for earth
connectIon
bottom
If
there
IS
a
short
or
open
CirCUIt
then the
rotor
should be
replaced
Check the
rotor
for
concentnclty
Fig
M 12
by clamping
the
rotor
between the centres of
a
lathe and
placing
a
dIal gauge
at
the
outer
diameter of the
rotor
If the
eccentricIty
exceeds 0 10
mm
0004
In
replace
the
rotor
Stator
Check
the stator for
conductIVity
uSing
a CIrcuit
tester
by
connectUlg
the lead
N
yellow
to the neutral
wire
of
the
stator
The connections
are In
order
If there
IS
COndUCtiVity
If
any of the other leads
IS
connected
to
the other Side of the
tester
If thiS
IS not
the
case
replace
the stator There should be
an
open CircUit conditIon between the
stator
body
and any of
the cOIl leads
Fig
M 13
M 14
Diode
Assembly
Good
or
defectIVe
diodes
are
claSSifIed
by
the resistance value
between
the
diode holder
heat SInk
and the diode
leads
To
perform
thIS test
remove
the diode holder from the stator
f11
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