MG MGB User Manual

THE
ELECTRICAL
SYSTEM
N
relay
contacts
close
and permit
current
to
■ow
to
the
lamps.
When
the
switch
is
opened the relay
contacts
open
and
interrupt
the
circuit.
Starter
motor
relay (Car Number
prefix
GHNS
and GHDS
cars)
The
non-adjustable relay
is
mounted
next to
the
four-way
fuse block.
Removing
Disconnect
the battery.
Remove
the electrical
connections
and
securing
screws.
Remove
the
relay.
Section
N .15
HORN
Removing
the
horn
Disconnect
the
electrical connections,
remove
the
screws
and
washers
securing
the horn
to
the bonnet
lock
platform
or
from the
wing
valance
and
withdraw
the horn.
Maintenance
If the horn
fails
to
operate,
or
operates
unsatisfactorily,
■rst
carry
out
the following
external
checks.
Check
the
current
consumption,
which
should
be
3
to
31/2
amps.
when
the horn
is
operating
correctly.
After making
a
thorough
external
check
remove
the horn
cover
and
examine
the
cable
connections
inside the
horn.
Examine
the
contact
breaker
contacts.
If they
are
burnt
or
blackened
clean them
with
a
fine
file, then
wipe
with
a
petrol-moistened
cloth.
Adjusting
Withdraw
the
cover
securing
screw
and
remove
the
cover
and
its
retaining
strap.
Slacken
the
locking
nut
on
the
■xed
contact
stem
and
rotate
the adjusting
nut
clockwise
until the
contacts
just
separate
(indicated by
the horn
failing
to
sound
when the
horn-push
is
operated).
Rotate
the adjusting
nut
one
Aaoezw
Fig. N.
18
The location
of the panel and
warning lights
MGB.
Issue6.
82448
Fig.
N.19
A
rear
number-plate lamp (early cars)
half-turn
in
the
opposite
direction
and
secure
it in
this
position
with
the
locknut.
Refit the
cover
and
strap.
Section N.16
FLASHER UNIT
Description
The
unit is
contained
in
a
small
cylindrical metal
container,
one
end of which
is
rolled
over
onto
an
insulated plate
carrying
the mechanism and three terminals.
The
unit
depends for
its operation
on
the
linear
expansion
of
a
length
of
wire
which becomes heated by
an
electric
current
■owing through
it.
This
actuating wire
controls the
movement
of
a
spring-loaded
armature
attached
to
a
central
steel
core
and
carrying
a
moving
contact—the
sequence
of
operation
being
as
follows.
When
the
direction indicator switch
is
turned
either
to
the
left
or
right,
current
■ows through the
actuating
wire,
ballast
resistor,
and
coil wound
on
[the central
core
and
hence
to
earth
via
the ■asher lamp filaments. This
current
is
limited by
the
ballast
resistor
to
a
value which will
ensure
that the
■asher
lamp
■laments
do
not
light
at
this
stage.
The
actuating wire increases
in
length under the heating
in■uence
of
the
current
and
allows
the
annature to
move
inwards
to
its
alternative
position,
thereby closing
a
pair
of
contacts
in
the supply
circuit
to
the
■asher
lamps
and
at
the
same
time
short-circuiting the
actuating wire.
The
increased electromagnetic
attraction
of
the
armature
to
the
core,
due
to
the
full lamp
current
now
■owing through
the
coils,
serves
to
hold the closed
contacts
■rmly
together.
At
the
same
time
a
secondary
spring-loaded
armature
is
attracted
to
the
core
and closes
a
pilot warning
lamp circuit
so
that
now
both ■asher lamps
and
warning
lamp
are
illuminated.
Since, however, heating
current
no
longer
■ows
through the
short-circuited
actuating wire,
the
latter
cools and
consequently
contracts
in
length. The
main
armature
is
therefore pulled
away
from the
core,
the
contacts
opened,
N.21

MG MGB Specifications

General

Brand	MG
Model	MGB
Category	Automobile
Language	English