Table of Contents
Advertisement
Page 16
Motor spindle. The
motor spindle
turns in
a
ball race
indise
the motor
and
on a
bearing holder
und erneath on the
end plate. It
can
happen
that a film
of lubricating oil and, on the
bearing holder,
a
l
ayer
of aluminium oxide
which
protects
the bearing
holder
and
the
chassis from corrosion,
becomes
sufficiently
insulating
so
that the
spindle
is no longer
effectively earthed.
In this case
the
parasitic
in the
motor find another route
to
earth.
The
parasitics so passin
g
may
in truth be extremely
small but it
is possible
that
this may
happen. This
trouble can
be
diagnosed
when
it
is found that
the noise
disappears,
then the spindle
is earthed
by
touching the capstan
with
a
wire to earth.
In general,
it is sufficient to
eliminate
these
parasitics
by carefully
earthing
the end bearing holder
and
removing
the
oxide
on the seat
of
the screw holding the bearing holder, but in a
very
bad case a little
metallic brush
on the back
of
the
capstan
is
obviously
the
most certain method.
Advertisement
Table of Contents
