Heathkit IM-16 - Page 41

MAINTENANCE
METER
Because
of
the
delicate
nature
of
the
meter
movement,
no attempt
should
be made
to
repair
the
meter.
Such
attempts
would
automatically
void the
standard warranty
coverage
of
the
meter
itself.
ELECTROSTATIC
CHARGE
The
clear
plastic
meter
cover has
been treated
to resist
an
accumulation
of static
electricity.
However,
should
a
static charge
accumulate
through
repeated
polishing
or cleaning
of
the
meter
cover, the
pointer
will deflect
in an
er-
ratic
manner,
regardless
of
whether
the
instru-
ment
is turned
off or
on.
This
condition
can be
corrected
quickly.
Apply
a
small
quantity
of
liquid dishwashing
detergent
to
a
clean,
soft
cloth and
wipe
the
surface
of
the
meter
coverc
The
accumulated
electrostatic
charge will
im-
mediately
disappear"
It is
not necessary
to
re-
move the
cover for this
correction.
AgCESSORY
CHECKING
METER
COIL
CONTINUITY
If
you
suspect
the meter
coil has
failed,
you
can
check the
continuity
of the
coil with
another
ohm-
meter
as
follows.
(NOTE:
Never
check
the
con-
ti.nuity
of
the
meter
coil directly
with another
ohmmeter. The
amount
of curient
that
would
be
drawn
could seriously
overload and
probably
ruin
the
meter
coil.)
Always
use a limiting
resistor
with a
value
of
at
least 10,000
Q in
series with
the
other
ohmmeter test
leads. The
value
of the
resistor will
depend
upon the
ohmmeter battery
voltage and
the
range
on
which the
ohmmeter is
being used. NOTE:
If
aHeathModelIM-25Solid-
State Voltmeter
is available,
it
can be used to
check
the
meter
coil directly
because
of
the
low
voltage and
current used.
TEST
LEADS
Because
of
their
constant
flexing
duringuse,
the
test
leads are
not
above
suspicion,
especially
after
the
Voltmeter
has
been
in use
for
several
year,sr
Erratic
or
improper
DC
voltage
measure-
ments
can
sometimes
be
caused
by afaultin the
shielded test
lead
orphoneplugor
inthe
connec-
tions
in the
test
probe.
PROBES
HIGH
VOLTAGE
TEST
PROBH
A
high
voltage
test
probe
is available
from
the
Heath
Company.
This
probewillpermittheVolt-
meter
to
measure
DC
up to
30,000 volts,
which
covers the
range
of
flyback power
supply
voltages
commonly
encountered
in
TV
receivers.
This
probe
consists
of
a
red
molded
housing
with
a
black molded
handle" It
contains a
2/6
precision
1090 megohm
resistor
and
provides
a
DC
range
multiplication
factor
of 100
for
ll megohminput
voltmeters"
The
Heath
Company
reserves
the
rightto
discon-
tinue
instruments
and
to
change
specifications
at
any
time
without
incurring
any
obligation to
RF
TEST PROBE
An
RF
test
probe
is available
from the
Heath
Company"
This probe
will
permit
the
Voltmeter
to
be used
for
RF measurements
up to
30 volts;
its response
is substantially
flatfrom
1000 Hzto
100
MHz.
A
built-in
isolating
capacitor
permits
a
DC
voltage
range
of up
to
500 volts. It
uses a
printed
circuit
board
for easy assembly
and its
housing
is
of
polishedaluminum
withpolystyrene
insulation"
incorporate
newfeatures
in instruments
pre-
viously
sold"