Sony PVM-9L2 Service Manual page 97

T
i
SAFETY CHECK-OUT
After correcting the
original
service problem,
perform the
following safety
checks
before
releasing the set
to
the
customer
:
Check
the
metal
trim,
"metallized"
knobs, screws,
and
all
other
exposed
metal parts
for
AC
leakage.
Check
leakage as described below.
LEAKAGE
TEST
The
AC
leakage from any exposed
metal
part to
earth
ground and from
all
exposed
metal parts
to
any exposed
metal part having
a
return to
chassis,
must
not
exceed
0.5
mA. Leakage
current
can be
measured
by any
one
of three
methods.
1
.
A
commercial leakage
tester,
such
as the
Simpson 229
or
RCA
WT-540A.
Follow the
manufacturers'
instructions to
use
these
instruments.
2.
A
battery-operated
AC
milliammeter.
The
Data
Precision
245
digital
multimeter
is
suitable
for this job.
3.
Measuring
the voltage
drop across a
resistor
by
means
of
a
VOM
or battery-operated
AC
voltmeter.
The
"limit"
indication
is
0.75
V,
so
analog meters
must have an
accurate
low-
voltage
scale.
The Simpson 250 and
Sanwa
SH-63Trd
are
examples
of
a
passive
VOM
that
is
suitable.
Nearly
all
battery
operated
digital
multimeters that
have a 2
V AC
range
are
suitable.
(See
Fig.
A)
To
Exposed
Metal
Parts on Set
Earth
Ground
AC
voltmeter
(0.75V)
Fig A.
Using an
AC
voltmeter
to
check
AC
leakage.
PVM-9I-2