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SAFETY RELATE
Components
identified
by shading
and
/A\ marked
on the
schematic diagrams and parts list are critical to safe operation.
Replace these components with SONY
parts whose part num-
bers appear as shown
in this manual
or in supplements pub-
lished by SONY.
SAFETY
CHECK-OUT
After correcting the original service problem, perform
the following safety checks before releasing the set.
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 ex-
posed metal part having a return to chassis, must not
exceed
0.5 mA
(500 microampers).
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 instru-
ments.
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 volt-
meter.
The
"limit"
indication
is 0.75V,
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
2V
AC
range
are
suitable.
(See Fig. A)
To Exposed Metal
Parts on Set
|
AC
0.15 uF
1.5k2
voltmeter
(0.75V)
+
Earth Ground
Fig. A.
Using an AC voltmeter to check AC leakage.
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