Sony PS-LX22 - Service and Safety Procedures; Safety Check-Out and Leakage Test; System Block Diagram

Ps-Lx2
2lB/C/(A)/B(A)
i
I
n
SAFETY
CHECK.OUT
(US
Mode!)
After
correcting the original service
problem,
perform
the
following
safety check
before releasing
the
set
to
the customer:
Check
the antenna
terminals,
metal
titn,"metaT)ized"
knobs, screws, aad 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
(500
microampers).
Leakage
current
can
be measured
by
any
one of three
methods.
A
commercial leakage tester,
such
as
the
Simpson
229
or RCA WT-540A. Follow
the
manufacturers'
instructions to
use
these
instru-
ments.
A
battery-operated AC milliammeter. The Data
Precision
245 digltal
multimeter
is suitable for
this
job.
RVl05
MAIN
3. Measuring
the
voltage
drop
4cross
a resistor
by
means
of a
VOM
or battery-operated
AC
volt-
meter.
The
"limit" indication
is
0.75V,
so
analog
meters
rnust 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 2Y
AC range
are
suitable.
(See
Fig.
A)
To Exposed Metal
Parts
on Set
O.l 5
ttF
AC
voltmeter
0.75v)
Fig.
A. Using
an AC voltmeter to check AC
leakage.
l.
2.
/1
l
I
SECTION
1
OUTLINE
1-1. BLOCK DIAGRAM
RVtOI
GAII{
RVIOS
OFFSET
B+
(
l0.5vt
a,l
BSL_MOTOR
STATOR
,-,
-l
(,
IlPEEnl
RV I07
45rpn
ilig--J"-*,,
a
CARTRIDGE
-3-
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