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PVM-3230
RM-785
SAFETY CHECK-OUT
{US
Model only)
After
correcting
the original service problem,
LEAKAGE TEST
perform
the following safety checks before
releasing
the
set
to
the customer:
1
.
Check the area of your
repair
for
unsoldered
or
poorly-soldered
connections.
Check the entire
board
surface for solder splashes and
bridges
.
2.
Check
the
interboard
wiring
to
ensure
that
no
wires are "pinched"
or contact high-wattage
resistors
.
3.
Check that all control knobs, shields,
covers,
ground
straps,
and
mounting
hardware
have
been replaced.
Be
abso
lut
ely certain
that
you
have replaced
all
the insulators
.
4.
Look
for unauthorized
replacement
parts,
par-
ticularly
transistors,
that wer
e
install
ed
during
a
previous
repair.
Point
them out
to th
e customer
and recommend
their
replacement.
5.
Loo
k
for
part
s
which, though
fun
ctio
ning
,
show
obvious signs of deterioration.
Poi
nt them out
to
the customer and
recommend their replace-
ment.
6.
Check the line cord for cracks and abrasion.
Recommend
the
replacement
of
any suc
h
line
cord
to the
custome
r.
7.
Check
the
co
ndition
of the monopole antenna
(if any).
Make
sure
the
end is
not
broken off,
and
has
the
plastic
cap on
it. Point
out
the
danger
of
impalement
on
customer,
and
replacement.
a
broken
antenna
to
the
recommend
the
antenna's
8.
Check
the B+
and
HV
to
see they are at
the
values specified.
Make
sure your instruments
are accurate;
be suspicious of your
HV
meter
if
sets
alway
s
h
ave low
HV
.
9.
Check
the
antenna
terminals
,
metal
trim,
"metallized"
knobs
,
screws,
and
all other
ex
posed metal parts
for
AC leakage.
Check
leakage as
described
below.
0
.15µ
F
To Exposed
Metal
Parts on
Set
1.5k
n.
-=-
Earth
Ground
AC
voltmeter
(0.
15V)
Fig.
A.
Using an AC
voltmeter
to
check
AC
leakage.
-
4
-
The
AC
leakage
from any exposed
m
eta
l
part to
earth ground and
from
all exposed
metal parts to
any
exposed
metal part having
a
return
to
ch
assis,
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
th
e
Simp
son 229 or
RCA WT-540A
.
Follow the
manufacturers
'
instructions
to use
th
ese
instru-
ments.
2.
A
battery-operated
AC milliammeter.
The Data
Precision
245
digital mu.ltimeter
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 .75
V
,
so
analog
meters
must
have
an accurate
lo
w-
voltage scale
.
The Simpson 250 and Sanwa
SH-63Trd are examp les of a
passive VOM
t
hat
is suitable.
Nearly
all battery operated
digital
multimeters
that
have a
2
V AC range
are
suitable
.
(See
Fig. A)
HOW TO FIND A GOOD EARTH GROUND
A
co
ld-water
pipe is guaranteed
eart
h
groun
d
;
the
cover-plate retaining
screw on
most AC
outlet boxes
is
also at earth
ground
.
If the retaining
screw is to
be
used
as your earth-ground,
verify
that
it
is
at
ground
by measuring
the resistance between it and
a cold-
water
pipe with an ohmmeter.
The reading
shou
ld
be
zero ohms.
If
a
col
d-water pipe is not
accessible,
connect a 60
-
100 watts trouble light
(not a
neon
lamp}
between
the
h ot
side of
the receptacle
an
d the
reta
ining screw
.
Try both slots
,
if
necessary
,
to locate
the hot side
of the
line, the lamp should light at
normal brilliance
if
the
screw
is at ground potential.
(See
Fig. B)
Trouble L ight
·:
AC Outlet Box
Ohmmeter
Cold-water
Pipe
Fig.
B.
Checking for earth ground.
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