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SAFETY
PRECAUTIONS
1. Before
returning
an instrument
to the customer,
always
make a safety check of the entire instrument,
including
but not limited to tl-te following
items.
a. Be sure
that
no
built-in
protective
devices
are
defective
and/or
have been deleted
during
servicing.
(1) Protective
shields
are provided
on this chassis to
protect
both
the
technician
and
the
customer.
Correctly
replace
all
missing
protective
shields,
including
any removed
for servicing
convenience.
(2)
When reinstalling
the chassis
and/or
other assembly
in the cabinet,
be sure
to put back
in place
all
protective
devices,
including
but not
limited
to,
nonmetallic
control
knobs,
insulating
fishpaper,
adjustment
and
compartment
covers/shields,
and
isolation
resistor/capacitor
networks.
Do not operate
this instrument
or permit
it to be operated
without
all
protective
devices
correctly
installed
and
functioning.
Servicers
who defeat
safety features
or fail to perform
safety
checks
may be liable
for
any resulting
damage.
b.
C.
d.
Be sure that there are no cabinet
openings
through
which an adult or child might be able to insert their
fingers
and
contact
a hazardous
voltage.
Such
openings
include,
but are not limited to
(1) spacing
between
the
picture
tube
and
cabinet
mask,
(2)
excessively
wide cabinet
ventilation
slots, and (3) an
improperly
fitted and/or
incorrectly
secured
cabinet
back cover.
Antenna
Cold Check
-With
the instrument
AC plug
removed
from any AC source,
connect
an electrical
jumper
across
the two AC plug prongs.
Place
the
instrument
AC switch in the on position.
Connect
one
lead
of an ohmmeter
to the AC plug prongs
tied
together
and touch the other ohmmeter
lead in turn to
each tuner
antenna
input,
exposed
terminal
screw
and,
if applicable,
to the coaxial
connector.
If the
measured
resistance
is less than 1.0 megohms
or
greater
than 5.2 megohms,
an abnormality
exists that
must be corrected
before the instrument
is returned
to
the customer.
Repeat this test with the instrument
AC
switch in the off position.
Leakage
Current
Hot Check
- With the instrument
completely
reassembled,
plug
the
AC line
cord
directly into a 120V AC outlet. (Do not use an isolation
transformer
during
this test.) Use a leakage
current
tester
or a metering
system
that
complies
with
American
National
Standards
Institute (ANSI) Cl01 .O
Leakage
Current
for Appliances
and
Underwriters
Laboratories
(UL) 1410, (50.7). With the instrument
AC switch first in the on position
and then in the off
position,
measure
from a known earth ground
(metal
waterpipe,
conduit,
etc.) to all exposed
metal parts of
the
instrument
(antennas,
handle
bracket,
metal
cabinet,
screw
heads,
metallic
overlays,
control
shafts, etc.), especially
any exposed
metal parts that
offer an electrical
return
path to the chassis.
Any
current
measured
must
not exceed
0.5 milliamps.
Reverse
the instrument
power cord plug in the outlet
and repeat test.
REVERSED
(USING
A@ ADAPTER
PLUS
AS REQUIRED)
AC Leakage
Test
ANY MEASUREMENTS
NOT WITHIN THE LIMITS
SPECIFIED
HEREIN
INDICATE
A POTENTIAL
SHOCK
HAZARD
THAT
MUST
BE
ELIMINATED
BEFORE
RETURNING
THE INSTRUMENT
TO THE
CUSTOMER
OR
BEFORE
CONNECTING
THE
ANTENNA
OR ACCESSORIES.
e. High Voltage
- This receiver
is provided
with a hold
down
circuit
for clearly
indicating
that voltage
has
increased
in excess
of a predetermined
value.
Comply will all notes described
in this Service
Manual
regarding
this hold down circuit when
servicing,
so
that this hold down circuit may correctly
be operated.
f. Service
Warning
-With
maximum
contrast,
operating
high voltage
in this receiver
is lower than 31.5 kV. In
case any component
having influence
on high voltage
is replaced,
confirm
that
the
high
voltage
with
maximum
contrast is lower than 31.5 kV.
To measure
H.V. use a high impedance
H.V. meter.
Connect
(-) to chassis earth and (+) to the CRT anode
button. (See the following
connection
diagram.)
Note:
Turn power switch off without fail before the
connection
to the anode button is made.
Chassis
ground
I
I
/
FBT
\
I
I
High tmpedance
/
(T702)
\
H.V. meter
High voltage
connector
Deflection
P.W.B.
3
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