SAFETY PRECAUTIONS
1. Before returning an instrument to the customer, always
make a safety check of the entire instrument, including
but not limited to the 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,
-
Y
nonmetallic control knobs, insulating fishpaper, ALSO TEST WITH PLUG
adjustment and compartment covers/shields, and REVERSED
(USING AC ADAPTER
isolation resistor/capacitor networks. Do not operate
PLUS AS REQUIRED)
this instrument or permit it to be operated without
all protective devices correctly installed and AC Leakage Test
functioning. Servicers who defeat safety features
or fail to perform safety checks may be liable for ANY MEASUREMENTS NOT WITHIN THE LIMITS
any resulting damage. SPECIFIED HEREIN INDICATE A POTENTIAL
SHOCK HAZARD THAT MUST BE ELIMINATED
b. Be sure that there are no cabinet openings through BEFORE RETURNING THE INSTRUMENT TO THE
which an adult or child might be able to insert their CUSTOMER OR BEFORE CONNECTING THE
fingers and contact a hazardous voltage. Such ANTENNA OR ACCESSORIES.
openings include, but are not limited to (1) spacing
between the picture tube and cabinet mask, (2) e. High Voltage - This receiver is prcvided with a hold
excessively wide cabinet ventilation slots, and (3) an down circuit for clearly indicating that voltage has
improperly fitted and/or incorrectly secured cabinet increased in excess of a predetermined value.
back cover. Comply will all notes described in this Service Manual
regarding this hold down circuit when servicing, so
C. Antenna Cold Check -With the instrument AC plug that this hold down circuit may correctly be operated.
removed from any AC source, connect an electrical
jumper across the two AC plug prongs. Place the f. Service Warning -With maximum contrast, operating
instrument AC switch in the on position. Connect one high voltage in this receiver is lower than 31.5 kV. In
lead of an ohmmeter to the AC plug prongs tied case any component having influence on high voltage
together and touch the other ohmmeter lead in turn to is replaced, confirm that the high voltage with
each tuner antenna input, exposed terminal screw maximum contrast is lower than 31.5 kV.
and, if applicable, to the coaxial connector. If the To measure H.V. use a high impedance H.V. meter.
measured resistance is less than 1 .O megohms or Connect (-) to chassis earth and (+) to the CRT anode
greater than 5.2 megohms, an abnormality exists that button. (See the following connection diagram.)
must be corrected before the instrument is returned to
the customer. Repeat this test with the instrument AC Note: Turn power switch off without fail before the
switch in the off position. connection to the anode button is made.
d. Leakage Current Hot Check - With the instrument
completely reassembled, plug the AC line cord
directly into a 12OV 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) Cl 01 .O
Leakage Current for Appliances and Underwriters
Laboratories (UL) 1410, (50.7). With the instrument
Chassis
AC switch first in the on position and then in the off
ground
position, measure from a known earth ground (metal
waterpipe, conduit, etc.) to all exposed metal parts of
FBT
the instrument (antennas, handle bracket, metal I I
(T702)
cabinet, screw heads, metallic overlays, control High impedance \
H.V. meter
shafts, etc.), especially any exposed metal parts that High voltage
/ connector
offer an electrical return path to the chassis, Any
Deflection P.W.B.
current measured must not exceed 0.5 milliamps.
Reverse the instrument power cord plug in the outlet
and repeat test.
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ACEC
