27N-S300
CN27S30
IMPORTANT SERVICE SAFETY PRECAUTION
(Continued)
BEFORE RETURNING THE RECEIVER? Connect the resistor connection to all exposed metal
parts having a return to the chassis (antenna, metal
(Fire & Shock Hazard)
cabinet, screw heads, knobs and control shafts,
Before returning the receiver to the user, performescutcheon and etc.) and measure the AC voltage
the following safety checks.drop across the resistor.
AII checks must be repeated with the AC line cord
1. Inspect all lead dress to make certain that leads areplug connection reversed. (If necessary, a non-
not pinched or that hardware is not lodged betwpolareenized adapter plug must be used only for the
the chassis and other metal parts in the receivpurerpose of completing these chec.k.)
2. Inspect all protective devices such as non-metallicAny current measured must not exceed 0.5 milliamp.
control knobs, insulating materials, cabinet bacAny measurements not within the limits outlinedks,
adjustment and compartment covers or shieldsabo,ve indicate of a potential shock hazard and
isolation resistor-capacity networks, mechanicalcorrective action must be taken before returning the
insulators and etc.instrument to the customer.
3. To be sure that no shock hazard exists, check for
leakage current in the following manner.
? Plug the AC cord directly into a 120 volt AC outlet,
(Do not use an isolation transformer for this test).
? Using two clip leads, connect a 1.5k ohm, 10 watt
resistor paralleled by a 0.15?F capacitor in series
with all exposed metal cabinet parts and a known
earth ground, such as electrical conduit or electrical
AC
ground connected to earth ground.VOLTMETER
? Use an AC voltmeter having with 5000 ohm per volt,
or higher, sensitivity to measure the AC voltage drop1.5k ohm
across the resistor.10W
0.15mF
TEST PROBE
TO EXPOSEDCONNECT TO
METAL PARTSKNOWN EARTH
GROUND
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SAFETY NOTICE
Many electrical and mechanical parts in teleFor continvisionued protection, replacement parts must be
receivers have special safety-related characteridentical to those used in the oristics.iginal circuit. The use of
These characteristics are often not evident from visualsubstitute replacement parts which do not have the
inspection, nor can protection afforded by them besame safety characteristics as the factory recommended
necessarily increased by using replacementreplacement parts shown in this service manual, may
components rated for higher voltage, wattage andetc.create shock, fire, X-radiation or other hazards.
Replacement parts which have these special safety
characteristics are identified in this manual; electrical
components having such features are identified b�"y "
and shaded areas in the Replacement Parts Lists and
Schematic Diagrams.
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ACEC
