IMPORTANT SERVICE SAFETY INFORMATION
1 SAFETY PRECAUTIONS
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Before returning a unit to the customer always make a safety check of the
entire unit including but not limited to the following items
a Be sure that no built in protective devices are defective and or have been
defeated during servicing
1 Protective shields are provided 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 assemblies in the cabinet
be sure to put back in place all protective devices including but not
limited to nonmetallic control knobs insulating fishpapers adjustment
and compartment covers shields and isolation resistor capacitor
networks Do not operate this unit or permit it to be operated without
all protective devices correctly installed and functioning
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 excessively wide cabinet
ventilation slots and an improperly fitted and or incorrctly secured cabinet
back cover
Leakage current Hot Check with the unit 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 nations standards institute ANSI
C101 1 Leakage current for appliances and underwriters Laboratories
UL 1410 50 7
With the unit AC switch first in the ON position and
then in the OFF position measure from a known earth ground metal water
pipe conduit etc
especially any exposed metal parts that offer an
electrical return path to the chassis Any current measured mus not exceed
0 5 milliamp Reverse the unit power cord plug in the outlet and repeat
test ANY MEASUREMENTS NOT WITHIN THE LIMITS SPECIFIED
HERENIN INDICATE A POTENTIAL SHOCK HAZARD TAHT MUST BE
ELIMINATED BEFORE RETURNING THE UNIT TO THE CUSTOMER
Insulation resistance test cold check
Unplug the power supply cord and connect a jumper wire between the two
prongs of the plug
Turn on the power switch of the unit
Measure the resistance with an ohmmeter between the jumpered AC plug
and each exposed metallic cabinet part on the unit such as screwheads
antenna control shafts handle brackets etc When the exposed metallic
part has a return path to the chassis the reading should be between 1
and 5 2 megohms When there is no return path to the chassis the
reading must be infinite
If it is not within the limits specified and
rechecked before it is returned to the customer
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2 PRODUCT SAFETY NOTICE
Some electrical and mechanical parts have special safety related
characteristics which are often not evident from visual inspection nor can
the protection they give necessarily be obtained by replacing them with
components rated for higher voltage wattage etc Parts that have special
safety characteristics are identified by a
On schematic and parts list
Use of a substitute replacement that does not have the same safety
characteristics as the recommended replacement part might create shock
fire and or other hazards Product safety is under review continuously
and new instructions are issued whenever appropriate
3 SERVICING PRECAUTIONS
CAUTION Before servicing the unit covered by this service manual and
its supplements read and follow the SAFETY PRECAUTIONS on this
page NOTE if unforeseen circumstances create a conflict between the
following servicing precautions and any of the safety precautions always
follow the safety precautions Remember safety first
General servicing Precautions
Always unplug the unit s AC power cord from the AC power source
before
1 removing or reinstalling any component circuit board module or any
other unit assembly
2 disconnecting or reconnecting any unit electrical plug or other electrical
connection
3 con ecting a test substitute in parallel with an electrolytic capacitor in
the unit
Caution
wrong part substitution or incorrect polarity installation of
electrolytic capacitors may result in an explosion hazard
Do not defeat any plug socket B voltage interlocks with which the unit
covered by this service manual might be equipped
Do not apply AC power to this unit and or any of its electrical assemblies
unless all solid state device heat sinks are correctly installed
Always connect a test unit instrument s ground lend to the unit s chassis
ground before connecting the test instrument s positive lead Always
remove the test instrument s ground lend last
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CAUTION
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a
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b
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AC Leakage Test
DEVICE
UNDER
TEST
2 WIRE CORD
ALSO TEST WITH
PLUG REVERSED
USING AC ADAPTER
PLUG AS REQUIRED
-
(
)
TEST ALL
EXPOSED METAL
SURFACES
READING SHOULD
NOT BE ABOVE
0 5mA
.
LEAKAGE
CURRENT
TESTER
EARTH
GROUND
ANTENNA
AERMINAL
EXPOSED
METAL
PART
OM
OHMMETER
USE OF CONTROLS ADJUSTMENTS OR PERFORMANCE OF
PROCEDURES HEREIN MAY RESULT IN HAZARDOUS RADIATION
EXPOSURE
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