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1. Parts that have special safety characteristics are identified by the symbol on
schematics or by special notes on the parts list. Use only replacement parts that have
critical characteristics recommended by the manufacturer.
2. Make leakage current or resistance measurements to determine that exposed
parts are acceptably insulated from the supply circuit before returning the unit
to the customer. Use the following checks to perform these measurements:
A. Leakage Current Hot Check
(1) 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 National
Standards Institute (ANSI) C101. "Leakage Current for Appliances" and
Underwriters Laboratories (UL) 1492 (71).
(2) 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.) to all
exposed metal parts of the unit (antennas, handle bracket, metal cabinet,
screwheads, metallic overlays, control shafts, etc.), especially any exposed
metal parts that offer an electrical return path to the chassis.
(3) Any current measured must not exceed 0.5 milliamp.
(4) Reverse the unit power cord plug in the outlet and repeat test.
ANY MEASUREMENTS NOT WITHIN THE LIMITS SPECIFIED HEREIN
INDICATE A POTENTIAL SHOCK HAZARD THAT MUST BE ELIMINATED
BEFORE RETURNING THE UNIT TO THE CUSTOMER.
B. Insulation Resistance Test Cold Check
(1) Unplug the power supply and connect a jumper wire between the two prongs
of the plug.
(2) Turn on the power switch of the unit.
(3) Measure the resistance with an ohmmeter between the jumpered AC plug
and each exposed metallic cabinet part on the unit. 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, there is the
possibility of a shock hazard, and the unit must be repaired and rechecked
before it is returned to the customer.
SAFETY INFORMATION
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