Bose 1800 서비스 매뉴얼 - 페이지 4

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SAFETY INFORMATION

1. Parts that have special safety characteristics are identified by the

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-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)

C101.1 "Leakage Current for Appliances" and Underwriters Laboratories

(UL) 1492 (71). With the unit AC switch first in the ON position, 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.

Any current measured must not exceed 0.5 milliamp. Reverse the unit power

cord plug in the outlet and repeat test. ANY MEASUREMENTS NOT WITHIN

THE LIMITS SPECIFIED HEREIN INDICATE A POTENTIAL SHOCK HAZ-

ARD 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 be-

tween 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 re-

checked before it is returned to the customer.

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