Harman kardon hk 3490 service manual

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1. Inspect all lead dress to make certain that leads are not pinched orthat hardware isnot lodged between the chassis and other metal parts inthe unit. 2.Be sure that any protective devices such as nonmetallic control knobs, insulating fish- papers, cabinet backs, adjustment and compartment covers or shields, isolation resistor -capacity networks, mechanical insulators, etc. Which were removed for the servicing are properly re-installed. Before returning the unit tothe user ,perform the following safety checks : 3. Be sure that no shock hazard exists ;check for leakage current using Simpson Model 229 Leakage Tester ,standard equipment item No. 21641, RCA Model WT540A or use alternate method as follows :Plug the power cord directly Into a120 volt AC receptacle (do not use an Isolation Transformer for this test). Using two clip leads, connect a 1500 ohms, 10watt Resistor paralleled by a0.15uF capacitor ,inseries with allexposed metal cabinet parts and aknown earth ground, such as awater pipe orconduit. Use aVTVM orVOM with 1000 ohms per volt, orhigher sensitivity tomeasure the AC voltage drop across the resistor .(See diagram) Move the resistor connection to each exposed metal part having areturn path to the chassis (antenna, metal, cabinet, screw heads, knobs and control shafts, escutcheon, etc.) and measure the AC voltage drop across the resistor .(This test should be performed with the 0.35 volt RMS ormore isexcessive and indicates apotential shock hazard which must be corrected before returning the unit tothe owner . HK3490 harman/kardon