Harman Kardon Harman/kardon HK3490, Service Manual

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1. Inspect all lead dress to make certain that
leads are not pinched or that hardware is not
lodged between the chassis and other metal
parts in the 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 to the 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 a 120 volt AC receptacle (do not use an Isolation
Transformer for this test). Using two clip leads, connect a
1500 ohms, 10watt Resistor paralleled by a 0.15uF capacitor, in series with all exposed metal cabinet parts and a known earth ground, such
as a water pipe or conduit. Use a VTVM or VOM with 1000 ohms per volt, or higher sensitivity to measure the AC voltage drop across the
resistor. (See diagram) Move the resistor connection to each exposed metal part having a return 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 or more is excessive and indicates a potential shock hazard which must be corrected before returning the
unit to the owner.
HK3490
harman/kardon