Harman kardon hk 3480 service manual 2
This is the 55 pages manual for harman kardon hk 3480 service manual 2.
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Extracted text from harman kardon hk 3480 service manual 2 (Ocr-read)
Page 1
Each precaution in this manual should be followed during servicing. Components identified with the IEC symbol in the parts list are special significance to safety. When replacing a component identified with, use only the replacement parts designated, or parts with the same ratings or resistance, wattage, or voltage that are designated in the parts list in this manual. Leakage-current or resistance measurements must be made to determine that exposed parts are acceptably insulated from the supply circuit before retuming the product to the customer. Some semiconductor (solid state) devices can be damaged easily by static electricity. Such components commonly are called Electrostatically Sensitive (ES) Devices. Examples of typical ES devices are integrated circuits and some field effect transistors and semiconductor "chip" components. The following techniques should be used to help reduce the incidence of component damage caused by static electricity. 1. Immediately before handling any semiconductor component or semiconductor-equipped assembly, drain off any electrostatic charge on your body by touching a known earth ground. Alternatively, obtain and wear a commercially available discharging wrist strap device, which should be removed for potential shock reasons prior to applying power to the unit under test. 2. After removing an electrical assembly equipped with ES devices, place the assembly on a conductive surface such as aluminum foil, to prevent electrostatic charge build-up or exposure of the assembly. 3. Use only a grounded-tip soldering iron to solder or unsolder ES devices. 4. Use only an anti-static solder removal device. Some solder removal devices not classified as "anti-static" can generate electrical charges sufficient to damage ES devices. 5. Do not use freon-propelled chemicals. These can generate electrical change sufficient to damage ES devices. 6. Do not remove a replacement ES device from its protective package until immediately before you are ready to install it. (Most replacement ES devices are packaged with leads electrically shorted together by conductive foam, aluminum foil or comparable conductive material.) 7. Immediately before removing the protective material from the leads of a replacement ES device, touch the protective material to the chassis or circuit assembly into which the device will be installed. Be sure no power is applied to the chassis or circuit, and observe all other safety precautions. 8. Minimize bodily motions when handling unpackaged replacement ES devices. (Otherwise harmless motion such as the brushing together or your clothes fabric or the lifting of your foot from a carpeted floor can generate static electricity sufficient to damage an ES devices. CAUTION : HK3480 ha rm an/kardon
Page 2
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 . HK3480 harman/kardon