Harman Kardon Harman/kardon HK3490, Service Manual

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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 :
HK3490
harman/kardon