Ricoh M000, Service Manual

Page: 27 / 138

ESD Precautions
Certain semiconductor devices can be easily damaged by static electricity. Such
components are commonly called “Electrostatically Sensitive (ES) Devices”, or ESDs.
Examples of typical ESDs are: integrated circuits, some field effect transistors, and
semiconductor “chip” components.
The techniques outlined below should be followed to help reduce the incidence of
component damage caused by static electricity.
ƒ Be sure that no power is applied to the chassis or circuit, and observe all other
safety precautions.
1. Immediately before handling a semiconductor component or semiconductor-equipped
assembly, drain off any electrostatic charge on your body by touching a known earth
ground. Alternatively, employ a commercially available wrist strap device, which should
be removed for personal safety prior to applying power to the unit under test.
2. After removing an electrical assembly equipped with ESDs, place the assembly on a
conductive surface, such as aluminum or copper foil, or conductive foam, to prevent
electrostatic charge buildup in the vicinity of the assembly.
3. Use only a grounded tip soldering iron to solder or desolder ESDs.
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 ESDs.
5. Do not use Freon-propelled chemicals. When sprayed, these can generate electrical
charges sufficient to damage ESDs.
6. Do not remove a replacement ESD from its protective packaging until immediately
before installing it. Most replacement ESDs are packaged with all leads shorted
together by conductive foam, aluminum foil, or a comparable conductive material.
7. Immediately before removing the protective shorting material from the leads of a
replacement ESD, touch the protective material to the chassis or circuit assembly into
which the device will be installed.
8. Maintain continuous electrical contact between the ESD and the assembly into which it
will be installed, until completely plugged or soldered into the circuit.
9. Minimize bodily motions when handling unpackaged replacement ESDs. Normal
motions, such as the brushing together of clothing fabric and lifting one’s foot from a
carpeted floor, can generate static electricity sufficient to damage an ESD.
CÓPIA NÃO CONTROLADA
CÓPIA NÃO CONTROLADA