Haier 21F3A-T Service Manual page 9

components are usually called Electrostatic ally 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 to prevent potential shock 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 buildup 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 type folder 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 charges 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.
CAUTION: 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
even some normally harmless motions such as mutual brushing of your clothes' fabric or
lifting of your foot from a carpeted floor might generate static electricity sufficient to damage
an ES device.)
General Soldering Guidelines
1. Use a grounded-tip, low-wattage soldering iron and appropriate tip size and shape that will
maintain tip temperature within the range of 500
2. Use an appropriate gauge of RMA resin-core solder composed of 60 parts tin/40 parts lead.
3. Keep the soldering iron tip clean and well tinned.
4. Thoroughly clean the surfaces to be soldered. Use a mall wire bristle (0.5 inch, or 1.25cm)
brush with a metal handle. Do not use freon-propelled spay-on cleaners.
5. Use the following unsoldering technique
o o
F to 600 F.
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Warning and Cautions