1 Precautions
1-2 Servicing Precautions
WARNING:An electrolytic capacitor installed with the wrong polarity might explode.
Caution:Before servicing units covered by this service manual, read and follow the Safety Precautions
section of this manual.
Note:If unforeseen circumstances create conflict between the following servicing precautions and any of the
safety precautions, always follow the safety precautions.
1-2-1 General Servicing Precautions
1. Always unplug the unitOs AC power cord from the4. Check the insulation between the blades of the AC
AC power source and disconnect the DC Powerplug and accessible conductive parts (examples:
Jack before attempting to:metal panels, input terminals and earphone jacks).
(a) remove or reinstall any component or assembly,5. Insulation Checking Procedure: Disconnect the
(b) disconnect PCB plugs or connectors, (c) connectpower cord from the AC source and turn the power
a test component in parallel with an electrolytic
switch ON. Connect an insulation resistance meter
capacitor.(500 V) to the blades of the AC plug.
2. Some components are raised above the printedThe insulation resistance between each blade of the
circuit board for safety. An insulation tube or tapeAC plug and accessible conductive parts (see
is sometimes used. The internal wiring is
above) should be greater than 1 megohm.
sometimes clamped to prevent contact with6. Always connect a test instrumentOs ground lead to
thermally hot components. Reinstall all such
elements to their original position.the instrument chassis ground before connecting
the positive lead; always remove the instrumentOs
3. After servicing, always check that the screws,ground lead last.
components and wiring have been correctly
reinstalled. Make sure that the area around the
serviced part has not been damaged.
1-3 Electrostatically Sensitive Devices (ESD) Precautions
Some semiconductor (solid state) devices can be easily damaged by static electricity. Such components are commonly
called Electrostatically Sensitive Devices (ESD). Examples of typical ESD are integrated circuits and some field-effect
transistors. The following techniques will reduce the incidence of component damage caused by static electricity.
1. Immediately before handling any semiconductor6. Do not remove a replacement ESD from its
components or assemblies, drain the electrostaticprotective package until you are ready to install it.
charge from your body by touching a known earthMost replacement ESDs are packaged with leads
ground. Alternatively, wear a discharging wrist-that are electrically shorted together by conductive
foam, aluminum foil or other conductive materials.
strap device. To avoid a shock hazard, be sure to
remove the wrist strap before applying power to7. Immediately before removing the protective
the monitor.material from the leads of a replacement ESD,
2. After removing an ESD-equipped assembly, place ittouch the protective material to the chassis or
on a conductive surface such as aluminum foil tocircuit assembly into which the device will be
prevent accumulation of an electrostatic charge.installed.
3. Do not use freon-propelled chemicals. These canCaution: Be sure no power is applied to the
generate electrical charges sufficient to damagechassis or circuit and observe all
ESDs.other safety precautions.
4. Use only a grounded-tip soldering iron to solder or
8. Minimize body motions when handling
desolder ESDs.unpackaged replacement ESDs. Motions such as
5. Use only an anti-static solder removal device. Some
brushing clothes together, or lifting your foot from
solder removal devices not classified as Oanti-static�a carpeted floor can generate enough static
can generate electrical charges sufficient to damage
ESDs.electricity to damage an ESD.
1-2NB17B*/NB19B* |
ACEC
