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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 unit's AC power cord from the AC
power source and disconnect the DC Power Jack before
attempting to:
(a) remove or reinstall any component or assembly, (b)
disconnect PCB plugs or connectors, (c) connect a test
component in parallel with an electrolytic capacitor.
2.
Some components are raised above the printed circuit
board for safety. An insulation tube or tape is sometimes
used. The internal wiring is sometimes clamped to
prevent contact with thermally hot components. Reinstall
all such elements to their original position.
3.
After servicing, always check that the screws,
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 semiconductor
components or assemblies, drain the electrostatic charge
from your body by touching a known earth ground.
Alternatively, wear a discharging wrist-strap device. To
avoid a shock hazard, be sure to remove the wrist strap
before applying power to the monitor.
2.
After removing an ESD-equipped assembly, place it on a
conductive surface such as aluminum foil to prevent
accumulation of an electrostatic charge.
3.
Do not use freon-propelled chemicals. These can
generate electrical charges sufficient to damage ESDs.
4.
Use only a grounded-tip soldering iron to solder or
desolder ESDs.
5.
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.
1-2
4.
Check the insulation between the blades of the AC plug
and accessible conductive parts (examples: metal panels,
input terminals and earphone jacks).
5.
Insulation Checking Procedure: Disconnect the power
cord from the AC source and turn the power switch ON.
Connect an insulation resistance meter (500 V) to the
blades of the AC plug.
The insulation resistance between each blade of the AC
plug and accessible conductive parts (see above) should
be greater than 1 megohm.
6.
Always connect a test instrument's ground lead to the
instrument chassis ground before connecting the positive
lead; always remove the instrument's ground lead last.
6.
Do not remove a replacement ESD from its protective
package until you are ready to install it. Most
replacement ESDs are packaged with leads that are
electrically shorted together by conductive foam,
aluminum foil or other conductive materials.
7.
Immediately before removing the protective 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.
Caution: Be sure no power is applied to the
chassis or circuit and observe all
other safety precautions.
8.
Minimize body motions when handling unpackaged
replacement ESDs. Motions such as brushing clothes
together, or lifting your foot from a carpeted floor can
generate enough static electricity to damage an ESD.
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Troubleshooting
