Table of Contents
Advertisement
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 Static Electricity 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.
Hide quick links:
Advertisement
Table of Contents
