Servicing Precautions; Static Electricity Precautions - Samsung T220 Service Manual

1. Precautions 1. Precautions

1-2. Servicing Precautions

1-2. Servicing Precautions
WARNING: WARNING: An An elec electrolytic trolytic
Caution: Caution: Before servicing units covered by this service manual, read and follow Before servicing units covered by this service manual, read and follow
this manual. this manual.
Note: Note: If unforeseen circumstances create conict between the following servicing precautions and any of the If unforeseen circumstances create conict between the following servicing precautions and any of the
safety precautions, always follow the safety precautions, always follow the
1-2-1 General Servicing Precautions 1-2-1 General Servicing Precautions
1. 1. Always unplug the unit's Always unplug the unit's AC power cord from AC power cord from th
attempting to: attempting to:
(a) remove or reinstall any component or assembly, (b) disconnect PCB plugs or connectors, (c) connect a test (a) remove or reinstall any component or assembly, (b) disconnect PCB plugs or connectors, (c) connect a test
component in parallel component in parallel with an electrolytic capacitor. with an electrolytic capacitor.
2. 2. Some components are raised above the printed circuit board Some components are raised above the printed circuit board
used. The internal wiring is sometimes clamped to prevent contact with thermally hot used. The internal wiring is sometimes clamped to prevent contact with thermally hot
elements to their original position. elements to their original position.
3. 3. After servicing, After servicing, alway always check that the sc s check that the
the area around the serviced part has not been damaged. the area around the serviced part has not been damaged.
4. 4. Check the insulation between the blades of Check the insulation between the blades of
input terminals and earphone jacks). input terminals and earphone jacks).
5. 5. Insulation Checking Procedure: Disconnect the power cord from the AC source and turn the power switch ON. 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 Connect an insulation resistance meter (500 V) to
The insulation resistance between each blade of The insulation resistance between each blade of
greater than 1 megohm. greater than 1 megohm.
6. 6. Always connect a Always connect a test instrument's test instrument's gr
always remove the instrument's ground lead last. always remove the instrument's ground lead last.

1-3. Static Electricity Precautions

1-3. Static Electricity Precautions
Some semiconductor (solid state) devices can be Some semiconductor (solid state) devices can be
called Electrostatically Sensitive Devices (ESD). Examples of typical ESD called Electrostatically Sensitive Devices (ESD). Examples of typical ESD
transistors. The following techniques will transistors. The following techniques will
1. 1. Immediately before handling any Immediately before handling any
body by touching a body by touching a known earth ground. Alternatively known earth ground.
be sure to remove the wrist strap be sure to remove the wrist strap
2. 2. After removing an After removing an ESD ESD-equipped assembly -equipped
accumulation of an electrostatic charge. accumulation of an electrostatic charge.
3. 3. Do not use freon-propelled chemicals. These can generate electrical charges sufcient to damage ESDs. Do not use freon-propelled chemicals. These can generate electrical charges sufcient to damage ESDs.
4. 4. Use only a grounded-tip soldering iron Use only a grounded-tip soldering iron
5. 5. Use only an anti-static solder removal device. Some solder removal devices not classied as "anti-static" can generate Use only an anti-static solder removal device. Some solder removal devices not classied as "anti-static" can generate
electrical charges sufcient to damage electrical charges sufcient to damage
6. 6. Do not remove a replacement ESD from its protective package until you Do not remove a replacement ESD from its protective package until you
are packaged with leads that are are packaged with leads that are
materials. materials.
7. 7. Immediately before removing the protective material from the leads of Immediately before removing the protective material from the leads of
material to the chassis or circuit assembly into which the material to the chassis or circuit assembly into which the
Caution: Caution: Be sure no Be sure no power is applied to the power is applied to the
8. 8. Minimize body motions when handling Minimize body motions when handling
or lifting your foot or lifting your foot from a carpeted oor can generate enough from a carpeted oor can generate enough
1-2 1-2
capacitor capacitor installed with installed with the wr the wrong polarity
safety precautions. safety precautions.
the AC pow e AC power source and disconnec
screws, components rews, components
the AC plug and accessible conductive parts (examples: metal panels, the AC plug and accessible conductive parts (examples: metal panels,
theblades of the AC plug. theblades of the AC plug.
the AC plug and accessible conductive parts (see above) should be the AC plug and accessible conductive parts (see above) should be
ground lead to the instrument chass ound lead to the instrument
easily damaged by static easily damaged by static
reduce the incidence of reduce the incidence of
semiconductor components or assemblies, drain the electrostatic charge semiconductor components or assemblies, drain the electrostatic charge
Alternatively, wear a , wear a
before applying power to the before applying power to the
assembly, place it on a conductive surfa , place it on a conductive
to solder or desolder ESDs. to solder or desolder ESDs.
ESDs. ESDs.
electrically shorted together by conductive foam, aluminum foil or other electrically shorted together by conductive foam, aluminum foil or other
chassis or circuit and observe all other safety precautions. chassis or circuit and observe all other safety precautions.
unpackaged replacement ESDs. Motions such as brushing unpackaged replacement ESDs. Motions such as brushing
ong polarity might might ex explode. plode.
the Safety Precautions section of the Safety Precautions section of
er source and disconnect the DC Power Jack t the DC Power Jack
for for safety safety. An insulation tube or tape i . An insulation tube or tape i
and wiring have been correct and wiring have been correctly reinstalled. Make sure th
chassis ground before connecting the pos is ground before connecting the
electricity electricity. Such components are . Such components are
are integrated circuits and are integrated circuits and
component damage caused by static component damage caused by static
discharging wrist-strap device. T discharging wrist-strap device.
monitor. monitor.
surface such as aluminum ce such as aluminum
are ready to install it. are ready to install it.
a replacement ESD, touch the protective a replacement ESD, touch the protective
device will be installed. device will be installed.
static electricity to damage an ESD. static electricity to damage an ESD.
before before
s sometimes s sometimes
components. Reinstall all such components. Reinstall all such
ly reinstalled. Make sure that
positive lead; itive lead;
commonly commonly
some eld-effect some eld-effect
electricity. electricity .
from your from your
To avoid a o avoid a shock hazard, shock hazard,
foil to prevent foil to prevent
Most replacement ESDs Most replacement ESDs
conductive conductive
clothes together, clothes together,
at