Samsung ML-6050, Service Manual

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Precautions
1-2
Samsung Electronics
1-2. Servicing Precautions
1. Before disassembly, pull the power plug from the AC
power connector.
2. To avoid spilling toner inside the machine, do not turn
the printer over or on its side before removing the
developer cartridge.
3. Faulty installation of DRAMs may cause permanent
damage to the Laser Printer.
4. Use only+5V power for video controller-related cir-
cuitry.
5. When replacing parts, use only the same type of part
as the original. Replacing components with a second
vendor’s part may cause faulty operation.
6. Check the insulation between the blades of the AC
plug and accessible conductive parts (examples : metal
panels and input ports).
7. Insulation Checking Procedure:
Disconnect the power cord from the AC power source.
Connect an insulation resistance meter (500V) to the
blades of the AC plug.
The insulation resistance between each blade of the
AC plug and accessible conductive parts (see left)
should be greater than 1 megaohm.
8. Never defeat any of the B+ voltage interlocks. Do not
apply AC power to the unit (or any of its assemblies)
unless all solid-state heat sinks are correctly installed.
9. Always connect a test instrument’s ground lead to the
instrument chassis ground before connecting the posi-
tive lead; always remove the instrument’s ground lead
last.
Note: Requirements for AC power are described on the label affixed to the rear of the printer. Check the AC
voltage rating requirement before use.
1-3. ESD Precautions
1. Immediately before handling any semiconductor com-
ponents assemblies, drain the electrostatic charge from
your body by touching a known earth ground.
Alternatively, wear a discharging wrist strap device.
(Be sure to remove the strap before applying power to
the unit under test to avoid potential shock.)
2. After removing 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 gen-
erate electrical charges sufficient to damage ESDs.
4. Use only a ground-tip soldering iron when soldering
or desoldering ESDs.
5. Use only anti-static solder removal device. Some sol-
der removal devices are not rated as “anti-static;”these
can accumulate sufficient electrical charge to damage
ESDs.
6. Do not remove a replacement ESD from its protective
package until you are ready to install it. Most replace-
ment ESDs are package 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 protec-
tive material to the chassis or circuit assembly into
which the device will be installed.
8. Minimize body motions when handling unpackaged
replacement ESDs. Motion such as your clothes brush-
ing together, or lifting a foot from a carpeted floor can
generate enough static electricity to damage an ESC.
9. Handle ICs and EPROMs carefully to avoid bending a
pin.
10. Pay attention to the direction of parts when mount-
ing or inserting them on a PCB.
11. Components can be permanently damaged if heated
for longer than necessary while welding. All compo-
nents are susceptible to heat damage.
Some semiconductor (“solid state”) devices are easily damaged from static electricity. Such components com-
monly are called Electrostatically Sensitive Devices (ESDs); examples include integrated circuits (ICs), Large-
Scale Integrated circuits (LSIs), some field-effect transistors, and semiconductor chip components. The follow-
ing techniques will reduce the occurrence of component damage caused by static electricity:
CAUTION: Be sure the power is off to the
chassis or circuit board, and
observe all other safety precau-
tions