Panasonic DVD-LS70EB / DVD-LS70EE / DVD-LS70EG / DVD-LS92EB / DVD-LS92EE / DVD-LS92EG Service Manual ▷ View online
5
2 SAFETY PRECAUTIONS
2.1.
GENERAL GUIDELINES
1. When servicing, observe the original lead dress. If a short circuit is found, replace all parts which have been overheated or
damaged by the short circuit.
2. After servicing, see to it that all the protective devices such as insulation barriers, insulation papers shields are properly
installed.
3. After servicing, make the following leakage current checks to prevent the customer from being exposed to shock hazards.
2.1.1.
LEAKAGE CURRENT COLD
CHECK
CHECK
1. Unplug the AC cord and connect a jumper between the
two prongs on the plug.
2. Measure the resistance value, with an ohmmeter,
between the jumpered AC plug and each exposed metal-
lic cabinet part on the equipment such as screwheads,
connectors, control shafts, etc. When the exposed metal-
lic part has a return path to the chassis, the reading
should be between 1M
lic cabinet part on the equipment such as screwheads,
connectors, control shafts, etc. When the exposed metal-
lic part has a return path to the chassis, the reading
should be between 1M
Ω and 5.2MΩ.
When the exposed metal does not have a return path to
the chassis, the reading must be
the chassis, the reading must be
.
2.1.2.
LEAKAGE CURRENT HOT CHECK
1. Plug the AC cord directly into the AC outlet. Do not use
an isolation transformer for this check.
2. Connect a 1.5k
Ω, 10 watts resistor, in parallel with a
0.15
μF capacitors, between each exposed metallic part
on the set and a good earth ground such as a water pipe.
3. Use an AC voltmeter, with 1000 ohms/volt or more sensi-
tivity, to measure the potential across the resistor.
4. Check each exposed metallic part, and measure the volt-
age at each point.
5. Reverse the AC plug in the AC outlet and repeat each of
the above measurements.
6. The potential at any point should not exceed 0.75 volts
RMS. A leakage current tester (Simpson Model 229 or
equivalent) may be used to make the hot checks, leakage
current must not exceed 1/2 milliamp. In case a mea-
surement is outside of the limits specified, there is a pos-
sibility of a shock hazard, and the equipment should be
repaired and rechecked before it is returned to the cus-
tomer.
equivalent) may be used to make the hot checks, leakage
current must not exceed 1/2 milliamp. In case a mea-
surement is outside of the limits specified, there is a pos-
sibility of a shock hazard, and the equipment should be
repaired and rechecked before it is returned to the cus-
tomer.
6
2.2.
Caution for AC Mains Lead (Only for LS70EB/LS92EB)
7
3 PREVENTION OF ELECTRO STATIC DISCHARGE (ESD)
TO ELECTROSTATICALLY SENSITIVE (ES) DEVICES
Some semiconductor (solid state) devices can be damaged easily by static electricity. Such components commonly are called Elec-
trostatically Sensitive (ES) Devices. Examples of typical ES devices are integrated circuits and some field-effect transistors and
semiconductor "chip" components. The following techniques should be used to help reduce the incidence of component damage
caused by electro static discharge (ESD).
trostatically Sensitive (ES) Devices. Examples of typical ES devices are integrated circuits and some field-effect transistors and
semiconductor "chip" components. The following techniques should be used to help reduce the incidence of component damage
caused by electro static discharge (ESD).
1. Immediately before handling any semiconductor component or semiconductor-equipped assembly, drain off any ESD on your
body by touching a known earth ground. Alternatively, obtain and wear a commercially available discharging ESD wrist strap,
which should be removed for potential shock reasons prior to applying power to the unit under test.
which should be removed for potential shock reasons prior to applying power to the unit under test.
2. After removing an electrical assembly equipped with ES devices, place the assembly on a conductive surface such as almi-
num foil, to prevent electrostatic charge buildup or exposure of the assembly.
3. Use only a grounded-tip soldering iron to solder or unsolder ES devices.
4. Use only an anti-static solder removal device. Some solder removal devices not classified as "anti-static (ESD protected)"
4. Use only an anti-static solder removal device. Some solder removal devices not classified as "anti-static (ESD protected)"
can generate electrical charge sufficient to damage ES devices.
5. Do not use freon-propelled chemicals. These can generate electrical charges sufficient to damage ES devices.
6. Do not remove a replacement ES device from its protective package until immediately before you are ready to install it. (Most
6. Do not remove a replacement ES device from its protective package until immediately before you are ready to install it. (Most
replacement ES devices are packaged with leads electrically shorted together by conductive foam, alminum foil or compara-
ble conductive material).
ble conductive material).
7. Immediately before removing the protective material from the leads of a replacement ES device, touch the protective material
to the chassis or circuit assembly into which the device will be installed.
Caution
Caution
Be sure no power is applied to the chassis or circuit, and observe all other safety precautions.
8. Minimize bodily motions when handling unpackaged replacement ES devices. (Otherwise hamless motion such as the brush-
ing together of your clothes fabric or the lifting of your foot from a carpeted floor can generate static electricity (ESD) sufficient
to damage an ES device).
to damage an ES device).
8
4 PRECAUTION OF LASER DIODE
Click on the first or last page to see other DVD-LS70EB / DVD-LS70EE / DVD-LS70EG / DVD-LS92EB / DVD-LS92EE / DVD-LS92EG service manuals if exist.