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
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 metallic cabine t
part on the equipment such as screwheads, connectors,
control shafts, etc. When the exposed metallic part has a
return path to thechassis, the reading should be between
1MΩ and 5.2MΩ.
When the exposed metal does not have a return path to
the chassis, the reading must be
Figure 1
.
2.1.2. LEAKAGE CURRENT HOT CHECK
(See Figure 1 .)
1. Plug the AC cord directly into the AC outlet. Do not use an
isolation transformer for this check.
2. Connect a 1.5kΩ, 10 watts resistor, in parallel with a 0.15µF
capacitors, between each exposed metallic part on the set
and a good earth ground such as a water pipe, as shown in
Figure 1.
3. Use an AC voltmeter, with 1000 ohms/volt or more
sensitivity, to measure the potential across the resistor.
4. Check each exposed metallic part, and measure the
voltage 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
measurement is outside of the limits specified, there is a
possibility of a shock hazard, and the equipment should be
repaired and rechecked before it is returned to the
customer.
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
Electrostatically Sensitive (ES) Devices. Examples of typical ES devices are integrated circuits and some field-effect transistorsand
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.
2. After removing an electrical assembly equipped with ES devices, place the assembly on a conductive surface such as alminum
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)" 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
replacement ES devices are packaged with leads electrically shorted together by conductive foam, alminum foil or
comparableconductive 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.
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 brushing
together of your clothes fabric or the lifting of your foot from a carpeted floor can generate static electricity (ESD) sufficie nt
todamage an ES device).
5.1. General description about Lead Free Solder (PbF)
The lead free solder has been used in the mounting process of all electrical components on the printed circuit boards used for this
equipment in considering the globally environmental conservation.
The normal solder is the alloy of tin (Sn) and lead (Pb). On the other hand, the lead free solder is the alloy mainly consists of tin
(Sn), silver (Ag) and Copper (Cu), and the melting point of the lead free solder is higher approx.30°C (86°F) more than that of the
normal solder.
Definition of PCB Lead Free Solder being used
Service caution for repair work using Lead Free Solder (PbF)
· The lead free solder has to be used when repairing the equipment for which the lead free solder is used. (Definition: The
letter of “PbF” is printed on the PCB using the lead free solder.)
·To put lead free solder, it should be well molten and mixed with the original lead free solder.
·Remove the remaining lead free solder on the PCB cleanly for soldering of the new IC.
·Since the melting point of the lead free solder is higher than that of the normal lead solder, it takes the longer time to melt
the lead free solder.
· Use the soldering iron (more than 70W) equipped with the temperature control after setting the temperature at 350±30°C
(662±86°F).
Recommended Lead Free Solder (Service Parts Route.)
The following 3 types of lead free solder are available through the service parts route.
·RFKZ03D01K-----------(0.3mm 100g Reel)
·RFKZ06D01K-----------(0.6mm 100g Reel)
·RFKZ10D01K-----------(1.0mm 100g Reel)
Note
* Ingredient: tin (Sn) 96.5%, silver (Ag) 3.0%, Copper (Cu) 0.5%, Cobalt (Co) / Germanium (Ge) 0.1 to 0.3%
The laser diode in the traverse unit (optical pickup) may brake down due to static electricity of clothes or human body. Use due
caution to electrostatic breakdown when servicing and handling the laser diode.
6.1. Grounding for electrostatic breakdown prevention
Some devices such as the DVD player use the optical pickup (laser diode) and the optical pickup will be damaged by static
electricity in the working environment. Proceed servicing works under the working environment where grounding works is
completed.
6.1.1. Worktable grounding
1. Put a conductive material (sheet) or iron sheet on the area where the optical pickup is placed, and ground the sheet.
6.1.2. Human body grounding
1. Use the anti-static wrist strap to discharge the static electricity form your body.
6.1.3. Handling of optical pickup
1. To keep the good quality of the optical pickup maintenance parts during transportation and before installa tion, the both ends of
the laser diode are short-circuited. After replacing the parts with new ones, remove the short circuit according to the correct
procedure. (See this Technical Guide.)
2. Do not use a tester to check the laser diode for the optical pickup. Failure to do so will damage the laser diode due to the power
supply in the tester.
6.2. Handling Precautions for Traverse Unit (Optical Pickup)
1. Do not give a considerable shock to the traverse unit (optical pickup) as it has an extremely high-precise structure.
2. When replacing the optical pickup, install the flexible cable and cut its short land with a nipper. See the optical pickup
replacement procedure in this Technical Guide. Before replacing the traverse unit, remove the short pin for preventing static
electricity and install a new unit. Connect the connector as short times as possible.
3. The flexible cable may be cut off if an excessive force is applied to it. Use caution when handlin g the cable.
4. The half-fixed resistor for laser power adjustment cannot be adjusted. Do not turn the resistor.
1. Slide the lever (A) in the arrow direction (to the opposite
side) till it stops.
2. Slide the lever (A) further by bending the tab at the right
side of the lever A in the right direction. (The right groove
opens and the boss becomes seen.)
3. Open the lever (B) to left. (The 2 grooves at the left side
open.)
8.6.1. Cautions to Be Taken in Handling the Optical Pickup Unit
The laser diode in the optical pickup unit may be damaged due to electrostatic discharge generating from clothes or human body.
Use due caution to electrostatic discharge damage when servicing the laser diode.
1. Do not give a considerable shock to the optical pickup unit as it has an extremely high-precise structure.
2. To prevent the laser diode from the electrostatic discharge damage, the Intermediate FFC of the optical pickup unit removed
from the PCB should be short-circuited with a short pin or a clip.
3. The Intermediate FFC may be cut off if an excessive force is applied to it. Use caution when handling the Intermediate FFC.
4. The antistatic FPC is connected to the new optical pickup unit. After replacing the optical pickup unit and connecting the
fIntermediate FFC, cut off the antistatic FPC.
The optical pickup self-diagnosis function and tilt adjustment check function have been included in this unit. When repairing, use
the following procedure for effective Self-diagnosis and tilt adjustment.Be sure to use the self-diagnosis function before replacing
the optical pickup when "NO DISC" is displayed. As a guideline, you should replace the optical pickup when the value of the laser
drive current is more than 55.
Note:
Press the power button to turn on the power, and check the value within three minutes before the unit warms up. (Otherwise,
the result will be incorrect.)
23
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