Sharp LC-60LE450U/LC-60LE452U Service manual
3
IMPORTANT SERVICE SAFETY PRECAUTION
Service work shoud be performed only by qualified service technicians who are thoroughly familiar with
all safety checks and the servicing guidelines which are as follows:
WARNING
1..For continued safety,no modification of any circuit earth ground,such as electrical or electrical
..should be attempted. around connected to an earth ground.
2..Disconnect AC power before servicing. • Use an AC voltmeter having with 5000 ohm per volt,
or higher,sensitivity or measure the AC voltage drop
across the resistor.
• Connect the resistor connection to all exposed metal
parts having a return to the chassis (antenna, metal
cabinet, screw heads, knobs and control shafts,
escutcheon, etc.) and measure the AC voltage drop
across the resistor.
All checks must be repeated with the AC cord plug
connection reversed. (If necessary, a nonpolarized
adaptor plug must be used only for the purpose of
completing these checks.)
Any reading of 0.75V peak (this corresponds to 0.5
BEFORE RETURNING THE RECEIVER 1 mA. peak AC.) or more is excessive and indicates
(Fire & Shock Hazard) a potential shock hazard which must be corrected
before returning the monitor to the owner.
Before returning the receiver,the user should perform
the following safety checks:
1. Inspect all lead dress to make certain that leads are
not pinched,and check that hardware is not lodged
between the chassis and other metal parts in the
receiver.
2. Inspect all protective devices such as non-metallic
control knobs,insulation materials,cabinet backs,
adjustment and compartment covers or shields,
isolation resistor-capacitor networks,mechanical
insulators,etc.
3. To be sure that no shock hazard exists,check for
leakage current in the following manner.
· Plug the AC cord directly into a 200 volt AC outlet,
and connect the DC power cable into the receiver’s
DC jack.(Do not use an isolation transformer for this
test) .
· Using two clip leads,connect a 1.5K ohm,10 watt
resistor paralleled by a 0.15uF capacitor in series
with all exposed metal cabinet parts and a known
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