DX-AT50H (serv.man21). complete - Sharp DVD Service Manual (repair manual). Page 2

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BEFORE RETURNING THE DVD VIDEO PLAYER

Before returning the DVD video player to the user,
perform the following safety checks.

1. Inspect all lead dress to make certain that leads are

not pinched or that hardware is not lodged between
the chassis and other metal parts in the DVD video
player.

2. Inspect all protective devices such as non-metallic

control knobs, insulation materials, cabinet backs,
adjustment and compartment covers or shields, isola-
tion resistor/capacitor networks, mechanical insula-
tors etc.

3. To be sure that no shock hazard exists, check for

current in the following manner.
Plug the AC line cord directly into a 230 volt AC outlet
(Do not use an isolation transformer for this test).
Using two clip leads, connect a 1.5 kohm, 10 watt
resistor paralleled by a 0.15 

µ

F capacitor in series with

all exposed metal cabinet parts and a known earth
ground, such as a water pipe or conduit.
Use an DVM or VOM with 1000 ohm per volt, or higher,
sensitivity or measure the AC voltage drop across the
resistor (See Diagram).

Move the resistor connection to earth exposed metal
part having a return path to the chassis (metal cabinet,
screw heads, knobs and control shafts, etc.) and
measure the AC voltage drop across the resistor.
Reverse the AC plug on the set and repeat AC voltage
measurements for each exposed part. Any reading of
1.4 V rms (this corresponds to 0.7 mA rms AC.) or
more is excessive and indicates a potential shock
hazard which must be corrected before returning the
DVD video player to the owner.

SSVM

AC SCALE

2k ohms.

10W

0.15

TEST PROBE

TO EXPOSED
METAL PARTS

CONNECT TO
KNOWN EARTH 
GROUNG

F