Advertisement
SAFETY PRECAUTIONS
WARNING
Before servicing this unit, familiarize yourself with the following precautions:
1. Many electrical and mechanical
parts in this
chassis have special safety characteristics that
often pass unnoticed
and the protection
afforded
by them
cannot
necessarily
be
obtained by using replacement components
Replacement
parts that have these special
safety characteristics are identified in this
manual
and
its supplements:
electrical
components
having
such
features
are
identified
by
/A\
in the schematic diagram
and the parts list.
Before replacing any of these components,
read the parts list in this manual carefully. The
use of substitute replacement
parts that do
not have the same safety characteristics as
specified in the parts list may create shock,
fire, or other hazards.
2. Before returning the set to the customer,
always do an AC leakage current check on the
AC Outlet
At 5000 Q per volt or greater sensitivity,
the reading should not exceed 0.75 V.
0.15 pF, 150 V AC
Place the probe on each exposed metalic part.
exposed metal parts of the cabinet, such as
terminals, screw heads, and metal overlays,
to be sure the set is safe to operate danger of
electrical shock. Plug the AC line cord directly
into a 230 V AC outlet.
(Do not use a
line isolation transformer
during this check.) Be sure your AC voltmeter
has a sensitivity of 5000 Q per volt or greater.
Then
connect
a 1500 2 10 watt resistor,
paralleled by a 0.15 uF 150 V AC capacitor,
between a known good earth ground (such as
a water pipe, or conduit) and the exposed
metalic is parts, one at a time. Measure the
AC voltage across the combination of a 1500
Q resistor and a 0.15 uF capacitor. Reverse the
AC plug at the AC outlet and
repeat AC
voltage measurements
for each exposed
metalic part. Voltage measured
must not
exceed 0.75 V RMS. This corresponds to 0.2
mA
AC. Any value
exceeding
this limit
constitutes a potential shock hazard and must
be corrected immediately.
AC Voltmeter
Good earth ground, such as
a water pipe or conduit.
Advertisement
