Important Safety Precautions - Sylvania 6842THG Service Manual

IMPORTANT SAFETY PRECAUTIONS

Prior to shipment from the factory, our products are strictly inspected for recognized product safety and electrical
codes of the countries in which they are to be sold. However, in order to maintain such compliance, it is equally
important to implement the following precautions when a set is being serviced.
Safety Precautions for Monitor Circuit
1. Before returning an instrument to the custom-
er, always make a safety check of the entire instru-
ment, including, but not limited to, the following
items:
a. Be sure that no built-in protective devices are de-
fective and have been defeated during servicing.
(1) Protective shields are provided on this chassis
to protect both the technician and the customer.
Correctly replace all missing protective shields, in-
cluding any removed for servicing convenience. (2)
When reinstalling the chassis and/or other assem-
bly in the cabinet, be sure to put back in place all
protective devices, including but not limited to,
nonmetallic control knobs, insulating fishpapers,
adjustment and compartment covers/shields, and
isolation resistor/capacitor networks. Do not oper-
ate this instrument or permit it to be operated
without all protective devices correctly in-
stalled and functioning. Servicers who defeat
safety features or fail to perform safety checks
may be liable for any resulting damage.
b. Be sure that there are no cabinet openings through
which an adult or child might be able to insert their
fingers and contact a hazardous voltage. Such
openings include, but are not limited to, (1) exces-
sively wide cabinet ventilation slots, and (2) an im-
properly fitted and/or incorrectly secured cabinet
back cover.
c. Leakage Current Cold Check - With the instru-
ment AC plug removed from any AC source, con-
nect an electrical jumper across the two AC plug
prongs. Place the instrument AC switch in the on
position. Connect one lead of an ohmmeter to the
AC plug prongs tied together and touch the other
ohmmeter lead in turn to each exposed metallic
cabinet part. If the measured resistance is less
than 1.0 megohm or greater than 5.2 megohm, an
abnormality exists that must be corrected before
the instrument is returned to the customer. Repeat
this test with the instrument AC switch in the off po-
sition.
d. Leakage Current Hot Check - With the instru-
ment completely reassembled, plug the AC line
cord directly into a 120V AC outlet. (Do not use an
isolation transformer during this test.) Use a leak-
age current tester or a metering system that com-
plies with American National Standards Institute
(ANSI) C101.1 Leakage Current for Appliances.
With the instrument AC switch first in the on posi-
tion and then in the off position, measure from a
known earth ground (metal water pipe, conduit,
etc.) to all exposed metal parts of the instrument
(antennas, handle brackets, metal cabinet, screw
heads, metallic overlays, control shafts, etc.), es-
pecially any exposed metal parts that offer an elec-
trical return path to the chassis. Any current
measured must not exceed 0.75 milli-ampere. Re-
verse the instrument power cord plug in the outlet
and repeat the test.
ANY MEASUREMENTS NOT WITHIN THE LIMITS
SPECIFIED HEREIN INDICATE A POTENTIAL
SHOCK HAZARD THAT MUST BE ELIMINATED
BEFORE RETURNING THE INSTRUMENT TO
THE CUSTOMER OR BEFORE CONNECTING
THE ANTENNA OR ACCESSORIES.
2. Read and comply with all caution and safety-relat-
ed notes on or inside the cabinet, or on the chas-
sis,
3. Design Alteration Warning - Do not alter or add
to the mechanical or electrical design of this mon-
itor. Design alterations and additions, including,
but not limited to circuit modifications and the ad-
dition of items such as auxiliary audio and/or video
output connections, might alter the safety charac-
teristics of this receiver and create a hazard to the
user. Any design alterations or additions will void
the manufacturer's warranty and may make you,
the servicer, responsible for personal injury or
property damage resulting therefrom.
4. Hot Chassis Warning -
a. Some monitor chassis are electrically connected
directly to one conductor of the AC power cord and
maybe safety-serviced without an isolation trans-
former only if the AC power plug is inserted so that
the chassis is connected to the ground side of the
AC power source. To confirm that the AC power
plug is inserted correctly, with an AC voltmeter,
measure between the chassis and a known earth
ground. If a voltage reading in excess of 1.0V is
obtained, remove and reinsert the AC power plug
in the opposite polarity and again measure the
voltage potential between the chassis and a
known earth ground.
1-2-1 L0604IMP