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IMPORTANT SAFETY PRECAUTIONS
4. Hot Chassis Warning—a. Some Monitor chassis are electrically connected directly to one conductor of the
AC power cord and may be safely serviced without an isolation transformer 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 opposite
polarity and again measure the voltage potential between the chassis and a known earth ground. b. Some
Monitor chassis normally have 85V AC (RMS.), between chassis and earth ground regardless of the AC plug
polarity. These chassis can be safely serviced only with an isolation transformer inserted in the power line
between the receiver and the AC power source, for both personnel and test equipment protection. c. Some
Projection Monitor chassis have a secondary ground systems in addition to the main chassis ground. This
secondary ground system is not isolated from the AC power line. The two ground system are electrically
separated by insulating material that must not be defeated or altered.
5. Observe original lead dress. Take extra care to assure correct lead dress in the following areas: a. near
sharp edges, b. near thermally hot parts—be sure that leads and components do not touch thermally hot
parts, c. the AC supply, d. high voltage, e. antenna wiring. Always inspect in all areas for pinched,
out-of-place, or frayed wiring. Do not change spacing between components, and between components and
the printed-circuit board. Check AC power cord for damage.
6. Components, parts, and/or wiring that appear to have overheated or are otherwise damaged should be
replaced with components, parts, or wiring that meet original specifications. Additionally, determine the
cause of overheating and/or damage and, if necessary, take corrective action to remove any potential safety
hazard.
7. PRODUCT SAFETY NOTICE—Many Monitor electrical and mechanical parts have special safety-related
characteristics some of which are often not evident from visual inspection, nor can the protection they give
necessarily be obtained by replacing them with components rated for higher voltage, wattage, etc. Parts that
have special safety characteristics are identified in this service data by shading with a
schematics and by shading or a ＊ mark in the parts list. Use of a substitute replacement part that does not
have the same safety characteristics as the recommended replacement part in this service data parts list
might create shock, fire, and/or other hazards.
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