14. Product Safety Notice
Some electrical and mechanical parts have special safety-related characteristics which
might not be obvious from visual inspection.
These safety features and the protection they give might be lost if the replacement
component differs from the original-even if the replacement is rated for higher voltage,
wattage, etc.
Components that are critical for safety are indicated in the circuit diagram by
shading( )
Use replacement components that have the same ratings, especially for flame
resistance and dielectric strength specifications. A replacement part that does not have
the same safety characteristics as the original might create shock, fire or other hazards.
1-2. Servicing Precautions
Warning 1First read the "Safety Precaution"section of the manual.
If some unforeseen circumstance creates a conflict between the servicing and
safety precautions, always follow the safety precaution.
Warning 2An electrolytic capacitor installed with the wrong polarity might explode.
1. Servicing Precautions are printed on the cabinet. Follow them.
2. Always unplug the units AC power cord from the AC power source before attempting
to (a) Remove or reinstall any component or assembly, (b) Disconnect an electrical
plug or connector, (c) Connect a test component in parallel with an electrolytic capacitor.
3. Some components are raised above the printed circuit board for safety.
An insulation tube or tape is sometimes used. The internal wiring is sometimes clamped
to prevent contact with thermally hot components.
Reinstall all such elements to their original position.
4. After servicing, always check that the screws, components and wiring have been
correctly reinstalled. Make sure that the portion around the serviced part has not been
damaged.
5. Check the insulation between the blades of the AC plug and accessible conductive parts
(examplesmetal panels,. input terminals).
6. Insulation Checking ProcedureDisconnect the power cord from the AC source and
turn the power switch ON. Connect an insulation resistance meter (500V) to the blades of
the AC plug.
The insulation resistance between each blade of the AC plug and accessible conductive
parts (see above) should be greater than 1 megohm.
7. Never defeat any of the B+ voltage interlocks. Do not apply AC power to the unit (or any
of its assemblies) unless all solid-state heat sinks are correctly installed.
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ACEC
HITACHI
