Precautions
1-2 Servicing Precautions
CAUTION : Before servicing units covered by this service manual and its supplements, read and follow the Safety Precautions section of this manual.
Note : If unforseen circumstances create conflict between the following servicing precautions and any of the safety precautions, always follow the safety pre- cautions. Remember: Safety First.
1-2-1 General Servicing Precautions
(1)a. Always unplug the instrument’s AC power cord from the AC power source before (1)
b.Do not defeat any plug/socket B+ voltage inter- locks with which instruments covered by this service manual might be equipped.
c.Do not apply AC power to this instrument and /or any of its electrical assemblies unless all
d.Always connect a test instrument’s ground lead to the instrument chassis ground before connect- ing the test instrument positive lead. Always remove the test instrument ground lead last.
Note : Refer to the Safety Precautions section ground lead last.
(2)The service precautions are indicated or printed on the cabinet, chassis or components. When servic- ing, follow the printed or indicated service precau- tions and service materials.
(3)The components used in the unit have a specified flame resistance and dielectric strength.
When replacing components, use components which have the same ratings. Components identi-
fied by shading, by( ) or by ( ) in the circuit dia- gram are important for safety or for the characteris- tics of the unit. Always replace them with the exact replacement components.
(4)An insulation tube or tape is sometimes used and some components are raised above the printed wiring board for safety. The internal wiring is sometimes clamped to prevent contact with heat- ing components. Install such elements as they were.
(5)After servicing, always check that the removed screws, components, and wiring have been in- stalled correctly and that the portion around the serviced part has not been damaged and so on. Further, check the insulation between the blades of the attachment plug and accessible conductive parts.
1-2-2 Insulation Checking Procedure
Disconnect the attachment plug from the AC outlet and turn the power ON. Connect the insulation resi- stance meter (500V) to the blades of the attachment plug. The insulation resistance between each blade of the attachment plug and accessible conductive parts(see note) should be more than 1 Megohm.
Note : Accessible conductive parts include metal pan- els, input terminals, earphone jacks, etc.
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