1-2 Servicing Precautions
Warning1: First read the �Safety Precautions� section of this manual. If some unforeseen circumstance creates a conflict between the servicing and safety precautions, always follow the safety precautions. Warning2: An electrolytic capacitor installed with the wrong polarity might explode. 1. Servicing precautions are printed on the cabinet. Follow them. 2. Always unplug the unit�s 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 (examples: metal panels, input terminals and earphone jacks). 6. Insulation Checking Procedure: Disconnect 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. 8. Always connect a test instrument�s ground lead to the instrument chassis ground before connecting the positive lead; always remove the instrument�s ground lead last.
