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1. SAFETY PRECAUTIONS
1.1. GENERAL GUIDELINES 1. When servicing, observe the original lead dress. If a short circuit is found, replace all parts which have been overheated or damaged by the short circuit. 2. After servicing, see to it that all the protective devices such as insulation barriers, insulation papers shields are properly installed. 3. After servicing, make the following leakage current checks to prevent the customer from being exposed to shock hazards.
1.1.1. LEAKAGE CURRENT COLD CHECK
1. Unplug the AC cord and connect a jumper between the two prongs on the plug. 2. Measure the resistance value, with an ohmmeter, between the jumpered AC plug and each exposed metallic cabinet part on the equipment such as screwheads, connectors, control shafts, etc. When the exposed metallic part has a return path to thechassis, the reading should be between 1M and 5.2M . / When the exposed metal does not have a return path to the chassis, the reading must be .
Figure 1
1.1.2. LEAKAGE CURRENT HOT CHECK (See Figure 1 .)
1. Plug the AC cord directly into the AC outlet. Do not use an isolation transformer for this check. 2. Connect a 1.5k , 10 watts resistor, in parallel with a 0.15 F capacitors, between each exposed metallic part on the set and a good earth ground such as a water pipe, as shown in Figure 1 .
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