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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, ensure that all the protective devices such as
insulation barriers and insulation papers shields are properly installed.
3. After servicing, check for leakage current checks to prevent 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. Using an ohmmeter measure the resistance value, 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 the chassis, the reading
should be between 1M
not have a return path to the chassis, the reading must be
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
capacitor, between each exposed metallic part on the set and a good
and 5.2M
, 10 watts resistor, in parallel with a 0.15
. / When the exposed metal does
Fig. 1
4
.
F
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