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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
exposed metal does not have a return path to the chassis, the
reading must be
1.1.2. LEAKAGE CURRENT HOT CHECK (See
1. Plug the AC cord directly into the AC outlet. Do not use an
isolation transformer for this check.
2. Connect a 1.5k
capacitors, between each exposed metallic part on the set and a
good earth ground such as a water pipe, as shown in
3. Use an AC voltmeter, with 1000 ohms/volt or more sensitivity, to
.
Figure 1
, 10 watts resistor, in parallel with a 0.15
5
and 5.2M
. / When the
Figure 1
.)
F
Figure 1
.
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