Panasonic PV 20DF63, Руководство по обслуживанию

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picture tube to the CRT ground of receiver beforehandling the tube.
8. After servicing make the following leakage current checks to
prevent the customer from being exposed to shock hazards.
1.2. LEAKAGE CURRENT COLD CHECK
1. Unplug the AC cord and connect a jumper between the two prongs
on the plug.
2. For physically operated power switches, turn power on. Otherwise
skip step 2.
3. Measure the resistance value, with an ohmmeter, between the
jumpered AC plug and each exposed metallic cabinet part on the
receiver, such as screwheads, connectors, etc. When the exposed
metallic part has a return path to the chassis, the readingshould
be between 1 M and 12 M . When the exposed metal does not
have a return path to the chassis, the reading must be infinity.
1.3. LEAKAGE CURRENT HOT CHECK
1. Plug the AC cord directly into the AC outlet.
Do not use a isolation transformer for this check.
2. Connect a 1.5 k , 10 W resistor, in parallel with a 0.15 F
capacitor, between each exposed metallic part on the set and a
good earth ground, as shown in Figure 1.
3. Use an AC voltmeter, with 1 k /V or more sensitivity, to measure
the potential across the resistor.
4. Check each exposed metallic part, and measure the voltage at
each point.
5. Reverse the AC plug in the AC outlet and repeat each of the above
measurements.
6. The potential at any point should not exceed 0.75 V RMS.
A leakage current tester (Simpson Model 229 equivalent) may be
used to make the hot checks. Leakage current must not exceed 1/2
mA. In case a measurement is outside of the limits specified, there
is a possibility of shock hazard, and thereceiver should be
repaired and rechecked before it is returned to the customer.
Figure 1
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