PANASONIC PVDF2704
Service Manual

Always discharge the anode of the picture tubeto the CRT ground of receiver before handling 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.
4