Panasonic PT-50LCZ70 Service Manual

Also see for LIFI PT-50LCZ7: Operating instruction Operating instructions Service manual

Contents

1 Safety Precautions1.1. General Guidelines1. For continued safety, no modification of any circuit shouldbe attempted.2. Disconnect AC Plug before disassembling this unit.3. It is advisable to use an isolation transformer in the ACsupply before servicing.4. When servicing, observe the original lead dress. If a shortcircuit is found, replace all parts which have beenoverheated or damaged by the short circuit.5. After servicing, see to it that all the protective devices suchas insulation barriers, insulation papers, shield, andisolation R-C combinations etc. are properly installed.6. After servicing, be sure to restore the wires, leads,insulation barriers, shields, etc.7. After servicing, make the leakage current checks to preventthe customer from being exposed to shock hazards.Caution:Use a separate Isolation Transformer for this unit whenservicing.1.2. Leakage Current Cold Check1. Unplug the AC cord and connect a jumper between the twoprongs on the plug.2. For physically operated power switches, turn power on.Otherwise skip step 2.3. Measure the resistance value, with an ohmmeter, betweenthe jumpered AC plug and each exposed metallic cabinetpart on the receiver, such as screwheads, connectors, etc.When the exposed metallic part has a return path to thechassis, the reading should be between 1 MΩ and 12 MΩ.When the exposed metal does not have a return path to thechassis, the reading must be infinity.1.3. Leakage Current Hot Check1. Plug the AC cord directly into the AC outlet.Do not use an isolation transformer for this check.2. Connect "A" to exposed metallic part on the set. Andconnect "B" to a good earth ground, as shown in Figure 1.3. Use an AC voltmeter, with 1 kΩ/V or more sensitivity, tomeasure the potential across the resistor.4. Check each exposed metallic part, and measure thevoltage at each point.5. Reverse the AC plug in the AC outlet and repeat each of theabove measurements.6. The potential at any point should not exceed 0.25 V RMS.A leakage current tester (Simpson Model 228 equivalent)may be used to make the hot checks. Leakage current mustnot exceed 1/2 mA. In case a measurement is outside ofthe limits specified, there is a possibility of shock hazard,and the receiver should be repaired and rechecked beforeit is returned to the customer.Figure 11.4. Disposal Lamp3PT-50LCZ70 / PT-56LCZ70 / PT-61LCZ70 / PT-50LCZ7 / PT-56LCZ7 / PT-61LCZ7