Panasonic TX-29FX20R Service Manual

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Panasonic TX-29FX20R Service Manual Manual pdf 3 page image

1. It is advisable to insert an isolation transformer in the AC supply beforeservicing this hot chassis.2. When servicing, observe the original lead dress, especially the leaddress in the high voltage circuits. If a short circuit is found, replace allparts which have been overheated or damaged by the short circuit.3. After servicing, see to it that all the protective devices such asinsulation barriers, insulation papers, shields and isolation R-Ccombinations, are properly installed.4. When the receiver is not to be used for a long period of time, unplugthe power cord from the AC cord outlet.5. Potential, as high as 32.0kV is present when this receiver is inoperation. Operation of the receiver without the rear cover involves thedanger of a shock hazard from the receiver power supply. Servicingshould not be attempted by anyone who is not thoroughly familiar withthe precautions necessary when working on high voltage equipment.Always discharge the anode of the picture tube to the receiver chassisbefore handling the tube. After servicing make the following leakagecurrent checks to prevent the customer from being exposed to shockhazards.1.2. Leakage Current Cold Check1. Unplug the AC cord and connect a jumper between the two prongs onthe plug.2. Turn on the receiver’s power switch. / Measure the resistance value,with an ohmmeter, between the jumper AC plug and each exposedmetallic cabinet part on the receiver, such as screw heads, aerials,connectors, control shafts, etc. When the exposed metallic part has areturn path to the chassis, the reading should be between 4 M and 20M . When the exposed metal does not have a return path to thechassis, the reading must be infinite.1.3. Leakage Current Hot Check (Fig. 1)1. Plug the AC cord directly into the AC outlet. Do not use an isolationtransformer for this check.2. Check a 2 k non-inductive resistor and an AC/DC current meter, inseries with each exposed metallic part on the receiver in turn and anearth such as a water pipe.3