Panasonic TC-21Z88RB Service Manual

Panasonic TC-21Z88RB Service Manual Manual pdf 3 page image

insulation 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,unplug the power cord from the AC cord outlet.5. Potential, as high as 27.0kV is present when this receiver is inoperation. Operation of the receiver without the rear coverinvolves the danger of a shock hazard from the receiver powersupply. Servicing should not be attempted by anyone who is notthoroughly familiar with the precautions necessary when workingon high voltage equipment. Always discharge the anode of thepicture tube to the receiver chassis before handling the tube.After servicing make the following leakage current checks toprevent the customer from being exposed to shock hazards.1.2. Leakage Current Cold Check1. Unplug the AC cord and connect a jumper between the twoprongs on the plug.2. Turn on the receiver’s power switch. / Measure the resistancevalue, with an ohmmeter, between the jumper AC plug and eachexposed metallic cabinet part on the receiver, such as screwheads, aerials, connectors, control shafts, etc. When the exposedmetallic part has a return path to the chassis, the reading shouldbe between 4 M and 20 M . When the exposed metal does nothave a return path to the chassis, 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 anisolation transformer for this check.2. Check a 2 k non-inductive resistor and an AC/DC current meter,in series with each exposed metallic part on the receiver in turnand an earth such as a water pipe.The current from any point should not exceed 0.7 mA peak AC or2 mA DC. In the case of a measurement being outside of theselimits specified, there is a possibility of a shock hazard and thereceiver should be repaired and rechecked before it is returned tothe customer.3