Panasonic TX-21S1T Service Manual

Also see for TC-14S1R: Operating instructions

Panasonic TX-21S1T Service Manual Manual pdf 2 page image

BX—21511/1C-21351RVELSMeSs onContentsSafety Precautions ...... Fed diode as act tected ve Metrutes DatsLocation of Controls 0.2... ... ccc cece cece eee eee e eee eeeSENWICE- POSTION v.30.c. hee co aa cohenteys bade ae ak ies CassAdjustment Procedure ............cece cece eee eee eee ee eeeeeBlock: Diagrams: sseces wed Sats eatice ew tw ete es whee SeenConductor VIEWS .......0.0 ccc cece een ee teen ee eeeanesSchematic DiagraMs ......... 0... eee cece eee eee eee eeeExploded VIOWS ......-.. cc cece cee e cece e een e eee e eee e eensParts iStick dadee wadne bee ee ieee a yee OE ee Saw EN es ON ee eeeSafety PrecautionsGeneral Guide Lines1. It is advisable to insert an isolation transformer in the ACsupply before servicing a hot chassis.2. When servicing, observe the original lead dress in the highvoltage circuits. If a short circuit is found, replace all partswhich have been overheated or damaged by the shortcircuit.3. After servicing, see that all the protective devices such asinsulation barriers, insulation papers, shields and isolationR—C combinations are correctly installed.4. When the receiver is not being used for a long period oftime, unplug the power cord from the AC outlet.5. Potentials as high as 26.4Kv kV are present when thisreceiver is in operation. Operation of the receiver withoutthe rear cover involves the danger of a shock hazard fromthe receiver power supply. Servicing should not beattempted by anyone who is not familiar with theprecautions necessary when working .on high voltageequipment. Always discharge the anode of the picture tothe chassis before handling the tube.6. After servicing make the following leakage current checksto prevent the customer from being exposed to shockhazards.Leakage Current Cold Check1. Unplugthe AC cord andconnect ajumper between thetwoprongs of the plug.Turn on the receiver's power switch.Measure the resistance value with an ohmmeter, betweenthe jumpered AC plug and each exposed metallic cabinetpart on the receiver, such as screw heads, aerials ,connectors, control shafts etc. When the exposed metallicpart has a return path to the chassis the reading should bebetween 4M Q and 20M Q. When the exposed metal doesnot have a return path to the chassis the reading must beinfinite.Leakage Current Hot Check1. Plug the AC cord directly into the AC outlet. Do not use anisolation transformer for this check.2. Connect a 2k ohm 10W resistor in series with an exposedmetallic part on the receiver and an earth such as a waterpipe.3. Use an AC voltmeter with high impedance to measure thepotential across the resistor.4. Check each exposed Metallic partand checkthe voltage ateach point.5. Reverse the AC plug at the outlet and repeat each of theabove measurements.6. The potential at any point should not exceed 1.4 Vrms. Incase ameasurementis outside the limits specified, there isa possibility of a shock hazard, and the receiver should berepaired and rechecked before it is returned to thecustomer.HOT CHECK CIRCUITA.C. VoltmeterWater PipeTo Instrument’s|(Earth)exposedmetallic parts 2K ohm 10WFig.1X—Radiation Warning1. The potential sources of X—Radiation in TV sets are thehigh voltage section and the picture tube.2. Whenusingapicture tube testjigfor service ensure thatthejig is capable of handling 28.0 kV(21S1 Series) and 23kV(14S1 Series) without causing X— Radiation.NOTE : itis important to use an accurate periodically calibratedhigh voltage meter 21. Set the brightness to minimum.2. Measure the high voltage. The meter should indicate:—26.4Kv + 1.5 kV (2181 Series)21.5Kv + 1.5 kV (1481 Series)ifthe meterindicationis out oftolerance, immediate serviceand correction is required to prevent the possibility ofpremature component failure.3. To prevent an X—Radiation possibility, itis essential to usethe specified tube.