Panasonic AG-MD830E Service Manual

SAFETY PRECAUTIONSGENERAL GUIDELINES1. When servicing observe the original lead dress. If a shortcircuit isfound, replac all parts which have been overheatedor damaged by the short circuit.2 . After servici ng, see to it that a II the protectiv devices such asinsulation barriers, insulation papers shields are properlyinstalled.3. After servicing make the following leakage current checksto prevent the customer from bei ng exposed to shockhazards.LEAKAGE CURRENT COLD CHECK1. Unplug the AC cord and connect a jumper between the twoprongs onthe plug.2. Measur the resistance value, with an ohm meter, betweenthe jumpered AC plug and each exposed metallic cabinetpart on the equipment such as screwhead connectors, contrlshafts, etc. When the exposed metallic part has a returnpath to the chassis, the reading shoulb be between 1 M Qand 5.2MQ.When the exposed metal dose not have a return path to thechassis, the read i ng m ust be 00 .AC VOLTMETERHot-Check CircuitTOAPPLIANCE'SEXPOSEDMETAL PARTS0.15,u FFigure 1COLDWATER PIPE(EARTH GROUND)LEAKAGE CURRENT HOT CHECK (See Figure 1)1. Plug the AC cord directly into the AC outlet.Do not use an isolation transformer for this check.2. Connect a 1.5KQ, 10W resistor, inparallel with 0.15,u Fcapacitor, between each exposed metallic part on the set ana good earth grou'nd such as a water pipe, as shown inFigure 1.3. Use an AC voltmeter, with 1000 ohms/volt or moresensitivity, to measur the potential across the resistor.4. Check each exposed metallic part, and measure the voltageat each poi nt.5. Reverse the AC plug in the AC outlet repeat each of theabove measurements.6. The potantial at any point should not exceed 0.75 voltsRMS. A leakage current tester (Simpson Model 229equivalent) may be used to make the hot checks, leakagecurrent must not exceed 1/2 milliamp. In case ameasurement is outside of the limits specified, there is apossiblity of a shock hazard, and the equipment should berepa i red and rechecked before it is returned to thecustomer.ELECTROSTATICALLY SENSITIVE( ES) DEVICESSome semiconductor (solid state) devices can be damagedeasily by static electricity. Such components commonly arecalled Electrostatically sensitive (ES) Devices. Examples oftypical ES devices are integrated circuits and some field-effecttransistors and semiconductor "chip" components. Thefollowing techniques should be used to help reduce theincidence of component damage caused by static electricity.1. Immediately before handling any semiconductorcomponent or semiconductor-equipped assembly, drain offany electrostatic charge on your body by touching a knownearth ground.Alternatively, obtain and wear a commercially availabledischarging wrist strap device, which should be removedfor potential shock reasons prior to applying power to theunit under test.2. After removing an electrical assembly equipped with ESdevices, place the assembly on a conductive surface such asaluminum foil, to prevent electrostatic charge buildup orexposure of the assembly.3. Use only a grounded tip soldering iron to solder orunsolder ES devices.4. Use only an anti-static solder removal device classified as"anti-static" can generate electrical charges sufficient todamage ES devices.5. Do not use freon-propelled chemicals. These can generateelectrical charges sufficient to damage ES devices.6. Do not remove a replacement ES device from its protectivepackage untilimmediately before you are ready to installit. (most replacement ES devices are packaged with leadselectrically shorted together by conductive foam,aluminum foil or comparable conductive material).7. Immediately before removing the protective material fromthe leads of replacement ES device, touch the protectivematerial to the chassis or circuit assembly into which thedevice will be installed.CAUTION: Be sure no power is applied to the chassis orcircuit, and observe all otner asfety precautions.8. Minimize bodily motions when handling unpackagedreplacement ES devoces. (Otherwise harm less mother suchas the brushing together of your clothes fabric or the liftingof your foor from a carpeted floor can generate staticelectricity sufficient to damage an ES device).-2-