NAD T512C Service Manual

NAD T512C Service Manual Manual pdf 5 page image

1-4SERVICING PRECAUTIONSCAUTION : Before servicing the DVD covered by this servicedata and its supplements and addends, read and follow theSAFETY PRECAUTIONS. NOTE : if unforeseen circum-stances create conflict between the following servicing pre-cautions and any of the safety precautions in this publica-tions, always follow the safety precautions.Remembers Safety First:General Servicing Precautions1. Always unplug the DVD AC power cord from the ACpower source before:(1) Removing or reinstalling any component, circuit board,module, or any other assembly.(2) Disconnection or reconnecting any internal electricalplug or other electrical connection.(3) Connecting a test substitute in parallel with an elec-trolytic capacitor.Caution : A wrong part substitution or incorrectpolarity installation of electrolytic capacitors may resultin an explosion hazard.2. Do not spray chemicals on or near this DVD or any ofits assemblies.3. Unless specified otherwise in this service data, cleanelectrical contacts by applying an appropriate contactcleaning solution to the contacts with a pipe cleaner,cotton-tipped swab, or comparable soft applicator.Unless specified otherwise in this service data, lubricationof contacts is not required.4. Do not defeat any plug/socket B+ voltage interlocks withwhitch instruments covered by this service manual mightbe equipped.5. Do not apply AC power to this DVD and/or any of itselectrical assemblies unless all solid-state device heatsinks are cerrectly installed.6. Always connect test instrument ground lead to theappropriate ground before connection the test instrumentpositive lead. Always remove the test instrument groundlead last.Insulation Checking ProcedureDisconnect the attachment plug from the AC outlet and turnthe power on. Connect an insulation resistance meter(500V)to the blades of the attachment plug. The insulation resis-tance between each blade of the attachment plug and acces-sible conductive parts (Note 1) should be more than 1M-ohm.Note 1 : Accessible Conductive Parts including Metal pan-els, Input terminals, Earphone jacks, etc.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 fieldeffect transistors and semiconductor chip components.The following techniques should be used to help reduce theincidence of component damage caused by static electricity.1. Immediately before handling any semiconductor compo-nent or semiconductor-equipped assembly, drain off anyelectrostatic charge on your body by touching a knownearth ground. Alternatively, obtain and wear a commer-cially available discharging wrist strap device, whichshould be removed for potential shock reasons prior toapplying power to the unit under test.2. After removing an electrical assembly equipped with ESdevices, place the assembly on a conductive surface suchas aluminum foil, to prevent electrostatic charge buildup orexposure of the assembly.3. Use only a grouned-tip soldering iron to solder or unsolderES devices.4. Use only an anti-static solder removal device. Somesolder removal devices not classified a “anti-static” cangenerate electrical charges sufficient to damage ESdevices.5. Do not use freon-propelled chemicals. These cangenerate electrical charge sufficient to damage ESdevices.6. Do not remove a replacement ES device from its protective package until immediately before you are ready toinstall it. (Most replacement ES devices are packaged withleads electrically shorted together by conductive foam,aluminum foil, or comparable conductive material).7. Immediately before removing the protective material fromthe leads of a 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 other safety precautions.8. Minimize bodily motions when handling unpackagedreplacement ES devices. (Normally harmless motion suchas the brushing together of your clothes fabric or the liftingof your foot from a carpeted floor can generate static elec-tricity sufficient to damage an ES device.)