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1、NODISK故障分析及排除〃NODISK〃fauItanalysisandeliminationofvideoplayer2001-08-05Theso-calledNODISKfaultis:whenthediscintothemachineforselfinspection,onthescreentodisplayNODISKEnglishcharacters,andthenthemachineisinthe"crash"state,andonlyaccess(EJECT)keycanwork.Th
2、atistosay,whenthemachinebreaksdown,onlythedisccangoinandalltheotherfunctionsarelost・Thiskindoffaultisacommonfaultinthevideoplayer,anditinvolvesawiderange,soitbringsgreatdifficultiestothemaintenancepersonnel・Inaconsiderablenumberofmaintenaneepersonnel,the
3、reisoftenasenseoflossandawe.Nowtheauthorsummarizedinthemaintenanceofthewriting,thispapermakesaroughanalysisofthisfaultforcolleaguesreferenee.ADVDofthetrackingandanalysisprocessAfterthevideoplayerisswitchedon,itscontrolsystemischeckedfirst・Intheselfinspec
4、tionsystemafternormal,thenatrackingcommandtracking・Ifthereisachipinthemachine,theSTOPisdisplayed,otherwisetheNODISKisdisplayed,andthenthemachineentersastopstate・Althoughthestopstateisoneoftheworkingconditionsofthewholemachine,itcanalsoberegardedasaprotec
5、tivemeasureinasense・LearnedfromtheexplorationandResearchontheprocessoftrackingofVCD,DVDtrackingprocesscanbedividedintotwosteps:first,trackingsearchmode・Thisprocessismainlycomposedofalaserheadlightdetectorforthephotosensitivetube,trackinginformationreadsk
6、ewdetectiontubeandrelevantcircuitiscompleted,itsmainroleiswhetherthereisaCDdetectionmachine・Second,thetrackingprogramdirectory.Theprocessisaccomplishedbyaphotosensitivetubethatreadsaudioandvideoinformationfromanopticaldetectoranditscircuitry.Themainfunct
7、ionistoreadtheprogramlistonthedisc・Whenthetwoprocessesarecompletelyover,thecontrolsysteminthemachineconfirmsthatthediscsinthestandardformat(suchasCLV,CAV,CD,CDV,etc・)exist,andthenenterthependingstate・Theactualmechanicalactionstepsareasfollows:first,after
8、theendofthepostplayer,orstopthedisc,thelaserheadstuckinacertainposition(i.e.,thecorrespondingLDdiskdirectorylocation).Secondly,whenthediscintothemachine,thelaserheadfirstinsitutoreadinformationsuchasmobi1etracking,readthro
