HardwareMaintenanceManual
LenovoN42–20Chromebook
HardwareMaintenanceManual
LenovoN42–20Chromebook
FirstEdition(June2016)
©CopyrightLenovo2016.
Contents
Chapter1.Safetyinformation......1
Generalsafety................1
Electricalsafety...............1
Safetyinspectionguide............2
Handlingdevicesthataresensitivetoelectrostatic
discharge..................3
Groundingrequirements............4
Safetynotices(multilingualtranslations)......4
Chapter2.Generalcheckout.....19
Whattodofirst..............19
Checkingtheacpoweradapter........20
Chapter3.IdetifyingFRUs(CRUs)..21
AllFRUs(CRUs)forLenovoN42–20
Chromebook...............21
Chapter4.RemovingaFRUorCRU.25
Generalguidelines.............25
Removetheuppercase(withkeyboard).....25
Removethebatterypack..........26
Removethespeakers............27
RemovetheUSBboard...........28
RemovetheWLAN&Bluetoothcombomodule..29
RemovetheLCDmodule..........29
RemovethesystemboardandtheDC-incable..30
DisassembletheLCDmodule.........32
RemovetheLCDbezel..........32
RemovetheLCDpanel.........33
RemovethecameraassemblyortheLCD&
cameracable.............34
Removethehinges...........35
AppendixA.Lenovopartnumbersfor
replacementFRUs..........37
AppendixB.Lenovopartnumbersfor
CRUsandmiscellaneousparts....39
AppendixC.Labellocations.....43
Trademarks................xlv
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Chapter1.Safetyinformation
Thischapterpresentsthefollowingsafetyinformationthatyouneedtobefamiliarwithbeforeyouservicea
Lenovonotebookcomputer.
Generalsafety
Followtheserulestoensuregeneralsafety:
•Observegoodhousekeepingintheareaofthemachinesduringandaftermaintenance.
•Whenliftinganyheavyobject:
1.Makesurethatyoucanstandsafelywithoutslipping.
2.Distributetheweightoftheobjectequallybetweenyourfeet.
3.Useaslowliftingforce.Nevermovesuddenlyortwistwhenyouattempttolift.
4.Liftbystandingorbypushingupwithyourlegmuscles;thisactionremovesthestrainfromthe
musclesinyourback.Donotattempttoliftanyobjectthatweighsmorethan16kg(35lb)orthat
youthinkistooheavyforyou.
•Donotperformanyactionthatcauseshazardstothecustomer,orthatmakestheequipmentunsafe.
•Beforeyoustartthemachine,makesurethatotherservicetechniciansandthecustomer'spersonnelare
notinahazardousposition.
•Placeremovedcoversandotherpartsinasafeplace,awayfromallpersonnel,whileyouareservicing
themachine.
•Keepyourtoolcaseawayfromwalkareassothatotherpeoplewillnottripoverit.
•Donotwearlooseclothingthatcanbetrappedinthemovingpartsofamachine.Makesurethatyour
sleevesarefastenedorrolledupaboveyourelbows.Ifyourhairislong,fastenit.
•Inserttheendsofyournecktieorscarfinsideclothingorfastenitwithanon-conductiveclip,about8
centimeters(3inches)fromtheend.
•Donotwearjewelry,chains,metal-frameeyeglasses,ormetalfastenersforyourclothing.
Attention:Metalobjectsaregoodelectricalconductors.
•Wearsafetyglasseswhenyouarehammering,drilling,soldering,cuttingwire,attachingsprings,using
solvents,orworkinginanyotherconditionsthatmightbehazardoustoyoureyes.
•Afterservice,reinstallallsafetyshields,guards,labels,andgroundwires.Replaceanysafetydevice
thatiswornordefective.
•Reinstallallcoverscorrectlybeforereturningthemachinetothecustomer.
•Fanlouversonthemachinehelptopreventoverheatingofinternalcomponents.Donotobstructfan
louversorcoverthemwithlabelsorstickers.
Electricalsafety
Observethefollowingruleswhenworkingonelectricalequipment.
Important:Useonlyapprovedtoolsandtestequipment.Somehandtoolshavehandlescoveredwithasoft
materialthatdoesnotinsulateyouwhenworkingwithliveelectricalcurrents.Manycustomershave,near
theirequipment,rubberfloormatsthatcontainsmallconductivefiberstodecreaseelectrostaticdischarges.
Donotusethistypeofmattoprotectyourselffromelectricalshock.
•Findtheroomemergencypower-off(EPO)switch,disconnectingswitch,orelectricaloutlet.Ifanelectrical
accidentoccurs,youcanthenoperatetheswitchorunplugthepowercordquickly.
•Donotworkaloneunderhazardousconditionsornearequipmentthathashazardousvoltages.
•Disconnectallpowerbefore:
–Performingamechanicalinspection
–Workingnearpowersupplies
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–Removingorinstallingmainunits
•Beforeyoustarttoworkonthemachine,unplugthepowercord.Ifyoucannotunplugit,askthecustomer
topower-offthewallboxthatsuppliespowertothemachine,andtolockthewallboxintheoffposition.
•Ifyouneedtoworkonamachinethathasexposedelectricalcircuits,observethefollowingprecautions:
–Ensurethatanotherperson,familiarwiththepower-offcontrols,isnearyou.
Attention:Anotherpersonmustbetheretoswitchoffthepower,ifnecessary.
–Useonlyonehandwhenworkingwithpowered-onelectricalequipment;keeptheotherhandinyour
pocketorbehindyourback.
Attention:Anelectricalshockcanoccuronlywhenthereisacompletecircuit.Byobservingtheabove
rule,youmaypreventacurrentfrompassingthroughyourbody.
–Whenusingtesters,setthecontrolscorrectlyandusetheapprovedprobeleadsandaccessoriesfor
thattester.
–Standonsuitablerubbermats(obtainedlocally,ifnecessary)toinsulateyoufromgroundssuchas
metalfloorstripsandmachineframes.
Observethespecialsafetyprecautionswhenyouworkwithveryhighvoltages;Instructionsforthese
precautionsareinthesafetysectionsofmaintenanceinformation.Useextremecarewhenmeasuring
highvoltages.
•Regularlyinspectandmaintainyourelectricalhandtoolsforsafeoperationalcondition.
•Donotusewornorbrokentoolsandtesters.
•Neverassumethatpowerhasbeendisconnectedfromacircuit.First,checkthatithasbeenpoweredoff.
•Alwayslookcarefullyforpossiblehazardsinyourworkarea.Examplesofthesehazardsaremoistfloors,
non-groundedpowerextensioncables,powersurges,andmissingsafetygrounds.
•Donottouchliveelectricalcircuitswiththereflectivesurfaceofaplasticdentalmirror.Thesurfaceis
conductive;suchtouchingcancausepersonalinjuryandmachinedamage.
•Donotservicethefollowingpartswiththepoweronwhentheyareremovedfromtheirnormaloperating
placesinamachine:
–Powersupplyunits
–Pumps
–Blowersandfans
–Motorgenerators
–Similarunitsaslistedabove
Thispracticeensurescorrectgroundingoftheunits.
•Ifanelectricalaccidentoccurs:
–Usecaution;donotbecomeavictimyourself.
–Switchoffpower.
–Sendanotherpersontogetmedicalaid.
Safetyinspectionguide
Thepurposeofthisinspectionguideistoassistyouinidentifyingpotentiallyunsafeconditions.Aseach
machinewasdesignedandbuilt,requiredsafetyitemswereinstalledtoprotectusersandservicetechnicians
frominjury.Thisguideaddressesonlythoseitems.Youshouldusegoodjudgmenttoidentifypotential
safetyhazardsduetoattachmentofnon-Lenovofeaturesoroptionsnotcoveredbythisinspectionguide.
Ifanyunsafeconditionsarepresent,youmustdeterminehowserioustheapparenthazardcouldbeand
whetheryoucancontinuewithoutfirstcorrectingtheproblem.
Considertheseconditionsandthesafetyhazardstheypresent:
•Electricalhazards,especiallyprimarypower(primaryvoltageontheframecancauseseriousorfatal
electricalshock)
•Explosivehazards,suchasadamagedcathoderaytube(CRT)faceorabulgingcapacitor
•Mechanicalhazards,suchaslooseormissinghardware
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Todeterminewhetherthereareanypotentiallyunsafeconditions,usethefollowingchecklistatthebeginning
ofeveryservicetask.Beginthecheckswiththepoweroff,andthepowercorddisconnected.
Checklist:
1.Checkexteriorcoversfordamage(loose,broken,orsharpedges).
2.Poweroffthecomputer.Disconnectthepowercord.
3.Checkthepowercordfor:
a.Athird-wiregroundconnectoringoodcondition.Useametertomeasurethird-wireground
continuityfor0.1ohmorlessbetweentheexternalgroundpinandtheframeground.
b.Thepowercordshouldbetheauthorizedtypespecifiedforyourcomputer.Goto:
http://www.lenovo.com/serviceparts-lookup
c.Insulationmustnotbefrayedorworn.
4.Checkforcrackedorbulgingbatteries.
5.Removethecover.
6.Checkforanyobviousnon-Lenovoalterations.Usegoodjudgmentastothesafetyofanynon-Lenovo
alterations.
7.Checkinsidetheunitforanyobviousunsafeconditions,suchasmetalfilings,contamination,wateror
otherliquids,orsignsoffireorsmokedamage.
8.Checkforworn,frayed,orpinchedcables.
9.Checkthatthepower-supplycoverfasteners(screwsorrivets)havenotbeenremovedortamperedwith.
Handlingdevicesthataresensitivetoelectrostaticdischarge
Anycomputerpartcontainingtransistorsorintegratedcircuits(ICs)shouldbeconsideredsensitiveto
electrostaticdischarge(ESD).ESDdamagecanoccurwhenthereisadifferenceinchargebetweenobjects.
ProtectagainstESDdamagebyequalizingthechargesothatthemachine,thepart,theworkmat,andthe
personhandlingthepartareallatthesamecharge.
Notes:
1.Useproduct-specificESDprocedureswhentheyexceedtherequirementsnotedhere.
2.MakesurethattheESDprotectivedevicesyouusehavebeencertified(ISO9000)asfullyeffective.
WhenhandlingESD-sensitiveparts:
•Keepthepartsinprotectivepackagesuntiltheyareinsertedintotheproduct.
•Avoidcontactwithotherpeople.
•Wearagroundedwriststrapagainstyourskintoeliminatestaticonyourbody.
•Preventthepartfromtouchingyourclothing.Mostclothingisinsulativeandretainsachargeeven
whenyouarewearingawriststrap.
•Useagroundedworkmattoprovideastatic-freeworksurface.Thematisespeciallyusefulwhen
handlingESD-sensitivedevices.
•Selectagroundingsystem,suchasthoselistedbelow,toprovideprotectionthatmeetsthespecific
servicerequirement.
Note:TheuseofagroundingsystemtoguardagainstESDdamageisdesirablebutnotnecessary.
–AttachtheESDgroundcliptoanyframeground,groundbraid,orgreen-wireground.
–Whenworkingonadouble-insulatedorbattery-operatedsystem,useanESDcommongroundor
referencepoint.Youcanusecoaxorconnector-outsideshellsonthesesystems.
–Usetheroundgroundprongoftheacplugonac-operatedcomputers.
Chapter1.Safetyinformation3
Groundingrequirements
Electricalgroundingofthecomputerisrequiredforoperatorsafetyandcorrectsystemfunction.Proper
groundingoftheelectricaloutletcanbeverifiedbyacertifiedelectrician.
Safetynotices(multilingualtranslations)
Thesafetynoticesinthissectionareprovidedinthefollowinglanguages:
•English
•Arabic
•BrazilianPortuguese
•French
•German
•Hebrew
•Japanese
•Korean
•Spanish
•T raditionalChinese
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