
HardwareMaintenanceManual
ThinkPadL420,L421,andL520

Note
Beforeusingthisinformationandtheproductitsupports,besuretoreadthegeneralinformationunder
AppendixA“Notices”onpage155
.
SixthEdition(March2012)
©CopyrightLenovo2011,2012.
LIMITEDANDRESTRICTEDRIGHTSNOTICE:IfdataorsoftwareisdeliveredpursuantaGeneralServicesAdministration
“GSA”contract,use,reproduction,ordisclosureissubjecttorestrictionssetforthinContractNo.GS-35F-05925.

Contents
Aboutthismanual...........iii
Chapter1.Safetyinformation......1
Generalsafety................1
Electricalsafety...............2
Safetyinspectionguide............3
Handlingdevicesthataresensitivetoelectrostatic
discharge..................3
Groundingrequirements............4
Safetynotices(multilingualtranslations)......4
Lasercompliancestatement(multilingual
translations)................17
Chapter2.Importantservice
information..............25
StrategyforreplacingFRUs.........25
Strategyforreplacingaharddiskdrive...26
Importantnoticeforreplacingasystem
board................26
Howtouseerrormessage........26
StrategyforreplacingFRUsforCTO,CMV ,and
GAV...................26
Productdenition............26
FRUidenticationforCTO,CMV ,andGAV
products...............27
Chapter3.Generalcheckout.....29
Whattodorst..............29
Checkoutguide..............30
SystemsupportingtheLenovoThinkVantage
ToolboxprogramandthePC-DoctorforDOS
diagnosticsprogram..........30
SystemsupportingtheLenovodiagnostics
programs...............34
Powersystemcheckout...........36
Checkingtheacpoweradapter......36
Checkingoperationalcharging......37
Checkingthebatterypack........37
Checkingthebackupbattery.......38
Chapter4.Relatedservice
information..............39
RestoringthefactorycontentsbyusingRecovery
DiscSet.................39
Passwords................40
Power-onpassword...........40
Hard-diskpassword...........40
Supervisorpassword..........41
Howtoremovethepower-onpassword...41
Howtoremovethehard-diskpassword...41
Powermanagement............42
Screenblankmode...........42
Sleep(standby)mode..........42
Hibernationmode...........43
Symptom-to-FRUindex...........43
Numericerrorcodes..........44
Errormessages............46
No-beepsymptoms...........46
LCD-relatedsymptoms.........46
Intermittentproblems..........47
Undeterminedproblems.........47
Chapter5.Statusindicators.....49
Chapter6.Fnkeycombinations...51
Chapter7.FRUreplacement
notices................55
Screwnotices...............55
Retainingserialnumbers...........56
Restoringtheserialnumberofthesystem
unit.................56
RetainingtheUUID...........56
ReadingorwritingtheECAinformation...57
Chapter8.Removingandreplacinga
FRU..................59
1010Batterypack.............59
1020ExpressCardblankbezelandMediaCard
blankbezel................60
1030Opticaldriveortravelcover.......62
1040Thermalcover.............63
1050Harddiskdriveorsolidstatedrive
assembly.................64
1060DIMM................67
1070Fanassembly.............67
1080CPU................70
1090SIMslotcover............71
1110WirelessWANslotcoverandPCIExpress
MiniCardforwirelessWAN..........72
1110mSATAsolidstatedrive.........73
1120Palmrestassemblywithcables......75
1130PCIExpressMiniCardforwirelessLAN..78
1140Backupbattery............80
1150Bluetoothdaughtercard........80
1160MediaCardReaderslotboardandMedia
CardReadercableassembly.........81
©CopyrightLenovo2011,2012
i

1170Keyboard..............83
1180Keyboardbezel............85
1190LCDunit...............87
2010T opshieldingassembly.........90
2020Systemboardassembly.........92
2030USBconnectorboardandUSBcable
assembly.................98
2040DC-incableandbasecover.......99
2050LCDfrontbezel............102
2060Speakerassembly...........103
2070Integratedcamera...........104
2080Antennaassembly...........105
2090Hinges,LCDpanel,LCDcable,andLCDrear
coverassembly..............107
Chapter9.Locations........111
Frontview................111
Rearview.................112
Bottomview...............112
Keyboard.................142
Miscellaneousparts............143
acpoweradapters.............145
Powercords...............145
Recoverydiscs..............146
WindowsXPProfessionalDVDs......146
WindowsVistaBusiness(32bit)DVDs...147
WindowsVistaHomeBasic(32bit)DVDs..148
Windows7HomeBasic(32bit)DVDs....148
Windows7HomeBasic(64bit)DVDs....149
Windows7HomePremium(32bit)DVDs..149
Windows7HomePremium(64bit)DVDs..150
Windows7Professional(32bit)DVDs....151
Windows7Professional(64bit)DVDs....151
Windows7Starter(32bit)DVDs......153
Windows7Ultimate(32bit)DVDs.....153
Windows7Ultimate(64bit)DVDs.....154
Commonservicetools...........154
Chapter10.Partslist........113
Overall..................114
LCDFRUs................137
AppendixA.Notices.........155
Electronicemissionsnotices.........156
Trademarks................156
iiHardwareMaintenanceManual

Aboutthismanual
ThismanualcontainsserviceandreferenceinformationforthefollowingThinkPad
ThinkPadL420
MachineType(MT)7826,7827,7829,7853,7854,and7856
ThinkPadL421
MT7826,7827,7829,7853,7854,and7856
ThinkPadL520
MT5015,5016,5017,5019,7859,and7860
®
Notebookproducts.
Usethismanualalongwiththeadvanceddiagnosticteststotroubleshootproblems.
Important:
ThismanualisintendedonlyfortrainedservicetechnicianswhoarefamiliarwithThinkPadproducts.Use
thismanualalongwiththeadvanceddiagnosticteststotroubleshootproblemseffectively.
BeforeservicingaThinkPadproduct,besuretoreadalltheinformationunderChapter1“Safety
information”onpage1
andChapter2“Importantserviceinformation”onpage25.
©CopyrightLenovo2011,2012
iii

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Chapter1.Safetyinformation
Thischapterpresentsfollowingsafetyinformationthatyouneedtobefamiliarwithbeforeyouservice
aThinkPadNotebook.
•“Generalsafety”onpage1
•“Electricalsafety”onpage2
•“Safetyinspectionguide”onpage3
•“Handlingdevicesthataresensitivetoelectrostaticdischarge”onpage3
•“Groundingrequirements”onpage4
•“Safetynotices(multilingualtranslations)”onpage4
•“Lasercompliancestatement(multilingualtranslations)”onpage17
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.
•Inserttheendsofyournecktieorscarfinsideclothingorfastenitwithanonconductiveclip,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.
©CopyrightLenovo2011,2012
1

Electricalsafety
Observethefollowingruleswhenworkingonelectricalequipment.
Important:
Useonlyapprovedtoolsandtestequipment.Somehandtoolshavehandlescoveredwithasoftmaterial
thatdoesnotinsulateyouwhenworkingwithliveelectricalcurrents.
Manycustomershave,neartheirequipment,rubberoormatsthatcontainsmallconductivebersto
decreaseelectrostaticdischarges.Donotusethistypeofmattoprotectyourselffromelectricalshock.
•Findtheroomemergencypower-off(EPO)switch,disconnectingswitch,orelectricaloutlet.Ifanelectrical
accidentoccurs,youcanthenoperatetheswitchorunplugthepowercordquickly.
•Donotworkaloneunderhazardousconditionsornearequipmentthathashazardousvoltages.
•Disconnectallpowerbefore:
–Performingamechanicalinspection
–Workingnearpowersupplies
–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
metaloorstripsandmachineframes.
Observethespecialsafetyprecautionswhenyouworkwithveryhighvoltages;Instructionsforthese
precautionsareinthesafetysectionsofmaintenanceinformation.Useextremecarewhenmeasuring
highvoltages.
•Regularlyinspectandmaintainyourelectricalhandtoolsforsafeoperationalcondition.
•Donotusewornorbrokentoolsandtesters.
•Neverassumethatpowerhasbeendisconnectedfromacircuit.First,checkthatithasbeenpoweredoff.
•Alwayslookcarefullyforpossiblehazardsinyourworkarea.Examplesofthesehazardsaremoistoors,
nongroundedpowerextensioncables,powersurges,andmissingsafetygrounds.
•Donottouchliveelectricalcircuitswiththereectivesurfaceofaplasticdentalmirror.Thesurfaceis
conductive;suchtouchingcancausepersonalinjuryandmachinedamage.
•Donotservicethefollowingpartswiththepoweronwhentheyareremovedfromtheirnormaloperating
placesinamachine:
–Powersupplyunits
–Pumps
–Blowersandfans
–Motorgenerators
–Similarunitstolistedabove
Thispracticeensurescorrectgroundingoftheunits.
•Ifanelectricalaccidentoccurs:
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–Usecaution;donotbecomeavictimyourself.
–Switchoffpower.
–Sendanotherpersontogetmedicalaid.
Safetyinspectionguide
Thepurposeofthisinspectionguideistoassistyouinidentifyingpotentiallyunsafeconditions.Aseach
machinewasdesignedandbuilt,requiredsafetyitemswereinstalledtoprotectusersandservicetechnicians
frominjury.Thisguideaddressesonlythoseitems.Y oushouldusegoodjudgmenttoidentifypotential
safetyhazardsduetoattachmentofnon- ThinkPadfeaturesoroptionsnotcoveredbythisinspectionguide.
Ifanyunsafeconditionsarepresent,youmustdeterminehowserioustheapparenthazardcouldbeand
whetheryoucancontinuewithoutrstcorrectingtheproblem.
Considertheseconditionsandthesafetyhazardstheypresent:
•Electricalhazards,especiallyprimarypower(primaryvoltageontheframecancauseseriousorfatal
electricalshock)
•Explosivehazards,suchasadamagedCRTfaceorabulgingcapacitor
•Mechanicalhazards,suchaslooseormissinghardware
Todeterminewhetherthereareanypotentiallyunsafeconditions,usethefollowingchecklistatthebeginning
ofeveryservicetask.Beginthecheckswiththepoweroff,andthepowercorddisconnected.
Checklist:
1.Checkexteriorcoversfordamage(loose,broken,orsharpedges).
2.Poweroffthecomputer.Disconnectthepowercord.
3.Checkthepowercordfor:
a.Athird-wiregroundconnectoringoodcondition.Useametertomeasurethird-wireground
continuityfor0.1ohmorlessbetweentheexternalgroundpinandtheframeground.
b.Thepowercordshouldbethetypespeciedinthepartslist.
c.Insulationmustnotbefrayedorworn.
4.Checkforcrackedorbulgingbatteries.
5.Removethecover.
6.Checkforanyobviousnon-ThinkPadalterations.Usegoodjudgmentastothesafetyofany
non-ThinkPadalterations.
7.Checkinsidetheunitforanyobviousunsafeconditions,suchasmetallings,contamination,wateror
otherliquids,orsignsofreorsmokedamage.
8.Checkforworn,frayed,orpinchedcables.
9.Checkthatthepower-supplycoverfasteners(screwsorrivets)havenotbeenremovedortamperedwith.
Handlingdevicesthataresensitivetoelectrostaticdischarge
Anycomputerpartcontainingtransistorsorintegratedcircuits(ICs)shouldbeconsideredsensitiveto
electrostaticdischarge(ESD.)ESDdamagecanoccurwhenthereisadifferenceinchargebetweenobjects.
ProtectagainstESDdamagebyequalizingthechargesothatthemachine,thepart,theworkmat,andthe
personhandlingthepartareallatthesamecharge.
Notes:
1.Useproduct-specicESDprocedureswhentheyexceedtherequirementsnotedhere.
Chapter1.Safetyinformation3

2.MakesurethattheESDprotectivedevicesyouusehavebeencertied(ISO9000)asfullyeffective.
WhenhandlingESD-sensitiveparts:
•Keepthepartsinprotectivepackagesuntiltheyareinsertedintotheproduct.
•Avoidcontactwithotherpeople.
•Wearagroundedwriststrapagainstyourskintoeliminatestaticonyourbody.
•Preventthepartfromtouchingyourclothing.Mostclothingisinsulativeandretainsachargeevenwhen
youarewearingawriststrap.
•Useagroundedworkmattoprovideastatic-freeworksurface.Thematisespeciallyusefulwhen
handlingESD-sensitivedevices.
•Selectagroundingsystem,suchasthoselistedbelow,toprovideprotectionthatmeetsthespecic
servicerequirement.
Note:TheuseofagroundingsystemtoguardagainstESDdamageisdesirablebutnotnecessary.
–AttachtheESDgroundcliptoanyframeground,groundbraid,orgreen-wireground.
–Whenworkingonadouble-insulatedorbattery-operatedsystem,useanESDcommongroundor
referencepoint.Youcanusecoaxorconnector-outsideshellsonthesesystems.
–Usetheroundgroundprongoftheacplugonac-operatedcomputers.
Groundingrequirements
Electricalgroundingofthecomputerisrequiredforoperatorsafetyandcorrectsystemfunction.Proper
groundingoftheelectricaloutletcanbeveriedbyacertiedelectrician.
Safetynotices(multilingualtranslations)
Thesafetynoticesinthissectionareprovidedinthefollowinglanguages:
•English
•Arabic
•BrazilianPortuguese
•French
•German
•Hebrew
•Japanese
•Korean
•Spanish
•T raditionalChinese
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Lasercompliancestatement(multilingualtranslations)
Thelasercompliancestatementsinthissectionareprovidedinthefollowinglanguages:
•English
•Arabic
•BrazilianPortuguese
•French
•German
•Hebrew
•Japanese
•Korean
•Spanish
•T raditionalChinese
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