Manual

Attention:Thedrivestartupsequenceinthecomputeryouareservicingmayhavebeenchanged.Be
extremelycarefulduringwriteoperationssuchascopying,saving,orformatting.Ifyouselectanincorrect
drive,dataorprogramscanbeoverwritten.
IfyourcomputerisshippedwithanmSATAdriveandasolidstatedriveorharddiskdrive,themSATAdrive
willbeseenasharddisk0inthesystem,andassigneddriveC:.Thesolidstatedriveorharddiskdrivewill
beseenasharddisk1,andassigneddriveD:.ThemSATAdriveisinstalledinthewirelessWANcardslotof
thecomputer.TheLenovopreloadedsoftwareisinstalledonthemSATAdrive.
Alwaystrytorunalow-levelformatbeforereplacingaharddiskdrive.Thiswillcauseallcustomerdataon
theharddisktobelost.Besurethatthecustomerhasacurrentbackupofthedatabeforedoingthistask.
Attention:Thedrivestartupsequenceinthecomputeryouareservicingmayhavebeenchanged.Be
extremelycarefulduringwriteoperationssuchascopying,saving,orformatting.Ifyouselectanincorrect
drive,dataorprogramscanbeoverwritten.
Importantnoticeforreplacingasystemboard
Somecomponentsmountedonasystemboardareverysensitive.Improperhandlingofasystemboardcan
causedamagetothosecomponents,andmaycauseasystemmalfunction.
Attention:Whenhandlingasystemboard:
•Donotdropasystemboardorapplyanyexcessiveforcetoit.
•Avoidroughhandlingofanykind.
•AvoidbendingasystemboardandhardpushingtopreventcrackingateachBGA(BallGridArray)chipset.
Howtouseerrormessage
Usetheerrorcodesdisplayedonthescreentodiagnosefailures.Ifmorethanoneerrorcodeisdisplayed,
beginthediagnosiswiththersterrorcode.Whatevercausesthersterrorcodemayalsocausefalseerror
codes.Ifnoerrorcodeisdisplayed,seewhethertheerrorsymptomislistedintheSymptom-to-FRU
Indexforthecomputeryouareservicing.
24ThinkPadT420andT420iHardwareMaintenanceManual