ThinkPad T420s - Page 49

2.Removethebatterypack.
3.Connecttheacpoweradapter.
4.Checkthatpowerissuppliedwhenyouturnonthecomputer.
5.Turnoffthecomputer.
6.Disconnecttheacpoweradapterandinstallthechargedbatterypack.
7.Checkthatthebatterypacksuppliespowerwhenyouturnonthecomputer.
Ifyoususpectapowerproblem,seetheappropriateoneofthefollowingpowersupplycheckouts:
•“Checkingtheacpoweradapter”onpage43
•“Checkingoperationalcharging”onpage44
•“Checkingthebatterypack”onpage44
•“Checkingthebackupbattery”onpage44
Checkingtheacpoweradapter
Youareherebecausethecomputerfailsonlywhentheacpoweradapterisused.
•Ifthepowerproblemoccursonlywhenthedockingstationortheportreplicatorisused,replacethe
dockingstationortheportreplicator.
•Ifthepower-onindicatordoesnotturnon,checkthepowercordoftheacpoweradapterforcorrect
continuityandinstallation.
•Ifthecomputerdoesnotchargeduringoperation,goto“Checkingoperationalcharging”onpage44.
Tochecktheacpoweradapter,dothefollowing:
1.Unplugtheacpoweradaptercablefromthecomputer.
2.Measuretheoutputvoltageattheplugoftheacpoweradaptercable.Seethefollowingfigure:
Pin
Voltage(Vdc)
1+20
20
3
Ground
1
2
3
(20V)
Note:Outputvoltageacrosspin2oftheacpoweradaptermightdifferfromtheoneyouareservicing.
3.Ifthevoltageisnotcorrect,replacetheacpoweradapter.
4.Ifthevoltageisacceptable,dothefollowing:
•Replacethesystemboard.
•IftheproblempersistsandyoursystemsupportsthePCdoctorforDOS,goto“FRUtests”on
page39
.
Note:Noisefromtheacpoweradapterdoesnotalwaysindicateadefect.
Chapter3.Generalcheckout43