ThinkPad T420 - Page 57

•LenovowillnotprovidereplacementiftheLCDiswithinspecicationaswecannotguaranteethatany
replacementLCDwillhavezeropixeldefects.
•OnepixelconsistsofR,G,Bsub-pixels.
Table6.LCD-relatedsymptoms
Symptomorerror
FRUoraction,insequence
Nobeep,power-onindicatoron,andablankLCDduring
POST.
Systemboard.
•LCDbacklightnotworking.
•LCDtoodark.
•LCDbrightnesscannotbeadjusted.
•LCDcontrastcannotbeadjusted.
1.ReseattheLCDconnectors.
2.LCDassembly.
3.Systemboard.
•LCDscreenunreadable.
•Charactersmissingpixels.
•Screenabnormal.
•Wrongcolordisplayed.
1.Seeimportantnotefor“LCD-relatedsymptoms.”
2.ReseatallLCDconnectors.
3.LCDassembly.
4.Systemboard.
HorizontalorverticallinesdisplayedonLCD.LCDassembly.
Chapter4.Relatedserviceinformation51
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