TipsandtricksonrepairingLCDmonitorsIf youareastudent like I am,sometimes it just tooexpensive tobuynewhardware.Andwhy should you? There aremany companies, faculties that throw away used nonworkingequipment.HereIwillshowyouhowyoucanrepairusedLCDmonitorspracticlyforfree.

InthepastyearorsoImanagedtorepairabout50LCDmonitorsoutof60, that Isourcedaround my town. From my experience I can tell you, that you can have a working LCDmonitorinunder20minutespracticlyforfreewithnoprofesionaltoolsrequired.

LCDmonitorsarenot thatcomplicatedassomeofyouthink.Theyaremadefrom4parts:LCDmodule,mainboard,switchedregulatedpowersupply(SMPS)andbuttonboard.

Frommyexperience,themainfaultsare:85%faultycapacitors10%faultyinverters5%otherissues(faultybuttons,mainboard,LCDmodule,CCFL,FETs)

Fixing this problems is very easy and very cheap.You can get capacitors and buttons inyourlocalelectronicsstore.Invertersaresometimesaproblemtoget,butebaywillprobablyhavetheoneyouarelookingforanditspriceisaround5$.

TherearemanydifferentbrandsofLCD.ThemostcommonareSamsung,LG,HPandDell.And they are all more or less the same. You should also know the fact that many LCDmodulesarecompatible.Forexample,IreplacedanLCDmodulefromHPtoSamsunganditwas a perfect fit. This is because themodules are basicly samedimensions and sameLVDSconnectorforalltypes.SadlyitisnotthesameformainboardsandSMPS.Buthey,SMPScanbefixedandmainboardsandLCDmodulesareveryrarelydefective.LCDissuescanprobablytellyouwhichpartisfaulty.Soletsgotothesymptons:

1.LCDlightsupforlessthen5seconds,thenitgoesblank(checkifyoucanseepicture):itcouldbedeadcapacitorsontheinverterlowvoltageline(highprobability)itcouldbeafaultyinverter(lowprobability)itcouldbeafaultycoldcathodflourescenttubeinsideLCDmoduleCCFL(veryrare)2.LCDpowerLEDblinksbutmonitordoesnotlightup:itcouldbedeadcapacitorsonthe5Vlogiclinetothemainboard(highprobability)itcouldbefaultymainboard(veryrare)itcouldbeadeadLCDmodule(veryrare)3.LCDturnson,thepictureisfuzzy:itcouldbefaultycapacitorsonSMPS(highprobability)itcouldbedefectivemainboard(lowprobability)itcouldbedefectiveLCDmodule(veryrare)flexcablesintheLCDmodulehaveaweakconnection(veryrare)LVDScableisdefective(veryrare)4.LCDturnson,backlightturnson,butgrayorwhitescreenappears:LCDmoduleisdefective(highprobability)poorconnectionofLVDScable(veryrare)5.LCDemmitsstrangebuzzsounds:deadcapacitorsorinverters(highprobability)

faultyCCFL(lowprobability)6.LCDworksok,butsometimesitseemslikethatbuttonsarepressedfornoreason(OSDmenuappears):faultybuttons(highprobability)faultymainboard(veryrare)7.LCDappearstobecompletlydead(noLEDsignallight)itcouldbefaultycapacitorsonthe5Vlogicline(highprobability)itcouldbethefuseonSMPS(rareandprobablyforareason)itcouldbefaultymainboard(veryrare)

These simptoms can tell you very much of your fault. Now lets beggin with ourdissasembly...Ihada17"Samsungmonitor,withanissuenumber1.

LCDs are encased in plastic housing which is hold together with few screws and a clicksistem. This is probably the tricky part of disassembly. When you remove the housing,carefullyremovetheLCDmodule.Butbeforeyouproceed,unplugtheCCFLcablesfromtheSMPSboardthathidebehindametalshield.

Metalshield

http://dl.dropbox.com/u/29967719/LCD%20repair/shield.JPG

When you are finished with CCFL cables, unscrew the LCD module and carefully unplugLVDScablefromthemodule.NowyouhaveafullviewofthemainboardandSMPS.

BE CAREFULL! The big capacitor on the mains voltage line on SMPS could still becharged.Somakesureyoudischargeitbeforeproceeding.

Now that youaredonewith that, unscrew theSMPSand look for faults. Inmost casesadeadcapacitorisvisible.Butifthereisnovisualsignofafault,replaceallcapacitorsontheSMPS.Thiswill fixall yourproblems inmost cases. I also recomend that you replaceallcapacitorsonvoltagelinesonSMPSeveniftheyappeartobegood.

Unplugthesecables

Electronics

http://dl.dropbox.com/u/29967719/LCD%20repair/lcd.JPGhttp://dl.dropbox.com/u/29967719/LCD%20repair/ccfl.JPG