LED显示屏IC脚位功能.docx

LED显示屏IC脚位功能.docx

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LED显示屏IC脚位功能

LED显示屏IC脚位功能

Theroleof74HC245:

signalpoweramplification.

FirstfeetDIR,fortheinputandoutputportconversion,DIR=,"1"highpowersignalbythe"A"endinput"B"sideoutput,DIR="0"lowpowersignalbythe"B"endinput"A"endoutput.

2~9pin"A"signalinputandoutput,A1=B1,,,,,and,A8=B8,A1andB1areagroup,andifDIR="1","G=","0",A1enterB1output,theothersimilar.IfDIR="0","G=","0",B1enterstheA1output,whichissimilar.

The11~18pin"B"signalinputandoutputfunctionisnotthesameasthe"A"end.

NineteenthfeetG,enablingtheend,ifthefootis"1",theA/Bsideofthesignalwillnotbeconnected,onlyfor"0"whentheA/Bterminalisenabled,thefootisplayedtheroleoftheswitch.

TenthfeetGND,powerground.

TwentiethfeetVCC,powerpositive.

Theroleof74HC04:

6bitinverter.

SeventhfeetGND,powerground.

FourteenthfeetVCC,powerpositive.

ThesignalisinputfromtheAterminal,theYendisinvertingoutput,theA1andtheY1areonegroup,andtheotherisanalogous.Example:

A1="1",Y1="0","A1=""0",Y1="1",andothergroupfunctions.

Theroleof74HC138:

eightbitbinarytranslationdecimaldecoder.

EighthfeetGND,powerground.

FifteenthfeetVCC,powerpositive

Pin1~3,A,B,C,binaryinputpins.

The4~6pinchipselectsignalcontrol,onlyin4,5feetto0feet6to1,willbegatedbyA,B,Coutputsignalcontrol.Anyothercombinationwillnotbeselected,andtheY0~Y7outputwillbe"1"".

Cascadethroughcontrolgatingtoextendittosixteenbits.

Example:

G2A=0,G2B=0,G1=1,A=1,B=0,C=0,Y0is"0"and"Y1~Y7"is"1".Seethetruthtablefordetails.

Theroleof74HC595:

LEDdriverchip,8bitshiftlatch.

EighthfeetGND,powerground.

SixteenthfeetVCC,powerpositive

FourteenthfeetDATA,serialdatainput,displaydatafromthisentry,mustbeaccompaniedbyaclocksignalinordertomove.

ThirteenthfeetEN,enablethemouth,whenthepinis"1",theQA~QHportisall"1",andwhen"0",theoutputofQA~QHiscontrolledbytheinputdata.

TwelfthfeetSTB,latchthemouth,whentheinputdataintheincomingregister,onlythesupplyofalatchsignal,inordertomovedatatotheQA~QHportoutput.

EleventhfeetCLK,theclockport,eachclocksignalwillbemovedtoadataregister.

TenthfeetSCLR,resetport,aslongasthereisresetsignal,thedatamovedintheregisterwillbeempty,thescreendoesnotusethisfoot,generallyconnectedtoVCC.

NinthfeetDOUT,serialdataoutput,thedatapassedtothenext.

Fifteenth,1~7feet,paralleloutputport,thatis,thedriveroutput,drivingLED.

4953function:

linedrivetube,powertube.

TheinterioristwoCMOS,1,2,4VCC3feet,2feetfootfootcontrol,outputcontrolof7,8feet,4feet,6feet5controloutput,onlywhenthe2foot,4to0,7,8,5,6willbeoutput,otherwisetheoutputisinthehighimpedancestate.

TheroleofTB62726:

LEDdriverchip,16bitshiftlatch.

FirstfeetGND,powerground.

Twenty-fourthfeetVCC,powerpositive

SecondpinDATA,serialdatainput

ThirdfeetCLK,clockinput

FourthpinSTB,latchedinput

Twenty-thirdpinoutputcurrentadjustmentend,resistanceadjustment

Twenty-secondpinDOUT,serialdataoutput

Twenty-firstfeetEN,enableinput

Otherfunctionsaresimilartothe74HC595,exceptthattheTB62726isa16bitshiftlatchwithanoutputcurrentadjustmentfunction,butthereisnohighlevelontheparalleloutputport,onlythehighimpedancestateandthelowlevelstate.The74HC595paralleloutputporthasahighandlowleveloutput.TheTB62726issimilarinstructuretothe5026pinfunction.

Two,LEDelectronicdisplaycommonsignalunderstanding

CLKclocksignal:

ashiftpulsesuppliedtoashiftregister,eachpulsecausingdatatobemovedinoroutofonebit.Thedataonthedataportmustbecoordinatedwiththeclocksignaltotransmitthedatanormally.Thefrequencyofthedatasignalmustbe1/2timesoftheclocksignal.Inanycase,whentheclocksignalisabnormal,itwillmakethewholeboarddisplaydisorganized.

STBlatchsignal:

thedataintheshiftregisterissenttothelatch,andthedatacontentisilluminatedbythedrivecircuittodisplaytheLED.ButbecausethedrivecircuitiscontrolledbytheENenablesignal,thepremiseofitslightingmustbetomakeitopen.Thelatchsignalalsoneedstobecoordinatedwiththeclocksignaltodisplaythefullimage.Inanycase,whenthelatchsignalisabnormal,itwillcausetheentireboardtodisplayconfusion.

ENenablesignal:

fullscreenbrightnesscontrolsignal,alsousedforscreenblanking.Aslongasthedutycycleisadjusted,thebrightnesschangescanbecontrolled.Whentheenablesignalisabnormal,thewholescreenwillappeardim,dimortrailing.

Datasignal:

thedataneededtoprovidethedisplayimage.Thedatamustbecoordinatedwiththeclocksignaltotransmitdatatoanydisplaypoint.GeneralinthedisplaydatasignalRGBseparated,ifadatasignalisshortedtopositiveornegative,thenthecorrespondingcolorwillappearbrightornotbright,whenthecorrespondingdatasignalissuspendedwhenthecolordisplayisuncertain.

ABCDsignal:

onlyexistsinthedynamicscanningdisplay,ABCDisactuallyabinarynumber,Aisthelowest,ifthebinaryrepresentationofABCDsignaltocontrolthemaximumrangeis16（1111）,1/4scanaslongastheABsignalcanbe,becausetheABsignalrangeis4（11）.Whenthecontrolsignalisabnormal,therewillbeadislocation,highlightorimageoverlapphenomenondisplay.

Three,commontroubleshootingmeans（tools:

multimeter,electriciron,blade,screwdriver,tweezers......Etal.）

Thejudgmentproblemmustbedealtwithfirst,secondandsecond,andtheobviousandseriousfirstshouldbedealtwith.

Shortcircuitshouldbethehighestpriority.

1,resistancedetectionmethod,themultimetertodetectaresistanceprofile,anormalcircuitboardtogroundresistancevalue,andthendetectthesamepointanotherpieceofthesamecircuitboardtestandnormalresistancevaluesaredifferent,ifdifferentfromthescopeoftheproblem.

2,voltagedetectionmethod,themultimetertovoltagefiles,

Detectsthevoltageofapointatapointinasuspectedcircuit,andcompareswhetheritissimilartothenormalvalue.Otherwise,thescopeoftheproblemisdetermined.

3,shortcircuitdetectionmethod,themultimetertoshort-circuitdetectionblock（somefilesorfilediodedropresistance,withalarmfunction）,checkwhetherthereisashort-circuitphenomenon,foundthatafterashortcircuitshouldgiveprioritytosolvingtheproblem,whichdoesnotburnotherdevices.Themethodmustoperateinthecaseofcircuitfailureandavoiddamagetothemeter.

4,thepressuredropmethod,themultimetertodetectdiodedropfiles,becauseallICiscomposedofmanysingleelements,onlysmall,sowhenapinitonacurrentispassed,willbeonthepinvoltagedropexists.Ingeneral,thesametypeofIC,thesamepressuredroponthepin,accordingtothevalueofthepressuredroponthepinisgoodorbad,thecircuitmustbeoperatedinthecaseofpowerfailure.Thismethodhassomelimitations,forexample,whenthedetecteddeviceishighimpedance,itcannotbedetected.

Four、themethodofunitboardroutingandthetreatmentofcommonproblems

1/16unitboardroutingmode:

1/8unitboard,3waysofrouting:

Staticlightplatewiringmode:

**thisisonlypartialrouting.Totheunknownunitboard,itisnecessarytomeasurebeforethemaintenance,toknowitswayofrunning,soastofacilitatethenextstepmaintenance,soastoimproveworkefficiency.

Boardfault:

A.thewholeboardisnotbright

1.Checkwhetherthepowersupplyisconnectedwiththesignalcable.

2,checkwhetherthetestcardtoidentifytheinterfacetestcardisnoredlightflashinglampplaterecognition,checkandtestwhetherthecomponentsofpower,orthelampboardinterfacesignalandshortcircuitleadtotheidentificationofinterface.（intelligenttestcard）

3,thereisnowelddetectionof74HC245shortcircuit,245correspondingenable（EN）signalinputandoutputpinwhetherweldorshortcircuittotheotherline.

Note:

themaincheckpowerandenable（EN）signal.

B.intheobliquescan,theregularlineisnotbright,thescreenoverlap

1,A,B,C,checktheDsignalinputportto245ifthereisadisconnectionorshortcircuit,.

2,detectionof245correspondingA,B,C,Doutputandthe138betweentheshort-circuitorweld.

3,detectA,B,C,D,whetherthesignalbetweentheshortcircuitorasignalandgroundshortcircuit.

Note:

ABCDlinesignalisdetectedmainly.

WhenC.isfull,oneormorelinesarenotlit

1,between138to4953ofthedetectioncircuitisshortcircuitorweld.

WhenD.scans,twoormorelines（usuallymultiplesof2,regular）arelitsimultaneously

1,detectA,B,C,D,whetherthesignalbetweentheshortcircuit.

2.Checkwhetherthe4953outputterminalisshortedtootheroutputterminals.

E.fulllightwithoneormoredots（irregular）notbright

1.Findthecontrolpincorrespondingtothismoduleandmeasureifitisshortedtothebank.

2.Replacemoduleorsinglelight.

WhenF.isfull,oneormorecolumnsarenotlit

1.FindthepinthatcontrolsthecolumnonthemoduleandmeasurewhetheritisconnectedwiththedriveIC（74HC595/TB62726,-）outputterminal.

G.hassingleorsinglecolumnhighlighting,orfulllinehighlighting,andisnotcontrolled

1.Checkwhetherthecolumnisshortcircuitedwiththepowersource.

2.Checkwhetherthelineisshortcircuitedwiththepowersupply.

3,replaceitsdriveIC.

TheH.displaysconfusion,buttheoutputtothenextboardisnormal

1.Checkwhetherthe245STBlatch