TCL T728 User manual
TCLT728 ServiceManual
TCLMobileCommunication CO., Ltd
1 页共32 页
T728 Service Manual
(GSMCellularPhone)
TCL MobileCommunicationCO., Ltd, China
July8, 2005
1stEdition
ForUsebyAuthorizedService/Maintenance PersonOnly
DocumentstoReceiveThisAddendum:
T728 Maintenance/Repair/OperatingManual
PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.com.cn
TCLT728 ServiceManual
TCLMobileCommunication CO., Ltd
2 页共32 页
Preface
ThisistheElectronicService Manualforthe GSMDigitalCellularTelephonefrom
TCLMobileCommunicationCO.,Ltd. Itcontainsspecificinformationonrepairand
testprocedures.
Fordetailson userfunctions, generaloperation and installation, pleaserefertotheUserGuide.
PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.com.cn
TCLT728 ServiceManual
TCLMobileCommunication CO., Ltd
3 页共32 页
Contents:
Precautions forRepair Work.....................4
Chapter1 Introduction ...............................6
1.1 Layout.................................................................................................................................6
1.2 Introduction.........................................................................................................................6
Chapter2Assembleand disassemble..............7
2.1 Schematicprocess ofdisassembly......................................................................................7
2.2 Theprocess ofassembly...................................................................................................16
Chapter3LogicPart...........................17
3.1 PMICMT6305.................................................................................................................17
3.2 CPUMT6205Bdescription..............................................................................................18
3.3 PowerON Control............................................................................................................18
3.4 ChargeCircuit...................................................................................................................20
3.5 Backlightcircuit forLCD................................................................................................20
3.6 Motorcircuit.....................................................................................................................20
3.7 AudioPart.........................................................................................................................20
3.8 LCDdisplayingcircuit......................................................................................................21
3.9 SIMCardcircuit...............................................................................................................21
Chapter4RF Part..............................22
4.1 RXPart.............................................................................................................................23
4.2 TXPart..............................................................................................................................24
4.3 PowerAmplifier................................................................................................................24
Chapter5ToolsandFAQ........................25
5.1 Tools..................................................................................................................................25
5.2 NoPowerOn....................................................................................................................25
5.3 NoDisplay........................................................................................................................26
5.4 Nobacklight......................................................................................................................27
5.5 NO transmitting................................................................................................................29
5.6 Noring tone......................................................................................................................30
5.7 Novibration......................................................................................................................30
5.8 NoNetwork......................................................................................................................31
PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.com.cn
TCLT728 ServiceManual
TCLMobileCommunication CO., Ltd
4 页共32 页
Precautions forRepairWork
(Providesgeneralguidelinesforundertakingsafeandefficientrepairwork.)
Pleasereadthefollowingcautions, notesandwarningsbeforeanyrepairaction.
l ACPowerCord：
Don tshortthepinstogetherwhenyouuse.
Don tdamagetheACpowercord.
Don tputtheACpowercordnearthefiresource.
Takecareabouttheinputpowerspecify.
l BatteryPack：
Don tshorttheterminalstogether.
Don tputbatterypacknearthefiresource.
Onlyusethestandardbatteryandcharger.
l Componentpolarity：
Pleasecheckthecomponentspolaritybeforesoldering
l ESD：
Semiconductordevicesareeasilydamagebyelectricdischarge
ToprotectthesedrivesfromESDawriststrapconnectedtogroundmust
beworn.Inadditiontothisworksurfacemustbecoveredwithan
anti-electrostaticmat, whichshouldbegrounded.
l Grounding：
Eachtestequipmentshouldhaveelectricallygrounding,thethirdpin
provideasafetyfeature.Ensuretheelectricaloutletcontainsgrounding
featureandconnecttoground
l SolderingandDe-soldering：
Firstthesoldering-iron（orhotairtools）shouldhaveESDprotective
featureandfixedthetemperatureabout300℃.
ThesolderingtipshouldnotbeincontactwithcomponentsorPCB tracks
forlongerthan2seconds.
Beforesolderingandde-soldering ensurethecellularphoneispoweroff
anddisconnectedfromthepowersource.
HeatthepadonthePCB andthelead,accuratelyandquicklyapplysolder,
removeheatandcool.
Aftersolderingisfinished,ensurethatall solderjointsareofgoodquality
suchasnodryjoints, solderbridges, cracksorexcess solder.
Aftersolderingisfinished, useacottonclothtocleanPCB.
l Testequipmentcalibration：
PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.com.cn
TCLT728 ServiceManual
TCLMobileCommunication CO., Ltd
5 页共32 页
Thetestequipmentshouldbecalibratedbeforeusedandshouldbe
calibrationperiodical.
l Cleaning：
Beforesolderingandde-soldering ensurethecellularphoneispoweroff
anddisconnectedfromthepowersource.
Useasoftcottonclothtocleancellularphone ssurface.
Neverusebenzeneoranyotherchemicaltocleancellularphone.
l Confidential：
Thecircuitrywithinthiscellularphonecontainsseveralcomponentswhich
areregardedascompanyconfidential.Only TCL specifiedpartsas
replacements.
l RFinjury：
ToavoidRFinjury,directexposuretoradiofrequencyenergyshouldbe
avoid.
ToavoidRFinjury, donottouchtheantennadirectly.
l PCB handling：
Itisrecommendthatcottonglovesarewornduringrepairwork.
Don tcrashconnectorfinger
PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.com.cn
TCLT728 ServiceManual
TCLMobileCommunication CO., Ltd
6 页共32 页
Chapter1Introduction
1.1 Layout
1.2 Introduction
T728 usesthesolutionofMediaTek(MTK)，its basebandpartiscomposedofCPU
MT6205 andPMIC MT6305。TheRFpartiscomposedofthetransceiverMT6129
andtheamplifierRF3146。Itsahighintegratedandvaluedfunction-price-ration
platform。
PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.com.cn
TCLT728 ServiceManual
TCLMobileCommunication CO., Ltd
7 页共32 页
Chapter2Assemble and disassemble
2.1Schematicprocess ofdisassembly
1、Removethetwoscrewsfromthephonewithascrewdriver.
2、Useaplectrumtoseparatethebasetopcasingfromthebasebottomcasing toward
thebackdirectionatfirst.Takecarethattherearetwobucklesoneachside.
Plectrum
PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.com.cn
TCLT728 ServiceManual
TCLMobileCommunication CO., Ltd
17 页共32 页
Chapter3Logic Part
3.1PMICMT6305
TheseriesofT728 mobilephonesusethepowermanagementchipMT6305, whichisthe
energysupplystationofthewholemobilephone sworking.Itisnotonlyplayingthevery
importantroleinthecircuitofmobilephones, butalsoitisoneofobjectstowhichweneedtopay
muchattention.Exclusionthebadness ofIC,thevoltagefiltrationwavenetworksoftheinputand
outputpartsplayanimportantroletothesystemworking.Thepowersupplypartsofdifferent
mobilephoneshaverespectivecharactersbuttheyhavemuchincommon. Soweneedtoanalyze
thespecificcircuit ofthemobilephones.Generallyspeaking,theworkingprinciplesofthepower
managementchipisthatthevoltagescausedbytransitionoftheseveralpowersupplymodules
supplypowertodifferentpartsofthemobilephonesuchasreceiving,transmitting,logic,display
etc.ifoneofthevoltagetransitionmodulescan tworkwell,thentherelativepartwill have
trouble.
MT6305 Features：
1、Handlesall GSMBaseband PowerManagement
2、2.8Vto5.5VInputRange
3、Chargeinputup to15V
4、SevenLDOsoptimizedforSpecificGSMSubsystems
5、High Operation efficiencyand lowstand-bycurrent
6、Li-Ion and NiMHbatterychargefunction
7、SIMCardInterface
8、Three open-DrainoutputswitchestocontroltheLED,Alerterand vibrator
9、Thermaloverloadprotection
10、Power-on resetand start-up timer;
11、48PinQFNpackage
Generaldescription
MT6305 isapowermanagementsystemchipoptimizedforGSMhandsets,especially
thosebasedontheMediaTekMT620Xsystemsolution.ItcontainssevenLDOS,oneto
powereachofthecriticalGSMsub-blocks.Sophisticatedcontrolsareavailablefor
power-upduringbatterycharging,keypadinterface,andRTCalarm.TheMT6305 is
optimizedformaximumbatterylife,featuringagroundcurrentofonly107uAonly107uA
and 187uAwhenthephoneisstandbyand operation respectively.。
ForPINconfiguration ofMT6305, pleasesee thefollowing figure:
PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.com.cn
TCLT728 ServiceManual
TCLMobileCommunication CO., Ltd
18 页共32 页
3.2CPUMT6205Bdescription
General:
1. Dual –corearchitecture
2. Integratedvoice-band and baseband analog frontends
3. 0.18umlow-leakageCMOSprocess, 1.8Vcorevoltage
4. TFBGA12mm*12mm 0.8mm pitch181 package
3.3PowerONControl
1) Signalvoltageforswitchingon
Therearetwokindsofwaystoswitchon thehandset: Onewayisthehigh-level-on. Inthiscase,
thesignalfromapressing ofon/off key triggerthecircuittoconnecttothebattery, andthe
handsetturnson;theotherwayislowlevelon. Inthiscase, thesignalfromapressing of
on/off key triggerthecircuittoconnecttoground, andturnsthehandseton. General
PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.com.cn
TCLT728 ServiceManual
TCLMobileCommunication CO., Ltd
19 页共32 页
speaking, ifoneendofon/off keyconnectstogroundinawholeelectriccircuit
diagram, thishandsethasalow-level-onsystem;otherwiseithasahigh-level-on
systemifoneendofon/off keyconnectstoabatteryinthewholeelectriccircuit
diagram. Thethree necessaryfactors, whichahandsetmusthave, are:powersupply,
signalofreset, andsignalofclock. Ifgettingagainthesoftware, thencanrealize to
turnthehandset.
T728 hasalow-level-on system. Thesignalforswitching on ahandsetisadirectcurrent voltage,
beingtopress theon/off key;itshouldbejumpedbyhighvoltagetoalowone. (Oris
eventojumpthehighvoltagefromthelowone). Canuseamultimeteror
oscillographtoformorshowthissignal. Pressingtheon/off key, observingthis
voltageshouldhavetheevenofhighandlowlevel, otherwise, itindicatesthatthe
on/off keyortheswitchoncircuitworkimproperlyoften, thencanproceedthe
examinationtothesepartsrespectively.
2)Theprocess ofswitching on
Ahandsetpacksabattery,normalconjunctionhereafter,thevoltageofbattery
VbatprovidespowertothepowermanagementIC---- MT6305,pressingon/off key,
starttheMT6305(U400)working,outputtheVcore-1.8V 、Vio-2.8V 、
Vmem-1.8Vor2.8V 、Vsim-1.8V 、Vrtc-1.5V、Va-2.8V、Vtcxo-2.8Vetc.Thesepower
supplygivespowertoeachpartsofelectriccircuitsofahandset,atthesametime
fromtheMT6305 24th pintheRESETsignalrestorethesystem,thehandsetis
placedintoaturningonstatus. All of Vcore、Vmem 、VrtcaresenttowardsCPUMT6205
togiveitspowersupply, theVtcxosupplypowertoacrystalmarkedwithU603 atthe
sametime,theU603producesabasissignalfromthe3rdpintowardsaIntermediate
Frequency(MT6129),afterdisposedbyMT6129,itwillsendtotheCPUMT6205B.
Witharestoredsystem,aftertheCPUgettheinformationthateverypartsofcircuits
worknormally, theCPUsendoutamaintaining signalBBWAKEUPtothe33rd pinof
PMIC,tomaintainthehandsetworking,makehandsetcancontinuetoworkingafter
looseningtheon/off key. Till nowthishandsetcompleteawholeswitch-onprocess.
3) Theprocess ofshutting down
Whileahandsetstayinginanormalidlemode, pressingtheon/off key, thepower
managementICU400 outputstheRESET signaltorestorethesystem, thesignalof
KEYON changesintoalowlevel. IftheCPUdetectedthatthislowlevellaststwo
seconds, itwill starttheprocedureofshuttingdownthephone, breakthesignal
BBWAKEUP thatletthephonekeepoperating. Looseningtheon/off key, theMt6305
stopworking, all thevoltagemoduleshutdown, all thebacklightandtheanimation
disappearimmediately.Now, thewholeshuttingdownprocess completes.
PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.com.cn
TCLT728 ServiceManual
TCLMobileCommunication CO., Ltd
20 页共32 页
3.4ChargeCircuit
Thechargingofabatteryisunderthecontrolofthechargingprocedureandthepower
managementIcU400. Withachargerinserting toachargingport,ifthehandsetisplacedin
workingstatus,thenbeinusethechargingproceduredirectly.If ahandsetisbeingplacedin
power=offstatus, the1stpinofU400 detectsthevoltagesignalforcharging first,thenstartsevery
circuit ofworkingpowersupplyofU400, the6thpinofU400 outputacharging –detectingsignal
CHRDETtowardtheCPU.TheCPUacceptsthissignal,startsthecharging-procedureofa
handset(displayingtheiconofchargeetc.)andoutputsacontrolling signalCHRCNTLtothe5th
pinofU400. Whileconnectingacharger,thelevelofthe4thpinofU401 changesfromlowto
highandmakestheU401 work.Andthenthecurrentpass throughtheD414, thebeginning
proceedstochargingabattery.Whenbatteryisfull andthe4thpinofU400 detectsthesituation,
thenthe2sec pinofU400 outputaswitch-offsignaltomaketheU401 shutdown,thecharging
procedureiscompleted.Inthefollowingdiagram,the4thpinofU400isusedtodetectthedegree
ofthecharging currenttoavoidthedamageofbatterywhilethereisatoo high current.
3.5Back lightcircuitforLCD
T728 isabartypephonewithaB/WLCD.TheBacklightcircuit forLCDissimple,andis
composedwithtwoLBD, whichisunderthecontrolofanenablesignalLCD-BLfromMT6305.
3.5.1 KEYLEDcircuit
ThebacklightforkeyiscontrolledbytheLEDsignalfromthe41stpinof
U400(MT6305).thereisa100Ωresistance followingwitheveryLEDinaserialway.Whenthe
LEDsignalisinalowlevel, thatmeansthecommon cathodeoftheLED(forkeyboard)hasalow
level, frombutmakekeyboardlightorderedbright.
3.6Motorcircuit
TheenablesignalforMotor(VIBEN)comesfromtheGPI015 J5ofCPUMT6205. Afterthe
signalissenttothe34thpinofU400 MT6305, it isamplifiedintheinsideofU400, andthen
the38th pinofU400 sendouttheVIBsignaltothecathodeend oftheMotor.If thisVIBsignal
isalowlevel,themotorvibrates;whileit isahighlevel,theMotorwillstopvibrating.The
functionofD705 istoprotecttheMotorwhilethereisconverse electromotiveforce
producedbythevibratingofMotor.
3.7AudioPart
3.7.1 Receiver&Speaker
TheT728 phoneadoptsawaythatSpeaker&Receiveruniteasone.Thetherearetwo
PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.com.cn
Table of contents
Other TCL Cell Phone manuals
