FLY Q120 TV User manual

Q120 TVMaintenance Manual
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Q120 TVMaintenance Manual
Document Name Q120 TVMaintenanceManual
Version V1.0
Draft date
Documentcode

Q120 TVMaintenance Manual
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TableofContents
1. Circuitdiagraminstruction.................................................................................3
1.1Mainboardexploredview...........................................................................3
1.2DetailedDescriptionofCircuitChart.........................................................4
1.3RFcircuit.....................................................................................................4
1.4Basebandcircuit.........................................................................................5
1.5Functioncircuit............................................................................................6
2Faultmaintenance..............................................................................................8
3Troubleshootingand flowchart...........................................................................9
3.1Unabletopoweronthehandset..................................................................9
3.2Noringtone...............................................................................................10
3.3LCD display fault......................................................................................11
3.4Chargingfault............................................................................................12
3.5Camerafault..............................................................................................13
3.6FailtoidentifySIMcard...........................................................................14
3.7MICfault...................................................................................................15
3.8Keypadfault..............................................................................................16
3.9Receiverfault.............................................................................................17
3.10 Vibratefault.............................................................................................18
3.11FMfault....................................................................................................19
3.12 Nosignal...................................................................................................20
3.13 FailuretoidentifyT-flashcard................................................................21
3.14 Earphonefault.........................................................................................22
3.15 UnabletouseUSB...................................................................................23

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1. Circuit diagraminstruction
1.1Mainboardexploredview

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1.2DetailedDescriptionofCircuitChart
1.3RFcircuit
ThisphoneisdesignedonMTK6252 platform.RFmainchipisintergradedinto
MT6252, PAuse RPF88162B-TB,TCXO uses26MHzcrystaloscillator.
(1)Receivingcircuit
TheGSMorDCSsignalreceivedfromabasestationviaantennaisinputtedfrom
thepinU102 27,andsenttoMT6252.Thesignalsareamplifiedbytheirown
low-noiseamplifier(LNA).Theamplifiedsignalissenttoadownconverter,where
thesignalismixedwithlocaloscillation(LO)outputfromRXVCOtogeneratezero
intermediatefrequency(ZIF)signals.Thezero-IFsignalpassesthroughafilterandis
amplifiedbyprogrammablegainamplifier(PGA), thenthesignalis outputtedtoIand
QdemodulatortogenerateI/Qbasebandsignals.ThedemodulatedIandQbaseband
signalsareoutputtedtothebasebandpartforfurtherprocessing.
(2) Transmittingcircuit
AtransmitterconsistsofI/Qmodulationcircuit,up-conversionmixercircuit,
poweramplifierandduplexswitch.TheI/Qsignalisinputtedtobeperformedsignal
modulationasthemodulationsignal.ThemodulatedTXIFsignalrestrainitsthird
harmonicbyharmonicsuppressionfilter.Thefollow-upTXIFsignalwillbesenttoa
discriminatorontheoffsetfrequencyphaselockloop(OPLL).Thenperform
射频PA
U102
高频滤波
器U103 CPU
U201
摄像头
按键板
马达
SIM卡
SIM卡切换
开关
麦克
扬声器
LCD
蓝牙 FM
RFPA+switch
U102
HighFrequencyFilter
U103/U104/U105
SIMcard
Switch
BlueTooth
Speaker
MIC
Camera
Keypad
Board
Motor
CPU
U202
SIMcard

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frequencydiscriminationtothissignalandthemixedsignalofTXVCOsignaland
RFVCOoutputsignal.ThediscriminatoroutputsthesignalcontrolRFVCOand
RFVCOphaseisenabledtolockatthephaseofTXIFsignal.TXVCOoutputRFis
stilldecidedbyRFVCOfrequency.ThephasesofRFVCOandIFVCOsignalslockat
thephaseofVCTXO reference signal.TheTXsignaloutputtedbyU102 pin11/12 is
transmittedtotheantennaviaantennaswitchtolaunch.
1.4Base bandcircuit
BaseBandadoptsMT6252A/B. .
MT6252 internalschematicblockdiagram

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1.5Functioncircuit
FMcircuit
U802 FMreceiving chip RDA5802E

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BTcircuit
U701 BTreceiverchip MT6612CN-L

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2Fault maintenance
Note:
ThePCBArepairing isaveryimportantworkduringthefinalproductionofcellular
phones. Thespeedandqualityofrepairing decides theyieldandproductionefficiency.
Therepairidea isveryimportantforagoodrepairing technician.Makesurenotto
heataboardrightawayonce aphonereachesathand.

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3 Troubleshooting and flowchart
3.1Unabletopoweronthehandset

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3.2Noringtone

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3.3LCD displayfault

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3.4Chargingfault

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3.5Camerafault
Checkcamerafordamage
Failuretousecamera
OK
Replacenewcamera
Yes
Checkifcameraissolderedor
assembledwell
No
Yes Soldercameraconnector
orRe-assemblecamera
Checkcameracircuitforfault
No
Yes Markthemainboard
withanalysisresult
Replacenewmainboard
No

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3.6Fail toidentifySIMcard

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3.7MICfault

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3.8Keypadfault
Check:DOMEispastedand
keymatisassembledcorrectly
Keypaddoesn’twork
correctly
OK
PastetheDOME or
assemblekeymatagain
Yes
Isthereanydirtyonkeypad
surface?
No
Yes Cleankeypadsurfaceand
test
No
Replace newmainboard
No
Issidekeysolderedwell?
Noshortcircuit Yes Solderorreplacesidekey

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3.9Receiverfault
Isreceiverok?
Nobrokenwire
Novoiceinreceiver
OK
Replace newreceiverNo
Checkreceiverconnectorfor
soldering defect
Yes
Yes Solderreceiverconnector
No
Replacenewmainboard
No
Checkreceivercircuitforany
fault Yes Markthemainboardwith analysisresult

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3.10 Vibrate fault

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3.11FMfault

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3.12 Nosignal
IsRFantenna assembledcorrectly?
NoRFsignal
OK
Re-assemble BTanntenaNo
Isthe phone setintoFlying
mode?
Yes
Yes ReturntoNormalmode
No
Replace newmainboard
No
CheckRFcircuit forany fault Yes Markthemainboardwith
analysisresult