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LG Electronics U250 service manual Checking VC-TCXO Block, Schematic of the VC-TCXO Block

Models: U250

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4. TROUBLE SHOOTING

4.4 Checking VC-TCXO Block

The reference frequency (19.2MHz) from X100 (VC-TCXO) is used in UMTS TX part, GSM part and BB part.

TCXO

X100

DSA321SCE-19.2M

VREG_TCXO_2.85V

TP1

C181		0.1u	C182		1000p
C181		0.1u	C182		1000p

TP4

7	NC3	NC2
8	NC4	NC1
3	OUTPUT GND
4	VCC	VCONT
	19.2MHz

6

5

2

1

100ohm R124

C183	BT 2.85V
0.01u	BT 2.85V
	VREG_

TRK_LO_ADJ

TP2

C185 100p

TCXO_PM

C187 1000p

RTR6275_TCXO

TP3

		R128	100K
				VCC
	C188	0.01u		5
	C188	0.01u	2	4
			2	4
		U104		3
		TC7SH04FU		GND

C186

1000p

TCXO_BT

Schematic of the VC-TCXO Block

TP3

TP4

TP2

TP1

Test Point of the VC-TCXO Block

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LG Electronics U250 service manual Checking VC-TCXO Block, Schematic of the VC-TCXO Block, Test Point of the VC-TCXO Block

Contents

U250/KU250 Table Of Contents Page Purpose Regulatory InformationInterference and Attenuation PicturesElectrostatic Sensitive Devices Specification System OverviewEnvironment Accessory Transmitter GSM ModeUsable environment Radio PerformanceCase of DCS a 1710, B Case of PCS a 1850, B Power Tolerance Transmitter Wcdma Mode Specification3Receiver GSM Mode Receiver Wcdma Mode Current Consumption U250/KU250 Current ConsumptionStand by Voice Call Level ChangeBattery BAR Indication StandbySound Pressure Level Test Item SpecificationCharging Block diagram of RF part General DescriptionTechnical Brief Antenna Switch Module Control logic GSM ModeGSM Receiver Technical Brief RTR6275 RX feature GSM Transmitter GSM Transmitter matchingReceiver Umts ModeTransmitter RTR6275 IC functional block diagram Off-chip RF Components LO generation and distribution circuitsWcdma PAM U103 WS2512-TR1G Front-End Module U500 D5011 Vctcxo X100 DSA321SCE-19.2MFront End Module control logic Pmic Functional Block Diagram U300 PM6650-2M UsbotgMSM6245 Interface PM6650 Block Diagram GSM PAM Schematic GSM PAM U101 SKY77318Umts DuplexerFL104ACMD-7602 Wcdma Rx SAW Filter Specification Umts Rx RF filter FL103 EFCH2140TDE1Bluetooth M100 LBRQ-2B43A MSM6245 Bluetooth BasebandDigital BasebandDBB/MSM6245 General DescriptionPM6650 RTR6275Nand Flash Block DiagramMSM6245512Mbit 76inch SubsystemMSM6245 Wcdma R99 featuresARM Microprocessor Subsystem Gprs features GSM featuresEdge features Supported interface features MSM6245 device audio processing featuresMSM6245 microprocessor subsystem Supported multimedia features Video telephony services QvideophoneTMQcameraTM QtvTMSummary of MSM6245 device features Description of RF configurations Stereo Wideband Codec Mode Select and Jtag InterfacesVocoder Subsystem Uart General-Purpose Input/Output InterfaceUSB General Power Block2. PM6650 12 PM6650 Functional Block Diagram 13 U250/KU250 Battery Bar DisplayStand By Condition Charging controlTrickle Charging Parameter Min Typ Max Unit Trickle Current 100Constant Current Charging Constant Voltage ChargingExternal memory interface Table#1. External memory interface512Mb 64MBDATA310 DQM30RF Interface 11 H/W Sub SystemRTR6275WCDMATx, GSMTx/Rx Others MSM Sub System Usim InterfaceGPIOMap Name Table. Uart InterfaceTable. USB Signal Interface USBHKADCHouse Keeping ADC Table. Hkadc channel tableKey Pad Table. Key Matrix Mapping Table21 Camera Socket Type Connector Camera InterfaceCAMDATAOUT3 Dvdd 22 Schematic of KEY back light circuit KEY side Keypad LightLCD Module NM176CN1 Tovis Display & LCD FPC InterfaceAudio Signal Processing & Interface 24 Audio Interface Detailed DiagramMSM6245MSM6245 Codec pins 25 Audio part schematicsMIC Audio part schematics Audio AMPAudio Mode Main Features LG-U250/KU250 Main featuresLogic Audio Bluetoot SW100 U101 U500 FL101 U100 FL104 U103 X100 Logic / Audio U301 S300Trouble Shooting RF ComponentUmts Signal Pathumts RF Signal Pathgsm RF Checking VC-TCXO Block Schematic of the VC-TCXO BlockTest Point of the VC-TCXO Block Check C312 of Pmic U300 Check R213 of MSM U201 Checking Front-End Module Block Schematic of the Front-End Module BlockTest Point of the Front-End Module Block Logic Table of the FEM Checking Umts Block For testing, Max power of UMT 2100 is neededChecking Tx level Trouble Shooting Checking Umts PAM Control Block PAM control signal Checking RF Rx Level TP2 TP4Trouble Shooting Checking GSM Block Schematic of RF Tx level Checking RF Tx levelTrouble Shooting Checking PAM Block TP1 TP4 TP2TP3Checking RF Rx Block TP1. DCS RX InputTrouble Shooting Checking Bluetooth Block BluetoothSignals exits? Change the M100 Signals exits?Start Change the Main boardPower on Troubleshooting Vregmsmc Vregmsme Vregmsmp Charger Troubleshooting ChargerConnection OK? Change the board Charger Troubleshooting FlowChange TA Or USB Cable Q301 Q302Charging part Main PCB Front USB Troubleshooting Go to power on trouble shootingCable is inserted? Insert cable Q400 pin 4 is 5V? Check Q300 pinSIM Detect Troubleshooting Start Re-insert the SIM cardYes EndUsim Camera Troubleshooting StartYes Camera is OK? Yes Check the CammclkYes Change the Main board 103U303C348 C349 C350 C447 U501104 Keypad Backlight Troubleshooting Figure.Keypad backlight LED part 105Main LCD Troubleshooting 106Receiver Path 107108 Headset path 109110 Speaker phone path 111112 Main microphone 113114 Headset microphone 115116 Work well? Yes End Vibrator117 118 U250/KU250 Download Downloading ProcedureIntroduction Connecting to PC 120EraseEFS Keep All Contents121 Choosing image files 122123 124 Downloading 125126 127 Tools 128Troubleshooting Download Errors 129130 NV Restore Error 131132 Port number 133U250/KU250 RF Functional Block Diagram 134 GSM & Umts RF BlockRF Block Component 135 1 RTR6275 & MSM6245 Interface Diagram Interface DiagramRTR6275 & MSM6245 Interface Diagram 136 Memory Interface Diagram 137 Memory Interface3 USB,UART,SIM,JTAG Interface USB, UART, SIM, Jtag Interface 138Main RF signal Control signal 139Placement Top Side 140Bottom Side 141142 Circuit Diagram 143144 Nand & LCD145 EBI2WEN Nandready Nandale Nandcle Resoutn EBI2OENLCD Connector 146147 148 Configuration of directory Configuration of HOT Kimchi149 150 151 MSVCP60D.DLL MSVCRTD.DLLProcedure How to use HOT Kimchi152 153 Test Program Setting 154Wcdma Test Mode 155GSM Test Mode 156Exploded View & Replacement Part List 157158 Replacement Parts Mechanic component 159160 Replacement Parts Main component 161162 163 164 165 166 167 DUPLEXER,IMT168 169 170 171 RES,ARRAY,R172 Vctcxo173 Accessory 174