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LG Electronics U250 service manual Power on Troubleshooting

Models: U250

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4. TROUBLE SHOOTING

4.9 Power ON Troubleshooting

Power On sequence of U250/KU250 is :

PWR key press → PM_ON_SW_N go to low, PM6650 KPDPWR_N (pin24) → PM6650 Power Up → VREG_MSMC_1.2V, VREG_MSME_1.8V, VREG_MSMP_2.7V, VREG_MSMA_2.6V, VREG_TCXO_2.85V power up and system reset assert to MSM6245 → Phone booting and PS_HOLD assert to PMIC

Start

Battery voltage. higher than 3.20V?

YES

Key press?

YES

VREG_MSMC_1.2V,VREG_MSMP_2.7V, VREG_MSME_1.8V, VREG_TCXO_2.85V, VREG_MSMA_2.6V power up?

YES

Is clock ok?

R306 : 19.2M

X300 : 32.768Khz

NO	Change or charging the
	Change or charging the
	Battery

NO

Check the Key Dome

NO

Change the Main board

NO

Check the TXCO

YES

Change the Main board

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LG Electronics U250 service manual Power on Troubleshooting

Contents

U250/KU250 Table Of Contents Page Regulatory Information PurposePictures Interference and AttenuationElectrostatic Sensitive Devices System Overview SpecificationTransmitter GSM Mode Environment AccessoryUsable environment Radio PerformanceCase of DCS a 1710, B Case of PCS a 1850, B Power Tolerance Specification Transmitter Wcdma Mode3Receiver GSM Mode Receiver Wcdma Mode U250/KU250 Current Consumption Current ConsumptionStand by Voice Call Level ChangeIndication Standby Battery BARTest Item Specification Sound Pressure LevelCharging General Description Block diagram of RF partTechnical Brief GSM Mode Antenna Switch Module Control logicGSM Receiver Technical Brief RTR6275 RX feature GSM Transmitter matching GSM TransmitterUmts Mode ReceiverTransmitter RTR6275 IC functional block diagram LO generation and distribution circuits Off-chip RF ComponentsWcdma PAM U103 WS2512-TR1G Vctcxo X100 DSA321SCE-19.2M Front-End Module U500 D5011Front End Module control logic Usbotg Pmic Functional Block Diagram U300 PM6650-2MMSM6245 Interface PM6650 Block Diagram GSM PAM U101 SKY77318 GSM PAM SchematicUmts DuplexerFL104ACMD-7602 Umts Rx RF filter FL103 EFCH2140TDE1 Wcdma Rx SAW Filter SpecificationMSM6245 Bluetooth Baseband Bluetooth M100 LBRQ-2B43AGeneral Description Digital BasebandDBB/MSM6245RTR6275 PM6650Block DiagramMSM6245 Nand Flash512Mbit 76inch Wcdma R99 features SubsystemMSM6245ARM Microprocessor Subsystem GSM features Gprs featuresEdge features MSM6245 device audio processing features Supported interface featuresMSM6245 microprocessor subsystem Video telephony services QvideophoneTM Supported multimedia featuresQcameraTM QtvTMSummary of MSM6245 device features Description of RF configurations Mode Select and Jtag Interfaces Stereo Wideband CodecVocoder Subsystem General-Purpose Input/Output Interface UartUSB Power Block General2. PM6650 12 PM6650 Functional Block Diagram Charging control 13 U250/KU250 Battery Bar DisplayStand By ConditionParameter Min Typ Max Unit Trickle Current 100 Trickle ChargingConstant Voltage Charging Constant Current ChargingTable#1. External memory interface External memory interface64MB 512MbDATA310 DQM3011 H/W Sub System RF InterfaceRTR6275WCDMATx, GSMTx/Rx Others Usim Interface MSM Sub SystemGPIOMap Name Table. Uart InterfaceUSB Table. USB Signal InterfaceTable. Hkadc channel table HKADCHouse Keeping ADCTable. Key Matrix Mapping Table Key PadCamera Interface 21 Camera Socket Type ConnectorCAMDATAOUT3 Dvdd Keypad Light 22 Schematic of KEY back light circuit KEY sideDisplay & LCD FPC Interface LCD Module NM176CN1 Tovis24 Audio Interface Detailed DiagramMSM6245 Audio Signal Processing & Interface25 Audio part schematics MSM6245 Codec pinsMIC Audio AMP Audio part schematicsAudio Mode LG-U250/KU250 Main features Main FeaturesLogic Audio Bluetoot SW100 U101 U500 FL101 U100 FL104 U103 X100 Logic / Audio S300 U301RF Component Trouble ShootingUmts Signal Pathumts RF Signal Pathgsm RF Schematic of the VC-TCXO Block Checking VC-TCXO BlockTest Point of the VC-TCXO Block Check C312 of Pmic U300 Check R213 of MSM U201 Schematic of the Front-End Module Block Checking Front-End Module BlockTest Point of the Front-End Module Block Logic Table of the FEM For testing, Max power of UMT 2100 is needed Checking Umts BlockChecking Tx level Trouble Shooting Checking Umts PAM Control Block PAM control signal TP2 TP4 Checking RF Rx LevelTrouble Shooting Checking GSM Block Checking RF Tx level Schematic of RF Tx levelTrouble Shooting TP1 TP4 TP2TP3 Checking PAM BlockTP1. DCS RX Input Checking RF Rx BlockTrouble Shooting Bluetooth Checking Bluetooth BlockChange the M100 Signals exits? Signals exits?Start Change the Main boardPower on Troubleshooting Vregmsmc Vregmsme Vregmsmp Charger Charger TroubleshootingChange the board Charger Troubleshooting Flow Connection OK?Change TA Or USB Cable Q302 Q301Charging part Main PCB Front Go to power on trouble shooting USB TroubleshootingCable is inserted? Insert cable Q400 pin 4 is 5V? Check Q300 pinStart Re-insert the SIM card SIM Detect TroubleshootingYes EndUsim Start Camera TroubleshootingYes Camera is OK? Yes Check the CammclkChange the Main board 103 YesC350 C447 U501 U303C348 C349104 Figure.Keypad backlight LED part 105 Keypad Backlight Troubleshooting106 Main LCD Troubleshooting107 Receiver Path108 109 Headset path110 111 Speaker phone path112 113 Main microphone114 115 Headset microphone116 Vibrator Work well? Yes End117 118 Downloading Procedure U250/KU250 DownloadIntroduction 120 Connecting to PCKeep All Contents EraseEFS121 122 Choosing image files123 124 125 Downloading126 127 128 Tools129 Troubleshooting Download Errors130 131 NV Restore Error132 133 Port numberGSM & Umts RF Block U250/KU250 RF Functional Block Diagram 134RF Block Component 135 Interface Diagram 1 RTR6275 & MSM6245 Interface DiagramRTR6275 & MSM6245 Interface Diagram 136 Memory Interface Memory Interface Diagram 137USB, UART, SIM, Jtag Interface 138 3 USB,UART,SIM,JTAG Interface139 Main RF signal Control signal140 Placement Top Side141 Bottom Side142 143 Circuit DiagramNand & LCD 144EBI2WEN Nandready Nandale Nandcle Resoutn EBI2OEN 145146 LCD Connector147 148 Configuration of HOT Kimchi Configuration of directory149 150 MSVCP60D.DLL MSVCRTD.DLL 151How to use HOT Kimchi Procedure152 153 154 Test Program Setting155 Wcdma Test Mode156 GSM Test Mode157 Exploded View & Replacement Part List158 159 Replacement Parts Mechanic component160 161 Replacement Parts Main component162 163 164 165 166 DUPLEXER,IMT 167168 169 170 RES,ARRAY,R 171Vctcxo 172173 174 Accessory