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U8950 Maintenance Guide V1.0

10 Principles and Failure Analysis

2012-10-22

Huawei Proprietary and Confidential

Working Principle

The U8950 uses Qualcomm BCM4330 to provide the Bluetooth, FM, and WLAN functions.

Bluetooth adopts an independent antenna, and the FM adopts the left- and right-audio
channels as the antenna.

The MSM7225A provides PCM and UART interfaces that are connected to the Bluetooth
module's PCM and UART signals. The following table describes the signals' definitions.

MSM8225
A

Signal Line

Definition

GPIO_44

UART1_CTS_N

The ready to receive information sent
to the Slave by the Host

GPIO_43

UART1_RFR_N

The clear to send information sent to
the Host by the Slave

GPIO_46

UART1_TX

Transmission signal

Summary of Contents for U8650

Page 1: ...50 Maintenance Guide V1 0 Prepared by Bi Xiaotao and Zhang Shunzhi Date 2012 08 15 Reviewed by Wei Baoquan Date 2012 08 17 Approved by Zhao Xianfeng Date 2012 08 20 Huawei Technologies Co Ltd All rights reserved ...

Page 2: ...de V1 0 INTERNAL 2012 10 22 Huawei Proprietary and Confidential i Change History Date Version Change Reason Changed Chapter Change De scription Author 2012 08 15 V1 0 Released the first version Bi Xiaotao and Zhang Shunzhi ...

Page 3: ...Software Upgrade 13 5 1 Upgrade Preparation 13 5 2 Hardware Connection 13 5 3 Upgrade Using the Phone Driver 14 5 3 1 Installing the Phone Driver 14 5 3 2 Performing a Normal Upgrade 17 5 3 3 Performing a Forcible Upgrade 19 5 4 Troubleshooting Upgrade Failures 19 6 Maintenance Tools 21 7 Disassembly Procedure 23 7 1 Disassembling a Bare Phone 23 7 2 Disassembling the Touchscreen 25 7 3 Disassembl...

Page 4: ... Unit 65 10 2 1 Power Amplifier 66 10 2 2 Troubleshooting Process 67 10 3 Peripheral Circuits 70 10 3 1 Display 70 10 3 2 Vibration 73 10 3 3 Receiver and Speaker 75 10 3 4 Microphone 78 10 3 5 Headset 81 10 3 6 SIM Card 83 10 3 7 I O Connector 86 10 3 8 microSD Card Connector 87 10 3 9 FM and Bluetooth 88 11 Solder Points on the PCB and BGA Chips 92 12 Functional Tests 96 12 1 Keys 96 12 2 MMI Te...

Page 5: ...ntenance Guide V1 0 1 Product Overview 2012 10 22 Huawei Proprietary and Confidential 1 1 Product Overview 1 1 Appearance Figure 1 1 shows U8950 Figure 1 1 U8950 1 2 Features Table 1 1 lists the product features ...

Page 6: ...MA 900 MHz 880 915 MHz uplink 925 960 MHz downlink W CDMA 2100 MHz 1920 1980 MHz uplink 2110 2170 MHz downlink U8950 51 U8950N 51 GSM 850 MHz 824 849 MHz uplink 969 894 MHz downlink GSM 900 MHz 890 915 MHz uplink 925 960 MHz downlink GSM 1800 MHz 1710 1785 MHz uplink 1805 1880 MHz downlink GSM 1900 MHz 1850 1910 MHz uplink 1930 1990 MHz downlink W CDMA 850 MHz 824 849 MHz uplink 869 894 MHz downli...

Page 7: ...to 40 C Storage 10 C to 40 C Battery Capacity 1930 mAh Standby time depending on user habits and network conditions up to 380 hours 2G up to 380 hours 3G Talk time up to 400 minutes 2G up to 400 minutes 3G Charging duration 3 hours Operating humidity 5 to 95 RH Camera 8 0 MP BSI AF rear camera 0 3 MP FF front camera FM radio Built in FM radio Bluetooth 3 0 EDR WLAN WLAN WLAN routing and C CDMA W W...

Page 8: ...ed Data Rate FF fixed focus FM frequency modulation GPRS general packet radio service GSM Global System for Mobile Communications HSDPA High Speed Downlink Packet Access HSUPA High Speed Uplink Packet Access MP Megapixel RAM random access memory ROM read only memory TFT thin film transistor W CDMA Wideband Code Division Multiple Access WLAN wireless local area network ...

Page 9: ...ied technicians are allowed to perform repair and calibration Perform all operations in electrostatic discharge ESD rooms and wear ESD wrist straps throughout the operations Ensure that all the components screws and insulators are properly installed after repair and calibration and all cables and wires are installed and connected correctly Ensure that the soldering is lead free and compliant with ...

Page 10: ...roprietary and Confidential 6 3 Exploded View and Components 3 1 Exploded View The components listed in Figure 3 1 are structural parts of the phone and cannot be used as reference when requesting spare parts Figure 3 1 shows the U8650 exploded view Figure 3 1 U8650 exploded view ...

Page 11: ...een 1 3 Receiver ornament 1 4 LCD 1 5 Front cover assembly 1 6 Receiver 1 7 M1 4 screw 2 8 Receiver FPC 1 9 Main PCBA 1 10 Waterproof label 2 11 Rear camera 1 12 Flash PCBA 1 13 Back cover assembly 1 14 Battery cover assembly 1 15 M1 4 x 3 5 screw 1 16 Battery 1 17 Network Access Flag 1 18 Type label 1 19 Main FPC 1 20 Cable 1 21 Tamper resistant label 1 22 Speaker 2 23 Front camera support 1 24 F...

Page 12: ...e Guide V1 0 3 Exploded View and Components 2012 10 22 Huawei Proprietary and Confidential 8 No Description Quantity NOTE CMII FPC flexible printed circuit LCD liquid crystal display PCBA Printed Circuit Board Assembly ...

Page 13: ...axial cable connector Faults caused if damaged No or weak RF signals J1006 board connector Faults caused if damaged Proximity sensor fault J1703 headset jack Faults caused if damaged Headset fault J1601 TP BTB connector Faults caused if damaged Touchscreen fault J1402 microSD card slot Faults caused if damaged microSDcard detection failure C245 button capacitor Faults caused if damaged System time...

Page 14: ... channel fault U3801 RTR6285 Faults caused if damaged RF related faults J1006 front camera connector Faults caused if damaged Front camera error garbled image U1002 Faults caused if damaged Flash fault or loading failure U1402 microSD card filter Faults caused if damaged microSD card fault or loading failure U1204 U1205 Accelerometer and compass Faults caused if damaged Compass fault Table 4 1 is ...

Page 15: ...ted U3702 39200333 Terminal Dedicated IC WCMDA GSM Radio Transceiver RTR6285A 2 7V 2 6V 2 1V 137CSP Terminal Dedicated U3801 47090053 RF LNA 1575MHz 14dB min 1 6dB max SOT886 Terminal Dedicated U4101 39210010 Terminal Baseband process IC Single Band 2 4GHz WLAN Bluetooth 2 1 FM Single chip BCM4330 2 3 5 5V WLBGA1 33 Pb free U6011 12020216 Crystal 37 4MHz 10pF 8 3pF 9pF 10ppm 80ohm 2016 Terminal De...

Page 16: ...053 Microphone 44dB D4 0mm 1 3m m SMT Terminal Dedicated MIC1502 07050089 NTC 47000ohm 0402 1 0 0 5 0 35m m Terminal Dedicated RT501 38020055 Analog Switch P channel MOSFET load switch 1 2 3 6V 50mohm WLCSP Terminal dedicated U1231 15040295 Transient Suppression Diode 6V 25V 3A 9 channel TVS EMI filter CSP Terminal Dedicated U1402 12070013 Temperature Compensated Crystal Oscillator 19 2MHz 0 2ppm ...

Page 17: ...ndows 2000 Windows XP USB cable BOM code 02450768 Upgrade tool NewMultiDownloadU microSD card The available space must be greater than 2 GB Battery The power remaining must be more than two bars Upgrade file NewMultiDownloadU This version is provided for reference only Please download the latest version when upgrading the phone Upgrade method USB cable Normal upgrade Forcible upgrade microSD card ...

Page 18: ...are connection U8950 USB Cable PC 5 3 Upgrade Using the Phone Driver 5 3 1 Installing the Phone Driver To install the phone driver on the computer perform the following steps Step 1 Double click the Handset Windriver exe file and click Next in the displayed dialog box to start the installation Step 2 Click I Agree ...

Page 19: ...U8950 Maintenance Guide V1 0 5 Software Upgrade 2012 10 22 Huawei Proprietary and Confidential 15 Step 3 Click Install ...

Page 20: ...enance Guide V1 0 5 Software Upgrade 2012 10 22 Huawei Proprietary and Confidential 16 The installation progress is displayed as shown in the following figure Step 4 After the installation is complete click Finish ...

Page 21: ... computer s Device Manager shown in the following figure End 5 3 2 Performing a Normal Upgrade To conduct a normal upgrade perform the following steps Step 1 Power the phone on and use the USB cable to connect the phone to the computer on which the phone driver and the upgrade tool have been installed Step 2 Double click NewMultiDownloadU to run the upgrade tool The following dialog box is display...

Page 22: ...l 18 Step 3 Enter the password Huawei and click OK In the displayed dialog box select Allow upgrade for the Second time Firmware and Please Choose The Configuration File and select the XML configuration file in the upgrade tool s root directory as required Click Next Step 4 Click Scan Download ...

Page 23: ...nds before installing the battery again Step 2 Press and hold the volume up and volume down keys and press the power key The phone will start the forcible upgrade The specific download process is similar to the project menu download End Approach 2 Without a battery press and hold the volume up and volume down keys and connect the phone to a charger The phone can also start the forcible upgrade NOT...

Page 24: ... for the upgrade Check that the USB driver has been properly installed Check that the USB cable has been properly connected Failed to upgrade the phone using the USB cable Check that the USB cable has been properly connected Perform the upgrade again Failed to upgrade the phone using the microSD card 1 Check that the upgrade file is correct 2 Check that the upgrade method is correct 3 Check that t...

Page 25: ... 21 6 Maintenance Tools Name constant temperature heat gun Usage to heat components Name constant temperature heat gun Usage to heat components Name soldering iron Usage to maintain and solder components Name DC power supply Usage to supply DC current Name soldering table Usage to secure the PCBA ...

Page 26: ...2 Huawei Proprietary and Confidential 22 Name lead free solder wire Usage for soldering Name digital multimeter Usage to measure during repair Name toolkit Usage to assemble and disassemble components Name electric screwdriver Usage to fasten and remove screws ...

Page 27: ... and Confidential 23 7 Disassembly Procedure 7 1 Disassembling a Bare Phone For details see the following figures 1 Ensure that the ESD wrist strap is properly connected to the ground 2 Remove battery cover 3 Remove the screws from the rear cover 4 Separate the front and rear covers ...

Page 28: ...ietary and Confidential 24 5 Detach the RF cable 6 Separate the FPC connector from the front cover 7 Remove the screws from the PCBA and front cover 8 Take out the rear camera 9 Lift the BTB connector The PCBA and front cover are separated 10 Separate the front camera and PCBA ...

Page 29: ...e from the PCBA 12 Take out the PCBA 7 2 Disassembling the Touchscreen For details see the following figures 1 Place the front cover assembly to the touchscreen disassembling fixture 2 Push the four blocks to fix the front cover 3 Move the suckers to the top of the touchscreen 4 Rotate the knobs to drop the suckers until the ...

Page 30: ...en 7 Keep rotating the knob until the touchscreen s lower part is raised to a certain distance from the front cover Place a long soft object between the touchscreen and front cover so that they will not stick to each other again Note that the long soft object must be placed on the adhesive area on the front cover rather than on the LCD 8 Lift the sucker and detach it from the touchscreen Remove th...

Page 31: ... eject the LCD gently from the hole at the bottom of the front cover assembly Do not eject the LCD hard If the LCD cannot be ejected heat the adhesive area again to undermine its adhesion Ensure that the no dent occurs on the ejection position of the LCD 3 Use a flat ruler like object to lift the LCD from the bottom of the LCD 4 Take out the LCD from an appropriate angle to protect the LCD FPC aga...

Page 32: ... assembly procedure for the U8950 is similar to the C8950D For details see the following figures 1 Ensure that the ESD wrist strap is properly connected to the ground 2 Attach the LCD to the front cover Pay attention to the BTB connector on the FPC 3 Attach the dust proof net to the touchscreen 4 Fit the touchscreen and LCD ...

Page 33: ...nd Confidential 29 5 Install the power key and volume key FPC to the front cover 6 Install the receiver to the front cover 7 Install the tri color indicator and receiver FPC to the front cover 8 Secure the screws 9 Connect the RF cable and PCBA 10 Connect the FPC connector and PCBA ...

Page 34: ...ntial 30 11 Install the front camera to the PCBA 12 Fit the PCBA and front cover and fasten the BTB connector 13 Install the rear camera to the PCBA 14 Secure the screws on the PCBA and front cover 15 Install the antenna board to the front cover 16 Attach the FPC connector to the front cover ...

Page 35: ...ei Proprietary and Confidential 31 17 Attach the RF cable to the antenna board 18 Effect diagram after the preceding components are installed 19 Install the speaker to the rear cover 20 Fit the front and rear covers and secure the screws 21 The phone is now assembled ...

Page 36: ...ip was heated and re soldered V3 Loading Poor loading The data was lost The board was formatted and reloaded and the test then passed V3 CT MMI06A vibrator malfunction The vibrator was faulty The faulty product was retained as required by the R D department for analysis by the vendor V3 MMI MMI06A vibrator malfunction The FPC and BTB connector were not fit in place The BTB connector was refitted V...

Page 37: ...d further analysis V3 MMI MMI05A front camera malfunction The problem was confirmed by the R D as one caused by software The problem was retained as it occurred for analysis by the R D department V3 MMI MMI04F flash malfunction The J1001 shrapnel was mis mounted during the SMT Re solder J1001 V3 MMI MMI04C touch key backlight malfunction The BTB connector on the antenna board was poorly soldered T...

Page 38: ...placed V3 MMI MMI01B startup failure The board clip on the front cover was broken resulting in poor contact between the board and startup shrapnel on the front cover The front cover was to be replaced V3 MMI MMI01B startup failure The startup shrapnel on the main PBCA failed to contact the FPC The startup shrapnel and FPC were re assembled V3 CT CT20001Y The test equipment was unstable No current ...

Page 39: ...3 CT 26201N The unit U3402 was poorly soldered and proved to attenuate signals by 10 dBm when tested using W CDMA The unit U3402 was re soldered V3 CT 262010 During a manual test RF signal output was detected and closed after a while The faulty product was retained for further analysis by the R D department V4 Loading The loading failed at 82 The loading program was faulty The program was eliminat...

Page 40: ...ring the pre assembling resulting in the failure of speaker test After confirmation by the product line and PE the speakers were installed and the test then passed V4 MMI MMI04D proximity light malfunction The test was stuck in the state of proximity for long It might be caused by poor transparency due to dirty protective film on the touchscreen The touchscreen protective film was removed and the ...

Page 41: ...ulting in overflow of the glue from the holes on the shielding cover to the gaps The assembly was then hindered A photo was taken to confirm with the PE The overflow of glue was heated using the heat gun and then cleaned using a pair of nippers VN1 Loading No Android Adapter PCUI interface after the loading VPH_PWR VREG_S2 and U401 were short circuited The PMU chip and relevant capacitors were rem...

Page 42: ...as re soldered VN1 PT PT H00001 POWER ON FAIL The product software design was defective It took too long to start up resulting in the failure determined by the test program The normal startup time must not exceed 60s The initiation of sensor failed resulting in the delay of I2C read and write VN1 PT PT H00001 POWER ON FAIL The startup was slow After the startup the Android screen was displayed for...

Page 43: ...ormat was incorrect in the property settings The barcode format was reset and the test then passed VN1 MT MT 568214 The test value was a critical one The test position was changed and the test then passed VN1 MMI MMI09D U4401 was poorly soldered The NFC_TX signal could not be detected using an oscillator and remained undetectable after U4401 was re soldered It was preliminarily determined that the...

Page 44: ... became normal VN1 MMI MMI06C receiver malfunction The receiver contact shrapnel was inversely installed The receiver was re installed VN1 MMI MMI06B speaker malfunction The speaker was reversely installed during the pre processing of the rear cover The speaker was re installed VN1 MMI MMI06B speaker malfunction The foam object from the white package was introduced during the pre installation The ...

Page 45: ...creen The incoming material of the front camera was faulty The front camera was replaced VN1 MMI MMI05A front camera malfunction The chip U1231 was damaged The material replacement was unavailable and to be applied for VN1 MMI MMI05A front camera malfunction The incoming material of the front camera was faulty The front camera was replaced and the test then passed VN1 MMI MMI05A front camera malfu...

Page 46: ...r indicator malfunction light leakage The incoming material of proximity light foam was faulty The foam was covered by a layer of PET through which the light was leaked The PET on the foam was removed VN1 MMI MMI04A tri color indicator malfunction R1201 was poorly soldered resulting in the missing blue light R1201 was re soldered VN1 MMI MMI04A tri color indicator malfunction The light guiding pol...

Page 47: ... was detected on the pin The microSD card slot was not re soldered since the CPU was right on the front and heating the slot was risky VN1 MMI MMI02C microSD card detection failure The Dat0 signal of the microSD card slot s 7th pin was 42 ohm normally it should be 4 Mohms It was determined that the filter U1402 was short circuited It was determined according to the batch number of this task order ...

Page 48: ...rate a 20 V voltage The U1303 was found faulty Keep the component and conduct further analysis VN1 MMI MMI01E Defective U1303 Replace U1303 VN1 MMI MMI01E D1302 was reversed Re solder R1 VN1 MMI MMI01D The grounding pin is deviated to connect to the power on pin Replace the grounding pin using the discard board and test again VN1 MMI MMI01C The volume down spring was deformed Adjust the spring pos...

Page 49: ...n and test the phone VN1 BT BT300003 A voltage gap of 0 042 V existed in the battery voltage test Keep the sample and conduct further analysis VN1 BT BT300003 A voltage gap of 0 05 V existed in the battery voltage test Keep the sample and conduct further analysis VN1 Upload B03A VREG_S4 output nothing and U1002 and U1402 were short circuited Replace U1002 and U1402 in order to locate the problem V...

Page 50: ...N1 Upload Upload fails U3801 was short circuited and VREG_S4 output nothing U3801 was found defective which is reported to R D for further analysis VN1 Upload Upload fails No port was found The VREG_S3 voltage was 3 6 V and VREG_S4 output nothing It is determined that U201 is faulty Keep the sample for further analysis VN1 MT 568214 The coaxial cable was poorly connected to the sub board Check wit...

Page 51: ...rapnel All the preceding units plus the covers and battery comprise a finished mobile phone Besides the basic voice and message functions the U8950 also provides two storage methods for contacts and messages on the UIM card or internal storage of the mobile phone The U8950 supports storage on the microSD card It also supports the FM radio and recording function The U8950 uses a color TFT LCD with ...

Page 52: ...Startup Management Circuits Circuit Block Diagram Working Principle The U8950 uses an independent power management chip PM8029 with the startup principle controlled using Qualcomm codes During the startup process the PM8029 power management chip converts the main power supply voltage VHP_PWR to various voltages listed in the following table ...

Page 53: ...lures are caused by power supply exceptions Troubleshoot the faults as follows No current Power the mobile phone using DC and press and hold the power key The current is displayed as 0 mA to 5 mA Weak current Power the mobile phone using DC and press and hold the power key The current is displayed as 5 mA to 100 mA Excessive current Power the mobile phone using DC and press and hold the power key ...

Page 54: ...No current failure troubleshooting Connect the phone to the fake battery and maintenance power supply press the power key and test the current on the phone Is the power key copper foil oxidized No current Clean the key Is the clock normal Check U201 N Y Y N Power on failure Check X401 and U3101 Y Return the phone to the manufacturer for repair N Test whether the VPH_PWR voltage is normal 2 Weak cu...

Page 55: ...upply press the power key and test the phone current Check whether the PM output voltage is normal Weak current Check U201 Test whether the X301 transmission frequency is 32 768 kHz or the U3101 output frequency is 19 2 MHz Return the phone to the manufacturer for repair Re solder or replace X301 and U3101 Y N Y N Power on failure 3 Excessive current failure troubleshooting ...

Page 56: ... maintenance power supply press the power key and test the current on the phone Check whether pin 3 of J1501 is grounded Excessive current Check U201 and J1501 Check whether the U201 voltage is normal Return the phone to the manufacturer for repair Re solder or replace U201 N Y Y N Power on failure 10 1 2 Charging Management Circuits Circuit Block Diagram ...

Page 57: ...etary and Confidential 53 Working Principle The PM8029 chip integrates a charging solution which supports three charging states trickle charging constant current charging and constant voltage charging The three charging methods adopt the same route VEXT_DC VCHG VPH_PWR Q201 and pin 3 VBAT ...

Page 58: ...on and control with two interfaces GPIO13 I2C_SCL_DCDC and GPIO98 I2C_SDA_DCDC respectively This charging management chip BQ24152 sources the power from VCHAG in the USB interface and is controlled by I2C The BQ24152 chip outputs VPH_PWR to supply power to the PM and battery Figure 10 1 shows the functional blocks of the BQ24152 chip Figure 10 1 Charging chip s functional block diagram Figure 10 2...

Page 59: ...U8950 Maintenance Guide V1 0 10 Principles and Failure Analysis 2012 10 22 Huawei Proprietary and Confidential 55 Figure 10 2 Block diagram of the charging circuit ...

Page 60: ...oltage in the beginning of constant voltage charging after the constant current charging ends IO CHARGE current during the constant current charging I IN_LIMIT limit current during the constant current charging alternative by IO CHARGE I SHORT current during the trickle charging V RCH charging voltage The chip uses the pin CSOUT to monitor the main voltage When battery voltage V SHORT the trickle ...

Page 61: ...e to save the power FAN5402UCX is also capable of continuously detecting the charging voltage VBUS When VBUS is lower than the threshold VIN min the charging stops and waits for a TINT to re consider charging FAN5402UCX has the following features Charging over voltage protection Battery over voltage protection Battery presence detection Start up without battery Troubleshooting Process There are tw...

Page 62: ...place the charger N Check whether the USB connector J103 is poorly soldered Y Y Re solder J103 N Check whether C231 bears voltages Check whether VPH_PWR voltages exist N Y Check F101 and LB101 N Replace Q201 Is the battery damaged Y Replace J902 Y End N Check whether pin 3 of Q201 outputs signals Replace U901 N Y Check whether J902 is damaged N Y Replace the battery ...

Page 63: ...external USB power supply and the charging chip 0 5 V I2C_SCL_DCDC Charge control signal None I2C_SDA_DCDC Charge control signal None VPH_PWR Primary power supply to the power module Voltage range 0 4 2 V BAT_FET_N Control signal of the MOS Q201 VBAT Battery voltage Battery voltage range 0 4 2 V USB_HS_DP Positive electrode input of USB differential data bus None USB_HS_DN Negative electrode input...

Page 64: ... has two filtering circuits from R204 to C232 and from R3101 to C3101 which outputs to the main chip through the PM8029 as the system main clock The 32 768 kHz oscillator signal outputs to the PM8029 and is provided to the system Troubleshooting Process Failures The phone cannot be powered on or frequently freezes Check whether 32 768 kHz X301 and U3101 have no output and whether the output is sta...

Page 65: ...unction Test Reference Value or Oscillogram XTAL32K _OUT Output from the 32 768 kHz main clock XTAL32K_IN Input from the 32 768 kHz main clock VREG_TCXO 19 2 MHz oscillator power supply 2 9 V TRK_LO_ADJ Control signal of the 19 2 MHz output frequency None RTR6285_TCX O 19 2 MHz clock output TCXO 19 2 MHz clock output 10 1 4 Flash Memory Circuit Circuit Block Diagram ...

Page 66: ...U8950 Maintenance Guide V1 0 10 Principles and Failure Analysis 2012 10 22 Huawei Proprietary and Confidential 62 ...

Page 67: ...ential 63 Working Principle The MSM7227A is able to visit the LPDDR2 through two high speed buses EBI1 The LPDDR2 is connected to the MSM8255 0 in PoP Package on package mode Meanwhile the MSM7227A can also visit the external storage eMMC through a low speed bus EBI2 as shown in the following Figure 10 4 ...

Page 68: ...roubleshooting Process Failure symptom The phone cannot be powered on or the startup current is less than 100 mA Solution Upgrade or reinstall the phone s firmware and check whether the VREG_DCDC_2P85 voltage and peripheral components of the flash memory are normal If the problem persists replace U1700 Circuit Diagram Symbols in this Section Signal Name Function Test Reference Value or Oscillogram...

Page 69: ...cillogram SDC3_DATA1 Data line SDC3_DATA0 Data line SDC3_DATA7 Data line SDC3_DATA6 Data line SDC3_DATA5 Data line SDC3_DATA4 Data line SDC3_CLK Clock SDC3_CMD Command VREG_DCDC_2P8 5 Flash power 2 9 V VREG_S3 Power supply 2 9 V MSM_RESOUT_N Reset signal VPH_PWR 2 85 V system power supply which supplies power to the DC DC chip 10 2 RF Unit Circuit Block Diagram ...

Page 70: ... 1 lists the control logic of 47140032 RF antenna switch 47140032 RF antenna switch control logic Frequency Band ANT_SEL0 GPIO75 ANT_SEL1 GPIO74 ANT_SEL2 GPIO73 ANT_SEL3 GPIO72 GSM 850 900 TX 1 1 0 0 GSM 1800 1900 TX 1 0 0 0 GSM 850 RX 0 1 1 0 GSM 900 RX 0 1 0 0 GSM 1800 RX 0 0 1 0 GSM 1900 RX 0 0 0 0 WCDMA210 0 TX RX 1 0 1 0 WCDMA190 0 TX RX 1 0 1 1 WCDMA850 900 TX RX 1 1 1 0 10 2 1 Power Amplifi...

Page 71: ...ce Guide V1 0 10 Principles and Failure Analysis 2012 10 22 Huawei Proprietary and Confidential 67 10 2 2 Troubleshooting Process No reception failure troubleshooting process for IMT PCS CELL is shown in the following ...

Page 72: ... Y Check U3301 N Check whether the IQ signals on U3801 pins 11 12 13 and 14 are normal and whether the power supply voltage is about 2 6 V Check whether U3202 RF switch control signals are normal Check whether J3201 pin1 and pin 2 are connected NOTE Check the control signals of U3202 switch using a multimeter or oscilloscope The truth table for control signals is as follows TRX_IMT TRX_PCS TRX_CEL...

Page 73: ...e following procedure IMT PCS CELL transmission failure Check whether J3201 pin 1 and pin 2 are connected Do not connect the RF cable Check J3201 Check whether U3201 control signals are normal Check U201 End Check whether the maximum CELL PA output is about 28 dBm Check U3201 and U201 Check U3302 Y N Y Y Y N N Check whether U3801 pins 50 51 52 and 53 output IQ signals Check U3801 N Y In W900 just ...

Page 74: ...U8950 Maintenance Guide V1 0 10 Principles and Failure Analysis 2012 10 22 Huawei Proprietary and Confidential 70 10 3 Peripheral Circuits 10 3 1 Display Circuit Block Diagram ...

Page 75: ...employs the MIPI interface It requires only two pairs of low voltage differential signal LVDS cables and a pair of power cables and supports 60 Hz refreshment rate With frame synchronization function the LCD uses MDP_VSYNC of GPIO_030 as the data transmission synchronization signal to avoid LCD breakage Troubleshooting Process Fault symptom The phone can be powered on but its LCD is blank Solution...

Page 76: ...ymbols in this Section Signal Name Function Test Reference Value or Oscillogram VREG_L12_2P85 LCD analog voltage 2 8 V 2 85 V VREG_S3 I O connector digit voltage 1 8 V MIPI_DSI_LANE2_P Differential signals 1 8 V MIPI_DSI_LANE2_N Differential signals 1 8 V MIPI_DSI_LANE1_P Differential signals 1 8 V MIPI_DSI_LANE1_P Differential signals 1 8 V LCD_RST_N LCD power on reset signal 1 8 V MDP_VSYNC_P Ve...

Page 77: ... 73 10 3 2 Vibration Circuit Block Diagram Working Principle The PM8029 s VIB_DRV_N pin functions as the drive pin for the vibrator which locates on the main board When the motor is not vibrating VPH_PWR and VIB_DRV_N are both at high level Troubleshooting Process Failure The vibrator fails to vibrate Solution ...

Page 78: ...turer for repair Is the problem solved after the software is loaded Check whether the vibrator power supply is normal and the negative end outputs a lower voltage in the vibration test Does the phone function properly after having the vibrator replaced Circuit Diagram Symbols in this Section Signal Name Function Test Reference Value or Oscillogram VPH_PWR Main power supply supplying power to the m...

Page 79: ...U8950 Maintenance Guide V1 0 10 Principles and Failure Analysis 2012 10 22 Huawei Proprietary and Confidential 75 10 3 3 Receiver and Speaker Circuit Block Diagram ...

Page 80: ...U8950 Maintenance Guide V1 0 10 Principles and Failure Analysis 2012 10 22 Huawei Proprietary and Confidential 76 Working Principle ...

Page 81: ... output The U8185 is designed with a stereo headset Signal Name Function Test Reference Value or Oscillogram EAR1_M_OUT Output to the receiver None EAR1_P_OUT Output to the receiver None SPK_P1 Output by the PM8029 to the PA and then the speaker None SPK_N1 Output by the PM8029 to the PA and then the speaker None SPK_P2 Output by the PM8029 to the PA and then the speaker None SPK_N2 Output by the ...

Page 82: ...et presence After a call is established no sound can be heard by the other party Is the problem solved after the software is loaded Is the volume setting is normal Check the receiver is properly connected to the phone Replace the volume key Does the phone function Properly after having the Receiver replaced Check whether the surrounding circuits of U2002 are poorly soldered 10 3 4 Microphone Circu...

Page 83: ...le The U8950 board provides the primary and secondary microphones for collecting different voice signals The U8950 processes the collected voice signals to filter environmental noises The U8950 adopts the following power supplies HSED_MICBIAS headset microphone PM8029 HSED_BIAS1 SND_MICBIAS secondary microphone PM8029 HSED_BIAS2 ...

Page 84: ... microphone function properly after being re soldered N End Y N Is MSM_MIC_BIAS voltage normal Check C311 N Y End Y N Return the phone to the manufacturer for repair After a call is established no sound can be heard by the other party Is the problem solved after the software is loaded Is the problem solved after the MIC is replaced Circuit Diagram Symbols in this Section Signal Name Function Test ...

Page 85: ...5 Headset Circuit Block Diagram Working Principle The earphone connect status is identified according to the HS_DETECT_N GPIO_026 Before connecting the headphone HS_DETECT_N is pulled up to high level by VREG_S3 After connecting the headphone HS_DETECT_N is dropped down to low level The headphone MIC is supplied with power by MIC_BIAS1 PM8029 HSED_BIAS1 and it is used for headphone answer detectio...

Page 86: ...e phone to the manufacturer for repair Do the phone function properly after having the headset replaced Is the volume setting is normal Test whether HS_DETECT voltage changes after the headset is inserted Circuit Diagram Symbols in this Section Signal Name Function Test Reference Value or Oscillogram FM_ANT FM antenna None HPH_OUT_L Stereo headset output None HPH_OUT_R Stereo headset output None H...

Page 87: ...rietary and Confidential 83 Signal Name Function Test Reference Value or Oscillogram HSED_HSKEY_AD C Headset microphone test Voltage change HS_DETECT Headset insertion detection Voltage change GND_MIC3 Grounding signal of the headset microphone None 10 3 6 SIM Card Circuit Block Diagram ...

Page 88: ...s 2012 10 22 Huawei Proprietary and Confidential 84 The U8950 SIM card interface is controlled by the input and output signals provided by the PM8029 Troubleshooting Process Failure The USIM card cannot be detected Solution Verify that the UIM card slot is normal ...

Page 89: ...9 s MPP pin converts the level for connecting to the SIM card The voltage of VREG_L16_UIM1 can be set to 1 5 3 05 V The USIM interface s operating voltage is usually 1 8 V or 3 0 V The following table describes the voltage level conversion interface of the PM8029 Signal for Interfacing with the MSM Voltage Level Signal for Interfacing with the USIM Card Voltage Level VREG_S3 UIM1_RESET_AP VREG_L16...

Page 90: ...computer using a USB cable USB_HS_DN and USB_HS_DP are used for communication for upgrading the phone s firmware reading information from the phone and so on between the phone and the computer Troubleshooting Process Failure The phone cannot be charged or detected by a computer Solution Clean re solder or replace the USB connector Circuit Diagram Symbols in this Section Signal Name Function Test R...

Page 91: ...2 10 22 Huawei Proprietary and Confidential 87 10 3 8 microSD Card Connector Circuit Block Diagram Working Principle The U1402 is added to provide the ESD protection and EMI filtering Troubleshooting Process Failure The microSD card cannot be detected or read Solution ...

Page 92: ...rd detection failure End Y N N Re solder U1402 Y End Y N Return the phone to the manufacturer for repair Check whether the problem is solved after U1701 is replaced Check whether U1402 pins are connected Upgrade the phone software and check whether the phone resumes its functions 10 3 9 FM and Bluetooth Circuit Block Diagram ...

Page 93: ...e FM adopts the left and right audio channels as the antenna The MSM7225A provides PCM and UART interfaces that are connected to the Bluetooth module s PCM and UART signals The following table describes the signals definitions MSM8225 A Signal Line Definition GPIO_44 UART1_CTS_N The ready to receive information sent to the Slave by the Host GPIO_43 UART1_RFR_N The clear to send information sent to...

Page 94: ...Waking up the Bluetooth The PM8029 provides audio input interfaces that are directly connected to the FM module s left and right channels The following table describes the signals definitions BCM4330 Network MSM8225 Description FM_RXP FM_ANT FM antenna headset FM_RXN FM_VDD2P5 SR_AVDD2P5 FM_AOUT1 FM_OUT_L PM8029 LINE_IN_LP FM OUTPUT FM_AOUT2 FM_OUT_R PM8029 LINE_IN_RM FM OUTPUT Troubleshooting Pro...

Page 95: ...nction failure Does the phone resume its FM radio function after having the headset replaced End Y N Does the phone resume its FM radio function after having the headset jack re soldered Y End N Does the phone resume its FM radio function after having software re loaded Y End N Return the phone to the manufacturer for repair ...

Page 96: ...1 Solder Points on the PCB and BGA Chips 2012 10 22 Huawei Proprietary and Confidential 92 11 Solder Points on the PCB and BGA Chips Figure 11 1and Figure 11 2 show the solder points on the PCB and BGA chips Figure 11 1 Top surface ...

Page 97: ...re 11 2 Bottom surface NOTE The blank grounding and solder points must be clearly marked Colors used for the solder points figures must be distinguished and the color indication must be explained In the above figures Spots in red are signal pins spots in blue are grounding pins and spots in green are suspended pins Attachment ...

Page 98: ...8950 Maintenance Guide V1 0 11 Solder Points on the PCB and BGA Chips 2012 10 22 Huawei Proprietary and Confidential 94 Figure 11 3 Top side silkscreen diagram Figure 11 4 Bottom side silkscreen diagram ...

Page 99: ...U8950 Maintenance Guide V1 0 11 Solder Points on the PCB and BGA Chips 2012 10 22 Huawei Proprietary and Confidential 95 Attachment ...

Page 100: ...end key to enter the MMI test Then select MMITEST and press the volume down key to start the MMI test You can touch the menu key to cancel the current test the volume down key to enter the next test the back key to return to the previous test and the home page key to exit the text and switch to the desktop You must complete each test one by one After all tests are complete a list is generated to i...

Page 101: ...er the speaker operates properly Mobile phone microphone loopback test Record and play an audio clip as instructed and check whether the playback is normal Mobile phone headset loopback test Record and play an audio clip as instructed and check whether the playback is normal FM test Insert the headset and operate as instructed Headset wire control test Insert and remove the headset and microphone ...

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