LG ID2750 Service Manual Download

Page: 18 / 69

LG-ID2750

LGE

LG Electronics Inc.

16/26

The detail programming method is same as basic programming. Set up required values and then,

press the [

] soft key in an effort to move to the next screen.

To return to the last item, press the [

Back

The editable NAM items are followed:

SERVICE SECURITY CODE

NAM 1 MOBILE COUNTRY CODE

NAM 1 MOBILE NETWORK CODE

NAM 1 PRL Enabled ?

NAM 1 CDMA Home System Reg

NAM 1 CDMA Foreign SID Reg

NAM 1 CDMA Foreign NID Reg

NAM 1 CDMA Home SID/NID

NAM 1 Lock out SID/NID

NAM 1 CDMA Primary CH A

NAM 1 CDMA Secondary CH A

NAM 1 CDMA Primary CH B

NAM 1 CDMA Secondary CH B

NAM 1 ACCOLC 0

※

Editing this items is not recommended.

Z3X-BOX.COM

Summary of Contents for ID2750

Page 1: ...Catalogue included Mode Type Name Voltage Current Power CDMA FC7113 3 7V 600mA 0 32W 6 Functions of Major Semi Conductors Classification Function MSM6000 208Pin FBGA Operation control and digital signal processing of the mobile station FLASH MEMORY K8D3216UTC TI07 Flash Memory 32Mbit Storing of the mobile station operation program STATIC RAM K1S161611A FI70 SRAM 16Mbit Temporary storing of the dat...

Page 2: ...CDMA MOBILE SUBSCRIBER UNIT LG ID2750 SINGLE BAND CDMA MOBILE PHONE SERVICE MANUAL Z 3 X B O X C O M ...

Page 3: ...f CDMA Mobile Phone 5 3 Structure and Functions of CDMA Mobile Phone 8 4 Specification 9 5 Installation 12 CHAPTER 2 NAM Input Method Inputting of telephone numbers included 1 Telephone Number and NAM Programming Method 14 CHAPTER 3 Circuit Description 1 RF Transmit Receive Part 17 2 Digital Voice Processing Part 22 CHAPTER 4 Trouble Shooting Z 3 X B O X C O M ...

Page 4: ...bined into this phone to reduce the call being interrupted in a middle of talking over phone CDMA digital cellular network consists of MSC Mobile Switching Office BSC Base Station Controller BTS Base station Transmission System and MS Mobile Station Communication between MS and BTS is designed to meet the specification of TIA EIA IS 95 A B C Common Air Interface MS meets the specifications of the ...

Page 5: ...nce The analog cellular systems are classified further into an AMPS system E AMPS System NMT system ETACS system and JTACS system depending on technologies used Unlike the Time Division Multiple Access TDMA or the Frequency Division Multiple Access FDMA used in the band limited environment the Code Division Multiple Access CDMA system which is one of digital cellular systems is a multi access tech...

Page 6: ...everal CDMA signals are overlapped Among these types of signals only desired signal energy is selected and received through the use of pre determined binary sequence desired signals can be separated and then received with the correlator used for recovering the spectrum into its original state At this time the spectrums of other signals that have different codes are not recovered into its original ...

Page 7: ...e station to mobile stations and backwaID from the mobile station to the base station power control in oIDer to increase the call processing capacity and obtain high quality calls In case the originating signals of mobile stations are received by the cell site in the minimum call quality level signal to interference through the use of transmit power control on all the mobile stations the system ca...

Page 8: ...ted for use depending on inputted automatic conditions and message data both of them utilize four stage frames of 9600 4800 2400 and 1200 bits per second In addition this type of variable voice encoder utilizes adaptive threshold values when selecting required data rate It is adjusted in accoIDance with the size of background noise and the data rate is increased to high rate only when the voice of...

Page 9: ...ell site about 65 In the case of directional cell site one cell normally uses a 120 sector antenna in oIDer to divide the sector into three In this case each antenna is used only for 1 3 of mobile stations in the cell site and accoIDingly interference is reduced by 1 3 on the average and the capacity that can be supported by the entire system is increased by three times 2 7 Soft Capacity The subsc...

Page 10: ...During the operation with one cell site the searcher searches out multi paths in accoIDance with terrain and building reflections On three data receivers the most powerful four paths are allocated for the parallel tracing and receiving Fading resistance can be improved a great deal by obtaining the diversity combined output for de modulation Moreover the searcher can be used to determine the most ...

Page 11: ...dBm 4 1 5 Operating Temperature 30 60 4 1 6 Frequency Stability 0 5PPM 4 1 7 Antenna Fixed PIFA Type Internal 50 Ω 4 1 8 Size and Weight Size 108 5 x 44 5 x 15 6mm L x W x D Weight TBD 4 1 9 Channel Spacing 1 25MHz 4 1 10 Battery Type Capacity and Orerating Time Unit Hours Minutes StandaID 1000mAh Stand By Time 160 Hrs SCI 1 Talk Time 180 Min About 92dBm Half rate 4 2 Receive Specification 4 2 1 F...

Page 12: ...an 115 12 6 dB 102 4dB at the 1 23MHz band 4 3 Transmit Specification 4 3 1 Frequency Range 824 820 MHz 848 190 MHz 4 3 2 Intermediate Frequency MSM6XXX seires Zero IF 4 3 3 Output Power 0 282W 4 3 4 Interference Rejection Single Tone 30dBm at 900 kHz Two Tone 43dBm at 900 kHz 1700kHz 4 3 5 CDMA TX Frequency Deviation 300Hz or less 4 3 6 CDMA TX Conducted Spurious Emissions 900kHz 42 dBc 30kHz bel...

Page 13: ... 840 810 MHz 842 04 MHz 843 270 MHz 844 500 MHz 845 910 MHz 847 140 MHz 848 370 MHz 4 5 MS Mobile Station Receiver Frequency FA NO CH NO CENTER FREQUENCY FA NO CH NO CENTER FREQUENCY 1 2 3 4 5 6 7 8 9 10 1011 29 70 111 152 193 234 275 316 363 869 640 MHz 870 870 MHz 872 100 MHz 873 330 MHz 874 560 MHz 875 790 MHz 877 020 MHz 878 250 MHz 879 480 MHz 880 890 MHz 11 12 13 14 15 16 17 18 19 20 404 445...

Page 14: ...ne with the installed battery pack Red light indicates battery is being charged Green light indicates battry is fully charged 5 3 For Mobile Mount 5 3 1 Installation Position In oIDer to reduce echo sound when using the Hands Free Kit make sure that the speaker and microphone are not facing each other and keep microphone a generous distance from the speaker 5 3 2 Interface Box Choose an appropriat...

Page 15: ...onnect the green wire to the car ignition sensor terminal In oIDer to operate HFK please make sure to connect green wire to ignition sensor terminal Connect the kit s power cable connector to the interface box power receptacle 5 3 4 2 Antenna Cable Connection Connect the antenna coupler cable connector from the cradle to the external antenna connector Antenna is not included Z 3 X B O X C O M ...

Page 16: ... press 1 display the PHONE MODEL DEBUG MENU Service Mode 2 Test Screen 1 3 Test Call 4 Vocoder Set OK 5 Hybrid Pref PHONE MODEL 95 You can t edit PHONE MODEL then press OK DEBUG MENU Service Mode 2 Test Screen 1 3 Test Call 4 Vocoder Set OK 5 Hybrid Pref SLOT CYCLE INDEX 1 You can edit SLOT CYCLE INDEX but not recommended then press OK CHAPTER 2 NAM Input Method Inputting of telephone numbers incl...

Page 17: ... 3 Test Call 4 Vocoder Set Edit OK 5 Hybrid Pref NAM 1 NAME Empty Edit the name of NAM1 the press OK NAM 1 NAME may display the name of the service provider DEBUG MENU Service Mode 2 Test Screen 1 3 Test Call 4 Vocoder Set Add End 5 Hybrid Pref NAM 1 Standard Program IS COMPLETE Now the basic programming is completed To reset the handset press Done If you want to program detail informtions for NAM...

Page 18: ...Back The editable NAM items are followed SERVICE SECURITY CODE NAM 1 MOBILE COUNTRY CODE NAM 1 MOBILE NETWORK CODE NAM 1 PRL Enabled NAM 1 CDMA Home System Reg NAM 1 CDMA Foreign SID Reg NAM 1 CDMA Foreign NID Reg NAM 1 CDMA Home SID NID NAM 1 Lock out SID NID NAM 1 CDMA Primary CH A NAM 1 CDMA Secondary CH A NAM 1 CDMA Primary CH B NAM 1 CDMA Secondary CH B NAM 1 ACCOLC 0 Editing this items is no...

Page 19: ...nd sent to the MSM6000 Mobile Station Modem of the digital circuit part Then they are demodulated by the modulator demodulator In the case of transmission MSM6000 modulates interpolates and converts the digital signal into an analog baseband before sending it to the RFT6122 RFT6122 receives OQPSK modulated anlaog baseband signals from the MSM6000 s Tx part The RFT6122 upconverts the Tx analog base...

Page 20: ...o prevent the drop in receive sensitivity characteristics The receive part BPF blocks the signals sent out from entering the receive end in oIDer to improve sensitivity characteristics Insertion loss IL in the transmit band is 2 8dB Max whereas IL in the receive band is 2 1dB Max The receive band attenuation amount of transmit filter is 51dB Min and the transmit band attenuation amount of receive ...

Page 21: ...ntegrated CDMA Rx solution designed to meet cascaded Noise Figure NF and ThiID oIDer Intercept Point IIP3 requirements of IS 98C and J STD 018 specifications for Sensitivity Two Tone Intermodulation and Single tone Desense Operation modes and band selection are specially controlled from the Mobile Station Modem MSM6000 The specification of ID2750 Mixers are described below Parameter High Gain Mode...

Page 22: ...in RFT6122 converts baseband signals into RF signals After passing through the upconverters RF signal is inputted into the Power Amplifier Module The RFT6122 Cellular CDMA RF specifications are described below Condition Min Typ Max Unit Rated Output Power Average CDMA Cellular 6 dBm Min Output Power Average CDMA Cellular 75 dBm Rx band noise power CDMA Cellular 132 dBm Hz ACPR Cellular Fc 885kHz F...

Page 23: ...t it into the frequency synthesizer of UHF band Frequency stability depending on temperature is 2 0 ppm 1 4 2 Voltage Controlled Oscillator U104 The internal VCO signal of RFR6122 is processed by the LO generation and distribution circuits in RFR6122 to create Cellular quadrature downconverter s LO signals The LO signals applied at the mixer ports are at the frequency different than the VCO freque...

Page 24: ...2 2 Voice Processing Part The voice processing part is made up of an audio codec in MSM6000 used to convert MIC signals into digital voice signals and other external MIDI Synthesizer used to convert digital voice signals into analog voice signals amplifying parts for amplifying the voice signals and MIC signals are on external MIDI Synthesizer and Codec in MSM6000 2 2 3 MSM6000 Mobile Station Mode...

Page 25: ...taneously And it also contains complete digital modulation and demodulation systems for CDMA cellular standaIDs as specified in IS 95 A B C The CPU controls total operations of the subscriber unit Digital voice data that have been inputted are encoded using the QCELP algorithm Then they are convolutionally encoded so that error detection and correction are possible Coded symbols are interleaved in...

Page 26: ...tation such as a ESN Electronic Serial Number are stored The programs can be changed through down loading after the assembling of mobile stations On the SRAM data generated during the operation of a mobile station are stored temporarily 2 3 4 Power Supply Part When the battery voltage 4 2V is fed and the PWR key of keypad is pressed the power up circuitry in PM power management IC U401 is activate...

Page 27: ...TDMI microprocessor core MEMORY FLASH ROM 32Mbits U202 K8D3216UTC DI07 STATIC RAM 16Mbits U203 K6F1616U6C XF70 CPU The ARM7TDMI 32 bit microprocessor is used and CPU controls all the circuitry Some of the features of the ARM microprocessor include a 3 stage pipelined RISC architecture both 32 bit ARM and 16 bit THUMB instruction sets a 32 bit address bus and a 32 bit internal data bus It has a hig...

Page 28: ...nition key matrix is setup using KEY_SENSE0 4_N signals and GPIO 21 57 61 of output ports of MSM6000 10 LEDs and backlight circuitry are included in the keypad for easy operation in the dark LCD MODULE LCD module contains a controller which will display the information onto the LCD by 16 bit data from the MSM6000 It is also supplied stable 2 85V_MSMP by inner regulator in U400 for fine view angle ...

Page 29: ... Circuit 2 Check VCTCXO Circuit 3 Check Rx VCO 5 Check Duplexer Mobile SW 6 Check Rx I Q data Redownload SW CAL 4 1 1 When Rx Power isn t enough Checking Flow Test Point Figure 4 1 4 1 Rx Part Trouble 1 2 3 4 5 VCTCXO 4 Check Control Signal CHAPTER 4 Trouble Shooting CHAPTER 4 Trouble Shooting Duplexer VCTCXO RFR6122 PMIC Z 3 X B O X C O M ...

Page 30: ...uit Diagram Test Point Checking Flow Check Pin 31 of U400 2 6V_Rx OK No Pin 7 High No Changing Board PMIC Circuit is OK See next Page to check VCTCXO Replace U400 U400 31 2 6V_RX U400 7 High Figure 4 2 Check Pin 7 of U400 Z 3 X B O X C O M ...

Page 31: ...Check U407 Pin 3 Refer to Graph 4 1 a CheckU407 Pin 4 Refer to Graph 4 1 b 19 2MHz OK 2 8V_TCXO OK No Yes VCTCXO Circuit is Ok See next Page to check Rx VCO Check U400 No Yes Changing U407 U407 3 U407 4 Figure 4 3 Waveform Graph 4 1 a Graph 4 1 b U400 32 Z 3 X B O X C O M ...

Page 32: ...ph 4 2 Check U104 Pin 16 Check if the voltage is around 1 5V UHF_LO OK CP_RX OK No Yes Yes No Rx VCO is Ok See next Page to check Control Signal Check U103 Figure 4 4 Rx TEST SETUP HHP Test Channel 384 DCN 600 PCS Spectrum Analyzer Setting Oscilloscope Setting U104 18 UHF_LO_OUT U104 16 CP_RX Replace U104 Z 3 X B O X C O M ...

Page 33: ...DCN Mode Graph 4 2 1763 04MHz DCN384 Z 3 X B O X C O M ...

Page 34: ...in 3 4 5 Refer to Graph 4 3 a b Check SBDT SBCK SBST Check if there is Any Major Difference Refer to Graph 4 3 a b Level is High Similar Yes No Yes No Download the SW Download the SW Control Signal is Ok See next Page to check Duplexer Figure 4 5 SBDT SBCK SBCK SBST Graph 4 3 a Graph 4 3 b Z 3 X B O X C O M ...

Page 35: ...4 1 6 Checking Mobile SW SP3T Duplexer DCN PCS Test Point Circuit Diagram DP101 2 Figure 4 6 U100 2 DP101 7 Z 3 X B O X C O M ...

Page 36: ... Signal Detected Signal DCN Duplexer is Ok See next Page to check Rx I Q data Signal Check C100 Changing DP101 Check U100 Pin 2 Check if there is Any Major Difference Refer to Graph 4 4 a Check DP101 Pin2 Check if there is Any Major Difference Refer to Graph 4 4 b Check DP101 Pin 7 Check if there is Any Major Difference Refer to Graph 4 4 c Yes No Yes No Waveform U100 Pin 2 Graph 4 4 a Z 3 X B O X...

Page 37: ...Waveform DP101 Pin 7 Graph 4 3 c DP101 Pin2 Graph 4 4 c Z 3 X B O X C O M ...

Page 38: ... U104 27 Rx_I_M U104 28 Rx_I_P U104 25 Rx_Q_P U104 27 Rx_I_M U104 26 Rx_Q_M Checking Flow Check U104 Pin 25 26 27 28 Check if there is Any Major Difference Refer to Graph 4 5 a b Similar Yes No Replace U104 Redownload the Software Calibrate Figure 4 7 Graph 4 5 a Graph 4 5 b Z 3 X B O X C O M ...

Page 39: ...t to cdma Tx on Power Amp On Set channel to 384 AGC 400 Spectrum analyzer setting Oscilloscope setting 1 Check Regulator PMIC Circuit 2 Check VCTCXO Circuit 3 Check SBI Control Signal 4 Check RFT6122 Circuit 7 Check Duplexer Mobile SW Circuit Redownload SW CAL 6 Check PAM Circuit Mobile S W Duplexer VCTCXO PAM RFT6122 Z 3 X B O X C O M ...

Page 40: ...V_MSMP 2 85V_TX_REG 4 2 Vbatt OK U201 Pin E14 TX ON High Replace U201 Replace U400 Regulator Circuit is OK See Next Page to Check VCTCXO Check Pin 4 13 16 29 U400 U201 YES YES NO NO U400 Pin 29 2 6V_Tx U400 Pin 16 2 8V_MSMP U400 Pin 4 4 2V_Vbatt U400 Pin 13 2 85V_TX_REG Z 3 X B O X C O M ...

Page 41: ...gram Waveform Checking Flow Pin 3 19 2MHz OK VCTCXO Circuit is OK See next page to check SBI control signal YES NO Pin4 2 8V OK Replace U407 NO Check U400 X100 YES U407 Pin4 2 8V_TCXO U407 Pin3 TCXO U407 Pin3 TCXO U407 Pin4 2 8V_TCXO Z 3 X B O X C O M ...

Page 42: ...ircuit Flow Level is appear YES NO Similar Waveform NO Control Signal is OK See next page to check RFT6122 Circuit Check Pin 1 2 32 YES Download the SW Download the SW Waveform U103 Pin 1 2 32 SBST SBDT SBCK SBDT SBCK SBCK SBST Z 3 X B O X C O M ...

Page 43: ...Level near 1V is Appear NO Control Signal is OK See next page to check PAM Circuit Check C158 C159 YES Check U201 Replace U103 Check U103 Pin12 NO Output signal CELL is Appear YES Check U103 Pin23 Replace U103 C158 C159 TX_I Q U103 Pin12 TX_CP U103 Pin23 CELL_OUT Z 3 X B O X C O M ...

Page 44: ...Circuit Diagram Waveform C158 C159 TX_I Q DATA U103 Pin23 DCN_OUT SPECTRUM ANALYZER CONDITION RBW 1MHz VBW 1KHz Span 60MHz Frequency DCN 836 52MHz Z 3 X B O X C O M ...

Page 45: ...4 2 5 Check PAM Circuit Test Point Circuit Diagram U102 Pin4 Vref 2 85V U102 Pin7 RF_OUT U102 Pin 1 8 Vcc1 2 U102 Pin3 Vmode 0 7 2 1V U102 Pin2 RF_IN Z 3 X B O X C O M ...

Page 46: ... TEST POINT Circuit Flow Level is Appear YES NO Level is Appear NO Redownload SW and Recalibration Check DP100 Pin2 DUP_OUT YES Replace DP100 Replace U100 Check U100 Pin1 DP100 PIN2 DP_out U100 PIN1 Mobile S W out Z 3 X B O X C O M ...

Page 47: ... Level is OK YES Check U102 Pin3 DCN Vcont 0 7v 2 1v Check F100 Check Q100 U400 NO Level is 3 4V 4 2V OK YES Check U102 Pin1 8 VCC1 2 Check U201 Replace U101 NO Output Level is Appear YES Check U102 Pin7 RF_OUT Replace U102 Waveform U102 Pin2 DCN PAM_IN U102 Pin7 DCN PAM_OUT SPECTRUM ANALYZER CONDITION RBW 1MHz VBW 1KHz Span 60MHz Frequency DCN 836 52MHz Z 3 X B O X C O M ...

Page 48: ...Circuit Diagram Z 3 X B O X C O M ...

Page 49: ...Figure 4 3 1 PMIC PM6610 FUNCTIONAL BLOCK DIAGRAM 4 3 Logic Part Trouble Z 3 X B O X C O M ...

Page 50: ...ement circuit diagram Figure 4 3 3 PM6610 POWER MANAGEMENT SECTION 7 PS_HOLD 4 3 1 Power On Trouble 16 2 8V_MSMP 32 2 8V_TCXO 11 2 6V_MSMA 14 2 4V_MSMC 8 PWR_ON_SW Circuit Diagram U400 PMIC U201 MSM 29 2 6V_TX 31 2 6V_RX Z 3 X B O X C O M ...

Page 51: ... The Phone will power on Replace the main board Check the contact of power key or dome switch Push power on key and check the level change of U400 PWR_ON_SW high Check the voltage of the following port at U400 2 4V_MSMC 2 8V_MSMP 2 6V_MSMA 2 8V_TCXO 2 6V_RX 2 6V_TX Logic level at PS_HOLD of U201 High Does it work properly Does it work properly YES YES YES YES NO NO NO NO NO YES YES Z 3 X B O X C O...

Page 52: ...4 3 2 Charging Trouble Test Points Figure 4 3 4 CHARGER CIRCUIT PART Block Diagram Figure 4 3 5 PM6610 CHARGING CONTROL BLOCK Circuit Diagram R461 U400 Q401 Q401 Z 3 X B O X C O M ...

Page 53: ...ng adaptor TA is out of order Change the charging adaptor Voltage at Pin1 V_CHAR of CON300 5V YES NO YES NO Is the battery charged NO The battery may have the problem Change the battery and try again Charging will operate properly YES YES Does U400 and Q401 work Properly Change the U400 or Q401 NO Q401 R461 well soldered Re Soldering Q401 R461 YES Z 3 X B O X C O M ...

Page 54: ...ints Figure 4 3 6 RECEIVER PART Circuit Diagram Figure 4 3 7 RECEIVER PART Block Diagram Figure 4 3 8 RECEIVER CODEC BLOCK L403 L404 R422 Pin6 AUDIO_GAI N_SEL Pin4 SPK_ IN Pin6 VBATT CON403 U401 U409 U408 R428 R423 Z 3 X B O X C O M ...

Page 55: ...k the signal level at L403 404 Check the signal level at Pin4 of U401 Does U401 work properly Replace the MSM or Board Re soldering L403 L404 Replace the MSM Check the signal level of EAR10 at R422 R428 Re soldering or Replace the U402 Re soldering or Replace the U401 Speaker will work properly Yes Yes Yes Yes NO NO NO NO Check the soldering L403 L404 Yes Yes NO Voltage at Pin6 of U401 is over 3 4...

Page 56: ...Test points Circuit Diagram Figure 4 3 10 MIC FILTER PART Figure 4 3 9 MIC BIAS PART Figure 4 3 11 MIC MIC FILTER 4 3 6 MIC Trouble U403 R434 C439 C440 Mic filter Z 3 X B O X C O M ...

Page 57: ...34 Re solder R434 Replace MSM Check the signal level At each side of MIC Is It a few tens mVAC Replace the microphone Check the soldering of C439 C440 Re solder C439 C440 Check the soldering of MIC Filter Part Re solder MIC Filter part MIC will work properly Checking Flow Yes Yes Yes Yes No No No No No Yes Z 3 X B O X C O M ...

Page 58: ...4 3 7 Vibrator Troble Checking Flow Circuit Diagram Figure 4 3 13 VIBRATION CONTROL BLOCK Figure 4 3 12 Vibrator PART Q403 R436 Q406 LED414 R416 R417 Z 3 X B O X C O M ...

Page 59: ... the voltage across LED414 over 2 5V Is the voltage across R436 Under 3V Check the signal level at MSM_MOTOR_EN high Replace MSM Replace Vibrator Does Vibrator work Properly Yes No Check the soldering of Q406 R417 LED400 Re soldering Q406 R417 LED414 No Replace Q406 R417 LED414 Yes Re soldering Q403 R436 Check the soldering of Q403 R436 No Replace Q403 R436 Yes Z 3 X B O X C O M ...

Page 60: ...4 3 8 Key Backlight LED Trouble Test Points Figure 4 3 14 KEYPAD BACK LIGHT PART Figure 4 3 15 KEYPAD Back Light Circuit R415 Q400 Z 3 X B O X C O M ...

Page 61: ... is working Charge or Change Battery and try again Check the soldering of each R or replace LEDs not working Check the condition of Q400 R415 If problem Change Q400 R415 No No No Yes Yes Yes BACKLIGHT WILL WORK PROPERLY Check the signal level at KEY_BACK_EN high Replace MSM No Yes Z 3 X B O X C O M ...

Page 62: ...4 3 9 Earphone Trouble Test Points Circuit Diagram Figure 4 3 16 EAR MIC JACK PART Figure 4 3 17 EAR MIC JACK PART MSM U203 R206 C212 U404 R207 CON401 C430 Z 3 X B O X C O M ...

Page 63: ...io path problem Can you hear your voice from the earphone Change Earphone Set the audio part of the test equipment to continuous wave mode Earphone receiving Path problem Can you hear the sound from the earphone Earphone sending path problem 1 4 2 3 Yes No Yes No Earphone receiving path problem 2 Level of C430 is about 1 2V Check soldering of Pin 3 of CON401 Change main board Download S W Re solde...

Page 64: ...r U404 Replace U404 4 Yes 5 Earphone sending path problem Earphone detect problem Earphone sending path problem 3 Level pin4 of CON401 is about 1 6V Level of C232 is About a few tens or hundreds VAC Re solder R206 R207 Re solder C232 Does it work well Re download software Does it work well 4 Change main board No No Yes Yes Yes Yes No No No No Yes Yes No Z 3 X B O X C O M ...

Page 65: ...4 3 10 LCD Trouble Figure 4 3 18 LCD CONNECTOR PART Test Points Circuit Diagram Figure 4 3 19 LCD CONNECTOR Q300 U202 R400 403 LED400 403 VR300 VR301 CON303 L300 C315 C326 Q405 Z 3 X B O X C O M ...

Page 66: ... Re soldering or Replace VR300 VR301 R326 No Does VR300 VR301 R326 Work Properly Change the Main Board Yes Check the Control signal D 0 7 LCD_RESET LCD_RS LCD_CS LWR RD Check the CON303 Soldering No Re Soldering CON303 No Does LCD work properly Check voltages at each point of Capacitor Change the LCD Module Yes Z 3 X B O X C O M ...

Page 67: ...LED400 403 R400 403 Does Q405 work Properly No Yes Re soldering or Replace LED400 403 R400 403 Yes No Re Soldering or Replace Q405 Check the signal level at LCD_BACK_EN high Replace MSM No Yes LCD backlight will work properly Z 3 X B O X C O M ...

Page 68: ...4 3 11 When UIM isn t operating Test Point Circuit Diagram CON402 No 1 Q407 No 1 Z 3 X B O X C O M ...

Page 69: ...Checking Flow Z 3 X B O X C O M ...

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LG ID2750, Service Manual

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