TROUBLESHOOTING NHC–4 6–2–1 9526ARo Technical Documentation Copyright Nokia Mobile Phones Contents Troubleshooting for Base Band Overview to base band troubleshooting General Current consumption failures in flash station Phone takes all available current Phone does not take current at all Current consumption OK during power–up, then fail Troubleshooting Diagram; Flash Programming OK, part 1 Troubleshooting Diagram; Flash Programming OK, part 2 Troubleshooting Diagram; Flash Programming OK, part 3 Trou
TROUBLESHOOTING 9526ARo Technical Documentation ERROR A69–70; Tuning ST/audio deviation ERROR A72; The I/Q Tuning fails ERROR A73; Digital AGC tuning fails ERROR A00; RF side supply voltages NHC–4 6–2–2 Copyright Nokia Mobile Phones 6–2–48 6–2–49 6–2–51 6–2–53
TROUBLESHOOTING 9526ARo Technical Documentation NHC–4 6–2–3 Copyright Nokia Mobile Phones Troubleshooting for Base Band Overview to base band troubleshooting The purpose is to define fault block of the module and then find out the defect component. Baseband oriented failures are usually found out in the flash station of the production line.In the first phase,before programming the flash,the phone is started to minimum mode and current consumption is measured.
TROUBLESHOOTING 9526ARo Technical Documentation NHC–4 6–2–4 Copyright Nokia Mobile Phones General The purpose is to define fault block of the module and then find out the broken component. The trouble shooting diagram has been planned so that the fault, whatever it is, can be found by as simple measurements as possible. The flow diagrams give you the overview of the blocks.
TROUBLESHOOTING NHC–4 6–2–5 9526ARo Technical Documentation Copyright Nokia Mobile Phones Current consumption failures in flash station Current consumption can fail in three ways in flash station.Typical to all these failures is,that phone can not be programmed or tested via MBUS.The most common failure is that phone takes almost normal current during startup and after couple of seconds all circuits are powered down.Reason for this failure is in power–,clock– or reset distripution of the phone.
TROUBLESHOOTING 9526ARo Technical Documentation NHC–4 6–2–6 Copyright Nokia Mobile Phones cuits D300 (FLASH) pins 31 and 32,D305 (RAM) pin 28 and D307 (EEPROM) pin 8 3.Check voltage VL1 from ASIC (D401) pins 1,36,57,73,108 and 122.Check also supply voltage of RFC buffer (D402) from pin 5 4.Check voltage VL2 from DSP (D200) pins 8,11,36,39,49,64,76,87 and 90.Voltage should be around 4.65V.VL2 is also fed to DSP RAMs D201 and D202 to pin 28. 5.Check voltages of RFI (N450).VL1 is fed to pins 48,52 and 60.
TROUBLESHOOTING NHC–4 6–2–7 9526ARo Copyright Nokia Mobile Phones Technical Documentation Troubleshooting Diagram; Flash Programming OK, part 1 FLASH programming OK MBUS registration OK? YES NO Display: selftest failed D302/MCU/pin 3 D401/ASIC/pin 56 rstrobex YES 3 Power stays on? YES Display: selftest failed NO NO Check X1 VBATT pins 5, 20? NO Short circuits in data data lines.
TROUBLESHOOTING NHC–4 6–2–8 9526ARo Copyright Nokia Mobile Phones Technical Documentation Troubleshooting Diagram; Flash Programming OK, part 2 2 NO YES Change D302 9.72 MHz at D302 at pin 69 NO Check D402 G580,D401 NO 9.72 MHZ at D401 pin 70 YES Check R419 YES MCU/D302/pin 10 RESETX +5 V after power on? 9.
TROUBLESHOOTING NHC–4 6–2–9 9526ARo Technical Documentation Copyright Nokia Mobile Phones Troubleshooting Diagram; Flash Programming OK, part 3 3 MBUS registration OK? YES Display: selftest failed? YES EEPROM initialization OK? NO NO Check D302, R320,R321 D307 EEPROM /pins 5,6/SDA/SCL pulses +5 to 0 V during r/w action? YES Change D307 YES 4
TROUBLESHOOTING NHC–4 9526ARo 6–2–10 Technical Documentation Copyright Nokia Mobile Phones Troubleshooting Diagram; Flash Programming OK, part 4 4 D300/FLASH /pin 11 +12 V during programming? NO Check X1/pin 14 C302,L300 NO Check X1/pin 6 R304,R305 NO Check D302/pin 63 R314 YES D302/MCU /pin 64/HOOK/RXD2 pulses during prog? YES X1/pin 7 /PHFS/TXD2 pulses during programming? YES D300/FLASH /pin 12/PWD +5 V after power on? NO Check D302 YES D300/FLASH /pin 22/ROMSELX pulses from +5 to 0 V
TROUBLESHOOTING NHC–4 9526ARo 6–2–11 Copyright Nokia Mobile Phones Technical Documentation Troubleshooting Diagram; PWR Button Fault Nothing happens when PWR button is pressed Check X1 NO N100/PSL+ pin 10 +5 V when VBATT is connected YES NO N100/PSL pins 2,5 VBATT voltage YES Change N100 Change UI Check UI–conn.
TROUBLESHOOTING NHC–4 9526ARo 6–2–12 Technical Documentation Copyright Nokia Mobile Phones Troubleshooting Diagram; Display Selftest Failed Display selftest failed or phone doesn’t registrate to the system (tester) Use PCLocals to find out a reason MCU internal test MCU RAM bus test MCU ROM bus test MCU IMEI test YES Unprogrammed FLASH Unconnected pins in MCU address or data lines NO MCU DSP code download: failed, DSP tests: no responce RFI bus fault YES NO MCU audio codec test: failed YES
TROUBLESHOOTING NHC–4 9526ARo 6–2–13 Technical Documentation Copyright Nokia Mobile Phones Troubleshooting Diagram; Audio Fault Audio fault Microphone or earphone signal missing Microphone and earphone signal missing? YES CODEC pin 19/sync from ASIC CODEC pin 20/CODEC_CLK from ASIC DSP pins 29,37/PCMCOSYCLK from ASIC DSP pins 27,33/PCMDATRCLK from ASIC YES CODEC N150/pin 25,23 MICP,MICN CODEC N150/pin 17 PCMOUT CODEC N150/pin 21 MIC_EN NO Microphone signal missing? corresponding pins of UI–
TROUBLESHOOTING NHC–4 9526ARo 6–2–14 Copyright Nokia Mobile Phones Technical Documentation Power Up Sequency Diagram VCTCXO CLK 19.44 MHz D402 BUFFER CLK 19.44 Mhz VBAT 5.5...8 V VL1 5,20 VL2 CHRGDET 1.5 V 11 14 PSL DETIN 12 1 2 C106 14 ON 70 24 8 ASIC VREF 69 VA MCU CLK RESET IRQX 10 MCU 77 5 V=ON 5,42 VA2 XRESET 69 66 TXD R166 88 XPWROFF 9 43 XPWROFF 2 Hz PSL – Output voltages must be stay at high state at least 1.5 s when power is switched on.
TROUBLESHOOTING NHC–4 9526ARo 6–2–15 Technical Documentation Copyright Nokia Mobile Phones Repairing Instructions for Flash Faulty Units 1. When the phone doesn’t start (power off after 2 seconds) check following things: – VBATT is connected to the PSL N100 – XRES rise to high state – VL1 is 4.7 V – VREF is connected to the VCTCXO and the crystal is running frequency is 19.44 MHz Measure: – supply voltage of MCU D302 – reset signal for MCU (RESETX) rise high state – MCU clocksignal is 9.
TROUBLESHOOTING NHC–4 9526ARo 6–2–16 Technical Documentation Copyright Nokia Mobile Phones 4. If selftest (A) is failed, check: – Solderings of EEPROM D307 – Do factory set once again (setup error in EEPROM D307) 5. If selftest (B) is failed, check: – Reset signal DSPRSTX for DSP (D200 pin 69) is high state. – Clock signal at pin 66 (DSP) is 38.88 MHz (square wave; amplitude 5 V). – Check solderings of D200, D201 and D202. Calib BATT_VOLTAGE = 6.
TROUBLESHOOTING NHC–4 9526ARo 6–2–17 Technical Documentation Copyright Nokia Mobile Phones Troubleshooting Diagram; Power Up and MCU Selftest Malfunctions RADIO UNIT CHECK Press power on Current consumption OK? NO See Power Up Malfunction NO See Self Tests Malfunction YES Run self tests OK? YES Call process Audio check OK
TROUBLESHOOTING NHC–4 9526ARo 6–2–18 Technical Documentation Copyright Nokia Mobile Phones Power Up Malfunction Basicly there are two different cases, which could occur during powering up the phone. First case is that the current consumption is almoust zero all the time. Probably the fault is then at the power circuit PSL+(N100). Check all N100 connections including VBATT line. At the second case the phone’s current consumption is normal for a while (2–3 sec.) and goes to zero after that time.
TROUBLESHOOTING NHC–4 9526ARo 6–2–19 Technical Documentation Copyright Nokia Mobile Phones 3.1 Is DSA’s reset signal OK? – Check DSA reset line from PSL+ circuit (N100) pin 8 (or testpoint J101). While one (about 4.8 Vdc) GO to 3.12, if zero GO to 3.11. 3.11 Check PSL+ (N100) pin 12. Voltage should be about 1.23 Vdc (±70 mVdc), if not check R110, R111 and VBATT voltage(5.3...8.8 Vdc) from test point J108. NOTICE! Measure pin 10 from the PSL+ (N100) with oscilloscope.
TROUBLESHOOTING NHC–4 9526ARo 6–2–20 Technical Documentation Copyright Nokia Mobile Phones 5.0 Is FLASH line OK? – Measure FLASH line between DSA and FLASH (test point J400) with oscilloscope. – In case that there is nothing at the FLASH line check MCU’s connections. – If there are enormously edges or if there are couple of edges and then nothing, flashing has been probably failed. Flash memory again. 6.
TROUBLESHOOTING NHC–4 9526ARo 6–2–21 Copyright Nokia Mobile Phones Technical Documentation Troubleshooting Diagram; Power Up Malfunction Start 1.11 Check VCTCXO NO 1.1 VCTCXO running OK? NO YES 1.21 Check output and VL1 of D402 NO 1. MCU clock running OK? YES 1.2 DSA clock running OK? YES 2. MCU’s supply voltages OK? 1.22 Check connections between MCU and DSA NO 2.1 Check PSL+ (N100) VL1–line (pins 3,4,9,12) YES 3. MCU’s reset signal OK? NO 3.1 DSA reset signal OK? NO 3.
TROUBLESHOOTING NHC–4 9526ARo 6–2–22 Copyright Nokia Mobile Phones Technical Documentation Troubleshooting Diagram; MCU Selftests Malfunction Start 1.1 Check MCU and MCU’s pins (D302) NO 1. MCU internal self test OK? YES 2. MCU ROM tests OK? NO 2.1 Check MCU pins and clock YES 3. MCU RAM tests OK? NO 3.1 Check RAM pins YES 4.11 Check VBATDET and VC value via MBUS NO 4. PWRU tests OK? YES 4.21 Check VC and VBATDET value via MBUS NO 4. PWRU tests OK? YES NO NO 5. DSP tests OK? 5.
TROUBLESHOOTING NHC–4 9526ARo 6–2–23 Technical Documentation Copyright Nokia Mobile Phones Troubleshooting for RF The Red Line of this Repair Guide The fault finding that is described in this guide is based on manufacturing fault information from Alignment and Final stages. There are done several tests in each stage and all of them are numbered individually and which numbers are referred as error number.
TROUBLESHOOTING NHC–4 9526ARo 6–2–24 Technical Documentation Copyright Nokia Mobile Phones Final Stage References 10 / SERV TEST See baseband (10/Start current). 12 / MS CALLS BS and 25 / HANDOFF (A–D) See 13/Tuning AFC, 69/Tuning st deviation and 70/Tuning tx audio gain. Check that FM modulation is fine and that synthesizer could move from one channel to other. 70 / RX SINAD and 48 / RXD BER See 67/Measure SINAD and 73, 78/Tuning AGC.
TROUBLESHOOTING NHC–4 9526ARo 6–2–25 Technical Documentation Copyright Nokia Mobile Phones How to read those sheets? ERROR A00: Tittle of fault The letter and number refer to Flash and Alignment phases in production line. The number is used to refer each step in those phases. For example A13 refers for fail in AFC tuning in alignment place. Tittle of error is just a name for that error. BEHAVIOUR OR DUT Describes how the device will act when an error or inaccuracy in function occurs.
TROUBLESHOOTING NHC–4 9526ARo 6–2–26 Copyright Nokia Mobile Phones Technical Documentation NO HELP – NEXT STEP It is possible that the reason of fault cannot be solved according to this repair guide due to principle keep–it–simple, so an additional help, if any, where to continue is given here. INFORMATION TABLE Yes, a table where voltages, frequencies etc. are mentioned and where they could be found, but only those ones that are mentioned in this page.
TROUBLESHOOTING NHC–4 9526ARo 6–2–27 Technical Documentation Copyright Nokia Mobile Phones ERROR A10; The DUT does not turn on BEHAVIOUR OR DUT When powering on the supply current falls down (to zero) and any commands from NHC4SERV have no effect at all. OBVIOUS REASON The origin of all clock signals (VCTCXO, 19.44MHz) is not generated properly or at all caused by any reason. EXPLANATION If 19.
TROUBLESHOOTING NHC–4 9526ARo 6–2–28 Copyright Nokia Mobile Phones Technical Documentation 3. Does the VCTCXO oscillate at frequency of 19.44MHz with amplitude at least 600mV peak to peak? If yes, the VCTCXO is fine. If not, check that VCTCXO receive supply voltage VXAO and AFC voltage, and if even those voltages are fine then remove the VCTCXO and replace it by a new one. Case of no or wrong AFC voltage consult baseband’s repair guide or AFC repair guide. 4. Does the buffer of VCTCXO amplify the 19.
TROUBLESHOOTING NHC–4 9526ARo 6–2–29 Technical Documentation Copyright Nokia Mobile Phones ERROR A13a; AFC tuning fails BEHAVIOUR OR DUT AFC–dac value is out of limits after tuning or frequency error is too high. OBVIOUS REASON AFC control voltage is wrong or VCTCXO fails. EXPLANATION VCTCXO frequency is tuned with DC–control voltage. EQUIPMENT For voltages: DVM, Digital Voltage Meter For frequency: Frequency counter SETTINGS Connect voltages on.
TROUBLESHOOTING NHC–4 9526ARo 6–2–30 Copyright Nokia Mobile Phones Technical Documentation INFORMATION TABLE COMPONENT INFORMATION MEASUREMENT INFORMATION Comp. Ref Code T/B Location Name Value Notes PSL N100 4375588 B PIN 7 VBATT 6.0V +2.0V/–0.7V BATTERY VOLTAGE PIN 1 VREF 4.5V +/–100mV TO CRFCONT PIN 28 VXAO 4.5V +/–100mV TO VCTCXO PIN 15 VREF 4.5V +/–100mV FROM PSL PIN 13 BIAS 2.5V +/–50mV PIN 1 VBATT 6.0V +2.0V/–0.7V PIN 1 VXAO 4.5V +/–100mV PIN 2 AFC 2.
TROUBLESHOOTING NHC–4 9526ARo 6–2–31 Copyright Nokia Mobile Phones Technical Documentation 2. Check the supply voltages and bias of the local buffers. Receiver buffer V770 and transmitter buffer V970. Measure signal level with Rf probe in mixers. 3. Check the VHF–synthesizer too. NO HELP – NEXT STEP Probably a base band fault like broken ASIC. INFORMATION TABLE COMPONENT INFORMATION MEASUREMENT INFORMATION Comp. Ref Code T/B Location RX–BUF V770 4210346 B TX–BUF V970 4210346 T UHF CONT.
TROUBLESHOOTING NHC–4 9526ARo 6–2–32 Copyright Nokia Mobile Phones Technical Documentation WHAT TO DO Check the supply voltage and the control voltage of VHF VCO. 1. VCO control voltage is around 1.8V in analog mode. Measure the voltage from C575. If voltage is around 4V check the VHF level in PLL pin 15. IF voltage is 0V check the reference signal in PLL pin 8. 2. Check the supply voltages and bias of the VHF oscillator and VHF buffer. Oscillator transistor is V550 and buffer is V551.
TROUBLESHOOTING NHC–4 9526ARo 6–2–33 Technical Documentation Copyright Nokia Mobile Phones EQUIPMENT For voltages: DVM, Digital Voltage Meter. For clock signals: Oscilloscope. SETTINGS Connect supply voltage and give a command using NHC4SERV program that enables tuning of BC. NHC4SERV: SERVICES/RF–TUNINGS/BC Now, check immediately that current consumption is not limitless (explained later). It is preferred that current limit of power supply is adjusted to the value of 1500mA.
TROUBLESHOOTING NHC–4 9526ARo 6–2–34 Technical Documentation Copyright Nokia Mobile Phones is formed by transistor V960. The threshold voltage is –3.5V and attact time is 2us. 4. Adjust BC so that required current consumption will be reached. If the value of BC–voltage do not change check that there is life at PLL–circuits SCLK and SDATA lines when a command is given. PLL loading and control is explained in baseband’s repair guide.
TROUBLESHOOTING NHC–4 9526ARo 6–2–35 Copyright Nokia Mobile Phones Technical Documentation INFORMATION TABLE COMPONENT INFORMATION MEASUREMENT INFORMATION Comp. Ref Code T/B Location Name Value Notes BAV99 D400 4100285 T PAD 1 DNEGA –6.0V DEPENT ON PL D401 4100285 T PAD 1 –3.0V DEPEND ON PL TC7S00F (NAND) D403 4340126 T PIN 1 PIN 2 RFICLK TXPWR2 9.72 MHz / 4.5Vpp 4.5V RFICLK BUFFER UMA1018M N540 4340005 T PIN 10 BC 1.0V ADJ.
TROUBLESHOOTING NHC–4 9526ARo 6–2–36 Technical Documentation Copyright Nokia Mobile Phones SETTINGS Use NHC4SERV program to give command that allow power level adjusting. NHC4SERV: SERVICE/RF TESTING WHAT TO DO Check that device is in analog mode and dc–voltages in TX–amplifier chain are in the range that is given in information table. CRFRT –> CRFCONT –> BUFFERS & PA 1. Check at once that supply current do not exceed 900 mA or so.
TROUBLESHOOTING NHC–4 9526ARo 6–2–37 Copyright Nokia Mobile Phones Technical Documentation NO HELP – NEXT STEP Probably a cut in RF–path or improper function in power detection. Continue from repair guide Fail in power level table, part II. INFORMATION TABLE COMPONENT INFORMATION MEASUREMENT INFORMATION Comp. Ref Code T/B Location Name Value Notes CRFRT N701 4370091 T TXQN PIN 21 2.35V +/– 50mV NO AC IN ANALOG MODE TXQP PIN 22 2.35V +/– 50mV NO AC IN ANALOG MODE TXIN PIN 23 1.
TROUBLESHOOTING NHC–4 9526ARo 6–2–38 Technical Documentation Copyright Nokia Mobile Phones ERROR A22–57b; Fail in power level table, part II BEHAVIOUR OR DUT Reguired output power is not achieved by usual TXC value and DC–points seems to be correct. The GC_tx voltage at pin 5 on CRFRT is almost same as supply voltage instead of allowed maximum value about two volts. OBVIOUS REASON The signal path is broken somewhere in amplifier chain.
TROUBLESHOOTING NHC–4 9526ARo 6–2–39 Copyright Nokia Mobile Phones Technical Documentation of 90MHz signal – 10 dB) the local oscillator should be inspected. See synthetizer repair guide. 3. The TX buffers V903 and V904 should amplify the TX band signal about 30dB.
TROUBLESHOOTING NHC–4 9526ARo 6–2–40 Technical Documentation Copyright Nokia Mobile Phones ERROR A22–57c; Fail in power level..., part III BEHAVIOUR OR DUT Required output power is not achieved by usual TXC value, DC–points seems to be correct and RF signal passes to the directional coupler. TX_gc value is still quite undefined. OBVIOUS REASON The power control may not work properly.
TROUBLESHOOTING NHC–4 9526ARo 6–2–41 Technical Documentation Copyright Nokia Mobile Phones Although low power levels are defined only in digital mode of operation those levels are still available in analog mode (power level tunings). If TXLX do not operate as defined continue from baseband’s repair guide. Case of wrong dc value check components V917 (switch transistor), C939, L902, R938 (filtering components), V918 (diode switch), R937 (terminating resistor) and C950 (coupling capacitor).
TROUBLESHOOTING NHC–4 9526ARo 6–2–42 Copyright Nokia Mobile Phones Technical Documentation INFORMATION TABLE COMPONENT INFORMATION MEASUREMENT INFORMATION Comp. Ref Code T/B Location Name Value UMZ1 V729 4219922 B PIN1 COL VTX PIN2 BASE VTX PIN3 EMITTER TXC PIN4 COL GND PIN5 BASE TXC PIN6 EMITTER TXC’ PIN 37 TXL_pwc LOW CRFRT N701 4370091 T Notes FROM RFI FALSE TRANSMISSION PWR LEVEL INFORMATION PL TXC TXC’ DETO TX_gc PWR OUT TXLX PL2 2.9 2.4 2.4 27.
TROUBLESHOOTING NHC–4 9526ARo 6–2–43 Copyright Nokia Mobile Phones Technical Documentation EQUIPMENT For RF signal: Spectrum analyzer. SETTINGS Connect supply voltage and terminate RF–cable to the analyzer via attenuator. Use 1MHz span and set RES/VIDEO BW to 100kHz. Enable analog mode transmitter using NHC4SERV–program. NHC4SERV: SERVICE/RF TESTING WHAT TO DO Check the route from directional coupler to the system connector: COUPLER –> DUPLEX –> CABLE –> CONNECTOR 1.
TROUBLESHOOTING NHC–4 9526ARo 6–2–44 Technical Documentation Copyright Nokia Mobile Phones ERROR A66; RX audio gain tuning fail BEHAVIOUR OR DUT Audiosignal missing or wrong level. OBVIOUS REASON Receiver or audio signal failing. EXPLANATION Receiver signal in Rx–chain has attenuation or FM detector circuit fails or signal in baseband chain corrupts. EQUIPMENT For voltages: DVM, Digital Voltage Meter For audio signals: Oscilloscope, faster than 20MHz and 1:10 probes For testsignal: Rf generator (f.
TROUBLESHOOTING NHC–4 9526ARo 6–2–45 Copyright Nokia Mobile Phones Technical Documentation Only DC: Check the route from FM pin 9 to the RFI pin 1. NO HELP – NEXT STEP INFORMATION TABLE COMPONENT INFORMATION MEASUREMENT INFORMATION Comp. Ref Code T/B Location LNA V701 4210246 T V701 Name Value Notes C704 4.1V LNA SUPPLY VOLTAGE T R702 0.7V LNA BIAS VOLTAGE 1ST IFAMP V706 4210066 T R714 2.2V 2ND IFAMP V707 4210066 T R718/C 2.6V FM – DET.
TROUBLESHOOTING NHC–4 9526ARo 6–2–46 Copyright Nokia Mobile Phones Technical Documentation WHAT TO DO Check the audio signal in RFI input pin 1. 1. Is there 1kHz audio signal about 300mVpp in RFI input pin 1? If yes, then continue with baseband repair guide. 2. What kind of signal is the audio signal? Ia it noisy, distorted or only DC. Measure the supply voltages of the synthesizer and the receiver sections and UHF synthesizer control voltage. Check with Rf–probe the 44.545MHz oskillator works.
TROUBLESHOOTING NHC–4 9526ARo 6–2–47 Copyright Nokia Mobile Phones Technical Documentation ERROR A68; RSSI – level fail BEHAVIOUR OR DUT Signal strength measurement is wrong. OBVIOUS REASON If SINAD test works FM–detector broken or converter reference in baseband is wrong. EXPLANATION RSSI signal is produced by FM detector limitter amplifier. EQUIPMENT For voltages: DVM, Digital Voltage Meter. SETTINGS Set Rf–generator to the test channel: Rf–level –90dBm 1kHz modulation signal 8kHz deviation.
TROUBLESHOOTING NHC–4 9526ARo 6–2–48 Copyright Nokia Mobile Phones Technical Documentation ERROR A69–70; Tuning ST/audio deviation BEHAVIOUR OR DUT During analog transmission the signal deviations fails. OBVIOUS REASON During analog transmission the signal deviations fails. EXPLANATION Transmitter uses AMOD line only in analog mode.
TROUBLESHOOTING NHC–4 9526ARo 6–2–49 Technical Documentation Copyright Nokia Mobile Phones ERROR A72; The I/Q Tuning fails BEHAVIOUR OR DUT When tuning I/Q lines dc–levels so that carrier leakage (origin offset) is below required level that level is not achieved by any action. OBVIOUS REASON The dc–bias voltages at the input of modulator are unbalanced and thus the carrier will leak with modulated signal. EXPLANATION The dc–levels at I– and Q–lines are not controllable or do not exist at all.
TROUBLESHOOTING NHC–4 9526ARo 6–2–50 Technical Documentation Copyright Nokia Mobile Phones 3. Does any NHC4SERV commands that are supposed to make any changes in I– or Q–DACs dc–levels make anything in RFI side? One step correspond about 5mV increase or decrease at DAC’s output voltage. If not, continue from baseband repair guide, probably fault in RFI control logic. Check that those voltage changes are also seen in CRFRT side. 4.
TROUBLESHOOTING NHC–4 9526ARo 6–2–51 Copyright Nokia Mobile Phones Technical Documentation INFORMATION TABLE COMPONENT INFORMATION MEASUREMENT INFORMATION Comp. Ref Code T/B Location Name Value Notes RFI N450 4370015 T PIN 3 VB_ext 4.1V +/– 5mV REF DIODE V451 PIN 9 TXQN 2.35V +/– 50mV AC = 500mVpp SEE CRFRT PIN 8 TXQP 2.35V +/– 50mV AC = 500mVpp SEE CRFRT PIN 12 TXIN 2.35V +/– 50mV AC = 500mVpp SEE CRFRT PIN 11 TXIP 2.
TROUBLESHOOTING NHC–4 9526ARo 6–2–52 Copyright Nokia Mobile Phones Technical Documentation SETTINGS Set Rf–generator to the test channel: Rf–level –90dBm NHC4SERV: SERVICES/RECEIVER/CHANNEL digital WHAT TO DO Check the IF signal in RFI input ang AGD control in CRFRT–pin 39. 1. Check the 2.43MHz amplitude. If signal amplitude is very low check AGC voltage in CRFRT pin 39. AGC voltage is pulsed and chared with TX power control signal. 2. Check 45MHz signal amplitude in CRFRT pin 1. 3. Check IF2 2.
TROUBLESHOOTING NHC–4 9526ARo 6–2–53 Technical Documentation Copyright Nokia Mobile Phones ERROR A00; RF side supply voltages BEHAVIOUR OR DUT Functional error, supply current less than excepted in some situations. That kind of error can be described by any kind of error report. OBVIOUS REASON RF side is powered by one common IC–circuit, CFRCONT, which contains eight individual regulators, and one P–channel FET, IRFR9020. The FET is used only for power amplifier.
TROUBLESHOOTING NHC–4 9526ARo 6–2–54 Technical Documentation Copyright Nokia Mobile Phones (R911). If negative voltage is missing see reapair guide Fail in bias control tunig. Measure that zener diode (V929, BZX84C5V1) will stabilize voltage for 5.1V at its anode and that voltage is available at base of adjusting transistor (V932, UMT1, R939). The relationship of collector voltage of that transistor and gate voltage of PFET is diode voltage formed by other side of dual transistor V932 (about 0.7V).
