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Trouble Shooting Guide, Advanced

4/00021-3/FEA 209 544/25 C

Ericsson Mobile Communications AB

37(78)

11.2 How to find the fault

Phase and frequency error is a difficult measurement to perform, since the requirements on
e.g. instrument, cables and connections are very hard.
Therefore is fault usually due to bad connections or cables at the test site.

If the phone really is faulty, open it and check for liquid damage.

No further action should be taken for a liquid damaged unit, send it on according to the
local company directives.

Make sure the antenna connection is not damaged or dirty (dust, varnish or oxide).

The fault can also depend on a change in the characteristic of the transmitter, due to ageing or
an incorrect calibration.
Before you start to trouble shoot, perform a new radio calibration in EFRA and test the phone
again to eliminate this kind of fault.

Notice that the calibration demands test program in the phone while the Go/No Go –test
demands signal program.

The few times the fault is electrical, is it usually due to B320 or N400.
The fault can also be due to N392.

Содержание A2618s

Страница 1: ...BDATA Calibration 15 6 Current Calibration 16 7 Network Problems 20 8 LO Fault 30 9 VCXO 32 10 RSSI 34 11 Phase and Frequency Error 36 12 Transient Spectrum Spectrum due to switching 38 13 Modulation...

Страница 2: ...ur in tests without test program e g Go No Go tests In these cases you have to start the phone with test program in EFRA before starting to trouble shoot The classification of the components and a pos...

Страница 3: ...r used for communication to SIM data signal SIMCONRST Signal from the processor used for communication to SIM reset signal SIM VCC Feed voltage for SIM 5 0 0 10 VDC VBATT Battery voltage 3 70 0 5 VDC...

Страница 4: ...ttery and external accessory powering 2 GND Digital GND and DC return 3 VPPFLASH Flash memory Vpp Service 4 GND Audio signal GND 0 V reference 5 CFMS_PHFS Accessory Control From Mobile Station serial...

Страница 5: ...44 25 C Ericsson Mobile Communications AB 5 78 1 6 Pin placing Single diode PIN diode Electrolytic capacitor Double diode or single transistor Five pin circuit usually volt age regulator Double transi...

Страница 6: ...and GND An Hardlock connected and installed Follow the Start up instructions in EFRA If the fault really is electrical open the phone and make a visual check of the board Make sure there is not any li...

Страница 7: ...one does not start in the flash programmer go to section 2 4 1 If the phone can be programmed but does not start afterwards or is troublesome in the flash programmer go to section 2 4 2 If the phone s...

Страница 8: ...to the local company directives Make sure the pads of the system connector not are mechanically or liquid damaged Attach the board to the fixture Power up the board Measure the voltages VDIG and VCORE...

Страница 9: ...ide close to N300 with an oscilloscope the value of the measurements should be 500 mV p p If not change B320 if the fault still remains it is probably due to N700 Also check D602 pin 5 and 6 they shou...

Страница 10: ...CDAT N 700 D 600 D 602 EEPROM Fig 3 1 3 2 How to find the fault There is a possibility in the trouble shooting part of EFRA to test the communication and a limited part of the function in the self tes...

Страница 11: ...to pre load the TXVCO loop filter D E and F Word are default value for Homeros N300 that are stored in the EEPROM If it is impossible to read from EEPROM Open the phone and check for liquid damage Ch...

Страница 12: ...an 8 bit serial data word To make the measurement of the battery voltage exactly is it necessary to perform a calibration The calibration is performed on two voltages 3 2 VDC and 4 1 VDC The correspon...

Страница 13: ...nced 4 00021 3 FEA 209 544 25 C Ericsson Mobile Communications AB 13 78 Fig 4 2 The result is shown in two windows first High ADC calibration Fig 4 3 4 1 VDC and then Low ADC calibration Fig 4 4 3 2 V...

Страница 14: ...1 shows the limits for the ADC values at the calibration When calibrating there must be an accuracy of 15 mVDC Battery voltage min max 3 2 VDC 20 34 hex 4 1 VDC 73 87 hex Table 4 1 You can check the A...

Страница 15: ...TA The calibration assumes that there is a 100 kOhms resistor is mounted between BDATA and GND at the fixture Start the phone in EFRA with the test program Go to Logic BDATA Calibration A window will...

Страница 16: ...elow Fig 6 1 Fig 6 1 The information about the charging current is achieved by measuring the potential drop over the resistor R727 The current flow ICH is measured in the ADC and is converted to I2 C...

Страница 17: ...on Fig 6 2 telling you to set the DCIO voltage to 5 4 VDC The DCIO voltage is taken from a separate power supply and is connected to the system connector Fig 6 2 The next window Fig 6 3 tells you to t...

Страница 18: ...ented in hex Fig 6 5 Fig 6 5 The next window tells you to disconnect the DCIO Fig 6 6 Fig 6 6 The limits for the calibrations are displayed in the table below Table 6 1 Selected charge current MIN MAX...

Страница 19: ...est program Set the battery voltage at 3 7 VDC Set DCIO at 5 2 VDC and connect the DCIO voltage to the system connector Measure CHSENSE on R727 3 7 VDC Go to Logic Current calibration Perform the test...

Страница 20: ...is 2000 Hz If all values are within the accepted limits the fault probably is due to the LO go to chapter 8 LO fault If both the Peak phase error and the RMS phase error sometimes even the frequency e...

Страница 21: ...value of signal strength from the phone RX level E g The phone measures the signal strength to 102 dBm RX level 110 102 8 Table 7 1 When there is a RX level fault the calculated value in the EEPROM do...

Страница 22: ...its that the phone loops back to the base station The base station then compares the original pattern with the one the phone sent back and calculates a percentage on the difference This percentage is...

Страница 23: ...connector Raise or lower the amplitude on the GSM test set if necessary We have been using following settings on the spectrum analyser when measuring the transmitter CF 942 4 MHz SPAN 1 MHz RBW 10 kHz...

Страница 24: ...signals are correct the fault is due to D600 7 2 8 For GSM 1800 Set Radio in RX Static mode on channel 699 Fig 7 3 Static RX is active after you have clicked on the Apply button Fig 7 3 Set RX signal...

Страница 25: ...00 If all signals are correct the fault is due to D600 7 3 TX fault Check the voltage at N400 1 3 8 VDC with Tx off also check VEKA at N400 28 3 8V VDC If it is incorrect at N400 1 measure at C400 if...

Страница 26: ...le channel Anyone from 35 to 40 Anyone from 697 to 702 High channel Anyone from 120 to 124 Anyone from 880 to 885 Table 7 3 EGSM900 GSM1800 Lowest Power level 19 15 Middle Power level Anyone from 10 t...

Страница 27: ...e spectrum analyser We have been using the following settings on the spectrum analyser while measuring CF 897 400 MHz SPAN 0 Hz RBW 300 kHz VBW 100 kHz and Sweep 0 8 ms If the output power is correct...

Страница 28: ...ltage is too low the fault can be due to a short circuit in C510 but usually it depends on N400 N500 N700 or D600 If PAREG is correct measure the signal TXHB on N390 6 13 dBm and on L402 8 dBm If both...

Страница 29: ...If the calibration fail the fault is probably due to components that can not be replaced 7 5 The switched output power is correct but can not connect a call Check the modulation signals MODQN MODQP M...

Страница 30: ...e is incorrect check VVCO to N301 at R300 If the voltage is correct measure 13 MHz to N301 and that the voltage at C302 is 1 7 VDC at the side towards N301 If the frequency and voltage is correct chec...

Страница 31: ...ltage at C302 is 1 7 0 10 VDC at the side connected to N301 15 the side closest to the edge of the board If the frequency and voltage are correct check C310 C311 C312 R310 and R311 but usually the fau...

Страница 32: ...during different circumstances This is possible since the reference crystal is a Voltage Controlled Crystal Oscillator VCXO The schematic is shown in the figure below Fig 9 1 Fig 9 1 The crystal B320...

Страница 33: ...ce that the DAC value does not change until clicking at Close Measure the DC voltage at C320 2 5 VDC If both voltages are correct but any of the VCXO measurements are incorrect the fault usually is du...

Страница 34: ...rdered by the network and makes a TOP 6 ranking list The list is recovered once a measurement result differs from previous value The 6 STRONGEST RSSI levels from the surrounding non serving carriers a...

Страница 35: ...nel 37 Set RX signal from the GSM test to 942 42 MHz and amplitude 50 dBm and GMSK mod ulation on Make sure the right RF amplitude is chosen The RSSI value for an input signal of 50 dBm is about 0xC8...

Страница 36: ...el 5 and low channel anyone between 975 and 980 For GSM 1800 use power level 0 and low channel anyone between 512 and 521 The phase fault is presented as RMS and peak RMS is the average value during t...

Страница 37: ...be taken for a liquid damaged unit send it on according to the local company directives Make sure the antenna connection is not damaged or dirty dust varnish or oxide The fault can also depend on a c...

Страница 38: ...led transient spectrum or Spectrum due to switching To be able to get lower amplitudes for the over tones in the transient spectrum the up and down ramping does not change momentarily from zero to max...

Страница 39: ...1 Measure Transient Spectra is a part of the radio calibration in EFRA It is performed after the power calibration and measures the power levels at the middle channel frequency 400 kHz of the transmi...

Страница 40: ...nt at channel 64 400 kHz by changing CF at the spectrum analyser to 902 4 MHz The power level must be inside the limits Table 12 1 It is very difficult to make an exact transient spectrum measurement...

Страница 41: ...nsmitter in switched mode at full Power level Check the control voltage PAREG at R497 using the oscilloscope It should look like in the pictures below Fig 12 4 Note that the sweep time are different i...

Страница 42: ...early defined period on the timeaxis Two different time interval exist It is during this interval the real significant message is going to be sent Some of the messages are system information only and...

Страница 43: ...g Transients The digital modulation process Designated Spectrum due to the Modulation and wide band noise 13 2 Consequences in spectrum and testing In digital TDMA systems as EGSM 900 and GSM1800 the...

Страница 44: ...ain So called Gated Measurements The effect of the RF power level shift designated Spectrum due to switching transients will then be possible to separate from the total spectrum by setting the time ga...

Страница 45: ...orm spectrum components from both the switching and the modulation are visible Looking at the time axis we know that the transmitter is started before the useful burst at the upramp The instrument is...

Страница 46: ...F A specific designed base band signal for testing is generated by the test program and injected to the TX modulator The signal only used for testing has a digital pattern combined from a Pseudo Rando...

Страница 47: ...bursts is calculated but at a frequency 400 kHz from the carrier wave frequency One more average value is calculated now at a frequency 400 kHz from the carrier wave frequency The level 400 kHz or 400...

Страница 48: ...ed voltages of the radio or an appearance of unwanted frequencies e g noise in the output signal Open the phone and check for liquid damage Start the phone in the test program Start the transmitter of...

Страница 49: ...on If the radio calibration failed the fault can be due to noise in one of the feed voltages VRAD and VVCO Noise can be due to e g ageing filter capacitors usually the electrolytes or deteriorated per...

Страница 50: ...stem information are encoded and transmitted as a burst in a time slot Since several channels are sharing the same frequency is it vital for every burst to start and end at the correct time The GSM sp...

Страница 51: ...Min value Max value Absolute value Unit Power at 28 us 0 15 48 48 dBc dBm Power at 18 us 0 15 30 20 dBc Power at 10 us 0 15 6 dBc Power at 10 us 11 4 dBc Power at 10 us 12 2 dBc Power at 10 us 13 15...

Страница 52: ...is reduced This gives a control voltage without the straight vertical edges and the sharp corners that produces the over tones The two help steps in the up and down ramping of the power are called In...

Страница 53: ...ng way the power levels of the phone have to be as the base station expect This means that the power levels of the phone have to be calibrated to be accurate enough Fig 16 1 shows a very simplified sc...

Страница 54: ...155 21 0 0 5 12 138 19 0 0 5 13 125 17 0 0 5 14 115 15 0 0 5 15 107 13 0 0 5 16 101 11 0 0 5 17 97 9 0 0 5 18 93 7 0 0 5 19 90 5 0 0 5 Table 16 1 DAC Value lsb Power Level Default Output Power dBm 0 1...

Страница 55: ...rum analyser or a GSM test set Default values are used as starting DAC values The computer changes the DAC value to attain the correct output power for the current power level The value is temporarily...

Страница 56: ...78 17 Audio 17 1 Measurements in EFRA Fig 17 1 below shows a simplified schematic over the paths of the audio signals when measuring Fig 17 1 In the trouble shooting part of EFRA there is several way...

Страница 57: ...s a Tx filter band pass 300 3400 Hz and connects through the side tone switch to the Rx part In the RX part the signal passes an Rx filter band pass 300 3400 Hz then it is amplified and connected thro...

Страница 58: ...00 Hz and is then AD converted in N500 The data is sent as PCM code through PCMULD to D500 where the signal is speech coded The speech coded information is sent to the processor through DSPULD for fur...

Страница 59: ...ut both the microphone and the earphone are out of order during a connected call go to section 17 10 17 3 The microphone part is out of order When there is a microphone fault it is only the audio path...

Страница 60: ...tomer Measure the resistance between N500 C514 X850 12 and N500 C515 X850 11 both 0 0 ohm If the resistance is too large it can be due to a foil damage If the resistance is correct the fault probably...

Страница 61: ...ircuits that could be faulty 17 6 The AFMS output part is out of order When the AFMS output part is out of order it is only the audio paths Mic AFMS ATMS PCM AFMS and ATMS CPU AFMS that are faulty The...

Страница 62: ...l to determine which of the circuits that could be faulty 17 8 Both the CPU loops and the PCM loops are out of order When the CPU loops and the PCM loops are out of order is it only the side tone path...

Страница 63: ...N720 but if N700 VDIG is faulty If the resistance is too low use the circuit diagram Remove one component at the time that is fed from the short circuited voltage and measure the resistance after remo...

Страница 64: ...program in the phone At this type of fault all audio paths will work with test program in EFRA Open the phone and check for liquid damage No further action should be taken for a liquid damaged unit se...

Страница 65: ...by a voltage directly from D600 giving the rows a voltage of 2 7VDC When pressing one of the keys of the keyboard turns one of the KEYROW 0 4 low By doing so the processor knows that a key is pressed...

Страница 66: ...l the time and the rest as faulty The fault usually is due to a short circuit caused by dirt on the key shown as pressed in EFRA If all keys of a column are faulty the fault is due to D600 or a foil d...

Страница 67: ...isplay is missing one or more segments go to section 19 3 If nothing shows in the display go to section 19 4 19 3 Segments are missing Change display unit and make a new test 19 4 Nothing shows in the...

Страница 68: ...I2C DAT voltage is missing or incorrect measure the resistance of R850 0 ohm and C853 100 kohms If any of the resistances are incorrect replace the corresponding component If the voltage still is inc...

Страница 69: ...e buzzer with Buzzer ON Fig 20 1 Fig 20 1 Fig 20 2 Measure the signal at X850 4 Fig 20 2 a serrated negative signal 0 5V when the buzzer is activated Also check that there is VBATT at X850 3 If there...

Страница 70: ...test program Go to MMI Display Top Activate background light with Disp Keyb Led on Fig 21 1 Fig 21 1 Check that there is VBATT at X850 3 if not there is a foil damage Measure the ILLUM signal at R854...

Страница 71: ...the phone in EFRA with the test program Go to MMI Display Top Activate background light with Disp Keyb Led on Fig 22 1 Fig 22 1 Check the voltages on X850 14 VDIG and X850 13 TOPLED 2 7 0 10 VDC Fig 2...

Страница 72: ...e display it means that the customer has locked the phone with a personal code It will be unlocked in the reset program Available in the Built Swap process If PIN or Enter PIN is displayed it means th...

Страница 73: ...easure the voltage at pin 7 of J800 5 0 0 10 VDC If the voltage is missing go to section 23 5 SIMVCC must be activated when measuring SIMCONDAT Set SIMCONCLK high using the button SIM Clock Fig 23 1 M...

Страница 74: ...depend on D600 or a foil damage If it is correct the fault can depend on N700 R904 R807 C808 or V805 23 6 SIMCONCLK is missing Measure SIMCLK 2 7 0 10 VDC from D600 on R809 If SIMCLK is missing it ca...

Страница 75: ...D600 DSP D500 and analogue digital ASIC N500 Check if it is possible to write in and read from the EEPROM D602 Check the communication between the CPU AASIC and the DSP Test the Power ASIC by reading...

Страница 76: ...heck Speech DSP Speech coding Open the phone and check for liquid damage No further action should be taken for a liquid damaged unit send it on according to the local company directives Power up the b...

Страница 77: ...d the values once or continuously 25 1 Temperature ADC limits for Temperature is shown in the Table 25 1 below Min max Temperature 6E 82 HEX 105 135 DEC Table 25 1 The values in the table are valid fo...

Страница 78: ...te Changes Comments B 2000 11 14 Document updated to include A2628s_sc Schematics changed to Circuit diagram in the text Chapter 1 1_using the Go to call processing is added Chapter 2 4 1_ EMMA II fla...

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