1. Manuals
  2. Brands
  3. Ericsson Manuals
  4. Telephone
  5. R250S
  6. Troubleshooting manual

Ericsson R250s Troubleshooting Manual

Hide thumbs Also See for R250s:
Table of Contents

Advertisement

Quick Links

Download this manual See also: User Manual
Trouble Shooting Guide, Advanced
Trouble Shooting Guide R250s, Advanced
by Toko (toko@gsm-free.org)
4/00021-3/FEA 209 544/18 B
Approved according to 1776-3/FEA 209 544

Advertisement

Table of Contents
loading

Related Manuals for Ericsson R250s

Summary of Contents for Ericsson R250s

  • Page 1 Trouble Shooting Guide, Advanced Trouble Shooting Guide R250s, Advanced by Toko (toko@gsm-free.org) 4/00021-3/FEA 209 544/18 B Approved according to 1776-3/FEA 209 544...

  • Page 2: Table Of Contents

    Trouble Shooting Guide, Advanced Contents Explanations ........................3 Enter Test Program ......................8 Static TX ..........................13 Calibration IQ ........................19 Tx VCO..........................21 VCXO..........................27 Calibration RSSI.......................31 Calibration of Power Level ....................37 Calibration Intermediate Power..................42 Transient Spectrum, Spectrum due to switching............43 Modulation Spectrum Switched Mode................48 Write to EE-prom ......................55 ADC-calibration (Voltage-calibration) ................56 Current Calibration......................59...

  • Page 3: Explanations

    Trouble Shooting Guide, Advanced 1 Explanations Conditions All measurements described in this Trouble Shooting Guide are performed in EFRA with test program in the phone. Some of the faults can occur in tests without test program, e.g. Go/No Go -tests. In these cases you have to program the phone with test program before starting to trouble shoot using this guide.
  • Page 4 Trouble Shooting Guide, Advanced Abbreviations Crystal Capacitor Resistor Coil Over-voltage protection Digital circuit Buzzer, LED, pads for display Connector Analogue circuit Balun Transistor, diode Antenna connector, connector-surface on the board Filter EFRA: Trouble shooting and radio calibration software. AGND: Ground for analogue signal. DCIO: DC-voltage through the system connector for charging.
  • Page 5 Trouble Shooting Guide, Advanced SIMCONRST: Signal from the processor used for communication to SIM, reset signal. Programming voltage for the FLASH memory. 12,0 ± 0.50 V VPPFLASH: Feed voltage for SIM. 5,0 ± 0.20 V SIMVCC: TTMS: Serial communication to phone through the system connector. TFMS: Serial communication from phone through the system connector.
  • Page 6 Trouble Shooting Guide, Advanced Pin placing 4/00021-3/FEA 209 544/18 B 6(121)
  • Page 7 Trouble Shooting Guide, Advanced 4/00021-3/FEA 209 544/18 B 7(121)

  • Page 8: Enter Test Program

    Trouble Shooting Guide, Advanced Enter Test Program Introduction To be able to use EFRA the phone has to be programmed with test program. The programming is also performed in EFRA. If the phone does not start in the radio calibration or trouble shooting part of EFRA, despite an approved flash programming, go to section 2.2 If the phone can not be programmed, go to section 2.3.
  • Page 9 Trouble Shooting Guide, Advanced Also make sure the keyboard, dome-foil and the keyboard pads are correct and clean. If needed replace them according to the mechanical repair guide If there is signal program in the phone, you have to program it with test program. The phone can not be programmed Make sure: 1.
  • Page 10 Trouble Shooting Guide, Advanced You have found the faulty component when the resistance is raising after removing. You also should replace the circuits on which you lifted the pins. The short circuit is usually due to D610, D600 or anyone of C600, C602-C610 for VDIG and D900 or anyone of C900, C902-C906 for VDSP.
  • Page 11 Trouble Shooting Guide, Advanced If the resistance is correct, replace the corresponding circuit, VDIG - N702, VDSP - N701. If the resistance is too low, use the schematics. Remove one component (or lift the pin/pins feeding the circuit) at the time that is fed from the short circuit voltage and measure the resistance after removing it.
  • Page 12 Trouble Shooting Guide, Advanced If any of the voltage are too low, measure the resistance to ground, VDIG >500 ohms, VDSP >25 Kohms. If the resistance is correct, replace the corresponding circuit, VDIG - N702, VDSP - N701. If the resistance is too low, use the schematics. Remove one component (or lift the pin/pins feeding the circuit) at the time that is fed from the short circuit voltage and measure the resistance after removing it.

  • Page 13: Static Tx

    Trouble Shooting Guide, Advanced 3 Static TX Finding out if there is an amplitude or frequency fault Open the phone and check for liquid damage. No further action should be taken for a liquid damaged telephone. Make sure the antenna connection X101 is not mechanically damaged, badly soldered or dirty (varnish, glue, oxide...).
  • Page 14 Trouble Shooting Guide, Advanced If the transmitter locks on, start it in switched mode on channel 669 with DAC 7 value on ”FF”. Make sure the output power is 28 - 32 dBm by using the spectrum analyser. We propose the following settings on the spectrum analyser while measuring: CF- 1747.6 MHz, SPAN- 0 MHz, RBW- 300 kHz, VBW- 100 kHz and Sweep- 0.8 ms.
  • Page 15 Trouble Shooting Guide, Advanced For GSM 1800: Give the board power, start the test program and connect the negative -4 V again. Start the transmitter in static mode on channel 699. Measure the voltage at N450 pin 4 VREG +1.7 V If VREG is too low, measure the signal POWLEV +0.9 V at N450 pin 11.
  • Page 16 Trouble Shooting Guide, Advanced If the frequency is misplaced, try to lower the “Adjust sweep current” until the frequency of the transmitter has locked on. If the transmitter locks on, start it in switched mode on channel 62 with DAC 7 value on ”FF”. Check if there is an output power 30 - 35 dBm at the antenna plate using the spectrum analyser.
  • Page 17 Trouble Shooting Guide, Advanced If the amplitude and the frequency are correct, go to section 3.3.1. If the frequency is correct, but the amplitude is too low, check the feed voltage at N302 pin 6 +3.7 V If the voltage is correct, replace N302. If the voltage is incorrect, check VVCO +3.8 V , SYNTON_DCS +3.7 V and V301 with the...
  • Page 18 Trouble Shooting Guide, Advanced Change CF on the spectrum analyser to the calculated, by using the formula above. Frequency for TXIF_GSM, the frequency of the transmitter usually ends up on ~890 MHz when the synth does not lock on, that gives a frequency for TXIF_GSM at ~117 MHz and SPAN to 10 MHz.

  • Page 19: Calibration Iq

    Trouble Shooting Guide, Advanced 4 Calibration IQ What is calibration IQ An IQ-filter consists of two parts. The first part is a passive lowpass-filter between the waveform generator in D600 and N500 consisting of R642-R645, C105, C106, C114 and C115. The second part is a software- controlled filter in N500.
  • Page 20 Trouble Shooting Guide, Advanced If the transmitter does not lock on, lower the sweep current. Fig.4.2 Make sure the spectrum looks like Fig.4. 1. If the spectrum does not look like the figure is it either one of the modulation signals MODQN, MODQP, MODIN, MODIP that is missing from D600 or the lowpass-filter to the modulation signals is faulty, R642 - R645, C105, C106, C114, C115.

  • Page 21: Tx Vco

    Trouble Shooting Guide, Advanced 5 Tx VCO What is TxVCO – Calibration In the GSM900-system a phone can communicate with the base station at 124 frequencies in each direction, 890.2 - 914.8 MHz for the transmitter and 935.2 - 959.8 MHz for the receiver. In the GSM1800-system is it possible to communicate at 374 frequencies in each direction, 1710.2 –...
  • Page 22 Trouble Shooting Guide, Advanced Fig.5.2 The frequency of the transmitter has to lock on during a predestined time. For the lock-on to be fast enough the phone uses pre-learned TxVCO-values taken from EEPROM. The lock-on begins with the TxVCO- AC, that is transforming a for this particular channel saved EEPROM-value to a start value for the control voltage of the VCO, N570/N560.
  • Page 23 Trouble Shooting Guide, Advanced TxVCO Min. Max. Ch 94 Dec. CH 30 Dec. Oxfam Min. Max. Ch 570 Dec. CH 826 Dec. Table.5.1 How to find the fault The TxVCO calibration is the sixth step in the Radio calibration. If the first fault showing up is ”GSM Static TX Check Amplitude”, go to chapter ”Static TX- fault.
  • Page 24 Trouble Shooting Guide, Advanced We propose the following settings on the spectrum analyser while measuring: CF- 902.4 MHz, SPAN- 0 MHz, RBW- 300 kHz, VBW- 100 kHz and Sweep- 0.8 ms. Check if there is an output power, 30- 35 dBm, at the antenna-plate using the spectrum analyser. If the output power is correct, the phone is probably without fault.
  • Page 25 Trouble Shooting Guide, Advanced If the amplitude and the frequency are correct, go to section 5.2.2. If the frequency is correct, but the amplitude is too low, check the feed voltage at N302 pin 6 +3.6 V If the voltage is correct, replace N302. If the voltage is incorrect, check VVCO +3.8 V , SYNTON_DSC +3.8 V and V301 with the...
  • Page 26 Trouble Shooting Guide, Advanced 5.2.2 TX–synth fault for GSM1800 The fault usually is due to too large attenuation in the feed back of the TX-synth, either at TXIN or at TXIF. Give the board power and start the test program. Start the transmitter in static mode at channel 699.

  • Page 27: Vcxo

    Trouble Shooting Guide, Advanced 6 VCXO What is VCXO The phone has got a reference crystal of 13 MHz which signal is use for both the radio and the logic. The logic uses the clock signal MCLK as master clock and for the synchronisation of the digital circuits of the logic.
  • Page 28 Trouble Shooting Guide, Advanced VCXO measurements in the radio calibration in EFRA There are three measurements and one calibration, concerning VCXO, in the radio calibration in EFRA. The measurements are: 1. VCXO Control at DAC 00 Hex 2. VCXO Control at DAC 3FF Hex 3.
  • Page 29 Trouble Shooting Guide, Advanced Table below shows the limits for the VCXO measurements Table.6.1. Parameter Min. Unit VCXO Control at DAC 00 Hex VCXO Control at DAC 3FF Hex VCXO Control Range Calibrated VCXO Dec. Table.6.1 How to find the fault Open the phone and check for liquid damages.
  • Page 30 Trouble Shooting Guide, Advanced You can verify that the fault is gone by measuring the output frequency of the transmitter with VCXO-DAC at 00 and 3FF Hex and compare the result with table below Table.6.2 Parameter Min. Max. Unit VCXO Control at 1747.4829 1747.5773 DAC 00 Hex...

  • Page 31: Calibration Rssi

    Trouble Shooting Guide, Advanced 7 Calibration RSSI What is RSSI In the mobile phone, the received RF-signal strength is measured and indicated by a function called RSSI, Received Signal Strength Indicator. When switching the mobile phone ”ON” it starts searching the surrounding radio-channels ARFCN at the geographical site.
  • Page 32 Trouble Shooting Guide, Advanced The information about the amplitude corresponds to the strength of the received RF-signal, i.e. the RF-level at the antenna input of the receiver. The antenna signal is converted and amplified in two steps, through the 1st IF 175 MHz down to the 2nd IF 6.0 MHz.
  • Page 33 Trouble Shooting Guide, Advanced The RSSI measuring procedure is to compare the strength of the measured signals and compare them to a calibrated scale of reference levels and point out the one closest to the current RF- level. There are two scales; one for GSM 900 and one for GSM 1800, both are calibrated separately. To create these scales a learning procedure, where known RF-signal levels from –110dBm to –...
  • Page 34 Trouble Shooting Guide, Advanced If RSSI for an input signal of –50 dBm is between 0x96 and 0xDC steps, change the RX amplitude of the GSM test set to –100 dBm and make a new RSSI measurement. If RSSI is higher then 0x64 steps, measure the DC voltage at C530 – C535 +2.0 V If any of them is lower, replace the corresponding capacitor.
  • Page 35 Trouble Shooting Guide, Advanced The 175 MHz signal is mixed down to 6 MHz in N500. Measure the signal 6 MHz at Z500 pin 6 ~0 dBm, Z500 pin 1 ~ -7 dBm, N500 pin 44, -7 dBm, N500 pin 40 ~ -5 dBm. If the signal is attenuated too much from N500 pin 44 to N500 pin 40, and then the fault probably is due to L505 or C521, an alternative is C505 or C520.
  • Page 36 Trouble Shooting Guide, Advanced The 175 MHz signal is mixed down to 6 MHz in N500. Measure the signal 6 MHz at Z500 pin 6 ~0 dBm, Z500 pin 1 ~-7 dBm, N500 pin 44 ~-6 dBm, N500 pin 40 ~-5 dBm. If the signal is attenuated too much from N500 pin 44 to N500 pin 40, and then the fault probably is due to L505 or C521, an alternative is C505 or C520.

  • Page 37: Calibration Of Power Level

    Trouble Shooting Guide, Advanced 8 Calibration of Power Level Introduction In the GSM 900 system is it possible for a phone to transmit with 15 different power levels, from 33 dBm, power level 5 to 5 dBm, power level 19. In the GSM 1800 system is it possible for a phone to transmit with 16 different power levels, from 30 dBm, power level 0 to 0 dBm, power level 15.
  • Page 38 Trouble Shooting Guide, Advanced Table.8.1. GSM 900 and Table.8.2.GSM 1800 shows the allowed DAC values and the output power goal of the calibration. DAC Value (lsb) Output Power Power Level Min. (dBm) 32.5 ±0.3 30.5 ±0.3 29 ±0.5 27 ±0.5 25 ±0.5 23 ±0.5 21 ±0.7...
  • Page 39 Trouble Shooting Guide, Advanced The power calibration is a part of the radio calibration in EFRA The calibration is performed in 15 steps for GSM 900, from the highest 5, to the lowest 19. And in 16 steps for GSM 1800, from the highest 0, to the lowest 15. A computer control the calibration by setting the Power level DAC for the phone at the current power level and checking the output power using a spectrum analyser or a GSM test set.
  • Page 40 Trouble Shooting Guide, Advanced If the output power is too low, measure the control voltage POWLEV at N450 pin 1 using an oscilloscope. It should look like in figure below Fig.8.2. Fig.8.2 If the control voltage is too low, the fault usually is due to N800. It can also be due to D600.
  • Page 41 Trouble Shooting Guide, Advanced For some power levels can this make the output power or the DAC values ending up outside the limits. In that case, the fault usually is due to N401 or N450. The fault can also be due to N800, N570 or D600. If the output power is too low, measure the control voltage POWLEV at N450 pin1 using an oscilloscope.

  • Page 42: Calibration Intermediate Power

    Trouble Shooting Guide, Advanced 9 Calibration Intermediate Power What is Intermediate Power Intermediate Power is a calibration necessary to do to fulfil the demands of the GSM- specification for the up- and down-ramping of the power and to minimise the transient spectra at The up- and down-ramping of the control voltage of the power amplifier does not change momentarily from zero-to-max/max-to-zero, that would cause a large number of over tones due to the switch.

  • Page 43: Transient Spectrum, Spectrum Due To Switching

    Trouble Shooting Guide, Advanced 10 Transient Spectrum, Spectrum due to Switching 10.1 What is transient spectrum In the GSM-system is all communication between the base station and the phone done switched, in shape of bursts. The burst is a squared output power pulse with step up- and down ramping. Every time the voltage of the squared pulse changes rapidly there will be formed a number of over tones.
  • Page 44 Trouble Shooting Guide, Advanced The amplified and filtrated control voltage is called VREG and looks like the figure below Fig. 10.2 Fig.10.2 The actual up- and down- ramping are much shorter then other parts of the control voltage. Therefore is it only the up- and down-ramping in the figure that is timely proportional to each other.
  • Page 45 Trouble Shooting Guide, Advanced 10.2 How to measure the transient spectrum GSM 900: Give the board power and start it in the test program. Start the transmitter in switched mode at channel 64 and power level 5. Before performing a transient spectrum measurement you have to make sure the spectrum analyser has got the correct amplitude compensation.
  • Page 46 Trouble Shooting Guide, Advanced For the example in the picture we have measured the transient spectrum at channel 64 + 400 kHz. Do the same measurement at channel 64 - 400 kHz, by changing CF at the spectrum analyser to 902,4 MHz.
  • Page 47 Trouble Shooting Guide, Advanced Fig. 10.5 If the up- and down-ramping looks like the pictures above, the fault almost always is due to distortion caused by the power amplifier. Replace N401 and do a new radio calibration. The few times the fault are not due to N401 is it usually N560/N570 or C404, parts of the exponential amplifier, that is faulty.

  • Page 48: Modulation Spectrum Switched Mode

    Trouble Shooting Guide, Advanced 11 Modulation Spectrum Switched Mode (Spectrum due to modulation) 11.1 Description In the GSM system the mobile phone (MS) transmitter (TX) output RF- signal is time-shared, according to the principle of TDMA. This implies the transmitter to be STARTED exactly at a controlled point of time to reach a specific RF power-level.
  • Page 49 Trouble Shooting Guide, Advanced Fig. 11.1 Time mask for normal duration burst 147 bits 542.8 µS. There is also a shorter access burst 87 bits 321.2 µS. (not present). Both have the same time period-length for the RF-level shift. According to the principle of TDMA and the burst nature of the signal, the output RF spectrum results from two effects: The RF-power level shift at upramp and down ramp.
  • Page 50 Trouble Shooting Guide, Advanced Due to this rapid RF-level shift, in both the time- and frequency-domain, unwanted spectrum components are generated and occupying some space in the total spectrum distribution, in excess to the modulation from the wanted signal. The two effects of, the RF-power level shifts up ramp / down ramp and the digital modulation respectively, are specified separately in GSM 11.10 and 11.20.
  • Page 51 Trouble Shooting Guide, Advanced Fig. 11.2 Note that in this time waveform spectrum components from both the switching and the modulation are visible. Looking at the timeaxis we know that the transmitter is started before the useful burst at the up-ramp. The instrument is time gated and the START point is set to the beginning of the burst (0%).
  • Page 52 1524 TEST DATA written and approved by the Ericsson Test engineering and based on the GSM specification. The requirement is that the absolute RF levels in dBm and the levels in dBc relative to Fc, from all three results must not exceed the limit of a modulation spectrum mask decided in the GSM spec.
  • Page 53 Trouble Shooting Guide, Advanced Then a new average value over some other 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.
  • Page 54 Trouble Shooting Guide, Advanced Fig. 11.3 Turn the modulation on. Compare the inter modulation products with the one of a working phone. They can not be too high. If there is noise in the spectrum, the fault can be due to noise in one of the feed voltage, VRAD, VVCO or VANA.

  • Page 55: Write To Ee-Prom

    Trouble Shooting Guide, Advanced 12 Write to EE-prom 12.1 What is “Write to EE-prom” Large amount of data is stored in the RAM memory of the phone during the radio calibration in EFRA. This information is stored permanently in a 16 kb large EE-prom after interpolation. This is done at three occasions, Write Powertable to EE, Write RRS Table to EE and Write Local Table to EE, stores the parameters of the calibration of the IQ-filter.

  • Page 56: Adc-Calibration (Voltage-Calibration)

    Trouble Shooting Guide, Advanced 13 ADC Calibration (Voltage Calibration) 13.1 What is ADC calibration For the processor to be able to control the phone in a correct way it has to know the current battery voltage. The battery voltage is measure using N450 and N800. N450 compares VBATT and VRAD according to the formula below.
  • Page 57 Trouble Shooting Guide, Advanced Fig. 13.2 The result is shown in two windows, first ”High ADC calibration” (+6.5 V ). Fig. 13.3. and then ”Low ADC calibration” (+4.5 V ). Fig. 13.4. Fig. 13.3 Fig.13.4 Table 13.1 shows the limits for the ADC-values at the calibration. When calibrating there must be an accuracy of +15 mV.
  • Page 58 Trouble Shooting Guide, Advanced 13.3 How to find the fault Start the phone in the test program. Set the battery voltage to +6.5 V Measure the exact voltage at VBATT, N450 pin 17 and VRAD, N450 pin 13. Use the formula in section 1 to calculate VTRACK. Example: VBATT = +6.5 V , VRAD = +3.8 V gives VTRACK +1.9 V...

  • Page 59: Current Calibration

    Trouble Shooting Guide, Advanced 14 Current Calibration 14.1 What is current calibration A simplified schedule for the regulation of the charging current is shown below Fig.14.1 The information about the charging current do you get by measuring the potential drop over the resistor R421.
  • Page 60 Trouble Shooting Guide, Advanced The calibration is performed in two steps: Zero current calibration – You measure the level on IMEAS at idling when there is no charger connected, i.e. DCIO open. High current calibration – You do the same measuring as above, but with DCIO high and set on a certain voltage and current limited.
  • Page 61 Trouble Shooting Guide, Advanced Fig. 14.4 The result is shown in two windows, fast calibration Fig. 14.5. and slow calibration Fig. 14.6. The fast calibration is performed after 10-40 ms and verifies that C402 is mounted. The slow calibration is performed after 350 ms and is the real calibration. Fig.
  • Page 62 Trouble Shooting Guide, Advanced 14.3 How to find the fault The fault can be in either the current measuring or the logical part/the AD-transforming. You can find out which part is broken by measuring IMEAS and ICONT. Start the board in the test program. Set the battery voltage at +4.8 V Set DCIO at +8.7 V , but do not connect the DCIO-voltage to the phone.

  • Page 63: No Serv, Or Not Able To Connect A Call

    Trouble Shooting Guide, Advanced 15 No Serv, or Not Able to Connect a Call 15.1 Find out if the fault is related to RX or TX Connect the phone to a GSM test instrument. GSM test set must be set as active base station and use a test SIM for best result.
  • Page 64 Trouble Shooting Guide, Advanced Make sure the RX amplitude really is -50 dBm over Z205 pin 5 using a spectrum analyser. Raise or lower the amplitude on the GSM- test set if necessary. We propose the following settings on the spectrum analyser when measuring the transmitter: CF- 1842.6 MHz, SPAN- 1 MHz, RBW- 10 kHz, VBW- 10 kHz and Sweep- 30 ms.
  • Page 65 Trouble Shooting Guide, Advanced If the LO signal is correct as in Fig15.1. are there either too large losses in the signal path, a phase error or a logical fault. Fig.15.1 15.2.2 Too large losses in the signal path For GSM 900: Change CF on the spectrum analyser to 175 MHz.
  • Page 66 Trouble Shooting Guide, Advanced For GSM 1800: Change CF on the spectrum analyser to 175 MHz. Measure the signal 175 MHz, the frequency after the first mix, in to the filter Z250 ~ - 26dBm. The filter attenuates the signal 8 - 10 dBm in the pass band. If the filter attenuates the signal too much, is it usually Z250 or L206 that is faulty.
  • Page 67 Trouble Shooting Guide, Advanced 15.3 Connect a call against the instrument at power level 5 (GSM 900) or power level 0 (GSM 1800) and input signal - 68.5 dBm If it works, go to section 15.4. If it does not is it most likely a TX related fault. If it is only at low channels on GSM 900 you cannot connect a call, but you can connect at high channels, GSM900, and at GSM1800, is it usually N570 that is faulty.
  • Page 68 Trouble Shooting Guide, Advanced If the transmitter does not have any output power or if it does not lock on, go to chapter “Static TX-fault. If the transmitter locks on, start the transmitter in switch mode on channel 699, with DAC 7 value on “FF”.
  • Page 69 Trouble Shooting Guide, Advanced If the feed voltage is incorrect, it is usually because of L560, C560 (short circuit), V570, V571 or one of the following voltage are missing: SWDC, same voltage as VBATT, VVCO +3.8 V or TXON_GSM +3.7 V For GSM 1800: Measure the control voltage POWLEV on N450 pin 11 using an oscilloscope Fig.
  • Page 70 Trouble Shooting Guide, Advanced Fig. 15.3 If it looks like the one in the figure, but the phone cannot connect a call, is it a logical related fault and usually depends on D600 or N800. If the spectra does not look like the figure, is it either one of the modulation signals, MODQN, MODQP, MODIN, MODIP, missing from D600 or a faulty low pass filter to the modulation signals (R642, R643, R644, R645, C105, C106, C114, C115).
  • Page 71 Trouble Shooting Guide, Advanced If the phone passes the test, but can not connect a call against the “real” network, make sure the phone is not “locked out of the system due to theft” If it is not locked out, replace D600. If the output power is moving, open the phone and make sure the antenna connection not is damaged, dirties or badly soldered.

  • Page 72: Phase And Frequency Error

    Trouble Shooting Guide, Advanced 16 Phase and Frequency Error 16.1 What is ”Phase and frequency error” Phase and frequency error is a measurement in the Go/No Go – test where you check how big the phase and frequency variations of the transmitter are during a connected call. The phase and frequency fault is measured during 20 bursts.
  • Page 73 Trouble Shooting Guide, Advanced 16.2 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 shabby connections or bad cables at the test site. If the phone really is faulty, open it and check for water damages.

  • Page 74: Output Power

    Trouble Shooting Guide, Advanced 17 Output Power 17.1 What is ”Output power” Output power is a part of the measurement in the Go / No Go – test that checks what output power the transmitter gives at the highest, lowest and middle calibrated power level, at high, low and middle channels.
  • Page 75 Trouble Shooting Guide, Advanced GSM1800 Power Output Tolerance level power (dBm) (dBm) ±2 ±3 ±3 ±3 ±4 ±4 ±5 Table.17.4 If the output power value is higher than in Table.17.3. go to section 17.2. If the output power value is lower than in Table.17.3. go to section 17.3. NOTE! You have to program the phone with test program before calibration or trouble- shooting.
  • Page 76 Trouble Shooting Guide, Advanced We propose the following settings on the spectrum analyser while measuring: CF- 902.4MHz, SPAN- 0 Hz, RBW- 300 kHz, VBW- 100 kHz and Sweep- 0.8 ms. If the output power is correct, the fault was either the back cover or the antenna connection. If the output power is too low, measure the control voltage POWLEV at N450 pin 11 using an oscilloscope Fig.
  • Page 77 Trouble Shooting Guide, Advanced If the output power is too low, measure the control voltage POWLEV at N450: 11 using an oscilloscope Fig. 17.2. Fig. 17.2 If the control voltage is too low, the fault usually is due to N800. It can also be due to D600.

  • Page 78: Burst Timing (Power Time Template)

    Trouble Shooting Guide, Advanced 18 Burst Timing (Power Time Template) 18.1 What is burst timing The GSM system uses TDMA (Time Division Multiple Access). The radio spectrum is divided into both frequency band and time slots. The frequency band for GSM 900 is divided in 124 frequencies (per direction) and the frequency band for GSM 1800 is divided in 374 frequencies (per direction).
  • Page 79 Trouble Shooting Guide, Advanced Table.18.1. and Table.18.2. show the limits of the timing for all power levels in GSM 900 and GSM 1800. GSM900 Parameter Power level Relative Absolute Relative Power at -18 µs 5 - 19 -30 dBc -17 dBm Power at -10 µs 5 - 15...

  • Page 80: Sensitivity (Rx-Quality)

    Trouble Shooting Guide, Advanced 19 Sensitivity (RX-quality) 19.1 What is RX-quality The base-station sends out a pattern of data-bits, which 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.
  • Page 81 Trouble Shooting Guide, Advanced Fig. 19.1 Set RX-amplitude from GSM-test set to 947.4 MHz and -50 dBm. Use a non-modulated signal, GMSK off. Make sure the RX-amplitude really is -50 dBm at Z205 pin 5 with a spectrum analyser. Raise or lower the amplitude on the GSM test set if necessary. We propose the following settings on the spectrum analyser while measuring: CF- 947.4MHz, SPAN- 1MHz, RBW- 10 kHz, VBW- 10 kHz and Sweep- 30ms Fig.19.2.
  • Page 82 Trouble Shooting Guide, Advanced The mixers input signal usually is: 947.4 MHz: ~ -56 dBm at N201 pin 5, 6. Follow the signal from the antenna-connection -50 dBm, to the mixer. The input signal to the filter Z201 pin 2 should be ~ -51 dBm. The signal coming out of the filter is balanced Z201 pin 4,6.
  • Page 83 Trouble Shooting Guide, Advanced Fig. 19.3 Set RX-amplitude from GSM-test set to 1842.6 MHz and -50 dBm. Use a non-modulated signal, GMSK off. Make sure the RX-amplitude really is -50 dBm at Z205 pin 5 with a spectrum analyser. Raise or lower the amplitude on the GSM test set if necessary. We propose the following settings on the spectrum analyser while measuring: CF- 1842.6MHz, SPAN- 1MHz, RBW- 10 kHz, VBW- 10 kHz and Sweep- 30ms Fig.
  • Page 84 Trouble Shooting Guide, Advanced The mixers input signal usually is: 1842.6 MHz: ~ -56 dBm at N202 pin 5, 6. Follow the signal from the antenna-connection (-50 dBm) to the mixer. The input signal to the filter Z202 should be ~ -57 dBm. The filter attenuates the signal ~1dBm in the pass band.

  • Page 85: Rx Level

    Trouble Shooting Guide, Advanced 20 RX Level 20.1 What is RX-level-fault The phone receives a signal from the base station, the signal is first mixed down to 175 MHz and then to 6 MHz. The received signal is measured with an ADC. A high input signal gives a high value out from the ADC.
  • Page 86 Trouble Shooting Guide, Advanced 20.3 The RX level is too high When the RX-level is too high (some steps above the limit) it is often due to some component in the signal path that has changed characteristics because of ageing. The only thing you have to do is a new RSSI-calibration.

  • Page 87: Audio

    Trouble Shooting Guide, Advanced 21 Audio 21.1 Measurements in EFRA The figure below Fig.21.1. shows a simplified schematic over the paths of the audio signals when measuring. Fig. 21.1 In the trouble shooting part of EFRA there is several ways to test the audio function. There are five different ways to connect an audio signal.
  • Page 88 Trouble Shooting Guide, Advanced Mic – AFMS: The input signal is taken from the microphone pads (X830). The signal is amplified, passes 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 to the AMFS pin (pin 1) of the system connector.
  • Page 89 Trouble Shooting Guide, Advanced 21.2 How to find the fault The trouble shooting part assumes that the microphone, with the elastome, and the earphone are faultless and correctly mounted. Start the phone (assembled) in the test program. Go to Audio / Audio Fig. 21.2. Test the five different audio paths.
  • Page 90 Trouble Shooting Guide, Advanced At “ATMS – CPU – AFMS” the chosen input signal should be seen at the oscilloscope (input signal 1 kHz, 100 mVrms or 280mVp-p sinus gives an output signal of 120mVrms or 340mVp-p). Apply the signal with a zero ohm probe at J602: 2. Measure it with a standard probe at J602: 1.
  • Page 91 Trouble Shooting Guide, Advanced If the resistance is correct, the fault usually is due to N800 or its soldering, but in some cases it can be due to D600. If the resistance is too low, the fault probably is due to C851, but it can also be due to N800. If the voltage at the middle circuit board pad of the microphone, X830: 1, is too low the fault is due to N800, its soldering, a break in R812 or R814, a short circuit in C814 or maybe a foil damage.
  • Page 92 Trouble Shooting Guide, Advanced Go to Audio / Audio Fig. 21.2. Start ATMS – PCM – AFMS. An appropriate signal for ATMS is 1kHz, 100mVrms or 280mVp-p sinus. Apply the signal with a zero ohm probe at J602: 2 Measure it with oscilloscope and standard probe at J602: 1. If the signal does not exist at J600: 1, check if the signal exists at N800: 19 (75 mV rms.
  • Page 93 Trouble Shooting Guide, Advanced 21.7 The CPU loops are out of order When the CPU loops are out of order is it only the audio paths “ATMS – CPU – AFMS” and “Mic – CPU – Earphone” that are faulty. The other three should work.
  • Page 94 Trouble Shooting Guide, Advanced No further action should be taken for a liquid damaged telephone. Make sure the earphone connection (J900) pogo pins is correctly mounted, undamaged and not dirty. Give the board power and start it in the test program. Go to Audio / Audio Fig.
  • Page 95 Trouble Shooting Guide, Advanced 21.11 All audio paths are working in EFRA, but both the microphone and the earphone is out of order during a connected call If any of the signals EXTAUD or PORTHF is too low, short circuit against ground, the phone thinks there is a hands free unit connected and switches the audio paths to the system connector instead of the microphone and earphone of phone.

  • Page 96: Keyboard

    Trouble Shooting Guide, Advanced 22 Keyboard 22.1 How does the keyboard work Fig.22.1. below shows the schematics for the keyboard of R250s. Fig. 22.1 The function of the keyboard is build of nine signals connected as a matrix with five rows and four columns.
  • Page 97 Trouble Shooting Guide, Advanced 22.2 How to find the fault Start the phone in the test program. Go to MMI/Keyboard. Press all keys to find which one that is faulty. If one or more of the keys at the keyboard is faulty, go to section 22.2.1. If any of the volume keys is faulty, go to section 22.2.2.
  • Page 98 Trouble Shooting Guide, Advanced 22.2.2 The volume keys are faulty Open the phone and check for liquid damages, especially around the faulty keys. No further action should be taken for a liquid damaged telephone. Clean the pads of the keyboard thoroughly using alcohol. Give the board power and start the board in the test program.
  • Page 99 Trouble Shooting Guide, Advanced No further action should be taken for a liquid damaged telephone. Give the board power and start the board in the test program. Try the function of the Hall-element, N600. You activate the Hall-element by holding a magnet close to the Hall element. If necessary replace N600.

  • Page 100: Display

    Trouble Shooting Guide, Advanced 23 Display 23.1 The Control signals to the display The processor controls the display with serial data through an I2C-bus, Inter IC. The I2C-bus consist of two lines, I2CDAT for data and I2CCLK for clocking. To get as good readability as possible of the display in different angles and to get clear contrast; the display has to be regulated exactly.
  • Page 101 Trouble Shooting Guide, Advanced Fig. 23.2 The graphs below show the voltage at the points A Fig 23.3. B Fig. 23.4. and C Fig. 23.5 in the figure Fig. 23.2. above, when the capacitors is fully charged. Fig. 23.3 The PWM voltage in point A charges the capacitor between A and B to the PWM voltage minus the voltage drop over the diode connected to ground.
  • Page 102 Trouble Shooting Guide, Advanced Fig. 23.5 The voltage at point C will be the voltage at point B minus the voltage drop over the diode between B and C. The capacitor at point C, connected to ground, stores the voltage to maintain a constant level of the voltage.
  • Page 103 Trouble Shooting Guide, Advanced 23.4 The display does not show anything at all Open the phone and check for water damages. No further action should be taken for a liquid damaged telephone. Replace the display assy.according to mechanical repair guide. Try the phone again according to section 23.2.
  • Page 104 Trouble Shooting Guide, Advanced The PWM signals look like in the Fig. 23.3. below. Notice that the PWM signals for a phone with signal program and a phone with test program does not look the same. Fig. 23.3 A fault in the PWM signals is usually due to incorrect soldering at D600, a short circuit in the capacitors between the PWM generators and the diodes and sometimes on just a faulty D600.

  • Page 105: Buzzer

    Trouble Shooting Guide, Advanced 24 Buzzer 24.1 How to find the fault Start the phone in the test program. Go to Audio\Audio/Buzzer. Activate the buzzer with “Buzzer ON”. Fig. 24.1 Measure the voltage on activated buzzer according to fig above. Fig. 24.1 Connect a load 5.6 ohms across J600, if buzzer not is connected.
  • Page 106 Trouble Shooting Guide, Advanced If the voltage on pin 2 is wrong. Fig. 24.2. measure the voltage on R651 ~3.0V at 440 Hz squared wave on the side against the processor and ~0.9V at same frequency on the other side. If the voltage is incorrect on the side against the processor, the fault can be due to the solving or the component.

  • Page 107: Vibrator

    Trouble Shooting Guide, Advanced 25 Vibrator 25.1 How to find the fault Start the phone in the test program. Go to Audio\Audio/Vibrator. Activate the vibrator with “Vibrator ON”. Fig. 25.1 Measure the voltage on activated vibrator according to fig above Fig. 25.1. Connect a load 10 ohms across J601, if vibrator not is connected.
  • Page 108 Trouble Shooting Guide, Advanced If VBATT is to low then it is either foil damaged to R616; R617 or one of R616 R617, C613 or V615 is faulty. If the voltage on pin 2 is wrong Fig. 25.2. measure the voltage on R624 ~3.0V on the side against the processor and at N601 pin 4.

  • Page 109: Illumination

    Trouble Shooting Guide, Advanced 26 Illumination 26.1 The background light to the keyboard or to the display does not work Start the phone in the test program. Go to MMI\Display/Top indicator test. Activate background light with “Disp./Keyb. led on “ Fig. 26.1. Fig.
  • Page 110 Trouble Shooting Guide, Advanced No further action should be taken for a liquid damaged telephone. If VBATT occurs on both sides of the diodes, then it is most likely a short cut in one of the LED´s or a foil damage between the diode cathodes and the resistor R660. It can also be caused by a damage in R660, V613 or R607.

  • Page 111: Top Indicator

    Trouble Shooting Guide, Advanced 27 Top Indicator 27.1 The green or the red top indicator does not work Start the phone in the test program. Go to MMI\Display/Top indicator test Activate the half of the diode that does not work with “Green top indicator” or “Red top indicator”...
  • Page 112 Trouble Shooting Guide, Advanced If the voltage at pin 1 or 3 is incorrect, check the voltage on D600 pin 93, red top indicator or D600 pin 94, green top indicator (+0.2 V If the voltage is incorrect on D600, then the fault can be due to the soldering or the circuit. If the voltage is correct on D600, then the fault can be due to foil damage against H650, short circuit in C654 or C655 or a liquid damage.

  • Page 113: Sim-Fault (Insert Card)

    Trouble Shooting Guide, Advanced 28 SIM-Fault (Insert card) 28.1 What is SIM-fault Insert a functional SIM-card and a charged battery into the unit. If “Wrong card” or “Insert correct card” is displayed when starting the unit it means that the unit is SIM-locked, handle the unit according to the local company directives.
  • Page 114 Trouble Shooting Guide, Advanced Fig. 28.2. below shows the placing of the SIM-pads on the circuit board. Fig. 28.2 Set SIM VCC high using the button “SIM VCC”. Measure the voltage on J603: 5 +5 V If the voltage is missing, go to section 28.3. SIMVCC must be activated when measuring SIMCONRST, SIMCONDAT and SIMCONCLK.
  • Page 115 Trouble Shooting Guide, Advanced If the output voltage is correct on N605, measure the resistance of R683 and make sure there is not a foil damage against J603: 5. 28.4 SIMCONRST is missing Measure SIMCONRST on V622 pin 6 +5 V To be able to put SIMCONRST high, SIMVCC must be high, and correct.

  • Page 116: Self-Test

    Trouble Shooting Guide, Advanced 29 Self-Test 29.1 What is self test Self-test is a part of the test program, which tests the communication or a limited part of the function and also the revision on certain circuits. The tests that self test performs are: Check for the revision of the CPU (D600), DSP (D900), and analogue/digital ASIC (N800).
  • Page 117 Trouble Shooting Guide, Advanced 29.3 Check EEProm Open the phone and check for liquid damages. No further action should be taken for a liquid damaged telephone. Check the soldering at D600 pin 3, 4. Check R619, R620. Make sure there is no short circuit against ground at I2CCLK or I2CDAT. Give the board power and check VDIG +3.2 V Sometimes it can help to replace D600.

  • Page 118: Adc-Values

    Trouble Shooting Guide, Advanced 30 ADC-Values 30.1 What is ADC The processor ca not use analogue information, therefore it has to be converted from analogue to digital configuration. The conversion is done in an 8-bits A/D converter. Fig. 30.1. All of the analogue signals mentioned in the figure use the same ADC. It is possible since there is an 8-channel multiplexer on the input of the A/D-converter.
  • Page 119 Trouble Shooting Guide, Advanced The values are shown in a window as the one below Fig. 30.2. Fig. 30.2 You can choose to read the values once or continuously. If two or more values are incorrect, go to section 30.3. If only one value is incorrect, go to the responding section below.
  • Page 120 Trouble Shooting Guide, Advanced Measure the exact voltage of VBATT, N450 pin 17 and VRAD, N450 pin 13. Calculate VTRACK according to following formula: 0.7 * (VBATT – VRAD) = VTRACK For example: VBATT = +6.5 V , VRAD = +3.8 V and that gives VTRACK +1.89 V Measure the voltage VTRACK on N450 pin 2.

  • Page 121: Revision History

    Trouble Shooting Guide, Advanced 31 Revision History Rev. Date Changes / Comments 2000-03-28 Documents title and layout changed. Component placement added. Action added in chapter 3. Voltage tolerances added in chapter 1.1 and 1.3 4/00021-3/FEA 209 544/18 B 121(121)

Table of Contents