Ericsson T18s Trouble-Shooting Instruction
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Ericsson T18s Trouble-Shooting Instruction

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T18s, T18sc Standard Electrical Repairs
Approved according to 1776-2/FEA 209 544
Trouble-shooting
instruction
T18s, T18sc
Standard electrical repairs
4/00021-2/FEA 209 544/12.B

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  • Page 1 T18s, T18sc Standard Electrical Repairs Approved according to 1776-2/FEA 209 544 Trouble-shooting instruction T18s, T18sc Standard electrical repairs 4/00021-2/FEA 209 544/12.B...

  • Page 2: Table Of Contents

    T18s, T18sc Standard Electrical Repairs Table of contents Conditions ..................3 No SERV/Not able to connect calls..........6 Doesn’t start..................12 Audio....................21 Display..................... 30 Charging fault ................. 34 SIM fault ("Insert card") ............... 38 Keyboard ..................45 Illumination, buzzer and vibrator.

  • Page 3: Conditions

    T18s, T18sc Standard Electrical Repairs 1 Conditions 1.1 Component classifications. After each component, which fault can be verified by the trouble-shooting instruc- tions in this folder, the classification of the component is written. The components are divided into four classes, A,B,C and D. The classes are seperated depending on how much of the prestanda of the phone that is affected by replacing the component.
  • Page 4 T18s, T18sc Standard Electrical Repairs 1.2 Abbreviations. The power module at some phones. Crystal. Capacitor. Digital circuit. Over voltage protection. VCO. Buzzer, LED, pads for display. Connector. Coil. Analogue circuit, the power module at some phones. Resistor. Keyboard pads. BALUN. A circuit that converts a signal from balanced to unbalanced or the opposite.
  • Page 5 T18s, T18sc Standard Electrical Repairs RTC: Real time clock. The clock that keeps track of time and date. SIMCLK: Clock signal from the processor, through D901, used for communica- tions with the SIM. SIMDAT: Data signal from the processor, through D901, used for communica- tions with the SIM.

  • Page 6: No Serv/Not Able To Connect Calls

    T18s, T18sc Standard Electrical Repairs 2 No SERV/Not able to connect calls. 2.1 Find out if the fault is Rx or Tx related. Connect the phone (with signalling program) to a GSM test instrument and try to get SERV at –68.5dBm signal strength. Check both bands (GSM 900 and 1800).
  • Page 7 T18s, T18sc Standard Electrical Repairs Try again to get SERV at –102dBm. • If the phone gets SERV at –102dBm there’s probably nothing wrong with the phone. Run the phone through the final test (Go/No go-test). Open the phone. Give the board power and start it up by pressing the On/Off key.
  • Page 8 T18s, T18sc Standard Electrical Repairs Fig. 2.3 (60) 4/00021-2/FEA 209 544/12.B...
  • Page 9 T18s, T18sc Standard Electrical Repairs Connect a call at powerlevel 5 towards the instrument with an input signal of – 68.5dBm. If you’re not able to connect a call, open the phone and check for liquid damages. Make sure the back cover isn’t broken and that it is of the correct model as there are two to choose from (fig.
  • Page 10 T18s, T18sc Standard Electrical Repairs Fig. 2.4 Give the board power and start it up (in the fixture). Measure the VRAD voltage at C482 (~3.8V, fig. 2.3). • If the voltage is incorrect, replace N480 (class A, fig. 2.3). Check the solderings of G300 and Z440 (fig. 2.4).
  • Page 11 T18s, T18sc Standard Electrical Repairs No SERV at the GSM 900 or the GSM 1800 band. 2.4.1 No SERV at the GSM 900 band. Measure the voltage drop of the V213 diode (~0.6V, fig. 2.3, class A). Measure the resistance of R247 (~33 kohms, class A, fig. 2.3).

  • Page 12: Doesn't Start

    T18s, T18sc Standard Electrical Repairs 3 Doesn’t start. 3.1 Find out if the phone starts when pressing the On/Off key. Insert a fully charged battery into the phone and press the On/Off key. • If the phone doesn’t start, proceed to section 3.2.
  • Page 13 T18s, T18sc Standard Electrical Repairs Make sure the dome foil isn’t damaged, especially at the On/Off key. Make sure there are no faulty solderings at D600 (fig. 3.2, class B). Fig. 3.2 • If the fault is fixed, send the phone through the normal flow.
  • Page 14 T18s, T18sc Standard Electrical Repairs If the phone consumes more than 200mA, remove the display and check again. • The fault was due to the display if the current consumption went down. • If the current consumption still is too high, proceed to section 3.4.3.
  • Page 15 T18s, T18sc Standard Electrical Repairs Fig. 3.3 (60) 4/00021-2/FEA 209 544/12.B...
  • Page 16 T18s, T18sc Standard Electrical Repairs Fig. 3.4 • If there’s voltage at any of the regulators, replace the corresponding regulator (VDIG – N702, VRAD – N480, VVCO – N470, VCORE – N700, all four of class A). • If there’s voltage at all of the regulators, measure the voltage at pin 1 of V702 (~0V, fig.
  • Page 17 T18s, T18sc Standard Electrical Repairs 3.4.2 Consumes no current when the On/Off key is being pressed. Open the phone and check for liquid damages. Make sure the pads for the battery connector and system connector aren’t dirty, oxi- dised or liquid damaged.
  • Page 18 T18s, T18sc Standard Electrical Repairs 3.4.3 Consumes more than 200mA. Open the phone and check for liquid damages. Make sure the pads for the battery connector and system connector aren’t dirty, oxi- dised or liquid damaged. Put the board in the fixture, start it up and keep it running by keeping DCIO high.
  • Page 19 T18s, T18sc Standard Electrical Repairs Fig. 3.6 3.4.4 The phone works as long as the On/Off key is pressed. Open the phone and check for liquid damages. Make sure the pads for the battery connector and system connector aren’t dirty, oxi- dised or liquid damaged.
  • Page 20 T18s, T18sc Standard Electrical Repairs * If it isn’t, replace D600 (class B, fig. 3.2). • If the voltage is correct, measure the resistance of C692 (>200 kohms, fig. 3.4). * If it’s incorrect, replace C692 (class A). * If the resistance is correct, check the voltages at N706 (pin 1 – GND, pin2 –...
  • Page 21 T18s, T18sc Standard Electrical Repairs If the fault remains, send the phone to Advanced electrical repairs. (60) 4/00021-2/FEA 209 544/12.B...

  • Page 22: Audio

    T18s, T18sc Standard Electrical Repairs 4 Audio. 4.1 Kind of fault. Make a call from the phone that is to be tested (later called the phone) to a phone that is working correctly (later called the reference phone). Check the function of the microphone and the earphone.
  • Page 23 T18s, T18sc Standard Electrical Repairs Fig. 4.1 Check the solderings of N800 (fig. 4.2) Measure the resistance from one of the J810 pins to the other (~14 kohms, fig. 4.1). • If the resistance is too low, replace C842 (class A, fig. 4.1).
  • Page 24 T18s, T18sc Standard Electrical Repairs 4.3 Microphone out of order. Open the phone and check for liquid damages. Clean the system and microphone connector pads if needed. Most of the microphone faults are mechanical. Make sure C815 and C820 (both of class A, fig. 4.2) are mounted at the circuit board.
  • Page 25 T18s, T18sc Standard Electrical Repairs Check the solderings at pins 13-17 of N800 (fig. 4.2). If the fault really is electrical and the above mentioned components aren’t faulty, replace C818 and C819 (class A, fig. 4.2). Measure the resistance from one of the X830 pads to the other (~28 kohms, fig.4.2).
  • Page 26 T18s, T18sc Standard Electrical Repairs Fig. 4.3 Measure the voltage at both sides of R601 and at pin 70 of D600 (~3.1V, fig. 4.2, you follow the PHFI signal). Measure the voltage at both sides of R605 and at pin 67 of D600 (~3.1V, fig. 4.2, you follow the EXTAUDI signal).
  • Page 27 T18s, T18sc Standard Electrical Repairs Check the VDIG voltage at the marked sides of R635 and R636 (~3.2V, fig. 4.1). • If VDIG is missing at R635 and R636 but is at pin 5 of N702 there’s a foil dam- age and the phone is to be discarded.
  • Page 28 T18s, T18sc Standard Electrical Repairs Open the phone and check for liquid damages especially around pads 1, 2 and 4 of the system connector pads (J602, fig. 4.4). Measure the resistance from pad 2 of J602 (fig. 4.4) to ground (>30 kohms).
  • Page 29 T18s, T18sc Standard Electrical Repairs Open the phone and check for liquid damages, especially around the system connec- tor pads 1, 2 and 4 (J602, fig. 4.4). Measure the resistance from pad 1 of the system connector pads (J602) to ground.
  • Page 30 T18s, T18sc Standard Electrical Repairs Clean the marked area using a brush and alcohol. Measure the resistance from pad 3 of J602 to unmarked side of R635 (~0 ohms, fig. 4.4 and 4.1). Measure the resistance from pad 5 of J602 to unmarked side of R636 (~0 ohms, fig.

  • Page 31: Display

    T18s, T18sc Standard Electrical Repairs 5 Display. 5.1 Kind of fault. Insert a fully charged battery into the phone and start it up by pressing the On/Off key. • If it doesn’t start, proceed to chapter 3, “Doesn’t start”-fault. • If the display is missing one or more of the segments, proceed to section 5.2.
  • Page 32 T18s, T18sc Standard Electrical Repairs Fig. 5.1 If I CDAT or I CCLK voltage is missing, measure the resistance of R619 (~6.8 kohms), R620 (~6.8 kohms), R615 (~0 ohms) and R614 (~10 kohms, all of class A, R619 and R620 in fig. 5.2 and R615 and R614 in fig. 5.1).
  • Page 33 T18s, T18sc Standard Electrical Repairs • If the PWM0 and PWM1 signals are missing, check the resistances of C634 and C636 (both of class A and in fig. 5.2) to see if there’s a short circuit in one or both of them.
  • Page 34 T18s, T18sc Standard Electrical Repairs Fig. 5.2 5.4 Black display. Open the phone and check for liquid damages. Try mounting a display that you know works. • If that doesn’t help, replace R807, R808 and C824 (fig. 5.2, all of class A).

  • Page 35: Charging Fault

    T18s, T18sc Standard Electrical Repairs 6 Charging fault 6.1 Type of charging fault. Perform a visual check of the battery connector and the system connector. Replace if necessary. Start the phone using the On/Off-key and a fully charged battery. • If it doesn´t start at all, proceed to chapter 3, "Doesn´t start"-fault •...
  • Page 36 T18s, T18sc Standard Electrical Repairs • If the phone starts and shows charging and the current consumption on the power supply varies between ~700mA (the other method gives ~500-800 mA depending on the type of charger) and 0 mA with a few seconds interval, the charging function is without fault.
  • Page 37 T18s, T18sc Standard Electrical Repairs Check the feed voltages VDIG (~3.2 V) on the marked side of C600 (class A) and VRAD (~3.8 V) on the marked side of C482 (class A, Fig. 6.1). • If any of the feed voltages are incorrect, proceed to chapter 3, “Doesn´t start”- fault.
  • Page 38 T18s, T18sc Standard Electrical Repairs • If it is too high, it is either R453 or R648 (both class A and in fig. 6.1) that is faulty. Measure their resistance and replace the resistor that is faulty. Measure the resistance between J602 pin 1 (DCIO) and X800 pin 3 (VBATT).

  • Page 39: Sim Fault ("Insert Card")

    T18s, T18sc Standard Electrical Repairs 7 SIM fault ("Insert card") 7.1 What is a SIM fault? Insert a working SIM card and attach a fully charged battery. • If the phone shows "Wrong card" or "Insert correct card" when started, the phone is SIM locked to a specific operator and can´t be repaired at this repair...
  • Page 40 T18s, T18sc Standard Electrical Repairs This measurement is best performed using an oscilloscope, and that is also a com- mon instrument at the Repair Centers. Therefore is this measurement included in this instruction, even though the oscilloscope isn´t a required instrument.
  • Page 41 T18s, T18sc Standard Electrical Repairs If the fault still remains, send the phone to Advanced electrical repairs. Oscilloscope measuring. Measure the voltage VVIC (suitably on a multimeter) at D901 pin 1, it should be 3.2V . If it is missing, replace C901, C910 and R920 (class A).
  • Page 42 T18s, T18sc Standard Electrical Repairs SIMVCC (J603:1) SIMPWR (D901:1) SIMCONRST (J603:2) SIMRST (D901:7) SIMCONDAT (J603:7) SIMDAT (D901:5) Fig. 7.2. SIMCONRST Measure at the SIMCONRST- pad (see Fig. 7.1) while starting the phone. The phone sends 5 pulses with the amplitude 5 V at start up (see Fig. 7.2).
  • Page 43 T18s, T18sc Standard Electrical Repairs * If the signal (SIMRST) is missing, do the same test, but at D600 pin 73. * If SIMRST is missing here too, replace D600 (class B). * If SIMRST exists (at D600 pin 73), then there is a foil damage, and the board has to be discarded.
  • Page 44 T18s, T18sc Standard Electrical Repairs SIMVCC SIMCONCLK (J603:3) SIMCLK (D901:6) SIMCONCLK modulated clock frequency Fig. 7.3. SIMCONDATA Measure at the SIMCONDAT- pad (see Fig. 7.1) while starting the phone. The phone sends 5 pulses with the amplitude 5 V at start up (see Fig. 7.2).
  • Page 45 T18s, T18sc Standard Electrical Repairs • If SIMCONDAT is missing, do the same test as above, but at D901 pin 5 (see Fig. 7.1). The signal (SIMDAT) should look the same, but with the amplitude 3.2 V. * If the signal (SIMDAT) is missing, do the same test, but at D600 pin 74.

  • Page 46: Keyboard

    T18s, T18sc Standard Electrical Repairs 8 Keyboard 8.1 Type of keyboard fault. Insert a SIM card and attach a fully charged battery. Start the phone using the On/ Off-key. • If the phone doesn´t start at all, proceed to chapter 3, “Doesn´t start”-fault.
  • Page 47 T18s, T18sc Standard Electrical Repairs Fig. 8.1 8.4 One or more keys are faulty. Open the phone and check for liquid damages. Remove the dome foil and clean the pads. Give the board power and start it. Check if there is a voltage on the marked sides of the faulty pads (~4.8 V on the No/On-Off, ~3.2V on the other)(Fig.
  • Page 48 T18s, T18sc Standard Electrical Repairs Check the soldering at D600:1,120,122-128 (Fig. 8.3). Fig. 8.3. If the voltage is incorrect for a complete row (e.g. 1,2,3), measure the resistance from the marked side (Fig. 8.2) of the pads of that row to D600 (In this case D600:125).

  • Page 49: Illumination, Buzzer And Vibrator

    T18s, T18sc Standard Electrical Repairs 9 Illumination, buzzer and vibrator. 9.1 Kind of fault. Insert a dummy battery into the phone, start it up by pressing the On/Off key and wait for the phone to get serv (towards the test instrument or the network).
  • Page 50 T18s, T18sc Standard Electrical Repairs Fig. 9.1 Make sure the buzzer (H600, class A, fig. 9.1) isn’t incorrectly soldered at pins 1 and 2. • If the solderings are correct, replace H600. Try the buzzer (by starting the board in the fixture).
  • Page 51 T18s, T18sc Standard Electrical Repairs Measure the resistance from pin 91 of D600 to the marked side of R651 (~0 ohms, fig. 9.1). • If it’s correct, measure the resistance of R651 (1 kohms, fig. 9.1). * If it’s incorrect, replace R651 (class A).
  • Page 52 T18s, T18sc Standard Electrical Repairs • If the voltage is 0 V there’s a foil damage and the phone has to be discarded. If none of the LEDs are lit, measure the voltage at the marked side of them (~4.8 V, Fig.
  • Page 53 T18s, T18sc Standard Electrical Repairs * If the soldering is correct, replace D600 (class B, fig. 9.2). • If the voltage is incorrect there’s a foil damage and the phone is to be discarded. NOTE! Since the LEDs only are lit for ~10s you need to press a key before measuring.
  • Page 54 T18s, T18sc Standard Electrical Repairs • If the voltage at H650 is incorrect, send the phone to Advanced electrical repairs. 9.7 Red top indicator doesn’t work. Open the phone and check for liquid damages. Make sure the double LED (H650, fig. 9.3) is correctly soldered.
  • Page 55 T18s, T18sc Standard Electrical Repairs Fig. 9.4 Make sure: that there isn’t a cable breakage. that the connector is properly attached to X680 (fig. 9.5, class A). that X680 isn’t damaged or incorrectly soldered. (60) 4/00021-2/FEA 209 544/12.B...
  • Page 56 T18s, T18sc Standard Electrical Repairs Fig. 9.5 Measure the voltage at pin 3 of V620 (~4.8V, fig. 9.5). • If the voltage is missing, replace R685 (class A, fig. 9.5). Also measure the voltage at pin 2 of V622 (~3.2 V, fig. 9.5).
  • Page 57 T18s, T18sc Standard Electrical Repairs • If the vibrator doesn’t start when grounding pin 1 of V622, measure the voltage at pin 1 of V620 at the same time as you ground pin 1 of V622. * If it’s less than 4.5V, measure the resistance of R681 (~1.5 kohms, fig. 9.5).

  • Page 58: Rtc

    T18s, T18sc Standard Electrical Repairs 10 RTC 10.1 Finding the fault. Start the phone with a SIM-card and a fully charged battery attached. Set the clock at the correct time. Remove the battery and attach it again after one minute.
  • Page 59 T18s, T18sc Standard Electrical Repairs • If it is, replace it. Assemble the phone, start it and set the clock at the correct time. Wait a few minutes to allow the backup capacitor to begin charging. Remove the battery and attach it again after one minute.

  • Page 60: Component List

    T18s, T18sc Standard Electrical Repairs 11 Component list Component list in document 131 22- 2/FEA 209 544/12 (60) 4/00021-2/FEA 209 544/12.B...

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