Ericsson PF 768 Troubleshooting Instructions
  1. Manuals
  2. Brands
  3. Ericsson Manuals
  4. Cell Phone
  5. PF 768
  6. Troubleshooting instructions

Ericsson PF 768 Troubleshooting Instructions

Hide thumbs
Table of Contents

Advertisement

Quick Links

Download this manual
PF768, Standard Electrical Repairs
Approved according to 2/FEA 209 544
Trouble-shooting
instruction
PF 768
Service Manual by Toko
4/00021-2/FEA 209 544/11.C

Advertisement

Table of Contents
loading

Related Manuals for Ericsson PF 768

Summary of Contents for Ericsson PF 768

  • Page 1 PF768, Standard Electrical Repairs Approved according to 2/FEA 209 544 Trouble-shooting instruction PF 768 Service Manual by Toko 4/00021-2/FEA 209 544/11.C...
  • Page 2 PF768, Standard Electrical Repairs Table of contents Conditions ..................3 Component classes................3 Abbreviations.................. 4 Pin placements ................6 No serv/not able to connect calls............8 Doesn’t start..................11 Audio....................21 Display..................... 29 SIM (“Insert card”)................ 33 Keyboard ..................

  • Page 3: Conditions

    PF768, Standard Electrical Repairs 1 Conditions 1.1 Component classes. All the components in the phone are divided into classes and after every component in the troubleshooting guide you have a class written. The components are divided into four classes: A, B, C and D.The class of the component depends on how much of the phone’s performance is affected when replacing it.

  • Page 4: Abbreviations

    PF768, 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. Resistor. Keyboard pads. BALUN. A circuit that converts a signal from balanced to unbalanced or the opposite.
  • Page 5 PF768, Standard Electrical Repairs SIMCLK: Clock signal from the processor used for communications with the SIM. SIMDAT: Data signal from the processor used for communications with the SIM. SIMRST: Reset signal from the processor used for communications with the SIM. SIMVCC: Feed voltage for the SIM.

  • Page 6: Pin Placements

    PF768, Standard Electrical Repairs 1.3 Pin placements Single diode (PIN diode). Electrolytic capacitor. Double diode or single trans- Five pin circuit (usually volt- Double transistor. stor. age regulator). Eight pin circuit. Tx VCO circuit (G300) LO VCO circuit (G350) Sixteen pin circuit Twenty pin circuit Crystal (68)
  • Page 7 PF768, Standard Electrical Repairs N800 D900 D600 D620 D610 (68) 4/00021-2/FEA 209 544/11.C...

  • Page 8: No Serv/Not Able To Connect Calls

    PF768, Standard Electrical Repairs 2 No serv/not able to connect calls. 2.1 Finding 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. •...
  • Page 9 PF768, Standard Electrical Repairs • If the phone gets serv, proceed to section 2.3. • If the phone doesn’t get serv there is probably a LO-part fault or the losses in the signal path are too great. It’s also possible it could be a feed voltage fault. If the fault remains, send the phone to the next level.
  • Page 10 PF768, Standard Electrical Repairs Fig. 2.3 If the output power is too low or if the Rx-quality value or the RX-level vaule is too high, send the phone to the next level. If the Rx-level value is below 39 steps at –68.5dBm input signal strength or below 4 steps at –102.5dBm input signal strength, then the fault is Rx-related.

  • Page 11: Doesn't Start

    PF768, Standard Electrical Repairs 3 Doesn’t start. 3.1 Find out if the phone starts by pressing the On/Off key. Insert a fully charged battery and press the On/Off key. • If the phone doesn’t start, proceed to section 3.2. • If the phone starts, turn off the phone and check the charging function by con- necting a charger into the system connector.
  • Page 12 PF768, Standard Electrical Repairs Fig. 3.2 Send the phone through the normal flow as soon as you’ve fixed the fault. 3.2 Visual check. Make an outer visual check: • Make sure the battery connector is intact and that there aren’t any dirt or oxide at the connector pins.
  • Page 13 PF768, Standard Electrical Repairs Give the board power and start it up by pressing the On/Off key (in the fixture or in the back cover with a dummy battery inserted, mount system connector to make the board lie steady in the back cover). * If the phone still doesn’t consume any current when the On/Off key is pressed, proceed to section 3.4.2.
  • Page 14 PF768, Standard Electrical Repairs Fig. 3.3 Fig. 3.4 shows the measuring point for VANA and VDSP. Fig. 3.4 Fig. 3.5 shows the measuring point for VRPAD and VVCO. Fig. 3.5 (68) 4/00021-2/FEA 209 544/11.C...
  • Page 15 PF768, Standard Electrical Repairs Since the measuring point for VVCO is under the big radio shielding (E202) you have to measure the voltage carefully through one of the holes with a thin and pref- erably isolated probe as in fig. 3.6. Fig.
  • Page 16 PF768, Standard Electrical Repairs • If the phone still doesn’t consume any current, measure the resistances from the unmarked side of the “No” keypad (fig. 3.7) to pin 2 of V702 (~0 ohms, fig. 3.3) and from pin 3 of V702 to pin 3 if N702 (~0 ohms, fig. 3.3). Fig.
  • Page 17 PF768, Standard Electrical Repairs Also note that the measuring point for VVCO is under the big radio shielding (E202) and therefore you have to measure the voltage carefully through one of the holes with a thin and preferably isolated probe as in fig. 3.6. •...
  • Page 18 PF768, Standard Electrical Repairs * If all the voltages are correct, measure the VRTC voltage between the positive side of C720 (class A, ~3.1V, fig. 3.8) and ground. * If there’s no VRTC voltage, replace V711 (class A, fig. 3.8). * If there’s VRTC voltage, measure the resistance from the positive side of C720 (fig.
  • Page 19 PF768, Standard Electrical Repairs * If the resistance is too low there’s a short circuit in one of the circuits fed by the regulator. Send the phone to the next level. • If any of the voltages are too high, replace the corresponding regulator. Check the power reset voltage at C710 (fig.
  • Page 20 PF768, Standard Electrical Repairs 3.4.6 Able to program the phone but it doesn’t start afterwards or it is troublesome in the flash pro- grammer. Open the phone and check for liquid damages. Make sure the battery and system connector pads aren’t dirty, liquid damaged or oxidised.

  • Page 21: Audio.

    PF768, Standard Electrical Repairs 4 Audio. 4.1 Type 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. Connect a handsfree unit to the system connector of the phone.
  • Page 22 PF768, Standard Electrical Repairs Fig. 4.1 Check the solderings of N800 (fig. 4.3). Fig. 4.2 Fig. 4.3 If the fault remains, send the phone to the next level. (68) 4/00021-2/FEA 209 544/11.C...

  • Page 23: Fea 209 544/11.C

    PF768, Standard Electrical Repairs 4.3 Microphone out of order. Open the phone and check for liquid damages. Wash the system and microphone connector pads if needed. Make sure the sound channel gasket is properly mounted and free from dust. Replace the system connector and microphone with a pair you know work. Test the phone again.
  • Page 24 PF768, Standard Electrical Repairs Wash the circuit board if needed using alcohol and a brush. Assemble the phone and test it as in 4.1. If the fault remains, open the phone. Give the board power and start it up by press- ing the On/Off key without the system cable connected.
  • Page 25 PF768, Standard Electrical Repairs Fig. 4.6 • If the resistance is too low, wash carefully and measure again. * If the resistance still is too low, remove R601 (class A, fig. 4.3) and measure again. * If the resistance increased, replace D600 (class B, fig. 4.2). * If the resistance didn’t increase when removing the R601 resistor or if it didn’t help to replace D600, send the phone to the next level.

  • Page 26: Check The Solderings Of N800 (Fig

    PF768, Standard Electrical Repairs * If the resistance is correct, replace D600 (class B). • If the voltage is correct, check the solderings of N800 and D600 (fig. 4.3 and 4.2). If the fault remains, send the phone to the next level. 4.5 Handsfree microphone out of order.
  • Page 27 PF768, Standard Electrical Repairs • If there’s correct voltage at R825, check the resistance of C810 (>10 kohms), C812 (>100 kohms), R802 (~3.9 kohms) and R805 (~15 kohms, all of class A and in fig. 4.3). If the fault remains, send the phone to the next level. 4.6 Handsfree speaker out of order.
  • Page 28 PF768, Standard Electrical Repairs Both the microphone and the speaker of the handsfree out of order. Open the phone and check for liquid damages, especially at the components in fig. 4.5. Wash the above mentioned components using alcohol and a brush. Measure the resistance from X602 pad 3 to the unmarked side of R635 (~0 ohms, fig.

  • Page 29: Display

    PF768, Standard Electrical Repairs 5 Display. 5.1 Kind of fault. Insert a 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 segments, proceed to section 5.2. •...
  • Page 30 PF768, Standard Electrical Repairs Fig. 5.1 Measure the voltages at the V608 diode (class A). Compare the results to the values at fig. 5.2. Fig. 5.2 All values are approximately 0.2V . • If any of the voltages differ from the ones in fig. 5.2, measure the resistances of C633 (class A, >100 kohms, fig.
  • Page 31 PF768, Standard Electrical Repairs * If the resistances and the VRPAD voltage are correct, replace the V608 diode. * If the voltages at the diode (except VRPAD) still are incorrect after replacing it, make sure pin 96 of D600 is correctly soldered. * If the soldering is correct, replace C632 (class A, fig.
  • Page 32 PF768, Standard Electrical Repairs • If there isn’t, check the resistances from H622 pad 6 to V608 (the VLCD marked pin in fig. 5.2, ~0 ohms) and from pad 5 of H622 to ground (~0 ohms). * If any of the resistances are too high there’s a foil damage and the phone is to be discarded.

  • Page 33: Sim ("Insert Card")

    PF768, Standard Electrical Repairs 6 SIM (“Insert card”). 6.1 What is SIM fault? Insert a charged battery and a functional SIM card into the phone. Start it up by pressing the On/Off key. • If the phone displays “Wrong card” or “Insert correct card” in the display it means that the phone is SIM-locked and it can’t be repaired at this level.
  • Page 34 PF768, Standard Electrical Repairs Fig. 6.2 Give the board power and start it up. Measure the input voltage at N705 pin 2 (~3.1V, fig. 6.4). Fig. 6.3 shows the component side of the board. Fig. 6.3 (68) 4/00021-2/FEA 209 544/11.C...
  • Page 35 PF768, Standard Electrical Repairs Fig. 6.4 • If the input voltage is too low or missing, check the VDIG (~3.2V) feed voltage at C600 (fig. 6.4). * If the VDIG voltage is too low, measure the resistance from it to ground. * If the resistance is more than 500 ohms, replace N702 (class A, fig.
  • Page 36 PF768, Standard Electrical Repairs Assemble the phone with a new SIM card holder and try again. If the fault remains, disassemble the phone again. Measure the resistance of R704 (class A, ~100 kohms, fig. 6.4). Make sure pins 64 and 72-75 (fig. 6.3) are correctly soldered. Measure the resistances of R600 (~33 ohms), R627 (~0 ohms) and R628 (~100 ohms, allof class A and in fig.

  • Page 37: Keyboard

    PF768, Standard Electrical Repairs 7 Keyboard 7.1 Kind of keyboard fault. Insert a SIM card and a fully charged battery into the phone. Start the phone by pressing the On/Off key. • If it doesn’t start at all, proceed to chapter 3 (“Doesn´tstart”-fault). Press all the keys (including the volume keys at the side) and verify which are func- tional.
  • Page 38 PF768, Standard Electrical Repairs Make sure the S820 and S821 (both of class A) switches are intact and correctly sol- dered. Measure the resistance of the switch that isn’t functional. You measure between pin 1/3 and 2/4 (fig. 7.2). The resistance should be >100 kohms when not pressed and ~0 ohms when pressed.
  • Page 39 PF768, Standard Electrical Repairs If that doesn’t help, open the phone. Give the board power and start it up (by press- ing the On/Off key or setting DCIO high). Schematic of the keyboard functions is shown in fig. 7.4. Fig. 7.4 Measure the VDIG voltage (fig.
  • Page 40 PF768, Standard Electrical Repairs Measure the voltage at the unmarked side of the R630-R634 resistors (~3.2V). • If the voltage is too low at one or more of the resistor, measure the resistance of the corresponding resistor (all are of class A and ~100 kohms). * If all the resistances are correct, check the solderings at D600 1, 120 and 122-128.
  • Page 41 PF768, Standard Electrical Repairs ohms). The foil damage is most usually caused by liquid damages. If there, for instance, is voltage at the 4 and 5 keypads but not at the 6 and “volume up” keypads there’s a foil damage somewhere between key- pads 5 and 6 and the phone is to be discarded.

  • Page 42: Illumination And Buzzer

    PF768, Standard Electrical Repairs 8 Illumination and buzzer. 8.1 Type of fault. Insert a dummy battery and a SIM card into the phone, press the On/Off key and wait for the phone to get serv (towards the net or a GSM test instrument). •...
  • Page 43 PF768, Standard Electrical Repairs Make sure the buzzer (H600, class A, fig. 8.2) is correctly soldered. • If the solderings are correct, replace the buzzer. Assemble the phone and try the buzzer as in 8.1 again. • If the fault is repaired, send the phone through the normal flow. •...
  • Page 44 PF768, Standard Electrical Repairs Fig. 8.3 * If the VRPAD voltage is faulty or missing, proceed to chapter 3 (“Doesn´t start”-fault). * If it’s correct, check the resistance from pin 2 of N452 to pin 1 of V706 (~0 ohms). * If the resistance is too high it’s probably the L450 (~0 ohms, class A, fig.
  • Page 45 PF768, Standard Electrical Repairs If the fault remains, send the phone to the next level. 8.3 The background illumination for the display is missing or faintly glowing. Open the phone and check for liquid damages. Make sure all the LEDs (H651-H654, all of class A, fig. 8.1) are mounted and cor- rectly soldered.
  • Page 46 PF768, Standard Electrical Repairs Table 8.1 shows the symptoms when there’s incorrect resistance in any of the resis- tors. Missing or H651- H655- broken. H654 H660 R609 Not lit R610 Not lit R611 Faintly Not lit glowing R612 Not lit Faintly glowing Table 8.1...
  • Page 47 PF768, Standard Electrical Repairs correct resistance. Table 8.1 shows the symptoms when there’s incorrect resistance in any of the resistors. • If none of the H651-H660 LEDs are lit, measure the voltage at the marked side of R607 (~3.1V, fig. 8.4). Before measuring you have to press a key for the proc- essor to set the LED3K signal high for about 10s.
  • Page 48 PF768, Standard Electrical Repairs If the fault remains, send the phone to the next level. 8.6 Red top indicator doesn’t work. Open the phone and check for liquid damages. Make sure the double LED (H650, class A, fig. 8.2) is correctly soldered. Give the board power and start it up by pressing the On/Off key.
  • Page 49 PF768, Standard Electrical Repairs Measure the VRPAD voltage (~3.8V) at V706 pin 1 (class A, fig. 8.2). • If the VRPAD voltage is correct, replace V706 (class A). • If the voltage is missing at V706, check if there’s VRPAD voltage at pin 5 of N452 (fig.
  • Page 50 PF768, Standard Electrical Repairs 9 RTC 9.1 Determine the fault. Insert a SIM card and a fully charged battery into the phone and start it up. Set the correct time. Remove the battery and reinsert it after a minute. • If the time says 00:00, proceed to section 9.2. Compare to the correct time.
  • Page 51 PF768, Standard Electrical Repairs • If it is, replace it. Assemble the phone, start it up and set the correct time. Wait a few minutes for the backup capacitor to get charged. Remove the battery and reinsert it after a minute. Check if the fault is fixed (the backup capacitor needs a few hours of charging to reach full capacity).

  • Page 52: Component Lists

    PF768, Standard Electrical Repairs 10 Component lists 10.1 Explanations 10.1.1 Component list Position: The Components position number at the board Designation: Description of the component. Part No.: The components part number (or reference to Revision Change table) is specifed only if the component can be replaced with Standard Electrical Repair. Advanced means that the component can be replaced with Advanced Electrical Repair.

  • Page 53: Component List 2/Roa 117 3235/2

    PF768, Standard Electrical Repairs 10.2 Component list 2/ROA 117 3235/2 Trouble shooting Positon Designation Part No. NOTE instruction DOME SXA 120 9446 Doesn’t start, Key- SWITCHES board SHIELDING POT Advanced SHIELDING POT Advanced SHIELDING POT Advanced B551 QUARTZ CRYS- Advanced TAL UNIT B600 QUARTZ CRYS-...
  • Page 54 PF768, Standard Electrical Repairs Trouble shooting Positon Designation Part No. NOTE instruction C254 CAPACITOR Advanced C255 CAPACITOR Advanced C256 CAPACITOR Advanced C257 CAPACITOR Advanced C258 CAPACITOR Advanced C264 CAPACITOR Advanced C300 CAPACITOR Advanced C301 CAPACITOR Advanced C302 CAPACITOR Advanced C310 CAPACITOR Advanced C311...
  • Page 55 PF768, Standard Electrical Repairs Trouble shooting Positon Designation Part No. NOTE instruction C431 CAPACITOR Advanced C432 CAPACITOR Advanced C433 CAPACITOR Advanced C450 CAPACITOR Advanced C452 CAPACITOR Advanced C453 CAPACITOR Advanced C454 CAPACITOR Advanced C455 CAPACITOR Advanced C456 CAPACITOR Advanced C457 CAPACITOR RJE 599 1107/47A C458...
  • Page 56 PF768, Standard Electrical Repairs Trouble shooting Positon Designation Part No. NOTE instruction C545 CAPACITOR Advanced C551 CAPACITOR Advanced C553 CAPACITOR Advanced C554 CAPACITOR Advanced C556 CAPACITOR Advanced C600 CAPACITOR RJE 599 1108/1W SIM, Keyboard, Dis- play C602 CAPACITOR RJC 464 3035/68 C603 CAPACITOR RJC 464 3035/68...
  • Page 57 PF768, Standard Electrical Repairs Trouble shooting Positon Designation Part No. NOTE instruction C652 CAPACITOR RJC 463 3022/1 C656 CAPACITOR RJC 463 3022/1 C657 CAPACITOR RJC 463 3022/1 C660 CAPACITOR RJC 463 3022/1 C668 CAPACITOR RJC 464 3035/68 C669 CAPACITOR RJC 463 3022/82 C670 CAPACITOR See Rev.Change tab 1.
  • Page 58 PF768, Standard Electrical Repairs Trouble shooting Positon Designation Part No. NOTE instruction C721 CAPACITOR RJC 464 3035/68 Verify Real Time Clock function C730 CAPACITOR RJC 464 3047/1 Verify On/Off func- tion C731 CAPACITOR RJC 464 3024/1 Verify On/Off func- tion C760 CAPACITOR RJC 464 3035/68...
  • Page 59 PF768, Standard Electrical Repairs Trouble shooting Positon Designation Part No. NOTE instruction C851 CAPACITOR RJC 464 3035/68 Verify mic function Audio C853 CAPACITOR RJC 464 3035/68 C900 CAPACITOR RJE 599 1108/1W C902 CAPACITOR RJC 464 3035/68 C903 CAPACITOR RJC 464 3035/68 C904 CAPACITOR RJC 464 3035/68...
  • Page 60 PF768, Standard Electrical Repairs Trouble shooting Positon Designation Part No. NOTE instruction H659 LIGHT EMIT- RKZ 433 634/4 Verify Illumination Illumination and TING DIODE function Buzzer H660 LIGHT EMIT- RKZ 433 634/4 Verify Illumination Illumination and TING DIODE function Buzzer L211 INDUCTOR Advanced...
  • Page 61 PF768, Standard Electrical Repairs Trouble shooting Positon Designation Part No. NOTE instruction N703 MICROCIRCUIT RYT 113 6040/5C Doesn't start N705 MICROCIRCUIT RYT 113 048/C Verify SIM func- SIM, Audio tion N706 MICROCIRCUIT RYT 113 6071/5 Verify Real Time Doesn't start Clock function N800 PROD.
  • Page 62 PF768, Standard Electrical Repairs Trouble shooting Positon Designation Part No. NOTE instruction R506 RESISTOR Not available R521 RESISTOR Advanced R553 RESISTOR Advanced R562 RESISTOR Advanced R600 RESISTOR REP 622 452/33 Verify SIM func- tion R601 RESISTOR REP 622 454/1 Verify portable Audio handsfree function R602...
  • Page 63 PF768, Standard Electrical Repairs Trouble shooting Positon Designation Part No. NOTE instruction R627 RESISTOR REP 622 001/0 Verify SIM func- tion R628 RESISTOR REP 622 453/1 Verify SIM func- tion R629 RESISTOR REP 622 456/1 R630 RESISTOR REP 622 456/1 Verify keyboard Keyboard function...
  • Page 64 PF768, Standard Electrical Repairs Trouble shooting Positon Designation Part No. NOTE instruction R708 RESISTOR REP 622 456/1 Verify On/Off func- tion R709 RESISTOR REP 622 454/47 Verify On/Off func- tion R710 RESISTOR REP 622 656/1 R711 RESISTOR REP 622 656/1 R719 RESISTOR REP 622 455/47...
  • Page 65 PF768, Standard Electrical Repairs Trouble shooting Positon Designation Part No. NOTE instruction R900 RESISTOR REP 622 455/1 R901 RESISTOR REP 622 455/1 R902 RESISTOR REP 622 455/1 R903 RESISTOR REP 622 455/1 R904 RESISTOR REP 622 454/1 R905 RESISTOR REP 622 455/1 R907 RESISTOR REP 622 456/1...
  • Page 66 PF768, Standard Electrical Repairs Trouble shooting Positon Designation Part No. NOTE instruction V614 TRANSISTOR RYN 121 6086/1 Verify Illumination function V700 TRANSISTOR RYN 122 625/1 Verify SIM func- tion V701 TRANSISTOR RYN 121 6069/1 Verify On/Off func- tion V702 DIODE RKZ 123 647/1 Verify On/Off func- Doesn't start...

  • Page 67: Mounting Drawing Table

    PF768, Standard Electrical Repairs 10.3 Mounting drawing table Board part 2/ROA 117 3235/2 R1A, R1B, R2A, R2B, R3A R4A, R4B, R4C. Mounting 1078-2/ROA 117 3235/2 Rev C Rev E drawing 10.4 Revision change table 10.4.1 Rev. change tab 1 2/ROA 117 3235/2 Part number R-state C670...
  • Page 68 PF768, Standard Electrical Repairs (68) 4/00021-2/FEA 209 544/11.C...

Table of Contents