Ericsson LBI-31511B, Maintenance Manual

Page 1: ...S 17 MAINTENANCE MANUAL 403 430 MHz 450 512 MHz DELTA S NARROWBAND TWO WAY FM RADIO SERVICE SECTION DESCRIPTION The service section of this manual contains the diagnostic routines and other maintenance information to service this radio The service section includes System interconnections Mechanical layout Disassembly procedures Replacement of IC s chip capacitors and resistors Alignment procedures...

Page 2: ...er top casting MAINTENANCE CHECKS INTERVAL 6 Months As Required CONNECTIONS Groundconnections and connections to the voltage source should be periodically checked for tightness Loose or poor connections to the power source will cause excessive voltage drops and faulty operation When ground connections are not made directly to the battery the connection from the battery to vehicle chassis must be c...

Page 3: ...d discard the chip 3 Remove excess solder with a vacuum solder extractor 4 Carefully remove the epoxy adhesive and excess flux to prevent damage to the printed board To Replace Chip Components 1 Using as little solder as possible tin one end of the component and one of the pads on the printed wiring board 2 Place the tinned end of the component on the tinned pad on the board and simultaneously tou...

Page 4: ...synthesizer This mode will enable you to check the serial data clock channel change pulseand enable signals to the synthesizer Grounding the lock detect line into the microcomputer at U703 8 To stop the microcomputer from running disable the watchdog timer by shorting the collector and emitter of Q714 and ground the single step line at U705 5 MICROPHONICS Synthesized radios tend to be sensitive to...

Page 5: ...Program Plug RF Metering RX Input IF Input RX Inj Exciter Input Exciter Output Hand Programmer Enable Program Disable TX PA Metering VG Interface Fixed Squelch Channel Guard Aux Audio DPTT IGN A J601 J602 J603 J711 J101 P401 P404 P451 P102 P101 P103 P706 P707 J1 P612 P605 P608 P610 P402 P403 TRANSMITTER QUICK CHECKS Connect red system metering plug to J602 system metering Connect black plug of GE ...

Page 6: ...J101 and the power amplifier JACK J1 Typical readings for the various test positions and test points are given in the charts below SYMPTOM PROCEDURE ANALYSIS Little or No RF Output Key transmitter and check J1 10 Pos A for 0 5 V exciter output Refer to Schematic Diagram and verify voltage readings Unkey transmitter and check Q105 C for 9 0 Vdc Verify 9 0 volt supply Check R124 and L117 Check DC vo...

Page 7: ...lyzer in the 200 to 2000 Hz distortion range position 1000 Hz filter in the circuit Tune the filter for minimumreading or null on the lowest possible scale 100 30 etc C Place the RANGE switch SET LEVEL position filter out of the circuit and adjust the input LEVEL control for a 2 dB reading on a mid range 30 D Set signal generator output to 0 3 µV Switch the RANGE control from SET LEVEL to the dist...

Page 8: ...n operated in parallel with a 12 volt automotive storage battery Cont CAUTION TEST PROCEDURES These Test Procedures are designed to assist you in servicing a transmitter that is operating but not properly Once a defect is pin pointed refer to the Transmitter Troubleshooting Procedure Before starting be sure that the transmitter is tuned and aligned to the proper operating frequency Cont TEST PROGR...

Page 9: ...gh a 100 µF capacitor to J603 15 Set outputleveltoobtain a deviationof 2 0 kHz Note and maintain this voltage level while switching the output frequency to 10 Hz Adjust REF OSC Deviation Control R366 starting from the fully clockwise position for 2 0 kHz deviation Remove the modulation 5 Select a channel with Channel Guard nearest the center frequency and adjust R22 on the Channel Guard option boa...

Page 10: ...appropriate channel for the maximum reading indicated If the light is not out all readings are meaningless As long as the highest operating frequency VCO voltage does not exceed the maximum meter reading and the lowest operating frequency VCO voltage is not less than the minimum meter reading the adjustment is proper When the two frequency spread is minimal it is acceptable to center tune the VCO ...

Page 11: ...0 V Tune C9 for maximum meter reading Stop when maximum is reached EXCITER TRANSMITTER POWER AMPLIFIER Cont Fo is the transmit output frequency at the antenna The injection frequency is Fo 3 at J102 REFERENCE OSCILLATOR FREQUENCY STEP METERING POSITION TUNING CONTROL METER READING PROCEDURE GE TEST SET MULTIMETER TO A 10 C AMPL 3 J101 8 C10 0 01 Tune C10 for a dip 0 01 volts typical Note after C11...

Page 12: ...e probe and adjust the controls for 0 1V per div and 2 msec per div 5 Adjust the AM output level to make sure the scope is triggering Adjust the RF input signal level to keep the IF passband sweep pattern just below saturation typ 9 µV After using the vertical and horizontal positioning controls to center the waveform check for a scope pattern similar to the one below SERVICE NOTE L410 L411 L412 L...

Page 13: ...O A 3 G RX INJ J101 4 C7 Dip Tune C7 for a dip in Test Set reading 4 H RX MIX J101 3 C6 C7 L452 Peak Tune C6 for maximum Sequentially retune L452 C6 and C7 until there is no further increase in meter reading FRONT END ALIGNMENT 5 D IF AMP J602 10 C3 MAX Connect RF signal generator to antenna jack J2 Set frequency to desired receive channel or center tune frequency Set modulation frequency to 1 kHz...

Page 14: ...en tune C3 for a peak 13 D IF AMP J602 10 C4 C5 Detune C5 clockwise to minimum tuning screw height Tune C4 for a peak Then tune C5 to maximum tuning screw height Tune C5 for a peak reading 14 J101 3 C6 Select highest channel frequency and note meter reading Select lowest channel frequency and note reading Tune C6 slightly to equalize these two readings If they cannot be equalized tune C6 to improv...

Page 15: ... 19D901350 Sh 1 Rev 10 RECEIVER AUDIO AND SQUELCH WAVEFORM CHECKS LBI 31511 LBI 31511 14 ...

Page 16: ... 19D900977 Sh 1 Rev 20 MECHANICAL LAYOUT LBI 31511 LBI 31511 15 ...

Page 17: ... 19D900977 Sh 2 Rev 14 MECHANICAL LAYOUT LBI 31511 LBI 31511 16 ...

Page 18: ... 19D900980 Sh 1 Rev 4 INTERCONNECTION DIAGRAM LBI 31511 LBI 31511 17 ...