Service manual

ix
2.18.3 Automatic Gain Control Circuit .......................................................................................... 2-28
2.18.4 Frequency Generation Circuit............................................................................................ 2-29
Figure 2-21:800 MHz Frequency Generation Unit Block Diagram.................................. 2-29
2.19 Synthesizer.................................................................................................................. 2-30
Figure 2-22:800 MHz Synthesizer Block Diagram .......................................................... 2-30
2.19.1 Voltage Control Oscillator (VCO)....................................................................................... 2-31
Figure 2-23:800 MHz VCO Block Diagram ..................................................................... 2-31
2.20 Trunked Radio Systems ............................................................................................. 2-32
2.20.1 Privacy Plus Trunked Systems.......................................................................................... 2-32
2.20.2 LTR™ Trunked Systems ................................................................................................... 2-32
2.20.3 MPT Trunked Systems ...................................................................................................... 2-32
2.20.4 PassPort™ Trunked Systems ........................................................................................... 2-33
2.21 900 MHz Transmitter................................................................................................... 2-34
Figure 2-24:Transmitter Block Diagram .......................................................................... 2-34
2.21.1 Power Amplifier ................................................................................................................. 2-35
2.21.2 Antenna Switch.................................................................................................................. 2-35
2.21.3 Harmonic Filter .................................................................................................................. 2-35
2.21.4 Power Control Integrated Circuit (PCIC) ........................................................................... 2-35
2.22 900 MHz Receiver........................................................................................................ 2-36
Figure 2-25:900 MHz Receiver Block Diagram............................................................... 2-36
2.22.1 Receiver Front-End ........................................................................................................... 2-36
2.22.2 Receiver Back-End............................................................................................................ 2-37
2.22.3 Hear Clear IC..................................................................................................................... 2-37
2.22.4 Automatic Gain Control Circuit .......................................................................................... 2-38
2.23 Frequency Generation Circuitry ................................................................................ 2-39
Figure 2-26:Frequency Generation Unit Block Diagram ................................................. 2-39
2.24 900 MHz Synthesizer .................................................................................................. 2-40
Figure 2-27:Synthesizer Block Diagram.......................................................................... 2-40
2.25 900 MHz Voltage Control Oscillator (VCO) ............................................................... 2-41
Figure 2-28:VCO Block Diagram..................................................................................... 2-41
Chapter 3 Maintenance
3.1 Introduction ................................................................................................................... 3-1
3.3 Inspection ...................................................................................................................... 3-1
3.3.1 Cleaning .............................................................................................................................. 3-1
3.4 Safe Handling of CMOS and LDMOS........................................................................... 3-2
3.5 General Repair Procedures and Techniques ............................................................. 3-2
3.6 Recommended Test Tools ........................................................................................... 3-4
3.7 Replacing the Circuit Board Fuse ............................................................................... 3-5
Figure 3-1:UHF/VHF/Low Band/800MHz/900MHz Circuit Board Fuse Locations ............ 3-6
3.2 Removing and Reinstalling the Circuit Board............................................................ 3-7
Figure 3-2:Circuit Board Removal and Reinstallation ....................................................... 3-7
3.3 Power Up Self-Test Error Codes.................................................................................. 3-7
3.4 UHF Troubleshooting Charts ....................................................................................... 3-9
Troubleshooting Flow Chart for Controller........................................................................................ 3-9
Troubleshooting Flow Chart for Receiver (Sheet 1 of 2) ................................................................ 3-10
Troubleshooting Flow Chart for Receiver (Sheet 2 of 2) ................................................................ 3-11
Troubleshooting Flow Chart for Transmitter ................................................................................... 3-12
Troubleshooting Flow Chart for Synthesizer .................................................................................. 3-13
Troubleshooting Flow Chart for VCO ............................................................................................. 3-14