Motorola ASTRO Digital Spectra, Подробное руководство по обслуживанию

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Table of Contents ix
6881076C25-E September 5, 2008
3.7.2.1.3 Power Control Circuitry ...................................................................................3-69
3.7.2.2 40-Watt Power Amplifier.........................................................................................3-72
3.7.2.2.1 Transmitter ......................................................................................................3-72
3.7.2.2.2 Antenna Switch and Harmonic Filter ...............................................................3-73
3.7.2.2.3 Power Control Circuitry ...................................................................................3-74
3.7.3 800 MHz Band Power Amplifiers.....................................................................................3-77
3.7.3.1 15- and 35-Watt Amplifiers.....................................................................................3-77
3.7.3.1.1 Transmitter ......................................................................................................3-77
3.7.3.1.2 Antenna Switch and Harmonic Filter ...............................................................3-78
3.7.3.1.3 Power Control Circuitry ...................................................................................3-79
3.7.3.1.4 Temperature Sensing......................................................................................3-81
Chapter 4 Troubleshooting Procedures..............................................4-1
4.1 ASTRO Spectra Procedures ..........................................................................................................4-1
4.1.1
Handling Precautions ........................................................................................................4-1
4.1.2 Voltage Measurement and Signal Tracing ........................................................................4-2
4.1.3 Power-Up Self-Check Errors .............................................................................................4-2
4.1.3.1 Power-Up Sequence ................................................................................................4-3
4.1.4 RF Board Troubleshooting ................................................................................................4-5
4.1.4.1 Display Flashes “FAIL 001” ......................................................................................4-5
4.1.4.1.1 Incorrect Values at U602, Pin 19.......................................................................4-6
4.1.4.1.2 Incorrect Values at U602 Pin 25 (MODULUS CONTROL)................................4-7
4.1.4.1.3 Incorrect Voltage at Positive Steering Line .......................................................4-7
4.1.4.1.4 Incorrect Values at U602, pin 27 .......................................................................4-7
4.1.4.2 Review of Synthesizer Fundamentals ......................................................................4-7
4.1.4.3 Second VCO Checks ...............................................................................................4-8
4.1.4.4 Troubleshooting the Back-End .................................................................................4-8
4.1.5 Standard Bias Table..........................................................................................................4-9
4.2 ASTRO Spectra Plus Procedures ................................................................................................4-10
4.2.1
ASTRO Spectra Plus Power-Up Self-Check Errors ........................................................4-10
4.2.2 ASTRO Spectra Plus Power-Up Self-Check Diagnostics and Repair.............................4-11
4.2.3 ASTRO Spectra Plus Standard Bias Table .....................................................................4-12
4.3 VCO Procedures ..........................................................................................................................4-13
4.3.1
VHF Band........................................................................................................................4-13
4.3.1.1 VCO Hybrid Assembly............................................................................................4-13
4.3.1.2 Out-of-Lock Condition ............................................................................................4-13
4.3.1.3 No or Low Output Power (TX or RX Injection) .......................................................4-15
4.3.1.4 No or Low Modulation ............................................................................................4-15
4.3.2 UHF Band........................................................................................................................4-15
4.3.2.1 VCO Hybrid Assembly............................................................................................4-15
4.3.2.2 Out-of-Lock Condition ............................................................................................4-16
4.3.2.3 No or Low Output Power (TX or RX Injection) .......................................................4-16
4.3.2.4 No or Low Modulation ............................................................................................4-17
4.3.3 800 MHz Band.................................................................................................................4-18
4.3.3.1 VCO Hybrid Assembly............................................................................................4-18
4.3.3.2 Out-of-Lock Condition ............................................................................................4-18
4.3.3.3 No or Low Output Power (TX or RX Injection) .......................................................4-19
4.3.3.4 No or Low Modulation ............................................................................................4-19
4.4 Receiver Front-End (RXFE) .........................................................................................................4-20
4.4.1
VHF Band........................................................................................................................4-20
4.4.2 UHF Band........................................................................................................................4-20
4.4.3 800 MHz Band.................................................................................................................4-20