Motorola ASTRO Digital Spectra Service Manual

Table of Contents vii
6881076C25-D October 28, 2002
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
4.5 Power Amplifier Procedures.........................................................................................................4-21
4.5.1 VHF Band........................................................................................................................4-21
4.5.1.1 High-Power Amplifier..............................................................................................4-21
4.5.1.1.1 General Troubleshooting and Repair Notes....................................................4-21
4.5.1.1.2 PA Functional Testing .....................................................................................4-25
4.5.1.1.3 Power Control and Protection Circuitry ...........................................................4-28
4.5.1.2 25/10 Watt Power Amplifier....................................................................................4-29
4.5.1.2.1 General Troubleshooting and Repair Notes....................................................4-29
4.5.1.2.2 PA Functional Testing .....................................................................................4-30
4.5.1.2.3 Localizing Problems ........................................................................................4-34
4.5.1.2.4 Isolating Failures .............................................................................................4-35
4.5.1.2.5 Power Control and Protection Circuitry ...........................................................4-37
4.5.1.3 50 Watt Power Amplifiers.......................................................................................4-38

Motorola ASTRO Digital Spectra Specifications

General

Brand	Motorola
Model	ASTRO Digital Spectra
Category	Radio
Language	English