Motorola ASTRO Digital Spectra Plus Service Manual page 9
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Also See for ASTRO Digital Spectra Plus:
- Detailed service manual (442 pages) ,
- Service manual (248 pages) ,
- User manual (174 pages)
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Table of Contents
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
4.1.4
RF Board Troubleshooting ................................................................................................4-5
4.1.4.1
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
4.1.4.3
4.1.4.4
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
4.3.1.2
4.3.1.3
4.3.1.4
4.3.2
UHF Band........................................................................................................................4-15
4.3.2.1
4.3.2.2
4.3.2.3
4.3.2.4
4.3.3
800 MHz Band.................................................................................................................4-18
4.3.3.1
4.3.3.2
4.3.3.3
4.3.3.4
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
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
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
6881076C25-D
Power-Up Sequence ................................................................................................4-3
Review of Synthesizer Fundamentals ......................................................................4-7
Second VCO Checks ...............................................................................................4-8
Troubleshooting the Back-End .................................................................................4-8
VCO Hybrid Assembly............................................................................................4-13
Out-of-Lock Condition ............................................................................................4-13
No or Low Output Power (TX or RX Injection) .......................................................4-15
No or Low Modulation ............................................................................................4-15
VCO Hybrid Assembly............................................................................................4-15
Out-of-Lock Condition ............................................................................................4-16
No or Low Output Power (TX or RX Injection) .......................................................4-16
No or Low Modulation ............................................................................................4-17
VCO Hybrid Assembly............................................................................................4-18
Out-of-Lock Condition ............................................................................................4-18
No or Low Output Power (TX or RX Injection) .......................................................4-19
No or Low Modulation ............................................................................................4-19
High-Power Amplifier..............................................................................................4-21
25/10 Watt Power Amplifier....................................................................................4-29
50 Watt Power Amplifiers .......................................................................................4-38
vii
October 28, 2002
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Table of Contents
Troubleshooting
