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June 15, 2005
6815854H01-A
4-32
Troubleshooting Procedures
: Receiver Front-End (RXFE)
4.11 Receiver Front-End (RXFE)
This section provides band-specific troubleshooting procedures for the receiver front-end.
4.11.1 VHF (136–174 MHz) Band
Use this information, along with the theory of operation, to diagnose and isolate the cause of failures.
The principle tools needed to troubleshoot a circuit to the component level are the schematic and the
theory of operation.
In addition to the schematic and theory, you can use the troubleshooting flowcharts in
that will guide you through a sequence of tests and checks designed to
isolate problems.
Prior to troubleshooting, it is important to review the theory of operation including specific
precautions and troubleshooting methods. Because much of the radio’s circuitry operates at a high
frequency, measurements must be taken carefully.
4.11.2 UHF Range 1 (380–470 MHz) Band
Use this information, along with the theory of operation, to diagnose and isolate the cause of failures.
The principle tools needed to troubleshoot a circuit to the component level are the schematic and the
theory of operation.
In addition to the schematic and theory, you can use the troubleshooting flowcharts in
that will guide you through a sequence of tests and checks designed to
isolate problems.
Prior to troubleshooting, it is important to review the theory of operation including specific
precautions and troubleshooting methods. Because much of the radio’s circuitry operates at
400 MHz, measurements must be taken carefully.
Table 4-19. Standard Operating Bias: VIP Lines (Dash Configuration)
Nominal Value
Signal Name
Range/State
Probe Locations
NA
VIP_OUT_1_5v
Not accessible
J0401-13
NA
VIP_OUT_2_5v
Not accessible
J0401-14
NA
VIP_IN_1_5v
Not accessible
J0401-15
NA
VIP_IN_2_5v
Not accessible
J0401-16
SW_B+ level
VIP_OUT_1_12v
Deactivate = relay
closed
J0401-11, J2-18
0.3 V to 0.5 V
Activate = relay open
SW_B+ level
VIP_OUT_2_12v
Deactivate = relay
closed
J0401-12, J2-19
0.3 V to 0.5 V
Activate = relay open
Note
: The voltage levels on the microprocessor side are at 2.85 V levels. The microprocessor is
not designed to drive the relay, but instead, is intended to drive the transistors inside the control
head or on the interconnect board. Be careful when changing jumpers.
Note
: The impedance of the relay is why the SW_B+ does not damage the VIP line. Never connect
SW_B+ directly to a VIP line.
Summary of Contents for XTL 1500
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Page 19: ...xviii List of Figures June 15 2005 6815854H01 A This page is intentionally left blank ...
Page 25: ...June 15 2005 6815854H01 A xxiv CommercialWarranty Notes ...
Page 35: ...June 15 2005 6815854H01 A xxxiv Model Numbering Charts and Specifications Notes ...
Page 49: ...June 15 2005 6815854H01 A 2 12 Product Overview Controller Section Notes ...
Page 161: ...June 15 2005 6815854H01 A 4 36 Troubleshooting Procedures Power Amplifier Procedures Notes ...
Page 225: ...June 15 2005 6815854H01 A 5 64 Troubleshooting Charts Flowcharts Notes ...
Page 429: ...8 2 Flex Cable Pin Out Lists Flex Cables June 15 2005 6815854H01 A Notes ...
Page 441: ...June 15 2005 6815854H01 A Glossary 10 Notes ...
Page 451: ...Index x June 15 2005 6815854H01 A This page is intentionally left blank ...