5-18
N9927-90003
Theory of Operation
FieldFox Analyzer
Grounding and Power
Grounding and Power
Grounding
Each printed circuit board has a single ground plane. The ground planes on the A4 RF board and A5
System board are connected via the common shields at multiple points. The ground plane on the A3
Front Panel Interface board is connected to the ground plane on the A5 System board.
There are no separate grounds in the analyzer. There is no “star” ground point in the analyzer.
Batt Neg and Ext DC neg are connected to the A5 System board ground plane.
The A2 LCD assembly has two separate grounding circuits: the LCD power and control circuits and the
backlight LED’s.
•
The LCD power and control circuits share a ground that is connected to the ground plane on the A5
System board.
•
The ground for the backlight LED’s is connected to the ground plane on the A3 Front Panel Interface
board.
Voltages and Power Supplies
The following power supplies exist within the analyzer:
•
Digital 5 volts—generated from Unreg DC on the A3 Front Panel Interface board, controlled by the
System Monitor on the A5 System board, and used on the A3, A4, and A5 boards.
•
Digital 3.3 volts—generated from Unreg DC on the A3 Front Panel Interface board, on/off functions
controlled by the System Monitor on the A5 System board, and used on the A2 LCD assembly and
A3, A4, A5, and A6 boards.
•
Analog supply voltages—seven separate voltages generated from Unreg DC on the A5 System board,
on/off functions controlled by the System Monitor on the A5 System board.
•
LCD backlight voltage—generated on the A3 Front Panel Interface board from the digital 5 volt
supply voltage.
•
Power for the System Monitor circuit—3.3 volt circuit powered from Ext DC or Batt +, whichever is
greater. Used on A5 System board only.
•
Unreg DC—from Ext DC or Batt +, 21 volts max.
•
Ext DC—from external Power AC Adapter, nominal 15 volts, acceptable up to 19 volts.
•
Batt + —from main battery, nominal 12 volts.
All voltages except Ext DC, Batt +, and the System Monitor power can be turned on/off within the
analyzer. Refer to
“Power Management Circuitry” on page 5-12
for more information.
Summary of Contents for FieldFox MW N9913A
Page 8: ...Contents 4 Service Guide N9927 90003 Contents ...
Page 9: ...N9927 90003 1 1 1 Safety and Regulatory Information ...
Page 16: ...1 8 N9927 90003 Safety and Regulatory Information FieldFox Analyzer Regulatory Information ...
Page 17: ...N9927 90003 2 1 2 General Product Information ...
Page 27: ...N9927 90003 3 1 3 Tests and Adjustments ...
Page 37: ...N9927 90003 4 1 4 Troubleshooting ...
Page 50: ...4 14 N9927 90003 Troubleshooting FieldFox Analyzer Measurement Group Troubleshooting ...
Page 51: ...N9927 90003 5 1 5 Theory of Operation ...
Page 81: ...N9927 90003 6 1 6 Replaceable Parts ...
Page 95: ...N9927 90003 7 1 7 Repair and Replacement Procedures ...
Page 140: ...7 46 N9927 90003 Repair and Replacement Procedures FieldFox Analyzer Post Repair Procedures ...
Page 141: ...N9927 90003 8 1 8 General Purpose Maintenance and Service Procedures ...
Page 149: ...N9927 90003 Appendix 1 Appendix A ...
Page 156: ...Index 4 N9927 90003 Index ...