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Page 3-2
GNS 400W Series Maintenance Manual
Rev. A
190-00356-05
Main CPU
The Main Board contains the Main Processor, a Samsung S3C2410A 32-Bit RISC
microprocessor based upon an ARM920T core. The 2410 processor core operates up to
203MHz.
Memories
The Main Board includes SDRAM and NAND Flash memories. These memories are connected
directly to the 2410 processor, which includes interface support for both types of memories.
Display Interfaces
The Main Board provides the display interface for all models.
Front Panel/Display Backlighting/Controls Lighting
The front panel includes LED backlighting for the push buttons, rotary controls, and bezel
nomenclature. The LEDs are located on the keyboard assemblies and include current limit
resistors connected to +5 volts.
Front Panel Control Interfaces
The front panel controls are located in the front bezel assembly. The interconnect to the keypad
and the right rotary switch controls is included in J22, and the interface to the left rotary switch is
included in J14.
Volume Controls
All units include two volume control pots for the Com and Nav Receivers.
Data Card Interface
The Main Board design includes interface for two front panel accessible data base cards. The
interface connects to the front panel assembly through J14, a 70 pin socket, via a flex cable.
Rear Panel Connector Pinouts
Appendix A describes the pinouts of the Main Rear Panel Connector, J1.
Lightning and EMI/RFI Protection
The rear interface signals include circuitry for lightning and RF susceptibility protection and EMI
suppression. The output signals typically have either diode or transorbs included to protect the
output drivers. The diodes and transorbs are used to shunt the lightning current to ground. The
input circuits typically include current limit resistors with low power signal diodes for lightning
protection. The resistor will limit the pulse current to levels that can be easily shunted to either
ground or a supply voltage to protect the input circuits. These input circuits are also part of the
functional input circuit as well as used for EMI/RFI suppression.
The interface signals also include EMI/RFI suppression. In many cases, this uses EMI beads
along with capacitors. When the EMI beads are used on the same signals as the lightning
