Furuno 1715 Service Manual page 11

INT board (03P9322)
INT board mainly consists of CPU U4 that includes the RAM, ROM and analog ports, RS-422
interface U5, a motor drive circuit and a gain control signal generator.
CPU U4 receives control panel settings on the display unit through the RS422 interface U5. The
D/A converter U2 converts Gain, A/C RAIN, and tuning control signals from digital to analog.
A/C SEA and A/C RAIN circuit consisting of Q1, Q2 and Q3 outputs GAIN CONT signal to IF
board.
The CPU U4 controls the stepping motor drive circuit, Q4 to Q7 to keep the antenna rotation
speed constant.
The heading signal (HD) from the lead switch is mixed with the bearing pulse (BP) by Q9 to
Q11 and sent to the display unit.
The ship's main is supplied to the power supply circuit on the MD board via INT board.
MD board generates +5 V, +12 V and -6 V for the use on INT board.
Display
unit
Trigger
Ship's mains
Mixer
Serial
Reset
Ref. Osc.
Buffer
Filter
Fig.1-5 Block Diagram of INT Board (03P9322)
Interface
Conv.
Serial
Step
Buffer
Q4, Q5
motor
Q6, Q7
Bandwidth switch
Video signal
Pulsewidth signal
7
1.3 Scanner unit
Lead
Switch
IF
Board
Waveform
generator
MD
Board