1101/1201 Technical Manual
07/19/02 Page 9 1201 - JULY 19 '02
3.3 1101/1201 SPU
For 1101: pn 82888 Revision 3 (1 pcb version)
For 1201: pn 83747 Revision 1 (1 pcb version)
3.3.1 General Description:
The 1101 Revision 3/1201 Revision 1, SPU consists of one board. The board includes
microprocessor, EPROM and RAM, and the support circuitry and connectors to the distribution
box, the Head, the Compass, the Serial Data output, the Auxiliary Head, and the Drive circuitry
for a solenoid system. Note that the boards are the same for 1101 or 1201 but the E-PROMS are
different.
You can find the schematics for the 1101/1201 (1 pcb) SPU in Appendices D.
Appendix D is the 1101/1201 SPU Board - Microprocessor, PROM and RAM, connectors
to the Head, Distribution box, Compass, NMEA output etc.
Appendix E is the Distribution Board - Terminal connections and RAI interface circuitry
Note: if the 1101 SPU has two boards it is a revision 2. See the previous section.
3.3.2 Disassembly/Re-assembly (1 pcb version)
Disassembly of the 1101/1201 SPU (1 pcb version) is a straightforward process. First remove
the two Phillips screws from the rear of the autopilot and pull off the rear cover. Remove the four
screws which secures the chassis to the front cover. Carefully separate the front cover from the
chassis. The E-PROMS can now be replaced or the unit tested on the ComNav Test Bench.
Re-assembly is the reverse of disassembly.
3.3.3 Signals to and from the Distribution Unit
MOTOR F/B Motor Feedback signals from Remotes to the Distribution Unit.
NAV INPUT Signals from a navigation device in the standard NMEA 0183 format.
RUDDER POSITION Rudder position signal from the Rudder follower.
SPEED CONTROL Proportional signal for rudder control.
SHIELD Outer shield of the cable usually grounded to chassis at one end.
BATTERY (+) Battery power (positive side).
SWT POWER OUT The battery power which can be switched off and on by the processor.
PORT OUT “Open collector” signal that controls the rudder to Port. Ground indicates ON.
STBD OUT “Open collector” signal that controls the rudder to Starboard.
RUDDER POWER +5 volts which is supplied to the Rudder Follower.
BATTERY (-) Battery power (negative side).
RUDDER COMMON Ground signal from the Rudder Follower.
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