Seiwa SW AP03 - Manual (Page 43)

CHAPTER 4 TROUBLE-SHOOTING
4.1 GENERAL
If no error messages are showing, but the performance of the autopilot is unsatisfactory,
experience suggests looking initially at four factors. The compass heading should be steady.
Small deviations in the heading w ill not cause performance problems, but random changes
in heading of more than a degree or two indicate a defect in the compass performance.
If a rate gyro is fitted and selected, two faults indicate a defect in the gyro or its cable: either
the heading displayed lags well behind the actual heading or it starts increasing or
decreasing steadily w hen the actual heading is constant.
Secondly, if the rudder transducer is not centred correctly or its linkage is faulty, poor
steering will result. Finally, free-play or backlash in the steering drive will also cause steering
problems.
4.2 ERROR MESSAGES
The SW AP03 system is programmed to provide a number of messages on its display when
a fault occurs. Some of these are warnings arising out of the way the autopilot is being used.
Others mean that a real problem has developed.
They are listed alphabetically below and users are advised to read through the list so that
they know which ones call for action. After each message follows the direct condition which
triggers the message, the response of the AP03 to the condition and a list of possible
causes.
By using this as an aid, many problems can be fixed simply by the owner. If the assistance
of a Seiwa agent is required, quoting the error message will expedite repairs.
COMPASS FAULT
If a fluxgate is being used, the heading signals from the fluxgate are above or below the
preset limits. The fault must last more than 12 seconds before this alarm becomes active.
This prevents a false alarm from being triggered, for example by the fields in a rolling steel
vessel. If the system was in PILOT, it remains there w ith the alarm sounding. The alarm can
only be cleared if the fault is corrected.
Causes.
If the error comes up on all headings and cannot be cancelled, the possible causes are a
defective connection or cable to the fluxgate, a fault in the compass electronics in the
Junction Box, or a defective fluxgate unit.
If the message comes up only on some headings, the probable cause is the magnetic
environment of the compass - either an excessive horizontal field or vertical field due to local
magnetic material. In this case, consult the guidelines in Chap 3.
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