Simrad GI51 Gyro Interface
10
20221594 / B
2.7
Initial heading and heading change test
This section describes how to verify that the heading read-out
from the GI51 is following the correct direction of change along
with the gyro. In some cases, it may be encountered that the
autopilot heading read-out is different from the gyro heading.
Two possibilities of error may exist:
1
Compass read-out on the autopilot is different from the
gyro card read-out, but the heading difference is a constant
on all headings. This condition can be correct by simply
dialing in the correct heading value from the Seatrial
Menu item called Compass Offset, presented directly after
the Compass Calibration menu item, from the Seatrial
Settings Menu.
2
If there is a difference of approximately 120° or 240°
between the master compass heading and the
autopilot/repeaters when the NMEA signal is used, S1 - S2
- S3 and R1 - R2 connections between the master compass
and GI51 need to be changed. Use one of the alternatives
listed below.
If the compass can be slewed (heading changed) use the
procedure in Alternative 1. If it is not possible to slew the
compass, Alternative 2 should be used:
Alternative 1
-
Disconnect S1 - S2 - S3 from GI51 TB3.
-
Slew the master compass to 000
°
.
-
Use a multimeter and measure the AC voltage (0 - 90V
range) between S1 - S2 - S3 on the disconnected wires.
-
Locate the two phases where the voltage is approx. 0 volt.
These are the S1 and S3 lines. Connect S1 - S3 – S2
accordingly.
-
If the change in heading is in the same direction for the
master compass and the repeaters, but a constant 180°
offset is present, the R1 and R2 lines need to be
interchanged. (This does not reverse the rotation).
-
Rotate the master compass to make the heading increase.
If the repeater heading decreases, the S1 and S3 lines need
to be interchanged.
Alternative 2
-
The sequence of connections S1-S2-S3, R1 and R2 may be
wrong. Reversing two phases will change the direction.
Swapping S1 to S2, S2 to S3 and S3 to S1 will change the
response by 120° or 240°. Interchanging R1-R2 will
change the heading by 180°.
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