Figure 4-41.--Block diagram of a meridian gyro control system.

To change from the DG mode of operation to the

5. When the blue ready lamp comes on, check the

high latitude mode of operation when the heading is

OWN SHIP COURSE dial to see if the compass is

within 10 true north, turn the mode selector switch to

aligned with the ship's heading. If the dial does not

the high latitude mode at about 87 latitude.

indicate the ship's heading, you need to slew the

compass until the dial is aligned within a maximum of

To change from the DG mode of operation to the high

10. The nearer the OWN SHIP COURSE dial is set to

latitude mode of operation when the heading is more

than 10 from true north, perform the following steps:

the ship's heading, the quicker the compass will settle

to north when it is switched into the high latitude mode

1. Turn the master switch to the OFF position.

in step 7.

2. Leave the mode selector switch in the DG mode.

6. Press the RUN button.

3. Turn the master switch to the FIL'S position, and

7. Reset the latitude computer to the correct

wait about 30 seconds to allow the tube filaments to heat.

latitude.

4. Turn the master switch to the ON position. Now

8. At the end of 30 minutes, turn the mode selector

wait for the blue ready lamp located on the control panel

switch to the high-latitude mode. The compass will now

to light (approximately 11 minutes) before proceeding

to the next step.

settle to the north.

Figure 4-41.--Block diagram of a meridian gyro control system.