Raymarine R21 Service Manual download pdf (Page 9)

Step 2 - System checks

1. Check that the display shows a compass heading (the actual heading displayed is unimportant at this stage)

and that a rudder angle bar is displayed. This confirms that the Seatalk communications are functioning

correctly.

Note: From October 2005 revision E PCB s have Verado software installed. This software does not require an ex-

ternal rudder reference device. In standby mode the rudder reference bar will not be displayed.

Step 3 - Rate gyro

1. Using a DVM, measure the voltage at the rate gyro terminals (black and yellow leads). If the rate gyro is

serviceable, the nominal reading is 2.5 V ± 0.1 V.

2. With the multi meter still connected, turn the Course Computer slowly, first clockwise, then anticlockwise.

3. If the rate gyro unit is functioning correctly, the voltage should increase (from 2.5V) as the Course Computer is

turned in one direction and decrease (from 2.5V) as it is turned in the opposite direction.

If the signal levels are unstable or outside tolerances, replace the gyro (Refer to Tech Update TU232).

Step 4 - Compass

1. With the compass unit connected to the Course Computer, rotate the compass through 90º as shown below.

2. Slowly rotate the compass clockwise through 360º. As the compass is turned, check that the displayed head-

ing increases with no sudden changes in the reading (If the rate gyro is fitted, also rotate the Course Com-

puter).

Note: Ensure that you hold the compass with the cable protruding downwards.

D10042_1

+ 5V-DIG

HD-PWR

PWR-0V

Voltage test-point

locations

D8874-1

Vertical

Compass check without rate gyro

Hold the compass with the cable protruding

downwards and rotate through 90º

Check the control head display recognises the change

Repeat until the compass is rotated through 360º

Vertical

Compass check with rate gyro

Hold the course computer and

compass, then rotate through 90º

Check the control head display

recognises the change

Repeat until the compass is

rotated through 360º

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Raymarine R21 Service Manual Page 9