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3.7.4 Physical Zero
Ensure the extension sensor potentiometer is correctly set to its minimum Zero setting when the boom
is fully retracted. This ensures the sensor will correctly measure over the full telescoping range of the
boom.
1. Fully retract the boom.
2. Remove the Reeling Drum cover.
3. Disengage the main gear wheel connected to the extension sensor by pulling the sensor arm in
the direction shown.
FIGURE 3.8.4 - SENSOR BASEPLATE ASSEMBLY
4. Rotate the gear clockwise until the sensors clutch starts to drag. At the next click, stop rotating
the gear.
5. Measure the voltage between TB1-3 and TB1-1 (Figure. 3.8.3)
6.
Rotate the gear counterclockwise about half a turn setting the voltage to 0.2 volts. Then,
carefully release the sensor arm, ensuring the voltage remains at 0.2 volts as the gears re-
engage.
