Calibrating Auto Header Height System - MacDon FFT FD75 Assembly Instructions Manual

4. Fully lower combine feeder house until adapter is no
longer supporting header. The float indicator should
read 4.
NOTE:
You may need to hold HEADER DOWN switch for a few
seconds to ensure feeder house is fully lowered.
5. Measure voltage between ground and signal wires at
AHHC sensor in float indicator with a voltmeter (A). It
should be at low voltage limit for combine – 0.7 V.
6. If sensor voltage is not within low and high limits, or if
range between low and high limits is less than 3.0 V,
make adjustments according to
Limits, page 231.
Adjusting Voltage Limits
1. To adjust high voltage limit:
a. Extend guard angle fully. Header angle indicator
should be at D.
b. Position header 150–254 mm (6–10 in.) above
ground. Float indicator should be at 0.
c. Loosen sensor mounting bolts (A).
d. Slide sensor support (B) to right to increase high
voltage limit, or to left to decrease it.
e. Tighten sensor mounting bolts (A).
2. To adjust low voltage limit:
a. Fully extend center-link, (i.e., increase header/
guard angle to maximum). Header angle indicator
should be at D.
b. Fully lower header to ground. Float indicator should
be at 4.
c. Loosen potentiometer mounting bolts (C).
d. Rotate potentiometer (D) clockwise to increase low
voltage limit, or counterclockwise to decrease it.
e. Tighten potentiometer mounting bolts (C).
3. When readings are in proper range, auto header height
control can be calibrated.

Calibrating Auto Header Height System

The calibration procedure determines limits of auto header height sensor.
Calibrate auto header height system after initial header installation, and after replacing or adjusting any component
of auto header height system. If system does not function, calibrate it again.
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SETTING UP AUTO HEADER HEIGHT CONTROL
Adjusting Voltage
231
Figure 5.198: Float Indicator Reading 4.3 V
Figure 5.199: AHHC Sensor Assembly
Revision A