Electronics International MVP-50T, Руководство по установке

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the wires form catching fire in case of a short. These fuses should be located a short distance from the Shunt. The
wires are then routed to the EDC Amp input.
A. Symptom : Inaccurate, jumpy or zero reading.
1. Problem: A wire, fuse or fuse connection is open, shorted or mis-wired.
a) Action : Remove one of the signal wires on the Shunt and connect it to the other signal wire. This
will short the two signal wires together. The MVP should read 0.0 amps. A common problem is with
the fuses or fuse holders in line with each Amp signal wire from the Shunt to the EDC. The fuses
should be located a short distance from the shunt. Inspect the wires, fuses and fuse holders.
7.8 Resistive Fuel Level Problem:
Fuel can be measured in a fuel tank using a Resistive Float Sensor. The sensor must be connected to a RFLM
(Resistive Fuel Level Module). This module provides a pull-up resistor to produce a voltage as the float changes
resistance with changes in the fuel level. A signal wire connects the float to the RFLM and a wire connects the RFLM
to the EDC. The RFLM requires bus voltage to provide the pull-up.
As the float sensor arm moves up, the resistance will change, creating a higher or lower voltage on the signal wire
(depending on the float type). The EDC monitors the signal and produces a digital value (called sensor counts) based
on the signal voltage. The sensor counts can be viewed in the “Fuel Tank Calibration” screen. The sensor counts are
then converted to a fuel level based on the calibration data in the “Fuel Tank Calibration” screen.
Resistive floats are notoriously inaccurate and inconsistent. A float will move up and down millions of time during
its lifespan. They can move even when the aircraft is parked. The metal-to-metal contact of the wiper to the coil
wears and corrodes. The wiper force weakens. The bearing surfaces wear. It’s not uncommon to find even new floats
that work poorly. The MVP can calibrate out nonlinearity, but inconsistency will always cause reading problems. It
will cause you to perform the fuel tank calibration procedure over and over with little or no long-term improvement.
Consider using a capacitive probe or our magnetic float sensor if at all possible.
A. Symptom: Inaccurate, jumpy or zero reading.
1. Problem: The RFLM is mis-wired.
a) Action: Remove the signal wire to the Resistive Float. Check for a very high (or low, depending
on the float type) sensor count in the “Fuel Tank Calibration” screen. Be sure you are displaying the
data for the correct tank.
The voltage on the open signal wire should measure bus voltage.
Short the signal wire to ground. Check the sensor counts go to a low (or high, depending on the
float type) reading.
2. Problem: The Resistive Float does not operate properly.
a) Action: With the signal wire removed, measure the resistance of the float. This should not be
done with a full or empty tank but somewhere in-between. Record the resistance reading and the
variations. Lift the wing and allow it to return to its original position. Record the resistance reading
and the variations. This test can be done at different fuel levels. If the resistance value does not
return to its original value, you may have a defective Resistive Float.
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