Spektrum SPMAR6255 - Manual (Page 7)

operate erratically or not function at all. Amplified Y-harnesses were developed
several years ago to boost the signal for some older PCM systems and should not
be used with Spektrum equipment. Note that when converting an existing model
to Spektrum, be certain that all amplified Y-harnesses and/or servo extensions are
replaced with conventional non-amplified versions.
Preset Failsafe
The AR6255 features preset failsafe on all channels. Preset failsafe is ideal for
sailplanes, allowing the aircraft to automatically dethermalize if the signal is lost. With
preset failsafe, all channels will go to their preset failsafe positions if the signal is
lost, preventing a flyaway.
Receiver Power Only
• When the receiver only is turned on (no transmitter signal is present), all
channels have no output signal, to avoid overdriving the servos and linkages.
Note: Some analog servos may drift slightly during power-up even though no
signal is present. This is normal.
After Connection
• When the transmitter is turned on and after the receiver connects to the
transmitter, normal control of all channels occurs.
• After the system makes a connection, if loss of signal occurs Preset Failsafe
drives the throttle, aileron and elevator servos to their preset failsafe position set
during binding.
Receiver Power System Requirements
Inadequate power systems that are unable to provide the necessary minimum
voltage to the receiver during flight have become the number one cause of in-flight
failures. Some of the power system components that affect the ability to properly
deliver adequate power include:
• Receiver battery pack (number of cells, capacity, cell type, state of charge)
• The switch harness, battery leads, servo leads, regulators, etc.
• The BEC used in the speed controller won’t support the current required by the
servos.
The AR6255 has a minimum operational voltage of 3.5 volts; it is highly
recommended the power system be tested per the guidelines below.
Recommended Power System Test Guidelines
If a questionable power system is being used (e.g. a small or old battery that may
not support high-current draw, etc.), it is recommended that a voltmeter be used to
perform the following test.
Note: The Spektrum Flight Log (SPM9540) is the perfect tool to monitor voltage
in the test below.
Plug the Flight Log into an open channel port in the receiver and with the system
on, load the control surfaces (apply pressure with your hand) while monitoring the
voltage at the receiver. The voltage should remain above 4.8 volts even when all
servos are heavily loaded.
EN