Spektrum SPMAR6250 - Manual (Page 3)

• The BEC used in the speed controller won’t support the current required by the
servos.
The AR6250 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. The Flight Log is not compatible with the AR6250 for
recording flight data.
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.
Note: The latest generations of Nickel-Metal Hydride batteries incorporate a new
chemistry mandated to be more environmentally friendly. These batteries,
when charged with peak detection fast chargers, have tendencies to
false peak (not fully charge) repeatedly. These include all brands of NiMH
batteries. If using NiMH packs, be especially cautious when charging,
making absolutely sure that the battery is fully charged. It is recommended
to use a charger that can display total charge capacity. Note the number of
mAh put into a discharged pack to verify it has been charged to full capacity.
QuickConnect ™ With Brownout Detection
Your AR6250 features QuickConnect with Brownout Detection.
• Should an interruption of power occur (brownout), the system will reconnect
immediately when power is restored (QuickConnect).
• The orange LED on the receiver will flash slowly indicating a power interruption
(brownout) has occurred.
• Brownouts can be caused by an inadequate power supply (weak battery or
regulator), a loose connector, a bad switch, an inadequate BEC when using an
electronic speed controller, etc.
• Brownouts occur when the receiver voltage drops below 3.5 volts thus
interrupting control as the servos and receiver require a minimum of 3.5 volts to
operate.
How QuickConnect With Brownout Detection Works
• When the receiver voltage drops below 3.5 volts the system drops out (ceases
to operate).
• When power is restored the receiver immediately attempts to reconnect to the
last two frequencies that it was connected to.
• If the two frequencies are present (the transmitter was left on) the system
reconnects typically in about a fraction of a second.
QuickConnect with Brownout Detection is designed to allow you to fly safely
through most short-duration power interruptions; however, the root cause of these
interruptions must be corrected before the next flight to prevent catastrophic safety
issues.
Note: If a brownout occurs in flight, it is vital that the cause of the brownout be
determined and corrected.
ModelMatch ™
Some Spektrum and JR transmitters offer a feature called ModelMatch that prevents
the possibility of operating a model using the wrong model memory, potentially
preventing a crash. With ModelMatch, each model memory has its own unique code
(GUID) and during the binding process the code is programmed into the receiver.
Later, when the system is turned on, the receiver will only connect to the transmitter if
the corresponding model memory is programmed onscreen.
Note: If at any time you turn on the system and it fails to connect, check to be sure
the correct model memory is selected in the transmitter. Please note that the
Spektrum Aircraft Modules do not have ModelMatch.
Tips On Using 2.4GHz
While your DSM equipped 2.4GHz system is intuitive to operate, functioning nearly
identically to 72MHz systems, following are a few common questions from customers.
1. Q: Which do I turn on first, the transmitter or the receiver?
A: If the receiver is turned on first—all channels have no output pulses. When
the transmitter is then turned on, the transmitter scans the 2.4GHz band and
acquires two open channels. Then the receiver that was previously bound to the
transmitter scans the band and finds the GUID (Globally Unique Identifier code)
stored during binding. The system then connects and operates normally.
If the transmitter is turned on first—the transmitter scans the 2.4GHz band and
acquires two open channels. When the receiver is then turned on for a short
period (the time it takes to connect) all channels have no output pulses. The
receiver scans the 2.4GHz band looking for the previously stored GUID. When it
locates the specific GUID code, it confirms the uncorrupted repeatable packet
information, the system connects and normal operation takes place. Typically
this takes 2 to 6 seconds.
2. Q: Sometimes the system takes longer to connect and sometimes it doesn’t
connect at all?
A: In order for the system to connect (after the receiver is bound) the receiver must
receive a large number of consecutive uninterrupted perfect packets from the
transmitter. This process is purposely critical of the environment ensuring that
it’s safe to fly when the system does connect. If the transmitter is too close
to the receiver (less than 4 feet) or if the transmitter is located near metal
objects (metal Tx case, the bed of a truck, the top of a metal work bench, etc.),
connection will take longer and in some cases connection will not occur as the
system is receiving reflected 2.4GHz energy from itself and is interpreting this
as unfriendly noise. Moving the system away from metal objects or moving the
transmitter away from the receiver and powering the system again will cause
a connection to occur. This only happens during the initial connection. Once
connected, the system is locked in and should a loss of signal occur (failsafe),
the system connects immediately when the signal is regained.
3. Q: I’ve heard that the DSM system is less tolerant of low voltage. Is this correct?
A: All DSM receivers have an operational voltage range of 3.5 to 9.6 volts. With
most systems this is not a problem as, in fact, most servos cease to operate at
around 3.8 volts. When using multiple high-current draw servos with a single
or inadequate battery/ power source, heavy momentary loads can cause the
voltage to dip below this 3.5-volt threshold thus causing the entire system
(servos and receiver) to brown out. When the voltage drops below the low
voltage threshold (3.5 volts), the DSM receiver must reboot (go through the
startup process of scanning the band and finding the transmitter) and this can
take several seconds. Please read the receiver power requirement section as
this explains how to test for and prevent this occurrence.
4. Q: Sometimes my receiver loses its bind and won’t connect requiring rebinding.
What happens if the bind is lost in flight?
A: The receiver will never lose its bind unless it’s instructed to. It’s important to
understand that during the binding process the receiver not only learns the
GUID (code) of the transmitter, but the transmitter learns and stores the type
of receiver that it’s bound to. If the transmitter is placed into bind mode, the
transmitter looks for the binding protocol signal from a receiver. If no signal is
present, the transmitter no longer has the correct information to connect to a
specific receiver and in essence the transmitter has been “unbound” from the
receiver. We’ve had several DX7 customers that use transmitter stands or trays
that unknowingly depress the bind button and the system is then turned on,
losing the necessary information to allow the connection to take place. We’ve
also had DX7 customers that didn’t fully understand the range test process
and pushed the bind button before turning on the transmitter also causing the
system to “lose its bind.”