The rudder servo travels fully over in one direction about 1 second after power is switch on. Sometimes I need to unplug the servo and plug it back to make it work. When servo is plugged into the receiver it doesn't do it.

This issue affects Align and Savox servos and has been reported when using Spartan gyros as well as gyros of other brands.

Background information: Unlike receivers most gyros do not drive the servo for the first few seconds after power on; during the time that the gyro is calibrating. Due to the particular electronic design of these servos an unpredictable condition is sometimes created at power on which the servo interpreters as being commanded to go travel to the limit. The servo will continue to bind until it times out (1 second) or until a new command is received sending it back to its normal operating range. When the servo is connected directly to the receiver a new command is received almost immediately and thus the servo is not given the chance to travel to the end and bind.

From what we have seen and customers have reported:

• The majority of these servos will work correctly including the ones we have tested in our lab and use on our own helicopters.
• Only a very small number of these servos exhibit this problem.
• With some of these servos the problem happens every time the helicopter is powered on.
• With others it only happens occasionally and  in some cases it can change from day to day.

Unfortunately, if you happen to have one of the affected servos there is no immediate fix for this issue. Spartan RC is considering to provide a solution in the next firmware update where optionally the servo can be driven immediately after power on to ensure the servo stays at the mid-point until calibration has been completed.