Spartan won't initlialize with low gain setting (???).

[SoftwareDrone]

After installing my Spartan DS760, I noticed my heli (T-Rex 500, 9303, DS3400G) wagging and the tail intermittently jumping. We turned down the gain from 30 to 20, then ended up at 16 (gear channel). The problem is, when you first power up the system, the gyro refuses to initialize. It just sits there, dead. If I flip the gear switch to rate mode, the gyro works fine. If I flip the gear switch back to heading hold mode (while the system is still powered up), it initializes and works fine. When I set the gain (travel adj, gear channel, transmitter) back to 30, then power up the heli, the gyro initializes perfect in heading hold mode. When I put the gain back down to 16, it refuses to intialize.
The heli flies perfect (hard 3D) at a gain of 16. So how can this be fixed? Has anyone else ever seen this? Please help!

[MarkWebber]

Hmmm...wait to initialize with low gain is normal for the most recent firmware version. 16% is a very low setting. Where is your linkage ball positioned? Perhaps moving it a bit will allow you to get the gain up where it would normally be (30% is where most seem to start).

[SoftwareDrone]

I just checked the instruction manual as well as my tail servo linkage. My ball is 10.5mm from the axis of the servo. However, the manual states that the ball should be 13-17mm from the axis of the servo. Do you think that I might be able to turn my gain up if I repositioned the ball to within the recommended length?

[Angelos]

Trex's have quite high mechanical gain which means that should bring the ball link on the servo arm further in. This is also covered in the user guide where it states that ultimately the most important thing is that your servo has enough travel (around 45deg on either side). Given you very low gain I suspect that your endpoints are also very low and that the servo does not have much travel.

-Angelos

[SoftwareDrone]

I am using the standard JR servo horn that came with the tail servo, and am using the innermost hole (the closest to the axis of the servo). The endpoints are set correctly, and the total travel is greater than 90 degrees. When I *can* get the gyro into heading hold mode, the heli flies perfectly. The question is, why won't the gyro initialize in heading hold mode at 16%? Why won't the gyro initialize in heading hold mode at 1%?

[Angelos]

The question is, why won't the gyro initialize in heading hold mode at 16%? Why won't the gyro initialize in heading hold mode at 1%?

See FAQ topic 21 regarding firmware version v1.07 : http://www.spartan-rc.com/support.php?faq=20

It still seems though that the mechanical gain is quite high to end up with some small gain. Do you have a USB interface cable? What are the values of the servo endpoints?

-Angelos