Gyro off Center ( telebee )

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eurogee
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Gyro off Center ( telebee )

by eurogee » Sun Dec 13, 2009 9:57 pm

HI, I'm having a difficult problem with my Telebee GR302-AD (HH), and wondering if anyone else has any ideas. Everything was set up perfectly 4 months ago, but after leaving everything on the shelf for 4 months the gyro is now off.

Basically, when the gyro initializes it thinks the servo center point is at roughly 60% to the left. So with the rudder stick in the center, the rudder servo is turned 60% to the left. As I move the rudder from center, the servo does not move until I get to ~60% right, then the servo moves all the way to the right. If I move the rudder stick left, no movement until I get past 60% left and then the servo moves the small remaining distance to full left.

I'm flying this gyro on a Esky Belt CP, with the stock radio and receiver so I can't adjust the center point with the radio. I'm using Futaba and Hitec analog servos.

Here's what I know:
- The tail servo is ok, i swapped the servo and got the same behavior.
- I'm pretty sure it's the gyro since when I bypassed the gyro, connecting the servo straight to the receiver, the servo centered properly.
- I did the initial setup over the summer when the air temp was warm. And the temperature does seem to impact the gyro. I've tried to leave everything on for 5 minutes before trying to fly, but this does not help.
- I warmed the gyro with a hairdryer, and the problem was "decreased" although still present.
- For the 4 months that the heli was on the shelf, it was laying on it's side. I'm concerned that this damaged the crystal inside due to changing temperatures.
- I've adjusted both the Gain and ATV on the gyro, without much success

So any ideas? Any magic tips for adjusting, initializing, or tweaking the telebee gyros? At this point I'm at a bit of a loss. Is it at the point where I just need to buy a new gyro?

Thanks

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Killerheli
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by Killerheli » Sun Dec 13, 2009 10:19 pm

Yeah i'd say get a new gyro.
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dark_fox
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by dark_fox » Mon Dec 14, 2009 12:11 am

I would give it a quick test hover to see, everythings sounds fine with it.

Heading hold gyro's work differently to rate gyro's in that they wont move or center with a still helicopter, this is how they hold their heading. The only way to test it is to get it light on the skids and see if it holds.

Heading hold gyro's generally wont center themselves nor will they accept small movements untill they are moving properly. What you control with the rudder stick on a heading hold gyro isn't the actual servo, you are controlling the gyro telling it you want to go right at around 10% speed. When there is no movement on the helicopter it wont move because it can't sense the movement yet, when the tail goes to slide to the side it would then move to counted it if it is moving too fast.

Outside of testing it in rate mode the only way to truly 'test' a HH gyro is to get the model light on the skids and if everything seems fine, float it just off the ground and see how it holds. The worse thing that will happen is the tail wont hold and you will have to quickly drop the helicopter to the ground, which as you know from learning doesn't damage anything at low levels.

::EDIT:: If it fails to hold on a float though, then its a dead gyro as you know. Temperature causes drift, it wont cause gyro failures. And temperature only effects it when its changing temperatures, as in if you sit it in a car and let the gyro get hot, then bring it out to room temperature and try to fly it. To remedy gyro temperature changes you just sit it out in the temperature you are going to fly it in for around 10 minutes.

eurogee
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by eurogee » Tue Dec 15, 2009 2:53 am

Thanks for the feedback.

Good thought on the hover. I tried it, but the gyro did not regain its bearings when it got airborne. And the problem persists in both HH and rate mode. So looks like this gyro is going in the trash, but of course now I know what to buy myself for Christmas :roll: Thanks Fox and Killer!

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Killerheli
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by Killerheli » Tue Dec 15, 2009 8:30 am

No problem :D
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Trex 600N

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