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Nov 03, 2008, 07:55 PM
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Mini-HowTo

Align GP-750 Heading Lock Gyro


The Align GP-750 heading lock gyro that is included in the new T-Rex 250 super combo kits has setup steps that differ with most other gyros on the market. In order to take advantage of its capabilities, correct options must be set according to the specific application. I will try to walk through the setup steps and explain each setting.

Similar to other gyros, when it is powered up, the LED will flash rapidly indicating initialization is in progress. Do not touch the gyro or helicopter at this point. Once the initialization process completes, the status LED will remain lit in green or red. Green indicates gyro is in heading lock mode, red means it’s in normal rate mode.

Before you start, it’s best to understand what each option means.
• 1520/760: This represents the frame rate of the rudder servo used. Most commonly used analog or digital servos use the 1520us frame rate. 760us rate is used specifically for high frequency servos such as Futaba 9256 and BLS251. If unsure, always set this option to 1520us to avoid burning out your servo. 1520us is also the factory default settings.
• DS/AS: This sets the gyro for either Digital Servo or Analog Servo. DS is the factory default setting.
• NOR/REV: This sets the compensating direction for the gyro.
• Limit: This setting limits the rudder servo travel and is used to avoid binding in the tail linkage.
• Delay: This is the setting used to dampen the gyro compensating speed for slower servos that are unable to keep up, resulting in tail oscillation. There is also an imbedded setting for the size of helicopter used. Small includes 250/450 size, while large includes 500/600/700.
The setup steps involve the use of your transmitter’s rudder stick and the “SET” button on the gyro. You basically cycle through the 5 options with the set button, and select the setting using the rudder stick.
• To enter the setup mode, press and hold the SET button for 2 seconds until STATUS LED flashes.
• While in setup mode, momentary press of the SET button will cycle through each of the settings.
• Select the setting by moving the transmitter rudder stick left or right, and observe the color of STATUS LED.
• When correct color is observed, press the SET button to memorize the setting.
• The gyro will exit the setup mode if left idle for 10 seconds.
Below is the walk through of an example setup. Suppose you will be using this gyro on a T-Rex 250 with Align’s DS420 digital servo.
Last edited by Steph280; Nov 03, 2008 at 08:17 PM.
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Nov 06, 2008, 02:08 PM
1.21 Gigawatts!
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If you notice the rudder servo would only travel one direction, the frame rate setting is incorrect. It needs to be set to 1520 us.
Nov 06, 2008, 09:41 PM
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Its nice to see new products hitting the market. Any word on how it flies?
Nov 08, 2008, 05:01 AM
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does this gyro have independant limit setting? ie: limits set for both left and right travel? Or is it like a 401 which sets overall servo travel?
Nice setup log by the way.
Nov 10, 2008, 07:25 PM
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Somebody told me it has independent limit setting, although I have not had the need to use it on my T-Rex 250 yet.

The gyro flies really well. It was a bit sensitive, my gain ended up to be around 35%. With link ball around 5mm from center on the servo horn.
Nov 17, 2008, 08:16 PM
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thanks for the post, it was very helpful
Feb 01, 2009, 09:10 PM
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Thanks for the post. I noticed the caption for the last picture was truncated. What was the rest of the sentence? (see below)

Move rudder stick left or right and watch the STATUS LED. Green LED is large helicopter, red LED is small helicopter. The amount of rudder stick moved from center will determine how much delay is applied. For this example, the Align DS420 servo does no??
Aug 12, 2009, 04:43 AM
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ALAN SZABO jr uses that gyro on his 450 sport
Sep 24, 2009, 01:13 PM
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Quote:
Originally Posted by rightflyer
Thanks for the post. I noticed the caption for the last picture was truncated. What was the rest of the sentence? (see below)

Move rudder stick left or right and watch the STATUS LED. Green LED is large helicopter, red LED is small helicopter. The amount of rudder stick moved from center will determine how much delay is applied. For this example, the Align DS420 servo does no??
Didn't even notice that...complete sentence should be:
The amount of rudder stick moved from center will determine how much delay is applied. For this example, the Align DS420 servo does not need any delay, so rudder stick can be left centered.

By the way, this gyro is used in all Align helicopters Alan Szabo flies, from T-Rex 250 all the way to T-Rex 700.
Oct 31, 2009, 01:27 AM
LSW
LSW
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GP750 Gyro


I have a trex600esp with MX12 transmitter. Recently I have bought a Graupner MX22, which is the same as the JR X9303, but the gyro fails to respond. Can you advice me what to do. The ports on the receiver have been properly connected. Can I activate the gyro through the settings of the transmitter? Txs for yr support.
Jan 16, 2010, 11:44 PM
Registered User
Let's say I'm setting up the tail and the tail slider doesn't move far *enough* when setting the limits - so rather than restricting the endpoints I actually need to widen them. One way I could do this is to put the control rod on a ball with a larger radius. But is there any other way to tell the gyro to increase its usable limits on the rudder servo? Obviously changing the rudder ATV endpoints makes no difference.
Oct 03, 2011, 10:34 AM
bth
bth
Bjørn Terje Hansebråten
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My GP 750 will not hold tail !
I am use a HK 450. T-Rex clone.
I have try different holes in the servo horn. I use now 4,5 mm. When I use full pitch with 100 % throttle, the tail start to spin right. I use Futaba radio, and the gain is 80 % when the oscillation stop. (it goes from -100 % to +100 %)

What is wrong ?
Dec 12, 2012, 10:11 PM
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I have one for sale if anyone's interested! Make me an offer! Im switching to flybarless so I dont need it!
Feb 15, 2013, 05:42 PM
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This is an old but very helpful thread.

I recently bought a used T Rex 450 w/ the GP 750 gyro. I am running a DX8 Radio and a Hitec HSG 5084.

This isn't my first rodeo and the problem I am having is the gyro doesn't hold my settings. I can get it to stay on my settings, go back and check them and they are OK. Shut the heli off and recheck and they are gone. ANY Clues?

I did find out that I had to put my Rudder ATV at 150% in order to get any change in LED color.
Jun 09, 2013, 11:48 PM
Registered User
I'm having trouble with the gyro setup. I've followed all the instructions for building and setting up, mechanically, and electronically...at least as far as I can tell, and I have checked 3 times.

When spooling up on the ground, almost at take off speed, I test the rudder control to the left and I end up in a constant spin left. Same goes when I try right. When I try opposite rudder to correct, it requires almost full opposite before it stops, and then spins the other way (same direction of my corrective action). I'm guessing it's binding, but I can't tell how.

When testing rudder control, with motor disconnected, should it center itself after testing either left or right rudder, and releasing stick to center. Mine only comes back a fraction.


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