Spartan question

[Heliheaven]

I wonder if one of the Spartan guru's might be able to put my mind at ease here?

I have a DS760, my second Spartan, recently fitted to my Raptor 90. I have always used CSM until now so the quick setup seems quite familiar.

I set the gyro up and tested it but when I selected HH mode the servo is driven all the way to one side.

After some tinkering I realised that if I powered the gyro up in HH mode (previously started in normal) then HH function correctly.

So the question, is this normal for the DS760? Do I HAVE to turn it on in HH mode first every time or is there something wrong? My main reason for asking is that I have only hovered the model so far and during that hover the tail actually stopped moving (servo wouldn't respond to TX) but I haven't ruled out a dodgy extension lead causing that problem

Any help would be greatly appreciated

Cheers

[Jamin_00]

I always start in HH and have not encountered this problem with a Spartan.

Maybe have something to do with it.

A rebind after setup can always help too.

[Heliheaven]

Thanks Ben, I did do the rebind after setup , but I have mucked about with it quite a lot since. It'll be rebound before I fly it again.

[raptorheli2]

how have you done the binding?

there is no need to bind with rudder over anymore.

when you say the servo goes hard over does it go over slowly or instantly zip to the end point?

cheers

[Heliheaven]

The gyro is not new. I bought it S/H recently.

I did bind it with the stick held slightly across to one side.

If I power up in normal, when I select HH the servo just moves all the way to one end, at a steady rate - I wouldn't call it a zip! If I power up in HH then the gyro centres in normal and will hold last command in HH

[squeaky pete]

Rebind it mate, have u put the metal plate under it aswell as the thick sticky pads? Cld be vibes, also, make sure you got the right servo selected, u cld be running the wrong pulse width

[raptorheli2]

ok, rebind with rudder in the centre. i assume the gyro is upto date firmware wise. the need to bind with rudder offset was removed some time ago.

the pulse width being set incorrectly won't show itself like this normally. the servo just acts weird all the time. i don't know what servo your using but generally speaking 1 flash= most servos, 2 flashes = bls251, 9256 etc, 3 flashes = 8700G.

i assume you have the above correctly set

from spartan site-

42. Do I still have to bind my with rudder stick off centre or the gyro gain low?
This topic affects users of Spektrum / JR 2.4GHz systems only.

Background information: The great majority of RC receivers produce no signals at their servo outputs until the link with the transmitter has be established and up-to-date servo position information is received from the transmitter. Spektrum and JR 2.4GHz receivers however operate in a different way. When the receiver is powered on it will output the default servo positions which it had memorised during binding. When the link with the transmitter is established the receiver with then drive the servos to the positions defined by the transmitter.

How gyros work: All heading hold gyros including the Spartan range need to have very accurate knowledge of the rudder stick neutral. For this purpose the majority of gyros will first wait until a rudder signal is seen at its input, it will then perform the 2-3 second sensor calibration and last it will sample the position of the rudder stick and memorise it as a new rudder stick neutral.

The problem: The non-standard operation of the Spektrum and JR 2.4GHz receivers creates the following issue which affects almost all modern heading hold gyros. Because the receiver drives its servo outputs instantly after power on the gyro starts calibrating at the same time. If the gyro completes calibration before the receiver has linked to the transmitter, the gyro will see and memorise the bind/default rudder position. If the receiver links first the gyro will see the real rudder stick position. Ideally the bind/default rudder position should be the same as the real and as such no harm is done. However, if the rudder trim is moved and the default/bind position is not updated the gyro may occasionally see the incorrect default/bind rudder position rather than the new real position that now includes the trim adjustment. The same may happen for small shifts of the rudder neutral due to normal joystick potentiometer wear.

The solution: To better deal with the above issue Spartan gyros employ a mechanism that allows the gyro to understand when the Spektrum or JR 2.4GHz receiver has linked with the transmitter and only then initiate their own calibration. To achieve this the receiver must be bound while the gyro gain is set below 5% (gyro). After binding the gyro gain can be returned to its normal operating level. When the helicopter is powered on the gyro sees the very low gain value and waits until the receiver has linked. At this point the gyro gain is raised by the transmitter to the normal operating level which triggers the gyro's calibration and sampling of the real rudder stick neutral. Using this method is optional, however it is likely to save a lot of tail drift headaches in the event that the rudder trim is accidentally adjusted. This method also allows more time for the user to enter the gyro setup mode through switch toggling and is therefore recommended for users that may have difficulties in doing so.

Note: Previous versions of the ds760 gyro firmware offer the same functionality by binding the receiver while holding the rudder stick off centre. This method is no longer recommended and will be removed in future firmware versions. Please use gyro gain value less than 5% instead.

cheers

[squeaky pete]

Only mentioned it coz i put a ds620 on a gy611 by mistake and it creeps over then wldnt work lol

[raptorheli2]

it is worth checking yes, just doesn't normally show itself like that in my experience with it. double check it though.

cheers

[Heliheaven]

Thank you raptorheli2 and others, I will set it up that way and test it next time.

I did double check and the correct servo is selected - it's an 8900

I do not have the usb lead to connect the gyro to the pc. Is there any other way to tell what firmware is installed without it?

[raptorheli2]

from the support site-

Gyros produced since January 2009 show the firmware version on the barcode label at the back of the box.



If your gyro firmware version is 1.07 or earlier it is only possible to find the firmware version by connecting your gyro to a PC or Pocket PC using a Flash-Link or Blue-Link interface.

Starting from 1.08 it is possible to identify the firmware version through a series of short and long LED flashes.

After the configuration mode is completed the LED will remain switched on for a further 30 seconds. It will then briefly switch off before the flashing sequence begins. The sequence consists of sixteen LED flashes separated in four groups with a brief pause between groups. After the last flash there is a 10sec delay before the sequence repeats. At the example below we represent a short LED flash with a dot and a long led flash with a dash.

. . . . . . . _ . . . . _ . . . (10sec delay) . . . . . . . _ . . . . _ . . .

Each group represents one digit of the firmware version which can be interpreted using the table below. Using the table the above example represents digits 0 1 0 8 meaning firmware version 1.08

. . . . = 0
. . . _ = 1
. . _ . = 2
. . _ _ = 3
. _ . . = 4
. _ . _ = 5
. _ _ . = 6
. _ _ _ = 7
_ . . . = 8
_ . . _ = 9

[scallybert]

Isn't this the classic symptom of the gyro & Tx disagreeing about where the rudder zero-point is ?

The end result is that the gyro sees a rudder input, and increases the tail-pitch in response. Since the heli doesn't yaw, the gyro continues increasing the tail-pitch until it runs out of travel.

This should be dealt with by the calibration described in http://www.rcheliaddict.co.uk/servos...tml#post379057 "

Providing your bind rudder value is the same as the Tx rudder zero-point, when the calibration starts doesn't matter - though this is has its own problems, as the Tx rudder zero-point may change over time.

As people are saying, the right way is to defer the calibration until the Tx & Rx are connected, and the actual zero-point can be read. However, teh way you do this varies with firmware version (between unlikely gain & unlikely rudder input.)

[raptorheli2]

since it has been bound with rudder offset then that should be addressed first. what i'm not sure of is if the gyro gets a rudder input (worn pot for eg) i would ASSUME it would show the same behaviour in normal mode as well. i have never seen this myself so only going on what i have helped others with and it has cured it.

cheers

[scallybert]

since it has been bound with rudder offset then that should be addressed first.

Fair enough.

what i'm not sure of is if the gyro gets a rudder input (worn pot for eg) i would ASSUME it would show the same behaviour in normal mode as well. i have never seen this myself so only going on what i have helped others with and it has cured it.

In normal mode, the rudder input just corresponds to a rudder offset. This might not even be noticable in flight, as it could correspond to a mechanical offset/error.

OTOH, a rudder input in HH mode (with the model static) causes an increasing/decreasing tail pitch.

[Heliheaven]

Thanks for all your help guys. I will set it up as described in the text from the Spartan website and see how I get on.

I have checked the box and my label does not have a firmware noted on it so I am in the dark at the moment over firmware, but Russ (Bigbellypopper) has offered to lend me a USB lead so I will get it updated as well.