DX7 Causes Tail Wag!!!

[jeff.cotter]

Hi everyone,

I've been using Helifreak for a while for information-gathering (brilliant), but now I need real help!!

I've run into a very weird problem with my new T-Rex 500. I'm still a relative newbie and am just moving past hover into FF. I've put about 15 packs through my new T-Rex 500 using a DX6i radio, and everything has been fine until today. I've upgraded to a DX7 radio (the DX6i packed up) and all hell has broken loose. I now have a very severe tail wag (side-to-side, four or five times per second or so) which could almost be described as bad shaking.

All that has changed between yesterday and today is moving to the new radio. The heli was flying perfectly now has this horrible tail wag.

I set up the radio after going through Finless's video on DX7 setup and re-doing the basic swash-plate leveling and pitch adjustments. I'm using exactly the same pitch and throttle curves as before (flattish throttle curve at 90% by about three-quarter stick). All seems fine and the T-Rex now flies the same as it did on the DX6i in all respects except for the ferocious tail wag.

I've tried gain settings all the way from 55% up to 80% with little or no difference (it might be slightly less at the low gain values, but still very bad). I've gone through the tail and mechanically everything seems the same as before (servo arm positions, gyro moving in the right sense, no binding etc etc). Haven't had any crashes or even hard landings that could account for any structural problem.

The only thing mechanical that I can think of that's changed between yesterday and today is that I had a fair struggle getting the bind plug into the receiver (mainly because it's difficult to get at due to its location on the lower tray and wire lengths). Perhaps I damaged the receiver in some way.

The T-Rex has all standard Align servos and gyro (GP780).

If anyone's got any suggestions I'd be most grateful because at the moment, I'm stumped!

[Ozz58]

I went from a DX6i to a DX7 and just used my old setting and never had a problem. The gyro menu on the 7 is a lot different from the 6i, make sure you understand the differences. You can use endpoints or gyro menu, make sure you have everything the same as with the 6i, the 6i used the gear channel not the aux make sure you still have it set for gear unles you move the lead on the gyro.

Just some things to look for, as I said my switch was almost flawless,

Good luck,

Craig

[Cailid]

I'm using the DX7 and it works fine. I have the 750 gyro on my 500. One thing I noticed with the gyro setting over my B400 though is that in the radio it is in HH mode from 0 - 100 with the 750 but with the GY401 on my B400 HH is from 50-100. I had the same problem with tail wag until I turned the setting way below 50 in the radio and noticed the gyro was still in HH mode.

[RocketSled]

The fact that it's not making a difference over a large range of Tx Gyro Gain values suggests one of three possible problems; either you don't have the Gyro channel configured properly on the Tx, you have the Gyro plugged in to the wrong channel on the Rx, or your Gyro is busted.

[jeff.cotter]

Thanks very much guys for the replies and input. From your comments I think I see the problem. On checking my receiver (AR6200), I see that I've got the gyro connected to "rudder" and "gear", but in fact I've set up the radio to use "aux2" for the gyro (on the "input Select" menu). So I'll try changing that to "gear" (easier than changing the gyro wires around).

The other interesting thing is the gain adjustment range. I thought that the GP780 operates in HH mode above 50% and rate mode below 50% and that's also the case on the radio (I think it was that way on the DX6i from memory). So, Cailid, it's interesting that you found that for the GP750 and DX7 that it's still in HH mode below 50% for the radio setting. I'll experiment with my GP780 and see if it also behaves the same way. Thanks for your observation.

So hopefully I'll get things sorted with those changes. I'll have another go tomorrow and let everyone know how it goes.

Thanks again for the help. Much appreciated!

[Larry227]

Just set Aux2 = Aux2 and Gear = Gyro in the setup menu and then go to the gyro sens menu in the tx and set your gain just like with the DX6i.
Keep in mind though that it will not work with the Gear switch then like the DX6i does for switching between the two values. If you want it tied into the Gear switch you need to set Gear = Gear and that's a whole diferent ball of wax. I won't even get into it unless you are interested.

[Larry227]

BobO does some good explaining of the DX7/Gyro options in this thread if you would like to see how it works with endpoints.

[reALIGNed]

Originally Posted by jeff.cotter

Hi everyone,

I've been using Helifreak for a while for information-gathering (brilliant), but now I need real help!!

I've run into a very weird problem with my new T-Rex 500. I'm still a relative newbie and am just moving past hover into FF. I've put about 15 packs through my new T-Rex 500 using a DX6i radio, and everything has been fine until today. I've upgraded to a DX7 radio (the DX6i packed up) and all hell has broken loose. I now have a very severe tail wag (side-to-side, four or five times per second or so) which could almost be described as bad shaking.

All that has changed between yesterday and today is moving to the new radio. The heli was flying perfectly now has this horrible tail wag.

I set up the radio after going through Finless's video on DX7 setup and re-doing the basic swash-plate leveling and pitch adjustments. I'm using exactly the same pitch and throttle curves as before (flattish throttle curve at 90% by about three-quarter stick). All seems fine and the T-Rex now flies the same as it did on the DX6i in all respects except for the ferocious tail wag.

I've tried gain settings all the way from 55% up to 80% with little or no difference (it might be slightly less at the low gain values, but still very bad). I've gone through the tail and mechanically everything seems the same as before (servo arm positions, gyro moving in the right sense, no binding etc etc). Haven't had any crashes or even hard landings that could account for any structural problem.

The only thing mechanical that I can think of that's changed between yesterday and today is that I had a fair struggle getting the bind plug into the receiver (mainly because it's difficult to get at due to its location on the lower tray and wire lengths). Perhaps I damaged the receiver in some way.

The T-Rex has all standard Align servos and gyro (GP780).

If anyone's got any suggestions I'd be most grateful because at the moment, I'm stumped!

WOW, I'm experiencing the exact same thing, and I was just about to post for help.

[reALIGNed]

Originally Posted by Larry227

Just set Aux2 = Aux2 and Gear = Gyro in the setup menu and then go to the gyro sens menu in the tx and set your gain just like with the DX6i.
Keep in mind though that it will not work with the Gear switch then like the DX6i does for switching between the two values. If you want it tied into the Gear switch you need to set Gear = Gear and that's a whole diferent ball of wax. I won't even get into it unless you are interested.

TAH DAH., I just set it like you suggested, and now I'm back in the air...THANK YOU. Now that I can enjoy it w/a reliable radio, I will take the time to learn how to set it up the "better way".

[Larry227]

Understanding the gyro setup was the biggest challenge I had when I switched to the DX7. I'm not really sure if either way is better than the other.
I've really found no need to have it assigned to the Gear switch. With my GP750/DS520 I just centered the slider one time in Rate and haven't had to go back into Rate again.
When I do need to go into Rate for setup I just change value "1" to 25 and setup the gryo "auto sens" to switch to "1" when I hit TH. That way it goes into Rate when I turn TH on. Since I do all my setup in TH anyways it works for me. When I'm done I just change "1" back to 70 so if I power up with TH on it's still in HH mode.
You could also just manually change the value on "0" during setup if you don't want to assign 1 to TH/on.

[ourbail]

Originally Posted by Larry227

Understanding the gyro setup was the biggest challenge I had when I switched to the DX7. I'm not really sure if either way is better than the other.
I've really found no need to have it assigned to the Gear switch. With my GP750/DS520 I just centered the slider one time in Rate and haven't had to go back into Rate again.
When I do need to go into Rate for setup I just change value "1" to 25 and setup the gryo "auto sens" to switch to "1" when I hit TH. That way it goes into Rate when I turn TH on. Since I do all my setup in TH anyways it works for me. When I'm done I just change "1" back to 70 so if I power up with TH on it's still in HH mode.
You could also just manually change the value on "0" during setup if you don't want to assign 1 to TH/on.

+1 , i have all my birds set up to flight mode.....

[jeff.cotter]

Just tested again this morning with the correct radio settings (i.e. gear set to gyro rather than aux2). Everything is now sweet and back to normal.

As with many things in life, it turned out not to be the equipment but the brain behind it So the lesson is: when switching to a new radio, be careful to thoroughly understand the differences from your old one!

Thanks everyone for the help and advice.

[Larry227]

Also make sure you turn the TH switch on. I believe on the DX7 it's off by default on new models.

[jakalope]

The previous owner of my 500 had a DX7 and had the gain at 58. I used the same setting on my DX6i and had a bad tail wag. I set it to 36 and resolved the issue. Hope this helps.