Uncommanded motor blips in TH

[tkranz]

We have just finished a new build of a Trex 500 DFC Pro. Flies great.

However, we have a curious glitch that I have not experienced before. At random times after initializing, and while sitting undisturbed on the bench, the motor will turn on for a split second, enough to move the main blades about one half revolution. It does not turn full on, but the fear of that happening has me very concerned.

We are running all stock combo kit parts with two satellites.

The glitch occurred several times while we were doing initial setup, once while turned on before maiden flight, then nothing during next two flights, then twice last night before a fourth flight.

So far:
We have tried two DX8 TX's, and it is the same with each.

We have swapped out the 3GX with another new one. Same behavior with each.

We are stumped. Next plan is to swap out the ESC.

If that doesn't do it, what could it be most likely? Would a bad satellite in any way be able to cause this? Maybe a random fault in a servo?

Help!

[Xrayted]

Its strange because this was a topic of discussion in the Skookum forum for those of us with SK FBL controllers for a good while. I know exactly what you are talking about because it happens to many of us too. We were trying to decide if this was a Spektrum thing or not, but the Skookum guys claim they have isolated the issue and a future firmware update should take care of it. I don't know if that means its coming from the FBL unit itself, or if its the TX and they are just adjusting to FBL unit to deal with it? One of the Skookum guys managed to capture the anomaly with testing equipment to see what was happening, but I don't remember who.

Here is one of a few videos showing what you are describing. The good thing is that (as least for the SK users) is that it never does anything more than bump.

http://m.youtube.com/watch?feature=y...&v=_ayhCpCJcEg

[ahahn]

I'd say either one of the satellites or the ESC.

Have you tried disconnecting one of the satellites to see if the issue goes away? If not, try the other one.

I am not sure what the fbl controller does if it gets contradictory information from one of the two satellites.

Other thing that comes to mind is that your TH level might be very close to upper level for zero arming, and a noise blip somewhere in the system takes it over the threshold. So has the ESC and transmitters been calibrated for the endpoints?--Just guessing.

[BHChieftain]

Try setting the TH throttle to -5% vs. 0%.

Chief

[tkranz]

Keep the suggestions coming. Tried hard to duplicate issue today, but after 6 initializations and one full flight, I could not repeat the problem today. Grrrrr.

[Xrayted]

TH settings have no bearing on it it if its like mine. Mine will do it with throttle cut activated at -150

Its very random as you describe. I might go days without seeing it, and then start getting it on every power up for 5 flights in a row.

[tkranz]

Originally Posted by Xrayted

TH settings have no bearing on it it if its like mine. Mine will do it with throttle cut activated at -150

Its very random as you describe. I might go days without seeing it, and then start getting it on every power up for 5 flights in a row.

When you get the "bump" effect, is it always the same time after power up, or random times? I am not sure yet about mine, trying to see any pattern still.

[Xrayted]

Originally Posted by tkranz

When you get the "bump" effect, is it always the same time after power up, or random times? I am not sure yet about mine, trying to see any pattern still.

Completely random. Sometimes a few minutes after power up, and I carry he heli out to the flight line. Sometimes within 30 seconds of powering it up and adjusting on the bench. Sometimes not at all.

It will even happen after a full flight and I have shut down and walking over to the heli to pick it up, or while carrying it.

Here is our discussion about this phenomenon in the Skookum forum. Post #38 has a good bit of information. Not your FBL unit I know, but maybe something to learn that we have in common??? The fact that you are having this exact same issue makes me think this possibly isnt a specific FBL system issue as we were thinking..

https://www.helifreak.com/showthread...=601681&page=2

[Nobreeze]

If I am not mistaken, this "blip" is actually a firmware issue of the 3gx. My guess is that you're running V4, since you mentioned this is a new build.

I have over 50 flights on my 550, the "blip" has been there the entire time. The twitch I experience tends to be more servo oriented than motor oriented. My blades have never made a 180, a jump, yes, a spin, no. Irregardless, the twitching is quite unnerving.

I found this thread (below), which addresses the phenomenon we are speaking of. It has been reported to Align & hopefully the "fix" will come with V4.1.

Jump to response #25 on the link.

http://www.rcheliaddict.co.uk/align-...tting-yet.html

[simplechamp]

Yep I have also noticed random servo blips, and to a lesser extent random motor blips with the 3GX (v4 firmware) in my 450 DFC. I mainly noticed it during setup, since I was spending a good deal of time with the heli powered up on the workbench. Now when I'm flying I have the heli in the air within 30-60 seconds of powering up and so I don't see it much at all. But every now and then when I'm walking the heli out or carrying it back I'll catch a blip.

[Crowbar]

Very interesting. I could imagine some crosstalk between wires where for a split second, there's an erroneous throttle signal arriving at the ESC. In electronic systems, there's usually error correction that catches the odd signal and filters it out. Ferrite rings around the signal cables can minimise these signals in the first place.

It does sound like it's the 3GX firmware. I would personally be very uncomfortable having my heli do this. If it happens while you carry it to the flying area, it might have enough torque to free itself from your hand and drop to the ground. Or the body turns around and you get smacked into the back of your knees by the tail boom.

Hopefully that will get fixed soon. I hear the 3GX is pretty nice these days. Getting an AR7200BX until then might be your best and cheapest option to fly with confidence.

[Bonkievan]

Apparently it's a 3gx issue. Mine does it and it's very un-nerving to say the least. No more than a slight blip but 'dodgy' all the same.

There was a thread in the 3gx forum discussing this a while back and a UK Align rep confirmed such and said Align were aware of this.........

Hopefully 4.xx should have this glitch eliminated, along with tail issues some are having with V 4.0

[Rockarruda]

Originally Posted by Xrayted

Completely random. Sometimes a few minutes after power up, and I carry he heli out to the flight line. Sometimes within 30 seconds of powering it up and adjusting on the bench. Sometimes not at all.

It will even happen after a full flight and I have shut down and walking over to the heli to pick it up, or while carrying it.

Here is our discussion about this phenomenon in the Skookum forum. Post #38 has a good bit of information. Not your FBL unit I know, but maybe something to learn that we have in common??? The fact that you are having this exact same issue makes me think this possibly isnt a specific FBL system issue as we were thinking..

https://www.helifreak.com/showthread...=601681&page=2

Yeah I have this problem also.. Sk720be with Jeti R3 rx with PPM out.. My esc is a Jeti Mezon, and yes the times are completely random. I have thought about adding a toroid ring to the throttle cable at the esc in case some amount of noise is causing it..

[Xrayted]

Originally Posted by Rockarruda

Yeah I have this problem also.. Sk720be with Jeti R3 rx with PPM out.. My esc is a Jeti Mezon, and yes the times are completely random. I have thought about adding a toroid ring to the throttle cable at the esc in case some amount of noise is causing it..

Art at Skookum claims he has identified it and will fix it in the next firmware release. I thought it was just us suffering with it, but it appears the 3GX has the same issue to correct as well.

[marke]

has anyone tried going to the 3.0 Firmwear on there 3GX? that might be a temparary fix till the 4.0 gets worked out..what do you all think?

[Bonkievan]

Originally Posted by marke

has anyone tried going to the 3.0 Firmwear on there 3GX? that might be a temparary fix till the 4.0 gets worked out..what do you all think?

Yes, many have reverted to 3.1 but mainly for the tail issues seen in 4.0
I never had the throttle blip with 3.1 so you may want revert if the 'blip' is worrying you.

[Coolice]

Hey all.

This control blip is a glitch of V4 and also the beta V4.1 that Align pilots have been trying out to give feedback to Align on. I was running V4.1 on my 450L and after a while the twitches returned.
I found the first flight was always ok, it was on subsequent flights that it got worse until it pulsed the throttle, it was never bad but enough of a throttle pulse to make you wary.
I think the problem is that the feedback loops within the new firmware have been improved to get better performance, but this then has the 3GX looking and responding to movement when it is not needed.

I keep asking my sponsor about another 3GX firmware to try, but have not heard of anything yet.
V3.1 does not suffer the twitch while in flight mode, some have seen twitches while in DIR mode, but not when stationary on the flight line.
.

[marke]

well all I switch Toms back to 3.1 last night and I had it on throttle hold for 15 minutes and tryed everything to get it to Blip but it wouldnt -the 3.1 seemed to solve this-I havent flown it yet to see how the tail acts but I expect it to be better then the 4.0..ill keep everyone updated..but first impression is revert back to V3.1--it just works....

thank you

[marke]

well the 2 helis that i reverted back to 3.1 both have that great tail feel to it-also neather have an uncommanded throttle Blip. so for now 3.1 is the way to go till the 4.0 get fixed.

thank you