I am not sure if this is the right forum to post in, but since the Heli is an EXI-450 I figured I would start here.
First I had a TREX-450 that I was learning how to hover with. I crashed it and bought the EXI and moved all the electronics into it. I now think that my TREX crash may not have been my fault. Once I got the EXI set up I started to notice something strange was going on with the electronics. Its hard to explain but it is like a glitch that will happen every so often and the motor will spin up all on its on. It did this once when I was holding it [X(]. It is very brief and only last for one second or so. I also noticed that when it does this the cyclic servos go crazy and start glitching too. The problem is that I have not been able to figure out exactly what is causing this to happen and it is driving me nutts. At first I thought it might have been the receiver, but I was able to rule that out by trying another one. I have also ruled out the gyro as I unhooked it. I noticed that one of the servos in particular seemed to be moving a lot when this happens, so I am thinking it might be a bad servo, could that cause the motor to spin up? My other thoughts is maybe a bad ESC or motor. If anyone has any suggestions please let me know. The details of everything on the bird are below.


Radio Futaba 9C Super ( I have been testing with another radio just to make sure its not the radio but like I said it only happens every so often so its hard to tell)
RX (Already eliminated this as it still does it with another one)
Gyro Futaba 401 (Also ruled this out)
ESC Apollo-25 AMP (Since this is most likely to cause issues with the motor surging I am thinking this might be the problem, I have a Volcano 30 amp on order)
Servors JR-DS285 (I was thinking maybe that one servo has gone bad and was causing some kind of feedback into the ESC, so I have ordered 3 9G EXI Digital Metal Gear Servo D213F to replace them with.
Motor Align 430L

Like I said, I have another ESC and servos on the way, but I was just wondering if anyone had any other ideas. I have never had any kind of interference issues before so I am kind of lost as to what it could be.

Sounds like interference or brown-outs. Try the new speed controller first.
To me, it act's like an FM reciever when it loses it's signal. That is Exactly why i switched to spectrum technology.
I crashed my Trex 2 or 3 times and it was horrible. It would just get a mind of it's own and power plant itself right into the ground.
Wireless Routers and Cordless phones do affect fm recievers. I have not had anymore "what the heck just happened" incidents since the switch to spectrum.

The new speed controller is on order and should be here next week. I hope that fixes it, if it doesn't then I guess it has to be the motor, TX, or some sort of external interference. I "think" I got it to do the same thing with my test TX, but it is so hard to tell because it only does it every now and then. I'm going to do some more testing while waiting on my ESC and servos to get here. I would love to switch to the 2.4, but it is so expensive to make the switch because I have 5 RX's that I would need to change...This may force me to change though.
Thanks for your help.

Hi Kenny! It's been a while... Still have your AXE CP?

I think your interference could be caused by STATIC, from the tail belt & nylon gears. Also make sure your antenna from the RX is extended out behind the heli, not wrapped up under the landing gear. Also are you using a stand alone BEC, or the one built-in to your ESC. I found that the BEC that is built-in to most ESC's is weak and tends to overwork the ESC itself. Use a stand alone switching-BEC to power your RX & servos, also spray some STATIC-GUARD on the gears & tail belt, to reduce static interference.

Shadow

Yes Shadow99, its been awhile. I'm glad to see that you are still on here as well. No I no longer have the AXE CP, to be honest I never liked the size of it, plus I could never get that motor driven tail to work right.

Static, hmmm, I haven't thought of that. I guess that would be another good reason to go to 2.4g LOL.
I am still using the built-in BEC. Thats a good point, I guess I could try disconnecting it and see if that fixes the problem. I am thinking all I should have to do is un-hook the positive lead from the BEC and then hook a 4.8V battery into the RX.
Thanks

Just to let you know STATIC can and will effect a 2.4ghz RX as well, I had that issue on my Trex 500 using DX7. That's when I went to the separate BEC, and found out about static discharge from the nylon gears & tail belt. A couple of squirts of STATIC GUARD (available at any supermarket), down the tail boom and onto the tail drive gears.

Yup, you can by-pass the BEC off your ESC, by pulling the red wire out that plugs into the RX, then plug any 4.8v to 6v power feed into the RX.

Shadow

OK, thats a great idea, I dont know why I didnt think of it before ordering a new ESC ( But thats why I love these forums, to get ideas you haven't thought of). I will give it a shot and see what happens. Will also pick up some static guard the next time I'm out.

Good news and bad news.

Good news is I was able to get the "interference" to happen while using my test radio. This is good because it means the problem is not with my 9C (Thank God).
The bad news is disconnecting the BEC from the ESC and running the servos with another pack did not help.

I'm back to thinking there is some kind of short in either one of the servos, or most likely a bad ESC.

Sounds like it may be a bad esc but it may still be interference.

It's already been suggested to run the antenna straight, I see too many people wind the antenna around the antenna tube into a coil, this reduces reception and can cause interference.

Just from the fact that it's intermitent I'd say there's a good chance it's interference. Try flying the heli in a completely different location miles away a few times to see.

As was already mentioned above, I have seen static electricity do really crazy things, mostly on CF framed helicopters. I have seen first hand a CF framed heli sitting on the ground barely spooled up and all the servos started to just go crazy. Spraying some static guard on it solved the problem for a couple of flights. We ended up running a ground wire from the tail shaft bearing to the motor mount and it seemed to fix the problem. Just a thought as it could be something completely different.

I have a test RX on a table with the antenna straight and as far away from the Heli as possible, so we can rule that out.

It seems like the interference happens more often when the motor reaches a certain RPM. This heli has an aluminum frame and I have noticed that the motor almost touches it. If this is the problem I am not sure how I would fix it. It also would not make sense as it seems that any motor would cause this issue on this heli and there would be more people complaining about it. I'm going to pick up some static guard soon and give it a try.

EDIT: Just had another good idea, I will hook the servos into a separate 2nd RX that I can move away from the heli and then try to run the motor up. I can then move this closer and closer to the Heli. This should tell me if the problem is from outside interference or if something on the heli is causing it. I'll post back with results later.

Ok, I managed to get my results on video. Just when I think I have it figured out, something even stranger happens.

[youtube]http://www.youtube.com/watch?v=wcTFxjSPjqE[/youtube]

That's a very interesting video Kenny, I noticed however that you do not have a ferrite ring on the cable that plugs into the RX, all my ESC's have a ferrite ring (donut style magnet) installed onto the cable that plugs into the RX, it's wrapped around it several times, that could be what you need.
Notice the Align ESC pictured below, see the RX cable wrapped around the magnet? You can buy them at almost any local hobby shop, just remove the RX plug from the end of the cable (NOTE the pin order, an X-acto knife works great for releasing the pins), then make several wraps around the magnet positioning the magnet 1/2 way on the cable, re-install the pins into the plug.
That could make the difference!

Shadow

Yeah bro, you are using straight FM. Very susceptible to glitches...I would use nothing less than PCM, but since you are at FM, definitely get a ferrite ring and make sure your wires are nowhere near the battery wires, motor, etc.

During your testing, you have the antenna laying right next to the battery, etc....all of that matters with straight FM.

Skarn

Good idea with the Ferrite ring, I will have to pick some of those up. My new ESC will be here tomorrow, so I will give it a shot and see if that fixes the problem. Wish me luck

Well, the new ESC and servos did not fix the problem. As was mentioned above, I think that something nearby is causing external interference. Wireless phone, router, etc. I came to this conclusion by turning the radio off and just holding the heli to see what would happen, after a few seconds the motor just spun up all on its on. The only other thing I havent tried is replacing the motor, but at this point I am sure its just interference. I'm going to use this opportunity to make the switch to the Assan 2.4Ghz module. At least now I have enough spare parts to build another Heli.

Tried the static guard and the ferrite ring. Neither fixed the problem. Although I could tell a substantial difference with the ferrite ring, there was a lot less servo chatter, so I will be using them on all my models from now on. Waiting on my new motor and 2.4g module to get here.

Well that SUCKS, Kenny! I'd thought for sure that the ferrite ring would cure your servo-woes / interference issues.[:'(] I wonder if it could be the BL motor, have you tried removing the motor from the ESC (pull 2 of the BL wires off, motor won't run on 1 phase). Does it still twitch? If you change throttle position does that change anything?

Shadow

Shadow, I was hoping so too. I got my 2.4ghz module yesterday (and new BL motor just in case), preliminary testing has been good. So good in fact that I have started to put the bird back together (which shouldn't take long as I can do it in my sleep now). I think that something nearby starting causing interference on the FM channel I was using. Granted I could have tried switching to another FM channel and seen if it helped, but I figure this is as good of reason as any to go to 2.4 and not have to ever worry about someone/something shooting me down.
On the bright sight of things, I now literary have everything I need to build another whole bird except the gyro. I think I will go ahead and get the "back-up" bird setup as well and then if a crash is ever bad enough all I'll have to do is pop the gyro in and go

So any updates? Did the 2.4ghz module take care of the "possesed heli?" Are you flying it yet?!

Shadow

Yes, I was just about to post LOL. The heli exorcism was a success. The 2.4ghz module is working perfectly. Something in my area must have recently started interfering with my channel as when I go to the filed to fly my planes I have no problems, but I fly my heli in my front yard. I flew it twice yesterday and it worked great, now I just need to do some fine tuning with my pitch/throttle curves and I'll be good to go...Not to mention practice, practice, practice