I think I already know the answer to my own question here but looking for some confirmation before spending $100 on a new servo.

The tail servo (futaba 9254 digital) in my Raptor 50 went wild last week, after getting the chopper safely landed and moving it by hand it was obvious that it had stripped gears, David brought me a gear set at the meeting last night and I went home and replaced all of the gears, but the servo seems to still have a problem, one of the old gears was definatly stripped, it had two teeth gone. but after replacing all the gears with the new ones the servo does not spring back to neutral after moving it in one direction. In other words if I move the left stick all the way left and the servo goes left, then let the stick go back to center the servo stays all the way left, if I nudge it a little right and let it back center the servo goes back to center.

This happens the same way with all right movement, any ideas or just time for a new servo? If it makes a difference it has a 401 gyro setup in heading hold mode.

Sounds like motor or sensor problems... Time to send it in to futaba.. Better safe than..... I'd buy another servo and when this one comes back I'd have 2 :)

Thanks, is it really any cost savings to send it in VS. just buying a new one? Do you know roughly what it costs to send it in to be repaired?

Nope, no idea... Don't even know what a new one costs now..

Steve,
If you have not already:
Bypass the gyro by plugging servo directly in rudder channel in receiver or into another radio system any channel just to isolate servo for test. See how it works then.

If servo still shows problem, take apart and redo the new gears stackup to make sure they are proper and that the pins they rotate on are correctly going into the houseing top and bottom, not jaming or hanging up someway. The output gear will probably be also turning the pot, make sure that looks to be correct.
Also check for where those old broke off gear teeth went. If they were still in servo case, one of them could get hung up in new gears mesh.
If the old gears appeared to have been factory greased, grease the new gears with some plastic safe grease, best I remember, I used to use white lithium grease, but there is probably some super plastic servo gear grease available.
Nopt familar with that servo innards, asumming it has all plastic gears or mix of plastic/metal.

If still can't get it working with high confidence of reliability, a high dollar servo would be worth sending in to repair place. They will probably fix it at fair price, or offer to replace with a new servo at a discount.
Check with hobbyshop for where Futaba servos go for factory warrenty service. Or Radio South in Pensacola can do Futaba warrenty repair.

Been many years since I had any repair stuff done, so best to get advice form someone recently dealing with Futaba radio repair.

Steve,

Call Hobby Services. Thay are the Futaba Servive Center
3002 N. Apollo Drive Suite 1 Champaign, IL 61822 Ph (217) 398-0007 :thumbup:

make sure it is not in heading hold it will try and turn the heli but if the gyro never sees the move it will do that

Sounds like you might be okay Steve, perhaps it's just not reading the movement of the chopper (since there is none in this test) so it's holding at whatever position you set the tail servo to. After typing that, found this in the GY401 manual at futaba.com:

Sounds to me like since after you move the servo it doesn't detect movement, it stops right there. Or I could have no idea what I'm talking about since this heli stuff is all Greek to me. :unsure:

All of that makes good sense, I had not thought about the Gyro not detecting the movement. I have more ideas to go on now and will do some trouble shootin tonight.

Thanks for all the advice.

If I'm reading this right I don't think it's a gyro issue. Alvin is right, if the gears aren't stacked properly and you didn't get the old teeth out that were broken off, that could be what's causing the problem.

Thanks, we got home late tonight and I didn't get around to messing with it. I will work on it tomoorow night and post the conclusion.

Ok, maybe it was just me not knowing how a 401 heading hold Gyro was supposed to act. I connected the servo directly to the receiver bypassing the gyro and it moved like I am used to seeing a servo move.

I then connected the servo back to the 401 and it went back to the earlier described movements, I then took the gyro out of heading hold mode by switching channel 5 in my radio programming from reverse back to normal, (at least I think that is correct, the red light on the 401 goes out when I do this) the servo moves like a normal servo in this configuration also.

If anyone sees that I am way off base with any of this and don't know what I am doing please educate me, but as for now I am assuming everything is OK and I will bring it to the field and let one of you real experts give me a second opinion before attempting to fly it.

Hope everything checks out OK with it, cause if it does I'm gonna fly the H E L L (thanks Frits) out of it this week end.

that is the way it is supposed to act, all of mine do it.
the gyro did not see the movement you commanded so it was still trying to move it

Live and learn I guess, I just hadn't noticed it before the gears stripped and the Hawk which I have spent much more time with does not have a heading hold and does not do that. It made sense as soon as you pointed it out, thanks for the help.

We will see what it can do this week end, I think it will smoke Tony's hawk and make him jelous so he goes out and gets him a Raptor 50 (of course so will my Hawk w/OS .37 VS. his puny OS .32)

If he doesn't do it right away, he will as soon as I put #24 on the side of my Hawk.

Steve,

One thing to consider is that the gyro (in heading hold) on the ground will act really unorthodox as compared to in flight.

One really important thing to do is setting the pot limits on the gyro. Make sure the end points on the tail servo (channel 4) are 100%, set the gyro in normal or rate mode,(light off), make sure the tail pitch slider is centered on the tail shaft. The trim on your radio needs to be perfectly centered. Adjust the pitch slider manually by adjusting the push rod. Then move the tail stick on your radio all the way over, and adjust the limit until the pitch slider is just touching one side or the other. This will keep it from binding when you are flying.

Now, with that being said. When you go into HH mode,(light on) you might notice some binding when the servo goes full over, but this is only on the ground. I can't explain it, but I can find you literature to back it up, it will not bind when in flight.

There are a few other variables to consider when setting up a 401, but setting the limits is the most important and practical thing you can do to make the tail rock solid.


Hope this helps. :)


Scott

are you going to the field friday afternoon with the raptor

Yes

The servo checked out fine and the Raptor flew great, thanks for the help dudes.