Vibration or shakes? CHECK THIS!

[mejmea]

Originally Posted by VaderSS

Actually, that is a great idea for extending the life of the servos and decreasing the cleaing interval. That won't help me with my current problem, because It is causing the heli to jump whenever I am in that section of servo travel, but I think I'll try making that a preventative maintenance item from now on.

I don't have enough flights on mine to warrant doing this yet but if you implement this procedure I'd be curious to know how many turns you can go on the ball links/subtrim clicks before you start to run into potential binding/travel issues at full collective and cyclic inputs. I know you can go at least 2 turns because I did that originally when I discovered I had to put in 32 clicks of pitch subtrim (if I recall correctly) just to get 0 pitch at mid-stick out of the box.

[VaderSS]

I originally had to put in 58 clicks of positive sub-trim, and never had any binding. I later adjusted the links so that I would not need subtrim. Ironically, it is in the region that the servo lived when the links were "too short" that is now where it is glitching.

Without thinking about it, I had put your method to use.

I think that is why I got so many flights in before it started glitching.

[mejmea]

Originally Posted by VaderSS

I originally had to put in 58 clicks of positive sub-trim, and never had any binding. I later adjusted the links so that I would not need subtrim. Ironically, it is in the region that the servo lived when the links were "too short" that is now where it is glitching.

Without thinking about it, I had put your method to use.

I think that is why I got so many flights in before it started glitching.

That is ironic! So with 58 clicks that must have been maybe 4 turns on each ball link? About how many flights did you have before you adjusted the links? You said you had/have a total of about 100 so I'm curious if it was about 50/50.

I unscrewed each ball link 2 full turns to get rid of my original 32 clicks of pitch subtrim. I think I could perhaps go one more turn. Then, from there, if you could go 4-6 turns in and not bind (or run out of thread) the wear could be distributed a bit at least although it would still overlap near the middle of the servo. I'm not doing a lot of full range pitch stuff, I'm not that skilled yet, so moving the center/hover/basic FF pitch point a little bit one way or the other might be enough to help prolong the life.

[VaderSS]

I believe 4 turns is correct. I had it that way for about 1/4 of the time I've flow it.

[sjsamuel]

Thanks Chris! One more MCP X saved by this fix!!
Mine started developing the shake and withing 2-3 flights was almost uncontrollable! Cleaned the contacts and I"M BACK!!!

Great suggestion, I was just beginning to loose hope, after tearing the whole heli down and not finding anything else to fix!!

[ChrisH]

Originally Posted by sjsamuel

Thanks Chris! One more MCP X saved by this fix!!
Mine started developing the shake and withing 2-3 flights was almost uncontrollable! Cleaned the contacts and I"M BACK!!!

Great suggestion, I was just beginning to loose hope, after tearing the whole heli down and not finding anything else to fix!!

Glad to hear it!

[VaderSS]

Re-cleaned my servos and I still have a glitch on the port servo. There is a spot where it won't move as the sticks are moved, and then it jumps to the correct position after the sticks have been moving.

I wound up setting 100 points of positive pitch sub-trim and then adjusting the links to give zero at mid-stick, so I am out of that glitch area for normal indoor flight.

I will try to rebind tonight, but don't have much hope for it. I have replacement servos coming, so will fly it like this until they come. I believe I just need to replace one, and will keep the others as spares.

Before and after below.

[tracknoob]

Originally Posted by VaderSS

Re-cleaned my servos and I still have a glitch on the port servo. There is a spot where it won't move as the sticks are moved, and then it jumps to the correct position after the sticks have been moving.

... don't have much hope for it. I have replacement servos coming, so will fly it like this until they come.

I only offer this as a crazy idea to salvage an otherwise useless servo.

Conductive paint.

I have used it on rear window defrosters very successfully 'back in the day.' Not at all sure that it will work for servo strip repainting, but it just might ....





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[BladeSlap912]

ChrisH,

Thanks for the post. On my first mCP X I had the starboard servo stick on about the tenth flight. I re-binded to my 11x and it was fine. Then after a few more flights, it was stuck again. Re-binding didn't do much good so I decided to clean the silver strip as you suggested and it worked! It was a little dirty and the q-tip took a good amount of black gunk off of the strip. There may be other issues here but time will tell. For now, it's flying like it should. Thanks again!

[VaderSS]

Originally Posted by tracknoob

I only offer this as a crazy idea to salvage an otherwise useless servo.

Conductive paint.

Interesting idea. May have to try something like that once I replace it. It's working well enough for the moment, so I'd hate to "fix it" into not working at all...

[lyco46]

use a t rex 250 boom support hell of a lot cheaper just cut the wire and resolder i cut the wire in the middle cause soldering that little connector is a pain with my soldering skills

i used heat shrink to hold the cable in place on the outside of the shaft looks a bit messy but its a cheap fix considering how many tails u go through and the motor and wire are usually fine

[mejmea]

Originally Posted by VaderSS

Re-cleaned my servos and I still have a glitch on the port servo. There is a spot where it won't move as the sticks are moved, and then it jumps to the correct position after the sticks have been moving.

I wound up setting 100 points of positive pitch sub-trim and then adjusting the links to give zero at mid-stick, so I am out of that glitch area for normal indoor flight.

I will try to rebind tonight, but don't have much hope for it. I have replacement servos coming, so will fly it like this until they come. I believe I just need to replace one, and will keep the others as spares.

Before and after below.

Well it's good to know you can use 100 clicks although it's too bad you can't get it cleaned and fixed!

I'm intrigued by your description of the issue (bolded above). It sounds almost more like some sort of mechanical binding to me than it does an electrical/resistor issue. If there were a dead spot in the pot I'd sort of expect the servo to just die at that point and then not move any more until you manually moved it away from there by turning the little gears by hand. Alternatively, if it was dirty I'd expect the noisy, jumpy, jittery behavior originally described by Chris H. Have you looked at the mechanics of the servo (drive gear, lead screw etc) closely to see if there is a small burr, dirt, damage etc?


If anyone doesn't have a magnifiers the ones at the link below are inexpensive and work pretty well. They'd be nicer with LED lights but that can be changed if necessary!

http://www.harborfreight.com/magnifi...hts-38896.html

[WonderedUnder]

My heli got the shakes worse and worse to the point where i was scared to fly it anymore. Changed the feathering shaft, main grips, blades.... no change. Did the servo fix and ... VOILA... new heli.

I'm waiting for someone to come up with a more permanent fix than just cleaning... but until then, this is a great tip to keep in mind and horizon is hopefully watching.

[VaderSS]

Well, I did a rebind and, where it was not moving and then jumping, the servo chatters instead.

According to tracking, my new servos made it to the post office at 7 am, so it looks like I'll get them monday. It's still flyable though, so I can get a couple of hours of hovering practice in this weekend.

[Jskrapper]

Looks like I caught the bobble happening on film this time. It starts about 1/2 way through the flight and I bring it in close a few times to see. This is my other mcpx that only has about 35 flights on it and very few contacts with the ground. I did the cleaning and rebind again and it seems ok for now.

[ame]http://www.youtube.com/watch?v=UMv7H3nsEwM[/ame]

[vronny]

Hi guys, my heli had the shakes so I started doing servo cleaning of the little silver strip on the back of board no that wasn't. So tighten the fearthering shaft that wasn't it. By now I'm starting to wonder what the hell is wrong with her. I start to look closer an see the screws that hold the motor on frame have backed out that was the problem no more shakesCheck the screws that hold your motor guys.

[KDXFreestyle200]

My mCPX has this HORRIBLE wobble and the servo seems to be twitching more than normal around mid-stick with the throttle hold on. The thing is almost impossible to fly/hover because it kind of goes where it wants to. i finally got it in a hover and it was in fact, wobbling so badly the landing gear vibrated off! also, I have noticed along with this vibration/wobble, the tail seems to not hold as if the gyro was not in heading-lock mode. is this also a typical symptom of this vibration? I know the tail motor is good. It spools up when rotated to counter act, and spools up when the stick is pushed right. My other question is when you take apart this servo to clean it, do you have to worry about re centering it, or does it automatically re-center when powered up? thanks for the help. p.s. aside from slightly banged up blades, as said in the beginning of the post, EVERYTHING else has been gone through. Main gear (Up and Turned), feathering shaft, blade grips, etc. thanks again

[zeeflyboy]

KDX - Yes, if you have vibration you can expect the tail gyro to be rubbish... that's very normal with gyros.

No, you don't need to re-centre the servo, just pop it back together. Be careful when cleaning the little silver brushes - you don't want to bend them out of the way.

[KDXFreestyle200]

zeeFly.. i cleaned them. WHAT A DIFFERENCE! I am amazed. Twisted my tail prop a little more, and the tail holds unbelievable. i can now grab almost a full stick of positive from nothing (I cant fly inverted yet) It was vibrating so bad that the tail wouldnt hold as I has said before. Also, cause my blades arent the best, I added a piece of scotch tape to one, and that made a big difference too. Thanks for the help. much appreciated

[VaderSS]

Well, after replacing the port servo, I still had a jitter in the starboard one, which cleaning did not fix, so I replaced it and now have smooth flying again.

I'm beginning to think that the servos are going to be a routine maintenance item. I am thinking about gently cleaning them every 40 flights in an attempt to keep them from getting too dirty. Having to replace servos this soon at $20 a pop was not something I was expecting.