View Full Version : Servo Problems

2010.07.08, 01:06 PM
As of about 2 weeks ago, my servo has been acting up. Guessing that there was just something stuck in he gears or something, I completely disassembled it. I found nothing wrong so I put it back together and I still have the same problems. There is a buzzing sound when I'm not turning, like when idling. and when I do turn, it gets much louder. also, at about 3/4 turn, it sticks, then twitches to a full turn. Do I need a new servo? What could be causing this.

2010.07.08, 03:39 PM
I think the feedback potentiometer of your servo is dirty if not needing replacement.

Try to clean it first with an electronic contact cleaner and see if it improve. If it does not improve, then you might need to get a replacement.

2010.07.08, 04:41 PM
Alright, Thanks, could you link me to a servo? For the meantime, it doesnt cause many problems during racing.

2010.07.11, 07:40 PM
Anyone have an idea of what is causing this?

2010.07.12, 01:32 PM
hi , i had problems with servo too. i've open it and it broke some pastic wheels ( dont know how to call it inside the servo ) . i dont see for sale replacement wheels , anyone knows where to buy it ?

2010.07.12, 02:26 PM
Sounds like you may have stripped a gear tooth in the servo gearbox.The part number according to the MR03 manual is MZ404.This set will replace all of the gears and 3 pins in the servo gearbox.

2010.07.12, 06:03 PM
Check wires to see if they are free.

I had some similar problems with my 02s as they
just didn't like particular settings. Haven't had
those problems with 03s but that might be something
to look for.

Also, the servo may not be centered correctly either
through a slight bump or by reinstalling it improperly.
If you recentered it (while off) by hand with the tierod,
you may have thrown the pot off a little to one side.

Try reinstalling the set up again with care of getting
the pot as close to center as possible. Only set the
trim by the controller and not by manually pulling the

Hope it works out.


2010.07.12, 10:12 PM
I totally disassembled it though, made sure NOTHING was wrong and checked everything you guys just said. should I order those parts that nitrojunkie said? I just need to fix this, i have a race on the 24th and want my car working well. instead of buying the same plastic gears and pins, dont they have aluminum ones? I though i remembered hearing about them. so I will replace those, and then skvora recomended resetting the controller, would this work?

2010.07.13, 04:13 AM
Look at this thread and see if it is any help.The pot could be off centered just a bit also.http://mini-zracer.com/forums/showthread.php?t=34040

2010.07.13, 03:02 PM
im not having any problems with broken gears so that thread didnt help me much. thanks though. should I just replace all those gears?

2010.07.13, 05:00 PM
if the gears are not broken, have you checked the feedback potentiometer if it was working (properly giving the needed resistance)? you will need an ohm meter to check this.

when the surface of the potentiometer have been "scratched out" due to wear-and-tear it will have erratic resistance at that portion...so you will experience the one you just did.

2010.07.13, 05:24 PM
Ill look and see if it is scratched up. I am away from home until Saturday so are there a couple thingss that you could tell me to look out for? I know none of the gears or pins are broken.

2010.07.13, 07:02 PM
well without opening the potentiometer:

There is a possible problem with it if you attach the middle and one of the side prongs to an ohm meter and it yields an "eratic" resistance when you turn the potentiometer. The resistance reading should be "smooth" when you turn the pot. the presence of an eratic reading would likely be the one that causes the sudden twitch to full turn that you are observing.

this eratic resistance could be due to the "scratched" surface of the potentiometer OR there's dirt inside the pot that causes a "short" in the surface. in cleaning I use electronic contact cleaner if available and if not I use cotton buds dipped in rubbing alcohol, and if you can put back some electronic grease to improve contact again it would be a good option too.

if this does not work, you might need to replace the potentiometer.

2010.07.13, 09:29 PM
alright. I dont currently have an ohm meter although I do know how to use one so Ill see if i can get ahole of one. Ill try cleaning it first. Could you link me to the potentiometer? If I do need to buy a new one, I want to be able to order it as soon as i need. Thanks

2010.07.14, 05:01 AM


i am not just sure if MR03 pot is the same :(

2010.07.14, 07:56 AM
Let's hope it is. When I get back ill compare the pictures in those links to mine. Thanks for the links, at least those things are cheap. Is there any possibility that the actual servo is bad? Also I still can't find the aluminum servo gears online.

2010.07.14, 11:38 AM
Please update if you have found the aluminum servo gears online, I think I need them too.

2010.07.14, 05:10 PM
IMO the only way that the servo electronics will go bad is when you replace the servo motor and it does not match the load capacity .... where you will actually burn the servo "fets".

There is a topic somewhere in this forum that have discussed this issue - http://mini-zracer.com/forums/showthread.php?t=32093

your servo wouldn't be working at all if that was the case.

I also don't know if I should consider your case a tx glitch because 2.4Ghz tx shouldn't have the glitch problem... but then again I am not really well verse in electronics... if by any chance that your case was a tx glitch .... the addition of a 104 ceramic capacitor between the positive and negative pole of the servo motor should correct the problem.

2010.07.17, 10:13 PM
so what would you suggest me to do? i cant find out how to reset the kt18. i know you said its probably not the problem, but i still want to try it. can you find me a link?

2010.07.18, 06:35 AM
Please update if you have found the aluminum servo gears online, I think I need them too.


Part # MZW417-T01

2010.07.18, 06:53 AM
so what would you suggest me to do? i cant find out how to reset the kt18. i know you said its probably not the problem, but i still want to try it. can you find me a link?


see page 10

2010.07.18, 11:56 AM
That store just shows a single brass gear.
Thats the guide for pairing it. Thats not resetting it, is it?

2010.07.18, 09:41 PM
page 10 is a reset procedure (soft reset I think)