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Chattering servo, please help - 9/18/2012 2:41 AM

rc-sport

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OK, I'm going insane here. I have a GP Reactor bipe and it has 4 aileron servos. Spectrum mini's. I'm using a Spektrum 7200 receiver. I have the right servos on the aileron channel and the left sevos on Aux 1 channel. The upper and lower halves are connect via a Y connector.My problem is one of the servos chatters, just one. The chatter stops if I disconnect any of the other aileron servos. I tried changing the chattering servo, changed the receiver, changed the Y fittings and I have eliminated the servo extensions by soldering in twisted wire lengths. I'm running a 6 volt NiCad pack so I'm getting plenty of power. I'm at my witts end trying to troubleshoot this problem, please help.

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RE: Chattering servo, please help - 9/18/2012 2:53 AM

BuschBarber

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quote:

ORIGINAL: rc-sport

OK, I'm going insane here. I have a GP Reactor bipe and it has 4 aileron servos. Spectrum mini's. I'm using a Spektrum 7200 receiver. I have the right servos on the aileron channel and the left sevos on Aux 1 channel. The upper and lower halves are connect via a Y connector.My problem is one of the servos chatters, just one. The chatter stops if I disconnect any of the other aileron servos. I tried changing the chattering servo, changed the receiver, changed the Y fittings and I have eliminated the servo extensions by soldering in twisted wire lengths. I'm running a 6 volt NiCad pack so I'm getting plenty of power. I'm at my witts end trying to troubleshoot this problem, please help.

Have you tried a 4.8v Rx battery pack? Are the servos 6v compatible? Are you using any Reversing Y's? Have you tried just one servo in the Ail channel, one servo in the Aux1 channel, and tested all 4 servos that way? Have you tried a JR Matchbox instead of two Y Harnesses?

What Tx are you using?

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RE: Chattering servo, please help - 9/18/2012 3:44 PM

kevenoco

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The chattering stops even if you disconnect one of the servos on the other wing and hence into another servo port on your Rx? It sounds like you've really isolated everything. I would check with Horizon at this point. One other thing, try holding the Tx several feet away from the airplane.

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RE: Chattering servo, please help - 9/18/2012 10:28 PM

rc-sport

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quote:

ORIGINAL: BuschBarber

quote:

ORIGINAL: rc-sport

Have you tried a 4.8v Rx battery pack? Are the servos 6v compatible? Are you using any Reversing Y's? Have you tried just one servo in the Ail channel, one servo in the Aux1 channel, and tested all 4 servos that way? Have you tried a JR Matchbox instead of two Y Harnesses?

What Tx are you using?

I have not tried a 4.8v battery because the servos are 6v compatible. I am not using reversing Y's. I have not tried each servo individually, it's worth a try. the weird thing is if I unplug any of the aileron servos the chattering servo stops. If leave all four aileron servos plugged in and unplug all of the other channels the one servo still chatters. I'm using a DX7.

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RE: Chattering servo, please help - 9/19/2012 6:02 PM

Franco2fly

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Seems to me that the chattering servo doesn't like something. If it is always the same servo, no matter where you put in in the wiring scheme, I would go purchase a new one. Maybe if you have a real friendly local hobby store, you could take the bird in and have them loan you an additional servo that you could substitute.

One other thing to be aware of is the Current draw, NOT the voltage. When you do your testing, do you also have Rudder/Elevator/and Throttle hooked up? Current draw for all 7 servo's will be significant, even if they are in idle condition. What's the milliamp rating of your power pack?

Just my 2cents

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RE: Chattering servo, please help - 9/20/2012 6:28 PM

rc-sport

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I did swap out the servo and I get the same thing. I tried disconnecting all the other channels and the chattering continues.. I'm stumped

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RE: Chattering servo, please help - 9/20/2012 6:40 PM

RonR214

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Is the chattering always in the same positions, i.e., lower right, or does it move around? How long are the servo extensions assuming that you are using extensions. Do the wires from the chattering servo run close to the ESC? You may be operating on 2.4, but noise can enter the system through the output wiring.

Very curious to see what the results of this are. Good luck.

Ron

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RE: Chattering servo, please help - 9/20/2012 8:04 PM

Len Todd

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Y-connectors in my plane's ganged servos (i.e. two per Aileron) would not work, with Hitec's Digital Servos. I ended up using Smartfly's Equalizer IIs (i.e. one for each bank) instead of Ys and the servos immediately acted correctly w/o any further circuit modifications. The Equalizers take the place of a Y harness. As I understand it, you can't use Ys on digital servos. ?? Analog servos are "communicated with" in a serial manner (i.e. one at a time.) Digital servos can also be "communicated with" in a parallel manner (i.e. all at the same time.). Thus a Y does not work. So goes the explanation that I got, and I am not sure got the correct or whole story here. But the Equalizers solved my problem.

Also, if you gang any type servos, you should put a current meter on the first servo downstream from the receiver and then adjust the next downstream servo's linkage such that the current on the first servo drops to Zero (or minimum) milliamps. Otherwise, you have servos fighting each other at the mid-point which will cause some chattering and excessive noise, and excessive battery drain, etc. Actually, you also should match up your control surface's travel end-points too, to ensure the current used on the first downstream servo is at a minimum when the control surface is at maximum travel. Otherwise, the ganged servos are fighting each other out at the endpoints. The Smartfly Equalizer IIs are designed to accomplish mid-point and end-point balancing. However, I found that if you get the servos right at the mid-point, on my plane, they were very close at the end-points. But, it took the Equalizers to get the ganged servos working correctly in the first place, so they were worth the extra expense.

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RE: Chattering servo, please help - 9/20/2012 8:46 PM

BuschBarber

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quote:

ORIGINAL: Len Todd

Y-connectors in my plane's ganged servos (i.e. two per Aileron) would not work, with Hitec's Digital Servos. I ended up using Smartfly's Equalizer IIs (i.e. one for each bank) instead of Ys and the servos immediately acted correctly w/o any further circuit modifications. The Equalizers take the place of a Y harness. As I understand it, you can't use Ys on digital servos. ?? Analog servos are ''communicated with'' in a serial manner (i.e. one at a time.) Digital servos can also be ''communicated with'' in a parallel manner (i.e. all at the same time.). Thus a Y does not work. So goes the explanation that I got, and I am not sure got the correct or whole story here. But the Equalizers solved my problem.

Also, if you gang any type servos, you should put a current meter on the first servo downstream from the receiver and then adjust the next downstream servo's linkage such that the current on the first servo drops to Zero (or minimum) milliamps. Otherwise, you have servos fighting each other at the mid-point which will cause some chattering and excessive noise, and excessive battery drain, etc. Actually, you also should match up your control surface's travel end-points too, to ensure the current used on the first downstream servo is at a minimum when the control surface is at maximum travel. Otherwise, the ganged servos are fighting each other out at the endpoints. The Smartfly Equalizer IIs are designed to accomplish mid-point and end-point balancing. However, I found that if you get the servos right at the mid-point, on my plane, they were very close at the end-points. But, it took the Equalizers to get the ganged servos working correctly in the first place, so they were worth the extra expense.

Hitec Digital servos are Programmable. You can Match these servos and use them with a Y Harness if desired. I do not use Y's, but others do.

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RE: Chattering servo, please help - 9/20/2012 9:02 PM

Len Todd

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I know my Hitec servos are programmable, and I suspected that they could have been individually programmed to work together. But, as I understand it, that requires a programmer and/or the knowledge of how to program one, etc.. To me, the Equalizers seemed like a lot easier fix, seeing how I only had the one plane with ganged servos. Also, if I recall correctly, the pair of Equalizers were about the same price as just the Hitec programmer. Also, at this point in time, programming an individual servo is "Greek" to me.

So back to the OP's problem, ... Maybe they can be/need to be programmed to work together on a Y harness. ??

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RE: Chattering servo, please help - 9/21/2012 11:39 AM

Franco2fly

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RC sport,
I think we are getting closer, but I'm struggling to understand your wiring configureation. As I understand the chattering problem, you have
been able to determine the following:

1. that it is NOT due to a specific servo - you've swapped out the original servo
2. It is not an amperage problem, or current draw - all other servos were disconnect so only one servo drawing current
3. it is not wire placement - ie. the servo wire is not next to the ESC or any other noise source

This leads me to believe that something in the programming of the transmitter is flakey causing pulses to jitter, or the receiver itself has a bad output on this specific channel.

So for testing purposes, you need to swap out the receiver or try the same set-up using someone elses transmitter.

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RE: Chattering servo, please help - 9/21/2012 1:21 PM

Len Todd

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I think he said he already swapped the receiver. I kind of thought we were down to the servo programming necessary to allow digital servo ganging with a Y or using something other than a Y to avoid programming, etc.. But maybe he does not have digital servos. ? Or maybe it is just the linkage adjustments have the ganged servos fighting each other. He did not indicate that he balanced the ganged servos with a milliamp meter. How could a transmitter setting cause the effect he is seeing? Just trying to learn here.

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RE: Chattering servo, please help - 9/21/2012 3:35 PM

Franco2fly

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This problem reminds me of a Hardware Engineer that I highly respected and worked with many years ago. His term for these kinds of problems evoked this response, "I don't have a 3000mile long screwdrive to assist you with your problem." Here, we are lacking that
close up eyeball on the situation to determine what is and isn't hooked up. He states that he is using four Spectrum Mini servo's, two one each side. The right side is "Y'd" goes into Ail channel, the left side is "Y'd" goes into Aux1.

Seems to me the first step should have been just use two servos, Right side, and Left side. If you have a chattering servo, in this basic set up, there's something wrong, if not proceed, by adding ONE "Y". (three servos now, 2 on left one on right.) No chattering, move that "Y" to the other side., No chattering remove that Y and repeat the previous steps.

I'm guessing that the real problem is in one of those connectors.

KKKKFL

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RE: Chattering servo, please help - 9/22/2012 1:48 AM

rc-sport

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quote:

ORIGINAL: Franco2fly

RC sport,
I think we are getting closer, but I'm struggling to understand your wiring configureation. As I understand the chattering problem, you have
been able to determine the following:

1. that it is NOT due to a specific servo - you've swapped out the original servo
2. It is not an amperage problem, or current draw - all other servos were disconnect so only one servo drawing current
3. it is not wire placement - ie. the servo wire is not next to the ESC or any other noise source

This leads me to believe that something in the programming of the transmitter is flakey causing pulses to jitter, or the receiver itself has a bad output on this specific channel.

So for testing purposes, you need to swap out the receiver or try the same set-up using someone elses transmitter.

Yes I did try a second receiver and I even swapped out the servo. The problem still existed. I'm running a 5 cell 2000ma pack so power shoulden't be the issue. I even disconnected the rudder, elevator and throttle servos. The problem only exists when all four aileron servos are hooked up together. Horizon Hobby's tech support is baffled also.

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RE: Chattering servo, please help - 9/22/2012 1:52 AM

rc-sport

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quote:

ORIGINAL: Franco2fly

This problem reminds me of a Hardware Engineer that I highly respected and worked with many years ago. His term for these kinds of problems evoked this response, ''I don't have a 3000mile long screwdrive to assist you with your problem.'' Here, we are lacking that
close up eyeball on the situation to determine what is and isn't hooked up. He states that he is using four Spectrum Mini servo's, two one each side. The right side is ''Y'd'' goes into Ail channel, the left side is ''Y'd'' goes into Aux1.

Seems to me the first step should have been just use two servos, Right side, and Left side. If you have a chattering servo, in this basic set up, there's something wrong, if not proceed, by adding ONE ''Y''. (three servos now, 2 on left one on right.) No chattering, move that ''Y'' to the other side., No chattering remove that Y and repeat the previous steps.

I'm guessing that the real problem is in one of those connectors.

KKKKFL

That's exactly my set up. The weird thing is nothing happens until the fourth servo, any servo is hooked up. The minute I unplug a servo it stops. I even unplugged the elevator, rudder and throttle servo to make sure it wasn't a current draw issue.

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RE: Chattering servo, please help - 9/22/2012 3:04 AM

Len Todd

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I solved this with two Smartfly Equalizer IIs. Are those digital servos? What number are they.

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RE: Chattering servo, please help - 9/23/2012 1:29 AM

rc-sport

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They are Spektrum A5030, yes they are digital.

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RE: Chattering servo, please help - 9/23/2012 2:28 AM

Len Todd

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As I understand it, some ( maybe all) digitals will not work on a Y w/o programming the individual servo(s). I had the same problem with two ganged servos on a Y. I just used Smartfly Equalizer IIs to eliminate the Ys and the problem went away. If I had the programmer, I may have tried programming first. I am not trying to sell you the things. I just am telling you what I did to eliminate the same problem.

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RE: Chattering servo, please help - 9/28/2012 4:56 AM

chuckk2

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Does the chattering servo stop chattering when you place your finger on the control surface or servo arm?
By chance are you using the 11ms frame rate?

What happens when you swap aileron channels between Ail and Aux 1 or whatever the second aileron channel is?
Even with a decent battery, the current pulses from other servos can add noise. This can do some strange things.
Also, use a bit of alcohol and clean the connector pins.I had a battery pack that tested OK, then failed intermittently
under load. Turned out that there was some crud on one of the mating pins.

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RE: Chattering servo, please help - 9/28/2012 5:45 AM

dirtybird

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I don't know how the spectrum system works. If when you mix the ail channel with the aux channel the pulse is routed to the aux channel directly the problem could be the pulse is loaded to the point where the pulse amplitude is reduced and it will cause a servo to chatter.
It seems that all servos would chatter if that were the case. I am just guessing.

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RE: Chattering servo, please help - 9/30/2012 8:50 PM

rc-sport

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quote:

ORIGINAL: chuckk2

Does the chattering servo stop chattering when you place your finger on the control surface or servo arm?
By chance are you using the 11ms frame rate?

What happens when you swap aileron channels between Ail and Aux 1 or whatever the second aileron channel is?
Even with a decent battery, the current pulses from other servos can add noise. This can do some strange things.
Also, use a bit of alcohol and clean the connector pins.I had a battery pack that tested OK, then failed intermittently
under load. Turned out that there was some crud on one of the mating pins.

I'm not sure what you mean by 11ms frame rate. The servo continues to chatter even under load. I'm using both Aileron and Aux 1 channel

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RE: Chattering servo, please help - 10/1/2012 6:37 AM

chuckk2

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ODD! The Spectrum web site lists an AR7200BX, which is a heli specific receiver with stabilization.

If the 7200 you have is a discontinued receiver, it's likely a DSM2 receiver.
The 11ms refers to two possible frame rates in DSMX, and with say a DX8 TX.
Generally, analog servos must use a 20-22 ms rate, and some digital servos work with either 11 or 22ms rates.
It can get really aggravating when you look up digital servo specs, and they don't bother to say if the servo works on both.
Then, you have to assume that the 22ms rate is the correct one.

I have no bloody idea what would happen if you tried to use a flybar less heli receiver with beastX in an aircraft!

Short of using an oscilloscope to troubleshoot, I'd guess that - - -
Noise on the receiver power buses or signal line
Poor connections
not enough current/voltage from the battery

There are some things to try
Adding a 570 to 1000mf cap at the receiver power connector
Using a battery that can supply at least 3A without significant voltage drop, or a 3 to 6A BEC and a higher voltage battery (usually a LiPo).

A servo tester might be powered from the receiver channel with the receiver signal line disconnected, and the servo testers output connected to the servo. If this stops the chatter, it's likely that there is jitter or noise on the receiver signal line.

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RE: Chattering servo, please help - 10/3/2012 11:51 PM

rc-sport

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I Made a mistake it's an AR7000 receiver. At this point Ive had to put the problem aside because all it's done is drive me mad. It'll have to sit until spring

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