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Reversing Futaba Servo

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Old 03-16-2002, 12:31 AM
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Charlie H.
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Default Reversing Futaba Servo

Hi Guys
I need to reverse a Futaba 9202 servo,can this be done without using a servo reverser or can you buy one from Futaba ?

Thanks Charlie
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Old 03-16-2002, 03:27 AM
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LYLE "D".
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Default Reversing Futaba Servo

Can't you just put the control horn on the other side of the movement??
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Old 03-16-2002, 03:54 AM
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Default Reversing Futaba Servo

It is laying flat in a wing for a flaps,one for each side.
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Old 03-16-2002, 12:02 PM
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Default Check These Out

Just isn't as easy as it used to be


http://www.bestrc.com/hobbies-bin/futaba-search.pl

Can I purchase a reversed servo? or can you reverse an existing servo?
Unfortunately, no. Futaba servos cannot be reversed because of the surface mount technology used. However, there are servo-reversing servo leads, extensions, y-harnesses, etc, available from a variety of companies (Futaba does not offer an inline reverser at this time). If you are using PCM, be sure the unit you buy is compatible, as some are not.
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Old 03-16-2002, 01:46 PM
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Default Reversing Futaba Servo

Yes you can reverse the servo by switching the motor leads at the motor and then switching two of the three leads at the servo pot. Leave the center lead on the servo pot alone. You should not attempt this if you do not feel confortable with soldering. I am assuming that you do not have access to a computer radio.

Not all Futab servos use the surface mount techonology, some do, some don't.

Vince
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Old 03-16-2002, 05:04 PM
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Default Reversing Futaba Servo

The 9202 servo has no leads to reverse. The circuit board extends over the motor and the board is soldered directly to the back of the motor. The pot also is not wired but has long mounting legs extending to the board.

I believe the 9201 (same spec as 9202) was the previous model and it does have motor and pot leads which can be reversed. Check it out first????

For what it's worth - Al
http://www.rchelibase.com
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Old 03-16-2002, 11:28 PM
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Default servo

if ya have room just mount them so they are facing in the same direction......
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Old 03-17-2002, 12:04 AM
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Default Reversing Futaba Servo

Is it even possible to reverse a coreless motor?
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Old 03-17-2002, 12:25 AM
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Default Reversing Futaba Servo

Originally posted by ftomteen4cat
Is it even possible to reverse a coreless motor?
No, if it is mounted directly to the pc board.

Vince
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Old 03-17-2002, 01:12 AM
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Charlie H.
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Default Reversing Futaba Servo

Thanks guys for your input.I will try to come up with a different mounting.

Charlie
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Old 03-17-2002, 02:05 AM
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Default Reversing Futaba Servo

One solution might be to buy a couple of Hitec 605 or 605MG. They work fine on the flaps on my Ziroli Corsair and are easy to reverse by swapping the motor and outside pot leads. The screw holes might be pretty close.

Ken
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Old 03-17-2002, 02:37 AM
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Default Reversing Futaba Servo

Originally posted by Vince


No, if it is mounted directly to the pc board.

Vince
Mounted or not.. you could always rework the PCB. The reason I ask is because switched-field brushless motors such as those found in fans will not operate backwards, period.

Anyone tried it?
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Old 03-18-2002, 03:17 AM
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Default coreless reversing

There is no reason a coreless motor cannot be reversed if you can get at the connections. It works the same as any other DC motor. Even a brushless motor can be reversed if you can get at the connections. A brushless motor is really a three phase AC motor but you can change the rotation of the rotating magnetic field by changing the connections.
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Old 03-18-2002, 06:15 AM
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Default Reversing Futaba Servo

There are different types of brushless motors. The type you refer to are the likes of which you find for electric planes that have three wires coming out of them. A switched-field motor would really take some hacking to reverse the direction. You'd have to reroute all the drive Q's or drive IC output. It could be done, but you're talking board surgery here. Often, the motor will have just two wires, and hooking it up backwards yields nothing.

I can't get to my coreless motors, so I don't know what they look like. They seem potted in there pretty good.
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Old 03-18-2002, 06:21 AM
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Default Reversing Futaba Servo

Depending on the type of position sensing used to time the fields you may have to hack that too.

Saying it's impossible was a bit strong. I'd say it was out of the question though, at least for me.

So I guess my question is, are coreless servo motors this type of brushless motor?
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Old 03-18-2002, 05:07 PM
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Default Reversing Futaba Servo

Gentlemen, coreless motors are reversable. The coreless design where the armature is a epoxied drum of windings around a fixed magnetic core is used to speed up the motors response by reducing the mass of the armature to a minimum.

Look at it this way, if your coreless motor was not reversable, then your servo would only go around in one direction!

For what it's worth - Al
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Old 03-18-2002, 05:33 PM
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Default Reversing Futaba Servo

That answers that!

It seems obvious now.. what was I thinking?
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Old 03-19-2002, 07:04 AM
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Default Now you've gone and done it!!!

I have reversed many servos over the years, as well as modified them to turn a full 360 degrees (nice for propelling and turning a blimp!) over the years. Haven't done it in a while, because I haven't had the need....

I've got about 20 9202 servos. I will take one apart in the next couple days, and make the supreme sacrifice, and attempt to reverse one (I'll find a use for it, someplace) and report back here. I think it could be done, but I will let y'all know if it's possible, and if so, how hard it would be for the average person to accomplish. If it's really touchy, I will probably post it on my website, with instructions...

As for qualifications, I am an Electronic Technician, with a fair amount of SMT experience....

I LOVE a challenge!!!
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Old 03-19-2002, 06:03 PM
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Default One more way to reverse

I use a Futaba 8U transmitter and when I need to reverse the direction of a servo, such as two elevator servos mounted in the tail end of the fuselage, I use the method shown as the second item under 8U FAQs in the following link.

http://www.futabarc.com/faq/

This involves using the P-MIXES and linking channels. In one case, I use Ch 2 (elev) mixed to Ch 8 with the channel 8 knob turned off and Ch 8 reversed. Mixing the flaps this way would be easy if you have a computer radio with this functionality. Sure beats dragging out the old soldering iron.

Ken
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Old 03-19-2002, 06:41 PM
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Default Reversing Futaba Servo

Yeah, but without programmable radios, or enough channels, sometimes it's nice to have one reversed, where you can just "Y" them together - The Cap I just bought is that way, and it's kinda nice having another channel freed up...
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Old 03-21-2002, 09:13 PM
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Default Reversing Futaba Servo

Roger,
You can simply buy a servo reversing Y-harness. One servo commanded the normal direction, the other servo's command is reversed.

for details on these email support@futabarc.com and put "how do i reverse a servo" in the body of your email.

Sincerely,
Mrs. AnnMarie Cross
Senior Manager, Proprietary Service and Support
Great Planes Model Distributors
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Old 03-22-2002, 05:06 PM
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Default Servo reversing

MS Cross
There are those of us that prefer not to add the complex servo reversing Y harness. It has been known to cause problems with the radio.
Using the Ailevator function on my new 9C, I was also disappointed to learn that I cannot use the flaperon or other related built in wing functions when ailevator function is active.
It would be nice to be able to reverse a servo like you can with a Hitec.
What is needed is a built in elevator function to provide a reversed servo output without affecting the other functions or a simple means of reversing a servo.
PS I knpw I can also waste two p mixes to reverse the servo.
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Old 03-22-2002, 05:49 PM
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Default Reversing Futaba Servo

Hi Dirtybird!
The new Futaba servo reverser y-harness has passed every test we through at it and has never missed a beat. If you've had problems with others in the past, it's an easy solution I'd recommend.

Where did you hear that you can't use flaperon with ailevator? Perhaps you misread hte information? it is ELEVON That will not allow flaperon or aileron differential because you can have only one type of aileron control at a time. My apologies if something I wrote was unclear on that.

Sincerely,
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Old 03-22-2002, 06:07 PM
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Default servo reversing

OK I was wrong about not being able to use the Flaperon with ailevator.
I still think a reversable Y harness is a complex and expensive way to reverse a servo when it can be done by simply reversing the connections. There are plenty of things to go wrong without adding more failure prone components. A Y harness is not in a protective case. Parts that must be used in such a circuit are not designed to fly about in the tail or wing of an aircraft. I doubt that you have gone to the expense on making an IC for your Y harness.
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Old 03-22-2002, 06:13 PM
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Default Reversing Futaba Servo

Well, I said I'd do it - try to reverse a 9202. Well, they definitely DON'T want you in there! They are very tough to get the guts out, and not worth doing for the average modeler, in my opinion. I did it, and could reverse it, but not with an EXTREME amount of pain and trouble - plus, I would be concerned for the integrity of the servo when I got done...so I recommend not attempting it...

However, I found a "brew your own" reverser website, that I am going to use to build my own. It looks like the fellow has spent quite a bit of time, developing this...here's the url:

Servo Reversing Circuit

here's another website, with all kinds of goodies, that those of you who enjoy "tinkering" will like:

Electronics Projects for R/C

Like everything else involved with R/C airplanes, I recommend that you have a good amount of knowledge if you attempt these projects, that you thoroughly test them, range check with and without motor running, and everything else you can do to make sure they are working at 100%...
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