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-   -   servo reversing y-harness (http://www.rcuniverse.com/forum/questions-answers-154/10010095-servo-reversing-y-harness.html)

IMaflyer 09-17-2010 11:24 PM

servo reversing y-harness
Putting together a Hangar9 Showtime 50. The instructions recommend a y-harness for connecting the split elevator servos to the receiver. It will be necessary to get a servo-reversing y-harness so that the servos move the right direction. Problem is that there are several kinds out there and I don't know what the difference is between the standard Y-harness, the heavy duty y-harness and the Y-harness with an amplifier. What is the difference between these y-harnesses? The only function I know I need is the servo reversing and the Y. I don't know about the amplifier. Any suggestions?

Thanks for your consideration.




airbusdrvr 09-18-2010 05:58 AM

RE: servo reversing y-harness
You didn't mention which transmitter and receiver you have. If you have an unused channel that can be mated(slaved) to the elevator channel, that would be a much better choice for a several reasons.

jetmech05 09-18-2010 07:26 AM

RE: servo reversing y-harness
Airbusdrv is correct never use a reversing Y on a flight control if you don't have to....if you have a computerized transmitter you should be able to mix elevator to another channel.
Why not a reversing Y? Because they can fail easier than a regular Y and it will cost you an airplane....
It would be better to flip the servo horn over if you have the room

BarracudaHockey 09-18-2010 08:59 PM

RE: servo reversing y-harness
Spektrum warns against using them in their 2.4 installations as well.

carrellh 09-19-2010 09:21 AM

RE: servo reversing y-harness
If your radio does not support the mixing to use two channels for the elevator, you can get a reversed servo and use a regular Y.

Standard JR 537 http://www.horizonhobby.com/Products...ProdID=JRPS537
Reversed JR 537 http://www.horizonhobby.com/Products...rodID=JRPS537R

Less expensive is the Hitec 425 http://www.servocity.com/html/hs-425..._sport_bb.html $15 standard and $25 reversed

If you want more powerful, or faster, servos you can get several different reversed versions form JR; and Servo City offers reversed versions of many Hitec servos.

wahoo 09-19-2010 05:29 PM

RE: servo reversing y-harness
<div><span style="font-family: Verdana, Arial; font-size: 13px; -webkit-border-horizontal-spacing: 1px; -webkit-border-vertical-spacing: 1px; ">If your present radio does not support the mixing of two channels for the elevators, you could use this product.</span></div><div>

DGrant 09-19-2010 07:03 PM

RE: servo reversing y-harness
Just buy the heavy-duty Y w/reverse... I've had one of these in my Hanger9 Edge540 for 8yrs.... it has a potentiometer for micro adjustment to equalize your servos. They work fine.
Not sure about the "amplifier".. and don't even know if they had it when I bought mine... but they've carried the others for years.. and probably for good reason.

Like everyone said though.. if you have the ability to "mix" it in.. thats fine too... I do/did/still do.. but this thing is PNP, and works just as well... and you'll probably be in it just as much money for the leads to run 2 servos.. . whereas with the Y-harness .. you only run one lead to the back of the ship. :)

BarracudaHockey 09-20-2010 10:55 AM

RE: servo reversing y-harness
To the OP (original poster)

What radio system are you using?

IMaflyer 09-20-2010 12:29 PM

RE: servo reversing y-harness
Truly the choices are dizzying. Thank you so much, everyone, for your informative posts and for sharing your knowledge.

I am using a Futaba T6XA-S with an 8-channel receiver. I think the T6XA-S has the ability to mix channels for the elevator; that just means buying a couple more servo extensions. It's no biggie either way-a few bucks for the y-harness or a few bucks for extensions.

I'm not sure where the heightened concern is stemming from in regard to the servo reversing Y-harness. Are they especially prone to failure or something? The truth is that any part of the airplane could fail...even servo extensions. http://www.rcuniverse.com/forum/js/f...used_smile.gif I'm not trying to discount your comments. I'm aware of the possibility that the servo-reversing Ys aren't reliable.

jetmech05 09-20-2010 03:57 PM

RE: servo reversing y-harness
As said above by someone there is a pot for fine tuning the throws on a reversing Y....that is where the problem lies....a printed circuit board in the middle of a wire....or just a wire......
You'll find some folks that will tell you they have never had a problem with a fuel valve...although I think the majority on here will tell you not to use one as it will leak someday....
But it's your airplane....
Good luck

BarracudaHockey 09-20-2010 04:20 PM

RE: servo reversing y-harness
I dont think it has it but if it does, you want to enable AILEVATOR and set the AIL percentage to 0

If you need a P-Mix on that radio, i think its too low end to use linked mixing which means your elevator trim will only be active on the master half.

darrolair 09-20-2010 07:24 PM

RE: servo reversing y-harness
Barracuda has the right answer. The T6XA can only trim the master servo. On .40 or .60 size planes, if there's room just run the servo arms opposite each other (one arm up & one arm down). Use a Y harness and you'll not notice any difference on small planes. Keep it simple.
Good luck,

IMaflyer 09-20-2010 11:35 PM

RE: servo reversing y-harness
So the inherent problem is the reversing function of the Y harness?

The regular Y-harnesses are okay?

Steve Percifield 09-21-2010 05:29 AM

RE: servo reversing y-harness
I've been using reversing Y harnesses for years without any problems. You have a link to the JR harness with the Amplifier in it. This is NOT a reverser and can only be used with JR PCM..

But I have used the others with Futaba, Airtronics and Hitec and have had no issues.

steve o

carrellh 09-21-2010 11:15 AM

RE: servo reversing y-harness
The 6XAS does not support dual elevator servo mixing. It was developed long before dual elevator servos became common.

I do not know if reversing Ys are problematic. I do know you can buy a reversed servo, or reverse one yourelf, and that should not be problematic.

IMaflyer 09-21-2010 11:53 AM

RE: servo reversing y-harness
@carrellh: On the contrary, the manual of the T6XAS has specific instructions on programming a Pmix for dual elevator servos. Having said that, it sounds like Barracuda and Darrolair have tried that and discovered that trimming will only affect the master servo. So I feel stuck between a rock and a hard place.

Here are my options as I see them:
1) Make a leap of faith and use a servo-reversing Y harness.
2) Use regular ole servo extensions and program the radio for dual elevators. Any trim will have to be individually adjusted on the pushrod arm and clevis of the slave servo. This is workable, but feels a little cheesy.
3) Shell out $40 for the Smart-fly Equalizer II. (not going to happen; too pricey)
4) Pull out the soldering iron and reverse the servo myself. I'm leaning heavily towards this option; it will be fun to do some soldering and there is a plethora of informative instruction on the interwebz. Of course since I'm using DS821 servos, I'm not certain it will be as cut and dried as the how-to video I just watched.I'll learn more when I open it up. With this option I can use the standard Y harness I already have.
5) Purchase a reversed servo (What?!? Buy more servos? Uh...no)

IMaflyer 09-21-2010 12:00 PM

RE: servo reversing y-harness
About Option 4, it's out of the question. I just checked another RCU thread about this very question related to the same servo (DS821), and they are apparently mounted directly to the PC board.


Come to think of it, Ido have an extra Futaba standard servo. Any reason I couldn't reverse it and substitute it for one of the DS821s on one elevator half? I'm not crazy about having different torque applied to each elevator half...grrr This is starting to sound like a bad idea.

darrolair 09-21-2010 06:58 PM

RE: servo reversing y-harness
Just get a servo reversing Y and be done with it. They work. I use them. If they were that bad they wouldn't sell them.

carrellh 09-22-2010 07:27 AM

RE: servo reversing y-harness
I use a 6XAS and like it very much but it is fairly basic in its programming abilities.

Just my opinion, regardless of what the manual says, mixing channels without being able to trim them does not equal support of a function. The 72 mhz 7C has the same limitation. The added "real" dual elevator support to the 2.4 ghz version of it.

I would not use the Futaba on one side. The chances of it matching the DS821 throughout the range of travel are very slim.

I'd either pay the $40 for a DS821R http://www.horizonhobby.com/Products...rodID=JRPS821R or buy the 9 dollar Y with reverser.

Probably the 9 dollar Y......

ARUP 09-22-2010 09:41 AM

RE: servo reversing y-harness
Not familiar w airplane but if it is one of those where you mount the servos one the fuse outside surface under the stab then why not mount the servos on their sides? The servo will be facing 'up' on one side and 'down' on the other. Then you wont need a servo reversing 'Y' harness.

OldRookie 09-22-2010 10:45 AM

RE: servo reversing y-harness
Here is another reverser in either a single reverse, or Y reverse. This is the Cadillac of reversers.


I have used one of these in the past and it works great. Not affected by heat or vibration.
I have an extra one new in package if interested.
To reverse one servo I now use a Hitec digital servo, and just reverse it with the the Hitec servo programmer.


IMaflyer 09-22-2010 11:26 AM

RE: servo reversing y-harness
I'm not sure what you mean. The servos are mounted onto the fuselage sides, not vertically. So spinning the servo around won't change anything except the servo output arm would be slightly farther or closer. The arm will still move the same direction. And it doesn't look like the geometry of pointing the servo output arm the opposite way will work.

Now that looks like it's a good solution. I like the length of the Y too. It has a 6" input lead and 12" Y leads. I'm not thrilled about the extra money, but it truly feels like the right way to go.

Crash-RCU 09-22-2010 03:56 PM

RE: servo reversing y-harness
IMaflyer, PM me your address and I will send you a reversing y harmess I never used it, as it made my digital servo jitter. has futaba plug but that can be shavedand I have no instructions but pretty easy to vigure out. The small swew head adjusts the speed of the servo to match the other one. I live down in Kennewick area so you could probably get it by Fri Sat for sure. let me know

carrellh 09-22-2010 04:05 PM

RE: servo reversing y-harness
1 Attachment(s)
I think he means point one servo arm up and the other one down.

daveopam 09-22-2010 04:18 PM

RE: servo reversing y-harness
I have owned three of those reversing Y's. The first two would change the trim on one of the elevs in flight. That makes landings interesting when you run out of Aile trim. The third one I gave to someone I did not like.


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