maxpower1954

In the old days as most of you guys know, most radios came with at least one servo that worked in the reverse direction from the others (I think Kraft came with two.) With modern radios, say about 1980 on up TX have reverse switches or programming.

Well, that's just too darn easy, I say! I've been flying vintage transmitters on 27 with modern AM receivers and servos (Futaba) with great success - my 1966 Citizen-Ship DPT Transmitter got quite a few comments at the Mid-South meet.

When I've had a situation where I needed to change servo direction, I just did what I did in the old days - reverse the wiring at the pot on the stick, and re-center the servo. The problem with this method is unless you are amazingly lucky, you can only use that transmitter with one model.

What I would like to do is modify a modern Futaba servo for reverse direction. You radio guys out there - if I reverse the polarity at the servo motor and swap the red and black leads where they exit the circuit board that should do it, right? Help! Russ Farris

Dr1Driver

No, no, NO!!! If you reverse the black and red leads going into the servo, all you'll do is fry the circuit board.

A lot of servos now-a-days have the motor and feedback pot hardwired to the circuit board. These are extremely difficult to reverse.

If your servo has loose wiring from the pot and motor to the board, it's a little easier. Reverse the motor wires and the two outside wires of the feedback pot. I understand "doing it yourself" for the gratification. However, for the effort involved and the TINY spaces you'll have to work in, I'd either buy a commercial servo reverser or do as you suggested, reverse the stick wires.

Dr.1

maxpower1954

Well, at least I had the sense to post this question before I did something stupid! Actually, on reflection I already figured out reversing the wires to the amplifier would fry it.

Yep, the feedback pot is hard mounted to the board and so is the motor (Futaba S148.) Russ Farris

8178

My Feedback: (17)

The best solution rather than messing up the TX would be a servo reverser. There are a number available like this one http://www2.towerhobbies.com/cgi-bin...?&I=LXAFN1&P=0

JohnBuckner

My Feedback: (1)

The simplest solution is to just use a Hitec servo, any version. Hitec and Futaba servos are reversed from each other by factory default.

John

8178

My Feedback: (17)

But Futaba is the only servo that I know of that has output wheel splines offset so you can adjust the wheel to compensate for the pulse width of the old AM TXs.

aerowoof

or build your own
http://www.cliftech.com/html/pdf.html

GerryGerry

I have successfully modified a 148 servo by de-soldering the motor, turning it 180 degrees and soldering it back on. Then I cut out about 4mm of the two outside pot legs and cross soldered them using 2 very small lengths (7mm approx) of thin wire. this worked well, but I was not happy with the pot being supported by just the central leg, so I glued (with epoxy) an appropriately cut down matchstick underneath for added support. The whole mod took around 20 mins to complete and just requires a steady hand.

Hope this helps others

Dr1Driver

A cut-down matchstick supporting the controls of a $400 plane. Wonderful. How penny-pinching can we get here?

Dr.1

Gremlin Castle

My Feedback: (14)

In this case. it is the execution rather than the pedigree that is important.

GerryGerry

If the modification is done by a competent modeler, the finished result will be stronger than the original! We all use cheap components to hold together our planes such as cyno .... and I think in my case my modified servo will be more reliable than most of the shelf servo reverser's coupled with a servo. Its not penny pinching, its tinkering to achieve the best results without unnecessary components.