Airtronics Servos to Futaba FASST Rx
 

Good morning everyone. I'm attempting to convert my 20 yr old GPSportster 40 over to my Futaba 7Cradio. The old Airtronics Rx and servos with Sanwa connectors are currently in the plane, but my new R617FS Futaba Rx is 10g whereas the old Airtronics Rx is 41g (1/4 the weight) PLUSit's 2.4 so that's favorable as well... BUT,here's something I've never had to deal with before... the connector on the old Airtronics servos do not work with the new Rx. I'm assuming the three wires are in different order (i.e. Airtronics S3004 have a red wire at pin #3 whereas the Futaba should be pin #2 - I think).

Anyone have to deal with this?(Obviously some people have... that's why I'm writing in the forum!) Can you offer some instruction or advice? I also notice these old Sanwa connectors are too "thick" and I guess I need to order some Futaba plugs to convert the servos otherwise they don't fit in the Rx. I reckon' Tower Hobbies sells these connectors? I'll go look while waiting for some feedback on this thread...

Thanks in advance for the words of advice....

RE: Airtronics Servos to Futaba FASST Rx
 

Hi Jerome,

A few thoughts.   Changing the servo connectors is no big deal, you can either put new connectors on or get the little 3" conversion connector cables.  But if those servos are the old style plug, they're at least 14 yrs old.  The last servos sold that way are back from 1997.  You'll spend more time messing around with the connectors than you would picking up some new servos.  I can't tell from the photo what servos those are, but servo technology has come a long way to where even the inexpensive servos today are stronger, faster and center better than all but the very top of the line servos from back then.

Also, in this day of all digital, not all of the older analog servos are compatible with 2.4Ghz systems (regardless of brand).  So that's something to be aware of. 

As for the wiring, it's a simple change.   Swap the red and black from the old connectors.  The current servos (all brands are the same now) have the red positive lead in the middle and the black neutral on the outside. 

Hope this helps!

RE: Airtronics Servos to Futaba FASST Rx
 

Right, Irecognize that picking up some new servos is "easy" - but it's at a minimum $65 for four servos. The connectors are $10 from Tower Hobbies.

This would be the deal breaker for sure, then... but I won't know until I get the connectors set up.

There are three wires coming from Airtronics servos; whereas there are two on my Futaba servos. Not sure what the third wire is. Ihave one black with red stripe; then two solid black wires on the Airtronics servos. On the Futaba, there usually is only a red and black - but then sometimes there's a white wire....?




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RE: Airtronics Servos to Futaba FASST Rx
 

There has to be 3 wires.  Even on the Futaba's.  The White wire on the Futaba is the signal wire. The red and black is simply power.  The only futaba wire without a white wire should be the one from the switch harness that's supplying only power to the Rx.

On the old ATX servos, the wiring was Red, Black, Black (nice visual use of color eh??)  Red - Pos, Black - Neg, and Black - Signal.

What servos are they?  94???

RE: Airtronics Servos to Futaba FASST Rx
 

Iguess if I thought about what I was saying a little longer, I would have realized I was thinking about the power switch wires only having two while all the servos having three wires.


Iwill include a close-up picture of the old servos - which must be about 20 years old (circa 1991-1993). Model 94102

UPDATE:added a fun Rx comparison pic too.

RE: Airtronics Servos to Futaba FASST Rx
 

Hi Jerome,
If you do update the connectors on those old 94102 servos they'll work fine with your R617FS receiver. My old 4 Star 60 beater has five of them connected to an R617FS, they'll work fine and last a long time;)
If you're comfortable with splicing on new servo wires with the proper connecters, just splice the white (signal) wire of the new connector to the outer black wire of the servo lead, then just red to red and black to black. Airtronics had the negative lead in the center of the plug, requiring a plug which absolutely could not be plugged in bassakwards, since doing so would let out the magic smoke that servos need to operate:(
Some folks just reverse the center black and the red wires, this will work, but the thickness of the old style Airtronics plug is greater than modern servo plugs, so they may need to be sanded down a bit and mark the signal wire (outer black wire on the original servo lead) with some nail polish, then plug it in with the signal wire closest to the little slot in the case for the standard Futaba "J" connector. All this applies to all modern receiver, even post 1997 Airtronics;)
Best of luck and enjoy flying in the FASST lane[8D].
Pete

RE: Airtronics Servos to Futaba FASST Rx
 

Awesome Pete, thanks for the info! Will give her a shot....

RE: Airtronics Servos to Futaba FASST Rx
 

this pic describes the connectors and how to remove the pins to move the old style atx wires to match modern receivers

RE: Airtronics Servos to Futaba FASST Rx
 

That's a great diagram, thank you very much!

RE: Airtronics Servos to Futaba FASST Rx
 

YOU CAN NOT exchange the older Airtronics black ribbed connectors with Futaba or any other plastic plugs.
The internal pins are different and are locked in differently. To go to Futaba or any other plugs, even the newer
Airtronics "Z", you will need to replace the pins themselves. To do so, you will need a set of pins/plugs and
a crimping tool, such as available from www.cermark.net. Cermark also has adapters from Airtronics to
Futaba or the universal plugs.
The previous info about reversing the positive and negative, red and black, wires is correct.

RE: Airtronics Servos to Futaba FASST Rx
 

The link is actually www.cermark.com

Thank you Eloy.

Update:The adaptor appears to be $3.50 (a little pricey).

RE: Airtronics Servos to Futaba FASST Rx
 

I saved it from one of RCKen's posts. I have quite a few diagrams saved from the years on RCU.

Adapters are expensive. I'd move the pins around in the existing connectors and sand them until they fit the receiver.

RE: Airtronics Servos to Futaba FASST Rx
 

I just did an estimate in ordering 4 adaptors, with shipping - it's $23 bucks. I'm almost at 2 new servos at that price.... so I'm leaning towards what you're saying. :-)

RE: Airtronics Servos to Futaba FASST Rx
 

Sorry but yes you can modify the old Airtronics connector but it takes a bit of work. First exchange the center wire and the red wire. Now, sand or grind off the ribs on the side of the connector body to slim it down to what will fit in the modern receivers, you may have to chamfer a corner or two as well. I have done this successfully on several old Airtronics servos to use on some old beater/trainer planes and am still using them. A better way is to just cut off the old connectors and splice in some modern ones with the proper polarity carefully adhered to (red wire on the center pin).

RE: Airtronics Servos to Futaba FASST Rx
 

The pin swap took less than 30 seconds... and the dremmel tool took off the tabs in less than 15 seconds... so it's a pretty quick operation. SUCCESS!!

UPDATE:Iended up using an extension on each servo so that the plugs would fit neatly into the Rx. I had two 12" Futaba J extensions already, went to the local shop and bought two more at $5 / each. So for $10 bucks Ihave my plane now converted over to my 2.4 FASSTsystem. Now to finish recovering the plane.