Conference vmszoo::rc

  < I don't think that you can use the S28 servos(the most
    common servo Futaba makes) with the higher prices PCM Futaba systems.
    
    I have checked with the local Futaba expert and the facts are:
    	Any Futaba servo will work on any Futaba radio, except the AM
    	plugs are different to the FM plugs, change the leads and they
    	work ok.
    
  < You could probably cut off the Futaba connector on an S28 and solder
    on a JR and it would probably work. WHY BOTHER? 

    If you use JR and Futaba FM servos (say Futaba S121 and JR 8001)
    the connectors can be swaped without using an iron. The connectors
    will slip off if you use a pin to lift the retaining strips. 
    
    WHY BOTHER?. I have a box full of 121's and 8001 retail in Australia
    for around $120 each. Good reason.

Found this information last night and thought it may be of interest. Note that 
KO is a potential trap for young players with a black signal wire.

John.
-----------------------------------------------------------------------------
Wiring Diagram of Various Servo Connectors

Please add to this list.

Futaba
-----------
|         |----o Signal
|         |----o + Red
|         |----o - Black
-----------

JR
-----------
|         |----o Signal
|         |----o + Red
|         |----o - Brown
-----------

Sanwa
-----------
|         |----o Signal
|         |----o -
|         |----o + Red or White line
-----------

KO
-----------
|         |----o Signal Black
|         |----o -
|         |----o + Red
-----------

Yes, that's correct for most radios made in the last 10 or so
years.  As I've remarked before, most even use the same chips to
generate and decode the signal.  If your radio is made by a
well-known manufacturer, such as Futaba, you're safe.  Be careful of
the wiring.  If you state which servos you have, and which receiver
you want to use, chances are that someone here will have the correct
wiring changes.  There are already some posted in an earlier note.

    Re: last
    
    Kay,
        I know that this has been discussed elsewhere, but I'm still
    a bit fuzzy about JR vs Futaba connectors.
    
    My simple question is: can I use a Futaba servo (Connector) with
    my JR receiver ?  , and, I'm still confused about the wire color
    coding.  A little light please.  (Or tell me where I can find more
    in theses Notes files).
    
    Thanks,  John

    John,
    	I can't speak for servos but most of the guys in my club run
    Futaba G154 gyros with JR radios. This gyro has the FM connector.
    To install we trim off the alignment key that's on the connectot
    and then bevel the corners to fit the JR. The white wire of the
    Futaba ends up where the brown wire is on a JR.
    
    maybe this helps?
    
    Tom

    John,
    
    To add a bit more clarification, the [almost] compatibility between
    Futaba and JR _requires_ that the Futaba connectors be the FM or "J"-
    series type...Futaba AM connectors will NOT work with JR.  JR
    connectors will fit unmodified into Futaba receptacles but there's no
    polarizing keys so you must be very respectful of proper polarity.
    
    As Tom says, to fit a Futaba connector into a JR receptacle, you must
    trim off the polarizing key from the FM/"J" style connector and,
    perhaps, break (bevel) the corners (easily done by scraping with the
    edge of a no. 11 X-Acto blade).  Again, this eliminates automatic
    polarizing of the connector so be mindful of proper polarity EVERY time
    you plug in.
    
    I know this to be good info as I got it directly from Dan Parsons who
    has had occasion to fly his Hornet (w/Futaba servos) with a JR receiver.
    I've not had the need to do this so I'm not positive of what constitutes
    correct polarity and will yield to Tom or any other informed noter on
    this particular of the swap. 
						 __
				|      |        / |\	   	       
      	         \|/		|______|__(o/--/  | \	   	       
      | |        00	       <|  ~~~  ____ 04 ---- | --------------------
    |_|_|        (O>o		|\)____/___|\_____|_/	   Adios amigos, Al
      |     \__(O_\_	        |	  |___/	 o	   (The Desert Rat)

    Re: .205 and .207
    
    Again, thanks, Tom and Al.  I'm not comfortable with electronics
    and "Connectors" intimidate me - and I see by reading these notes
    that others have unwittingly "Smoked" their systems by not having
    Connector savvy.  This type of info is very useful and appreciated.
    
    John

    
    I beg your forgiveness. I got the color wrong. For the JR the orange
    colored wire is the same as a white on a futaba. Sorry!
    
    That's		JR (orange) + (white) Futaba.
    
    If you bevel only two corners (the two correct ones,check out JRplug)
    the futaba will still be polarized.
    
    
    Tom

When in doubt these connectors are easy to check out.

Just get a working installation and measure the pin voltage with
a cheap voltmeter.

There are only 6 combinations of possible measurements.

Just poke about till you are reading positive voltages.
Now there are only 3 combinations of possible readings.
The pair that gives the highest positive voltage (4.8 Volts
for most receivers) tells you the power and ground pins.
Now move the red (positive) lead to the only other pin and
It will be at some voltage less than 4.8 volts.  If you wiggle
the stick on that channel you will see the DC voltage change.
That is the signal line.  

Futaba and JR are compatible in that all three wires are always in
the same order.  That is you could plug them in backwards but if
you plug them correctly Futaba servo plugs will work with JR radios
and vice versa.  Airtronics swaps two wires relative to the standard
of Futaba and JR.  But in their defense Airtronics has better connectors.
Better than JR because I once crashed a plane because the JR power
connector failed to make a good contact.  Better than Futaba because they
have never changed and made servos with more than one type and they
are much less expensive.  Also every Airtronics radio manual lists the pin 
out of their servo connectors in the front.

It is interesting that my new Futaba 9VAP manual states that no other vendors
servos will work.  I can't comment on that because we have a new rule in
the notes file that forbids me from saying anything negative about a vendor.

But when I put a radio in a plane I use what ever servo is available and
appropriate - frequently cutting off the plug and soldering on a new
servo pig tail.

Bye          --+--
Kay R. Fisher  |
---------------O---------------
################################################################################

    Kay's measurement technique is great!  If you do this, you can't go
    wrong.  Just be sure not to short things or you could smoke your switch
    harness.  Those nicads can put out a bunch of amps.  
    	Also, take care to do a good job if you replace servo connectors. 
    It is quite common to have failures due to bad solder connections or
    wire breakage.  The solder will wick up the stranded wire and make a
    spot where the strands get stressed due to vibration up under the
    insulation.  I put a piece of 'shrink' tubing over the splice to
    stiffen it at least a half inch from the splice on either side and I
    still am very careful to try to keep vibration away from the wiring by
    wrapping it in bubble wrap with the receiver.  If you're careful to
    make good splices, you can do what Kay does.
    
    Charlie
    

    
    
    			JR		Futaba		Airtronics
    Negative		Brown		Black		2(black)
    Positive		Red		Red		3(black red stripe)
    Signal		Orange		White		1(black)
    
    The numbers under the Airtronics column refer to the numbers stamped on
    their plugs.
    
    No warentees implied......
    

    Now that I own radio systems from all three leading brands (JR, Futaba,
    and Airtronics), my interest in interchange has resumed.  None of the
    previous replies has all the applicable data, so this is an attempt to
    improve on Mark Antry's table.
    
    Wire usage and coding:
    
    		JR	Futaba	Airtronics servos	Airtronics extensions
    		--	------	-----------------	---------------------
    Negative	Brown	Black	black			black with a red stripe
    Positive	Red	Red	red   			red with a black stripe
    Signal	Orange	White	white 			black
    
    Pinning:  hold the servo connector with the pins showing & cable down
    
    	Futaba and JR (same)    	Airtronics (numbered 1, 2, 3)
    	--------------------		----------
    	signal, positive, ground	signal, ground, positive
    
    Keying:  (with the connector pins still facing you)
    
    	Futaba J:	spline on the front left
    	JR:		rear corners both beveled
    	Airtronics:	splines in front of each pin
    
    Mechanical issues:
    
    If the splines are removed from the Futaba and Airtronics servo
    connectors, all three are the same size, 0.10x0.30 inches, with nearly
    identical depths.  If these two were to have the "rear" corners beveled
    to match the JR keying, then, with some concern for pin dimensions and
    after appropriate reordering of the wires/pins, all three should be
    interchangable.  Tom Tenerowiczt in 95.5 reports that modified Futaba 
    servo connectors will indeed fit into JR radios.  I have verified that
    an unmodified JR servo will plug into both an Airtronics and a Futaba
    receiver; this verification was mechanical, not electrical; I do not
    have data that the male and female dimensions of the metal parts are
    sufficiently compatible to give reliable connections.
    
    I'm inclined to modify my Futaba and Airtronics connectors and to paint
    white dots on all connectors and receivers of all three brands for
    visual keying.  An alternative would be to put Dean's connectors on all
    servos and to make up a set of adaptors for each channel on each
    receiver.  The risk in all this is that a failure to re-order the power
    and ground pins properly would probably fry the servos electronics. So
    a safer alternative would be to make short adapter cables with
    re-ordering in the cable and unmodified connectors at each end; I would
    need:
    
    	To plug Airtronics into Futaba and JR receivers:
            
            JR connectors at the receiver end, Airtronics at the servo end
            
    	To plug Futaba and JR into Airtronics receivers:
            
            Airtronics connectors at the receiver end, Futaba at the servo end
            
    	To plug Futaba into JR receivers:
            
            No cable; just shave off the spline and bevel the back corners
            
    	To plug JR into Futaba receivers:
            
            No cable; just plug it in with caution.
            
    I would need at most one cable per channel per receiver.
    
    Comments are requested [before I buy all the appropriate cables].

    I use Futaba S-133 servos with my JR stuff on a regular basis. I just
    trimmed the connectors as you specified. That was one of my initial
    tests as I went from Futaba to JR to maintain my servo compatibility.

    Al,
    	I would try to avoid adapter cables as it just increases the number
    of connections.  The alternative is modify the connectors or replace
    them.  I'd go with the modify where possible and proceed with caution
    on the polarity.  The exception would be for aileron extensions where
    you need a cable anyway.  I have avoided the problem so far by using
    RCD receivers with Airtronics connectors with my old Airtronics servos
    and switches.  The TX is a JRX347.  I soon will have to deal with using
    JR servos with an Airtronics receiver since I plan to go with JR servos
    from now on.  I won't do any of this work when I'm not at maximum
    concentration levels because I don't want to smoke any servos.
    
    Charlie
    

    I'm using several Airtronics servo's in  the cub which has the
    JR FM receiver. The plugs were modified with little work. Only two
    wires need to be swapped and the ribs on the airtronics plugs need
    to be shaved off. Only took a couple of minutes per plug. Works fine.
    
    Steve

Are any of the big 3 compatible with a World Engines Expert 7 channel radio? I
bought the one Dave Walter had for sale. It came with 4 servos, but I need 7.
The receiver has a pretty funky style of connector. An Airtronics plug might
fit, but I've been a little leary of trying it. Any suggestions?


Dave, if your out there, are these the new or old style servo connectors that
I have seen a reference to here and there?

Thanks,

Randy

Randy, I think World Engines is compatible, pin-wise with Futaba.
Could've sworn there's some info on that somewhere in here...

I've made some adapters to go from my current Airtronics stuff to
the old Dean's connectors I have on my Ace servos.  I bought some
Airtronics aileron extensions that I cut and fit up with the Dean's
connector.

Another possibility would be to open the servos and install the
connector directly.  I can do this easily on the Ace servos since
I built them, (well, not so easily since my eyesight is not as
good as when I built 'em).  And I've replaced one connector on an
Airtronics servo too, but it really is tiny work and I'd not
recommend it to someone who doesn't do it often. 

    Randy,
    
    I can't really answer either of your questions. I think the connectors
    are the same as used in their current radios, but not sure. As for
    compatibility with Airtronics, I have vague memories of attempting to
    mix them with negative results. That's one of the reasons I wanted to
    concentrate on just one manufacturor (Airtronics).
    
    Dave

    My newly built Chuperosa has the new Airtronics micro FM receiver, an
    Airtronics 94501 micro servo, and a Futaba 133 micro servo, so I have
    the compatibility problem.  I knew I would inasmuch as I bought the
    Futaba servos *after* I sold my Futaba radio; they are slightly larger
    than the equivalent Airtronics 94501, but the price was less.

    I made a cross-over adapter cable, but I didn't trust my own soldering
    ("inept" would be a kind word).  The connector pins are incompatible in
    size, so the cross-over adapter cable cannot be made by merely
    switching the plastic housings.  So I decided to modify the plastic
    part of the Futaba connector so it would fit in the Airtronics receiver
    and to switch the order of the power pins accordingly.

    **** I smoked my just-out-of-the-box Airtronics receiver. ****

    The first time I plugged it in [with great care to observe orientation]
    it worked just fine.  The second time I wasn't careful enough, and I
    put the connector into the receiver the wrong way.  That puts the servo
    power load onto the signal output of the receiver; it evidently fried
    something; none of the channels work now.  After very carefully
    verifying that the problem was only in the receiver, I replaced (now
    very, very carefully) that receiver with another, identical receiver. 
    As expected, it works just fine.  The plane flew well [until I
    cartwheeled a landing].

    Summary [with some conjecture]:

    If a cross-over adapter cable is done right, it will work every time,
    albeit with some very slight possibility of a connection failure.

    If the connector modification is done right, you still have the
    possibility of a disaster *every* time you reconnect the servo --- 
    even if you plug it into it's own brand of receiver and especially if
    you have re-ordered the pins.

    Result:

    I will restore the Futaba servo to factory specs.
    I will find someone with a steady hand to solder a cable.
    I will send my receiver to Airtronics for repair.

I also just had a problem with an Airtronics receiver and Futaba servos, 
although my problem did not end in quite such a disaster.  

I also decided that the easiest way to go was to swap over two wires in 
the Futaba plug and shave off the locating strip so that it would plug 
into the Airtronics receiver.  I make sure that everything is electrically 
OK and that I have the elevator and rudder connected up to the right 
controls.

Well I am new to RC and flying so if things get out of hand, I can quickly 
get into trouble.  Two weeks ago I launch my GL, and it immediatly goes 
into wild up and down gyrations that no amount of playing the elevator can 
cure.  It ends up going straight in from about 50 feet.  Fortunatly it had 
rained the previous day and damage was limited to servo rails broken and 
some little stuff on the wing. 

On Saturday, after repairs I try again.  I get the GL up, fly around in 
circles a few times and then it gets into wild up and down gyrations again.  
Again it had rained the previous night and damage was limited. 

This time I field repair the GL with some tape and try again.  I get her up
and then hand the TX over to the expert to give it a dynamic CG test, as 
that is where I thought the problem lay.  He quickly broke out in a sweat 
as both servos were reversed.  He managed to bring the plane down safely, it 
is was just a matter of flipping the servo reversing switches, and then 
everything was OK. 

Now I know to test not only that I have elevator and rudder on the correct 
sticks, but also to test that they go in the correct direction.

    The plane was a bit nose heavy, but most of the wild gyrations were
    caused by my trying to correct the wild gyrations with the servos
    reversed, which had the opposite effect.  When you are new to flying
    you need to develop instincts, and these get pretty confused when you
    try to fly with servos reversed. 
    
    After getting the servos sorted out, I took an ounce out of the nose
    and got a nice flight, my first for some time.  

    I built a servo exerciser yesterday and checked it out with servos of
    all three major brands.  In doing so I discovered what Richard Taylor
    had learned the hard way --- the rotational directions of the servos
    are not the same.

    As the pulse width increases the

    	Airtronics 94102	rotates		clockwise

    	JR         NES-901	rotates		clockwise

    	Futaba     S148		rotates		counter-clockwise  <------

    I didn't make a measurement, but all three seemed to rotate about 140
    degrees or more as the pulse width went from 0.4 ms to over 2 ms.  If
    anyone cares, I'll make a formal measurement of angle vs width.  I
    think it was Bill Lewis who said that most servos only rotate 90 degrees; 
    his statement is not inconsistent with my observation --- the
    transmitter may not request more than that travel.  In particular, full
    stick movement on the Futaba FP-T2NCS transmitter causes the servo to
    move only 90 degrees as the pulse width changes from 1 ms to 2 ms.

    Note that 90 degree rotational travel provides 71% of the linear travel
    ordinarily available via a pushrod.  The JR347 can extend this to 135
    degrees which results in 92% of linear travel, the observed angular
    limit of the servos, and probably the free movement limit of the linkage
    connections.
    
    Alton, collector of technical trivia

    My Airtronics transmitters only move the servos 90 degrees (1-2 msec
    pulse)  It's nice to be able to move them further with the X347,
    especially on the throttle.  Linearity suffers when you use large
    rotation angles, but often that's not a problem.  It also figures that
    Futaba would be backwards on rotation since they are also backwards on
    the FM modulation (compared to my favored brands)  Some servos used to
    be available in reverse direction versions probably because reversing
    switches were not available on all radios.  It is also possible to
    reverse most servos by switching the end wires on the pot and switching
    the two motor leads.
    
    Charlie
    

    
    
       I found out about the difference in rotation between Futaba and
     JR servos the hard way. I had replaced Futaba s-133's with Jr 517's
     ( in a hurry ) on the ailerons on my Panic. You guessed it,
     I took off with reversed ailerons and did a very impressive ( until
     it crashed ) low altitude roll on take off. Miraculously, the
     damage was limited to a broken prop.
        I took the plane back to the pits, did a control check, and found
     the ailerons reversed. Since there was no way to plug them in backwards,
     I was baffled as to why they were going the other way. Eric Henderson
     figured it out after I told him of the servo switch. If he hadn't
     figured it out, I would have probably been baffled for weeks! I NEVER
     even thought of servos being wired differently.! 
    
       So......                                
    
          Never assume that different manufacturers products are 
       compatible, even on a basic level
    
          Never be in a hurry when performing any change that can effect
       control surfaces ( and safety ). An do a ( non hurried ) control
       check before taking to the air. 

Does anyone out there know the pinout of the Futaba G connectors?  These
are the ones that are on the OLD AM sets.  (The new AM sets come with
the J style connectors.)


     ___________
    |           |==================     (wires)
    |           |
    |           |
    |           |
    |           |
    |___________|
      |     |  |
      |     |  |
      |     |  |
      |     |  |

      A     B  C


I am quite sure pin A is the signal, but I can't remember which of B/C
is Power/GND.

    Dan,
    	I have it written down at home.  I'll try to remember to check it
    tonight.
    
    Charlie
    
    I'm pretty sure that Black wire is ground and Red is +V if that helps.
    
    Charlie
    

     ___________
    |           |==================     (wires)
    |           |
    |           |
    |           |
    |           |
    |___________|
      |     |  |
      |     |  |
      |     |  |
      |     |  |

      A     B  C

    
    
    A = signal
    B = power (+v)
    C = ground
    
    (I just happen to have a receiver and servo sitting on my desk today!)