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Old 12-13-2002, 02:04 PM   #1
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Default Servo Question

Hi there, didn't know where to place this one, so I'll go by the fact that it's in my electric onroad car and post it in here. Anyhoo, I just had a question about my Airtronics servo. I just got one for my 1/12th scale (94145), but I had to convert the plug to fit into a XXL for Futaba plugs/radios. Now, when I drove it last night, the servo seemed to have problems centering when I would get onto the throttle. When I was off throttle, centering was perfect. Now the question is do I need an external power source to power the reciever/servo (say a 6v battery)? Can I somehow get it to center well running straight off my race pack? I connected all the wires as they would go into an Airtonics reciever, I just cut off the end and put a Futaba plug with the wires on it. My only guess here is the servo is trying to draw power that isn't there when I'm using the throttle, and that's why it doesn't want to center. Any of you guys have similar problems?

The electronics in the car go as follows:
GT7 ESC
XXL 75mhz
Airtronics 94145

I had the problem running off of matched 2400 packs. I have some unassembled 33's that I might need to test out and see if that solves the problem. Thanks for any replies.
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Old 12-13-2002, 02:13 PM   #2
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Default Having the Jitters

Aeon Racer;

Are you sure that you have the plug wired correctly? Airtronics and Futaba servos have the + & - switched I believe. Check the Novak manual to be sure.
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Old 12-13-2002, 03:53 PM   #3
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It's probably your servo saver. Turn the car on and check the amount of play in the servo saver. If you have any, that's your problem. I prefer the Tamiya high torque servo saver for all rc car applications. They have hardly any play and will fit all standard servos.
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Old 12-13-2002, 05:13 PM   #4
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If I had it wired backwards (wrong + and -) wouldn't I have to reverse the servo on my radio? I went from a Futaba to an Airtronics and I didn't have to reverse it. I don't think my servo is the old style wiring anyway, it doesn't have two black/a brown wire. It's blue, red, and then black, in that order. I'm guessing the blue is the ground, and the red and black are + and - respectively. If that's the case, I have it wired correctly. I'll double check in the XXL manual.

I'll have to check my servo saver, but I don't think its the problem. It's brand new. And why would I have the problem under acceleration and then not have it during cruising? The servo saver wouldn't seem logical, but I'll check it none the less.

Last edited by Aeon Racer; 12-13-2002 at 05:18 PM.
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Old 12-13-2002, 05:32 PM   #5
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The Futaba plug has the black on the outside edge, the Airtronics has the red on the outside.

Just push the little silver inner plugs out of the plastic plug, and switch the red and black wires.
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Old 12-13-2002, 05:53 PM   #6
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Try this. Drive the car in a straight line and get it to where it goes straight. Then crank the steering to one side and then let it center again. If the car steers in one direction or the other, you either have some slop in your servo saver or possibly a broken tooth on one of the gears in the servo. It's also possible that the servo saver is moving, but there is too much resistance in it to recenter again. I hope that helps
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Old 12-14-2002, 12:39 AM   #7
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theRED5 - My Airtronics has the red in the middle. Am I understanding you correctly? This picture is how I have it setup right now:
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Old 12-14-2002, 07:05 AM   #8
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could be a problem with the BEC on your speedo not being powerful enough to run the receiver and the speed controller.

Try psycho's suggestion to see if its a mechanical fault.

If you are getting on the throttle and the servo is pulling to one side it sounds like its electrical. Try getting a Big CAP, maybe 10,000uF (and then going smaller) and put it across the + and - on you receiver, this will act like a resevoir to provide the extra current when required

hope this helps

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Old 12-14-2002, 07:49 AM   #9
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The way you have the servo connected seems right. Is this for mod class? If so your original post about not having enough power to your servo may be correct. I haven't used the GT7 in 1/12 apps so I can't say for sure how it will work. You may need to get an external micro pack for the servo. TTYL.


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Old 12-14-2002, 01:29 PM   #10
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Default Servo problems

I didn't notice how many cells that you are running. If you are running only 4 cells like alot of 1/12th scales do. you will HAVE to add a small 6volt pack just for the recieiver and servo. If you have a 6 cell pack then the problem lays elsewhere.
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Old 12-14-2002, 02:07 PM   #11
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i run a 12th with a gt7 and 4 cells, and i never had to use a reciever pack....just a thought. try this...i have found that with the gt7, the reciever is VERY sensitive to the placement of the big cap and also the wires for the cap. try moving that as far away from the reciever as possible and make sure the two wires DONT cross over the reciever or the antenna. I had a problem with glitches with my gt7 and i fixed it by moving the cap away from the reciever. hope that helps. good luck
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