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Question about sevo reversing...

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Old 01-13-2005, 07:35 PM
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crazycd1
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Default Question about sevo reversing...

I just have a quick servo reversing question, I just got a duratrax mini quake and it came with a futaba radio. I put the crystal in my JR XR2i and I had to turn the trottle and steering servos settings to reverse, while they are in normal on the other radio. Why would one be normal and the other radio be in reverse to get the same thing outta them? Nothing else is changed, just the transmitter.
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Old 01-13-2005, 07:59 PM
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exeter_acres
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Default RE: Question about sevo reversing...

if you are using a futaba radio with a JR Rx...I'm surprised it works at all.....

Futaba uses negative shift while JR uses positive... normally they are not compatible at all
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Old 01-13-2005, 08:02 PM
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Default RE: Question about sevo reversing...

I am using the futaba receiver and the JR radio, both are 75mHz AM 2 chan systems, all I had to do was put the chan 68 crystal from the stock radio into my JR radio and everything works fine except I had to use reverse mode.
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Old 01-14-2005, 02:14 PM
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Trogdor the Burninator
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Default RE: Question about sevo reversing...

That's funny about the positive/negative shift thing on 75mhz. 72MHZ wouldn't work... hmm.

I can say that Futaba and others have opposite ways of looking at min stick position and max. On my Hitec tx I set up a plane and all servos happened to be correctly set in normal mode. When I went to my new Futaba 7CAP I had to reverse all the servos!

I've read this somewhere else also and didn't understand or pay attention until I saw it on my own setup!
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Old 01-15-2005, 09:34 AM
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Default RE: Question about sevo reversing...

Since they are both AM radios They will work each other. There is no pos and neg shift in AM modulation The direction the servos move is a manufacturers call It makes little difference to the operation of the unit.It is generally not a good idea to swap crystals from one manufacturer to another it is also against the FCC rules.
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Old 02-09-2005, 09:56 PM
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Default RE: Question about sevo reversing...

Does anyone know if you can reverse the direction of a futaba 9202 servo? Tech at futaba say no, but I remember doing it on older servos (148). If so what wires do you switch? I want to avoid using a servo reverser if possible. I am currently using an MPI reversing Y harness and it chatters. Any ideas?
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Old 02-10-2005, 10:49 AM
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Default RE: Question about sevo reversing...

wcshort, yes, you can reverse the direction a servo moves. It requires switching two sets of wire inside the servo. You need to interchange the two wires going to the outside connections on the potentiometer (there are three wires on it, leave the center one as is) and reverse the two wires going to the motor. Unfortunately, some motors are soldered direct to the printed circuit board and are hard to change. You either have to cut the traces and solder jumper wires around them or, unsolder the motor from the board, turn it 180 degrees and resolder to the board. It is not a job for the novice. Now, most companys will sell you a reversed servo on special order, check it out with the local distributer. You might note that Hitec and Futaba servos rotate the opposite direction for the same transmitter stick movement. If you can find servos that are equivalent in power and speed, you might be able to mix two brands of servos.
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Old 02-10-2005, 05:46 PM
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Default RE: Question about sevo reversing...

Rodney, Thank you very much for the info. I am going to look at the servo tonight. Futaba tech support tells me there is a company called EMO that makes a servo reverser the will work wit PCM radios. I talked with them and they say they TRY and make theirs as quiet as possible. Doesn't sound like something I want to put in a 82" airplane!!
Again, thanks for your help.

Bill
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