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Old Nov 30, 2009, 03:31 PM
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Heli-max Axe CPV3 receiver conversion problem

Hey guys,

I recently have attempted to swap out the receivers in two of my Axe CPV3's that were otherwise working normally. The reason for the change was primarily to avoid getting *shot down* by other flyers in our rather informal group that gets together on Sunday afternoons. (it happened 2 weeks ago..) I decided to go with the AR6110 DSM2 receiver so that I could bind both of the Axe helis to my DX6i transmitter. When I tried to fly either one of my Axe CPV3's with the AR6110s installed, I found that the tail was very hard to keep under control. It wasn't vibrating excessively like I'd expect if the gyro gain was set too high, it just seemed to randomly kick out unexpectedly every couple of seconds or so forcing me to work much harder than in stock form to keep it under control. Both of my Axe's did this with the new receivers, and on one of them I went back to the old receiver and the tail problem cleared up??

I really like the setup for the cyclic control (from ewoodcox) as it's now far more stable than it was with the stock radio, but with the tail issue, the helis are almost unflyable. Have any of you run into this kind of weird issue with changing only the receiver on a Heli-max Axe CPV3 while using the original 3-in-1?

Thanks for any help!

Robbie
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Old Nov 30, 2009, 10:20 PM
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I took my oscilloscope out and looked at the rudder signal between the AR6110 receiver and the stock 3-in-1 input *the single orange wire*. With the AR6110, the amplitude of the pwm signal is 2.8V, the time period of the signal is 22mSEC, and the high time of the signal varies between 1 and 2mSEC. I then put the original receiver back and looked at the same signal. The amplitude is 4.8V, the time period of the signal is 20mSEC, and the high time of the signal varies between 1 and 2mSEC. The time period and amplitude difference also applies to all of the other signals for throttle, pitch, and roll. I suspect that the amplitude difference of 2.8V vs. 4.8V may be the problem?

Robbie
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Old Nov 30, 2009, 10:48 PM
Axes & Blades-Cutlery & Helis
West Monroe NY
Joined Feb 2009
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Oh yeah, that is a problem. This stuff is supposed to run at 5 V, so 4.8 V is pretty close. Need to call Spekrum, probably correct since it happens on both your helis two RXs can't fail in the same way....hmmmmm
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Old Dec 01, 2009, 08:59 AM
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Originally Posted by ewoodcox View Post
Oh yeah, that is a problem. This stuff is supposed to run at 5 V, so 4.8 V is pretty close. Need to call Spekrum, probably correct since it happens on both your helis two RXs can't fail in the same way....hmmmmm
I looked up the specifications of the AR6100 and the AR6110 receivers. A 3V signal amplitude is normal and further research has shown that most all modern DSM2 receivers provide a 3V amplitude servo control signal. This would mean that the 2.8V amplitude I'm seeing is actually correct. I'm getting away with it driving the three cyclic control servos which I suspect are designed to run at this voltage range and up to 5V, but the proprietary 3-in-1 tail rotor gyro input is not being driven adequately. Heli-max probably doesn't care as they probably never intended to sell this 3-in-1 as a seperate system component. It IS trying to work and the evidence of that is that I actually can fly the helicopter, but the signal seems to be *hiccuping* while in flight. It also demonstrates this tendacy on the bench when compared side by side against running with the stock receiver. At this point, the fix looks like I need to make a servo signal booster. This is easily done using the three receiver pins that drive the rudder and a couple of transistors, but I actually found a source online for such a cable. For less than $3.00 the work is already done for me! Great! I'm lazy.. LOL

Here's one source:

http://shop.rc-electronic.com/e-vend...&t=6&c=67&p=67

Here's the other one I used:

http://www.unitedhobbies.com/hobbyci...idProduct=8356

Probably dumb as they're over seas but it was late and I was tired .. LOL

Hopefully this will take care of this last issue and I'll be back in the air with the Axes!


Robbie
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Old Dec 01, 2009, 01:19 PM
Axes & Blades-Cutlery & Helis
West Monroe NY
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Originally Posted by robbiehatfield View Post
I looked up the specifications of the AR6100 and the AR6110 receivers. A 3V signal amplitude is normal and further research has shown that most all modern DSM2 receivers provide a 3V amplitude servo control signal. This would mean that the 2.8V amplitude I'm seeing is actually correct. ....Here's one source:

http://shop.rc-electronic.com/e-vend...&t=6&c=67&p=67

Here's the other one I used:

http://www.unitedhobbies.com/hobbyci...idProduct=8356

Probably dumb as they're over seas but it was late and I was tired .. LOL

Hopefully this will take care of this last issue and I'll be back in the air with the Axes!

Robbie
Very good info, I did not actually know that. Most servo specifications give specs at 6V, so torque and speed are measured at max voltage. At 3 V they have to perform poorly....apparently, good enough for our Axes
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Old Dec 01, 2009, 07:03 PM
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True about the Axe servos Ed! For ha ha's I'm going to try a booster cable on the three servos as well just to see if they behave noticeably different. I suspect they won't, but I did order 10 of these harnesses after all.. lol

Robbie
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Old Dec 01, 2009, 09:30 PM
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After I install one of these signal boosters, where does the "single orange wire" go? I've been trying this conversion for quite awhile now and making really slow progress. Also will one of these cables go in between the "throttle" cable to the reciever? I ordered 6!

Thanks,

G. (noobie)
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Old Dec 02, 2009, 08:49 AM
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One end of the booster will mate/go into the receiver. On the other end, plug the orange wire onto the signal pin and just leave the other two pins open.

There should be no reason why you can't use one of these booster cables for every connection between the receiver and the stock 3-in-1 gyro. It just may be overkill..

I must also state that I'm not 100% sure that this will fixe my tail problem, but I'm about 95% sure.. LOL

Robbie
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Old Dec 02, 2009, 09:20 AM
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I'll let you know how this works as soon as I get them from HK. My conversion is on an AXE CP (not CPv3). I also started out with an AR6110 with a bad AILE channel so the fits have been multiplied.

Thanks,

G.
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Old Dec 02, 2009, 07:02 PM
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Originally Posted by garyji View Post
I'll let you know how this works as soon as I get them from HK. My conversion is on an AXE CP (not CPv3). I also started out with an AR6110 with a bad AILE channel so the fits have been multiplied.

Thanks,

G.
I'm waiting from the same source so may the best man * r luckier one* who gets to try it out first win!! LOL

Robbie
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Old Dec 04, 2009, 09:53 PM
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I must admit I've cheated... I didn't get the booster cables today, so I stopped at the LHS and the local Radio Shack and got what I needed to make just one to try the concept on the bench. A quick check with the scope revealed a 4.8V signal to the rudder input wire. So far so good! No more jittering on the tail during a bench test! Hopefully tomorrow morning will be calm enough for a quick test flight. I'll let you all know..

Robbie
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Old Dec 05, 2009, 01:37 PM
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I did a quick test flight this morning. Problem solved! The tail holds normally!!

Robbie
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Old Dec 05, 2009, 07:34 PM
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I did a quick test flight this morning. Problem solved! The tail holds normally!!
Congrats on your fix! I think I may have the same problem because I have just converted my Axe to an AR6110 rx, E-flite 2-in-1 esc board and a GY401 (ewoodcox setup). I've changed to the direct drive tail and have noticed some erratic control issues after approximately 2 minutes of flight. Should I be using the booster on my setup? Would I use boosters on my three HS-55 servos as well as the 401 gyro?
Thanks,
Mark
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Old Dec 05, 2009, 10:39 PM
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Congrats on your fix! I think I may have the same problem because I have just converted my Axe to an AR6110 rx, E-flite 2-in-1 esc board and a GY401 (ewoodcox setup). I've changed to the direct drive tail and have noticed some erratic control issues after approximately 2 minutes of flight. Should I be using the booster on my setup? Would I use boosters on my three HS-55 servos as well as the 401 gyro?
Thanks,
Mark
Hey Mark,

I wouldn't think that you'd need the booster for your setup? The specs for the E-flite 2-in-1 esc board and the HS-55 servos state that they can be driven with a 3 to 5V peak-to-peak squarewave and the AR6110 rx puts out around 3V. The specs for the GY401 gyro don't state the amplitude of the rudder driving signal, but I would expect that 3 to 5V peak-to-peak would work fine with it as it's an item that's meant to be purchased seperately and this is fairly standard input for such items? I'm not sure what could be causing your problem?

Robbie
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Old Dec 05, 2009, 11:27 PM
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Hi Robbie,

Thanks for your reply. I think I may have found my problem, the tail motor was over-heating. I installed the E-Flite (EFLH1322) - N60 motor, but it seemed to get WAY too hot, so I used the old "Hummingbird" DD tail trick and flipped the engine over (prop on left side), reversed the direction the motor turns and let the prop cool the engine. This makes a huge difference in the temperature. I Only got in one short flight in before I had to quit, but, this seems to have made the difference.

Mark
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