Fluctuating voltage going to the tail motor off the 5-in1, help!

[chippies83]

Hi guys,

First off I'd like to apologize for butchering both electronics and helicopter terminology. Now that that's out of the way, here's what's happening to me. I've had my 120 SR for two weeks now. I've been flying it at work quite a bit in the shop where I've got ample room. Yesterday the heli started spinning out of control, the tail motor was pooched.

I disconnected the main motor, and turned up the throttle. When I pushed on the wires leading to the tail motor it would come back to life intermittently. It was obvious that I had a bad connection somewhere. Interested in determining which side of the motor plug my bad connection was, I enlisted the help of a more electronically capable friend. We broke out the voltmeter and got to it. Then we noticed something goofy, when the tail motor was spinning, it was periodically dropping speed even though the neither of us were touching the Tx and it was sitting at about half throttle. We disconnected the tail motor and tested the leads, and sure enough the voltage was fluctuating. It was dropping upwards of an entire volt at times. It seemed to be putting out steady voltage when the throttle was at 100%, but as soon as it dropped to around 75% and lower, there'd be a consistent surge every second or so. We kept testing the voltage, working our way back to the 5-in-1 and the lead coming right off the board was experiencing the exact same voltage fluctuation. We tested what we thought was a resistor for the tail motor (little black box on the board next to the tail motor leads) and that was even showing the voltage fluctuation.

We decided to see if the main motor was having the same problem, but interestingly enough it was smooth and steady at all throttle positions: A stark contrast to the tail motor.

I'm going to the LHS today to get a new tail motor to solve that issue (not going to bother trying to solder/fix the connection. The amount of time I'd spend dicking around with that isn't worth the $13 for a new motor). Once I've got the new tail motor in place, I'll put the bird back up in the air and see what effect if any the voltage fluctuation has on flight.

Has anyone else experienced these issues? Is my 5-in-1 kaput after only two weeks? Do I have any warranty, etc? I bought this heli in Edmonton, AB (Hobby Wholesale) over the Easter weekend while visiting family but I live in Regina, SK (8.5 hours away), so returning the heli to the not-so-LHS isn't really an option for me.

[flyin~mike]

I am very new to helicopters myself so forgive me if my information is not accurate and also please correct me. Anyway, I have experienced problems with my tail motor as well and I actually bought a new 5in1 because I was convinced it was the problem. Well I was wrong! It was the tail motor. Even though the motor was working it was not working right. Long story short - see how it works with the new motor before you decide it is the 5in1. I'm not sure about the fluctuating voltage but it might be normal because(and I'm guessing here) it may rise and fall as the board attempts to maintain your heading.
mike

[Pfloyd]

Just call HH....they will most likely send you a new 5n1.

[chippies83]

UPDATE: So I went to the LHS yesterday and picked up a new tail motor. Didn't have time to play around with the bird until just now. I installed the new motor (and the new protective sleeve, but I doubt that was related to the issue I described above).

I took the heli to my backyard to test out, and after a little trimming the tail seems to hold solid in a hover, like it did before. So the bird can fly now, I'm pleased!

There is however, the nagging issue of the voltage drop/surge/fluctuation. The tail motor still seems to be 'pulsing' at regular intervals. I'm starting to wonder if this isn't just the way the damned thing is supposed to run, because I can't detect any negative effects while in flight.

Can one of you guys do me a HUUUUUUGEE favour? Could you pop off your canopy, disconnect your main motor, and put your heli up to about half throttle? Does your tail rotor spin at a constant rate with no changes?

The problems I'm having are easily detected by the naked eye/ear, and don't require using a voltmeter. When I throttle up you can see and hear the tail rotor change speeds at regular intervals, like it's pulsing. If one of you can confirm that this is happening on your heli, I'll leave this alone and just keep on flying happily. If your tail rotor is running smooth and constant, I'll contact the shop I got this heli from and try to get a new 5-in-1 from them, as I haven't even had this thing for a month.

Thanks for your input so far guys!

[DM23]

Are you doing your run-up holding the heli steady while getting the speed change ?

[Well Driller]

My tail motor will pulse if on the ground. I think it is just the gyro "looking" for the right speed to hold itself steady. The ground is holding it steady so I think it just don't know what to do. It works prefect when in the air. I don't think it is anything to worry about.

[Tedolph]

Originally Posted by chippies83

UPDATE: So I went to the LHS yesterday and picked up a new tail motor. Didn't have time to play around with the bird until just now. I installed the new motor (and the new protective sleeve, but I doubt that was related to the issue I described above).

I took the heli to my backyard to test out, and after a little trimming the tail seems to hold solid in a hover, like it did before. So the bird can fly now, I'm pleased!

There is however, the nagging issue of the voltage drop/surge/fluctuation. The tail motor still seems to be 'pulsing' at regular intervals. I'm starting to wonder if this isn't just the way the damned thing is supposed to run, because I can't detect any negative effects while in flight.

Can one of you guys do me a HUUUUUUGEE favour? Could you pop off your canopy, disconnect your main motor, and put your heli up to about half throttle? Does your tail rotor spin at a constant rate with no changes?








during initialization. It confuses the giro.

Tedolph


durring initialization. It confuses the gyro and makes the tail rotor surge about once per second.



Tedolph

The problems I'm having are easily detected by the naked eye/ear, and don't require using a voltmeter. When I throttle up you can see and hear the tail rotor change speeds at regular intervals, like it's pulsing. If one of you can confirm that this is happening on your heli, I'll leave this alone and just keep on flying happily. If your tail rotor is running smooth and constant, I'll contact the shop I got this heli from and try to get a new 5-in-1 from them, as I haven't even had this thing for a month.

Thanks for your input so far guys!

during initialization. It confuses the giro. Reinitialize and you should be fine.

Tedolph

[Keldar]

A couple of thoughts....

1.) Its is hard to read DC voltage without a load. Sometimes a voltmeter may not be a sufficient enough "load" to give a true reading.

2.) Since the tail is voltage is controlled by the "gyro" effect, it will have a fluctuating voltage when compared to the main motor, especially if it senses movement while you are working with it..

[Oh no... not again!]

Originally Posted by Keldar

A couple of thoughts....

1.) Its is hard to read DC voltage without a load. Sometimes a voltmeter may not be a sufficient enough "load" to give a true reading.

2.) Since the tail is voltage is controlled by the "gyro" effect, it will have a fluctuating voltage when compared to the main motor, especially if it senses movement while you are working with it..

+1

The gyro is not that sophisticated so it does fluctuate the tail motor trying to find home..

Fly it like you stole it!!

Oh no....

[jchowdown]

I'm also having trimming issues and I'm seeing the same thing:
https://www.youtube.com/watch?v=O_Sk...avxPQaxe6FgDcw (with main rotor)
https://www.youtube.com/watch?v=DiqE...avxPQaxe6FgDcw (without main rotor)

In both cases the heli is perfectly stationary. Does this happen with anyone else?

[lnuss]

I'm also having trimming issues and I'm seeing the same thing:

Change the tail motor. I had similar symptoms (as as did some folks above) and wondered if it was the 5-in-1, since it was intermittent, and got worse as the battery went down -- everything I could see said 5-in-1). Changing the tail motor did the trick, and it's lots cheaper than the 5-in-1. It's easy to get fooled by the "antics" of the gyro.