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Old 04-02-2015, 11:20 AM   #1
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Question Axial SCX motor working intermittently

The other day, I charged up my battery and set up the transmitter for my SCX 10 and my trusty crawler responded just as it should, and has, many times before. I powered everything down and headed out to a crawling spot. After powering up, I realized that the throttle was not responding. The truck lights were on and the servo worked fine. No power to the motor though.

Back at home, I went through the basic binding set up, and everything worked again. So I powered down, headed out again, but the same problem occurred. In the field I went through the re-binding process a few times, turning the power off and on, and at one point, the ESC responded, and all worked again. (Went on to enjoy a great crawling run.)

I'm thinking now that I probably have a bad connection somewhere and want to troubleshoot it. Before I start taking everything apart, I thought I would gather some recommendations about how to check everything out in a logical order. Here's what I know:

The battery is charged.
The motor works fine (when it works.)
Signals from the transmitter to the receiver seem to work, since the servo responds.
The LED lights on the truck light up fine.

Should I begin by checking the connections from the motor to the ESC, and then all the other connections?
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Old 04-02-2015, 01:11 PM   #2
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Default Re: Axial SCX motor working intermittently

motor brushes are dirty or worn out. The next time it does this give it a little push and see if it starts driving. If so, Brushes.
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Old 04-03-2015, 09:21 AM   #3
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Default Re: Axial SCX motor working intermittently

Hmm. Thanks for that suggestion, but I don't think this is a brushes problem. Pushing the truck a bit while throttling doesn't work, while fiddling with re-binding does work.

Here's more detail about the symptoms:

Normally, when I turn on the transmitter, then turn on the ESC (and receiver), the truck emits a short beep or two, then there's a brief pause, then a second beep or two, and all the electronics are engaged and the truck works fine.

That first set of beeps seems to confirm that the servo is engaged, and the wheels do indeed twitch, signalling that the servo is powered up. The second set of beeps seems to be associated with the throttle, and as soon as those beeps are done, the throttle is fully engaged.

Now, I have an intermittent problem, where after turning on the transmitter, then the ESC, I receive the first set of beeps (servo), but do NOT receive the second set of beeps (throttle). This seems to signify that the ESC did NOT receive the signal from the transmitter.

I can "fix" this by fiddling with the re-binding procedure several times and know that I have succeeded when I get those two sets of beeps.

So, it feels a lot more like a connection problem than a mechanical motor problem.

Any other thoughts?
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Old 04-03-2015, 09:30 AM   #4
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Default Re: Axial SCX motor working intermittently

Beeps have nothing to do with the servo. It's the controller arming and telling you how many cells the lipo battery is.

Sounds like throttle trim or dead band issues.
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Old 04-03-2015, 10:00 AM   #5
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Default Re: Axial SCX motor working intermittently

Thanks for clarifying what the beeps signify, EeePee. I'll check the throttle trim but I don't know what you mean by "dead band" issues.
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Old 04-03-2015, 10:12 AM   #6
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Default Re: Axial SCX motor working intermittently

On some controllers you can adjust the dead band. It's like, making neutral more narrow or wider. It then takes less or more throttle position to get moving but also is related to how the controller sees the neutral position. It's almost compensation for throttle potentiometers not being all that great.

I can only think of Castle and Castle based controllers having it but Tekin might also.

You have yet to say what stuff you use.
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Old 04-03-2015, 02:55 PM   #7
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Default Re: Axial SCX motor working intermittently

My electronics include:

Axial AE-2 ESC
Axial AX3 Transmitter
HiTec HS645MG Servo
Axial AX24007 55T Electric Motor

Since my last post, I've been trying to bind the controller again but had trouble get it to work. When I turned on the controller, it emitted fast green flashing lights.

There are a number of posts about this, mostly centered on setting the sub-trim to 0. So, I've been fiddling witht that, which on the AX3 is a dial and it's hard to know where the exact center is.

Finally, while in the middle of following the rebinding process again, while both the transmitter and controller were on, I unplugged the battery, and plugged it back in. Right away, the green flashing stopped, and I got my first set of beeps, and was able to complete the reset with no problem.

So, I do NOT have a bad connection but did, in fact, lose the binding. I now know that if/when this happens again, I may have to try disconnecting and reconnecting the power.

With my current set up, would it be worthwhile to getting a Castle Link Programming kit to more clearly see what's happening?

Thanks for all your help.
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