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Jun 06, 2019, 08:50 AM
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slowmatch's Avatar
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Spektrum dX6i Problems with ESC Reverse?

I've been having issues trying to set up my Spektrum dX6i with a brushed 'bi-directional' ESC.

I've tried this 10A Braked Version in the past and just recently this 5A Version but neither work as hoped - they only run in one direction.

I have the rx failsafe bound in the mid stick position which allows the ESC to arm. If you advance the throttle you do get a single burst of forward but if you then use reverse, the forward no longer works. Restarting the 'model' resets this but you again only get one burst of forward. The RX is a cheap REDCON one from Banggood.

From watching this video I wondered if this may be some incompatibility with the brake not releasing ? (I don't need a brake particularly.) Fiddling around with the trims and sub-trim to give full range of stick moment doesn't make any difference.

So I'm looking for solutions before I can get a boat on the water:

1. Would an ESC without a brake be more likely to work?

2. Or is it an inherent Spektrum problem which means possibly getting a cheap pistol grip transmitter instead?

3. Or could it be the receiver that is the issue?

4. Or is there a programming/mixing hack with the dX6i that I've missed?

Thanks for your help,

Last edited by slowmatch; Jun 07, 2019 at 03:37 AM.
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Jun 06, 2019, 04:23 PM
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Might be the ESC. Try plugging it into the steering servo spot on the receiver and see if it works

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Jun 07, 2019, 03:34 AM
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slowmatch's Avatar
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Thanks - yes I have tried that and it does exactly the same thing on all channels. A single burst of one direction and then it will only work in the other.

This, and the fact that both the 10A and 5A braked ESC's do the same make me think it's a compatibility issue. I've ordered the brakeless version of the 10A to see if that makes a difference.

But I would like to get to the bottom of why these don't work!
Jun 08, 2019, 05:49 AM
Registered User
1. Yes. A braked ESC is pointless in a boat.
2. Don't know, I'm not a Spektrum guy.
3. Highly unlikely, a receiver should just take instructions and pass them on in a format that whatever is plugged in can understand, i.e. a pulse between 1 and 2mS long, 50 times a second. A receiver in a cheap, dumb configuration is much less likely to be susceptible to buing victuim of a particular manufacturers added "facilities".
4. Thats why I like simple, basic radio gear, with switches rather than a computer program fogging the issue, taking my instructions and turning them into something that it thinks I want.

Testing the ESC using a servo tester will give it basic standard conditions. If it performs as expected doing that, the problem is in the radio handing out wrong information. If it doesn't, its a problem ESC. Most testers can drive several items together - a servo connected like that can act as an indicator.
Last edited by mfr02; Jun 08, 2019 at 06:04 AM.
Jun 08, 2019, 09:03 AM
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posted a reply in your other post here
Jun 08, 2019, 09:50 AM
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slowmatch's Avatar
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Thanks for the input.

I managed to find the 10A Braked ESC and do some testing with a servo tester.

It seems that the 10A will not go straight from FWD into REV. Presumably going from FWD into REV is activating the brake. You have to go to full REV and then centre the stick at which point the brake resets and you can use REV in the normal way.

The problem with the dX6i (and I believe any plane TX) is that you don't automatically get full throws and so the brake won't release. It works if you set the dX6i trim (throttle stick switch) and sub-trim (computer) to permit full REV but then you lose a bit of the full FWD movement.

So in a sense the 10A Braked ESC works as intended but it's not very practical for use in a boat - centering the throttle stick with no spring is fiddly and would be a distraction on the water IMO.

The 5A ESC does not work properly even with the servo tester. You get the same situation where REV works initially but going from FWD to REV engages the brake or at least prevents REV form working. Even at 'full throw' I can't get the brake to reset. The Banggood blurb does not mention a brake on this ESC so I don't know if I have understood this correctly or if it's faulty or in some way incompatible with Spektrum as I feared.

Anyway we will see if the 10A Unbraked version is any better - I just have to wait another 2-3 weeks for it to arrive!
Old Jun 15, 2019, 12:46 PM
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Jun 17, 2019, 09:13 AM
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Finally some good news!

I ordered this Unbraked 10A ESC from Ebay it arrived relatively quickly (9 days) and it works!

Fine on both the servo tester and the Spektrum dX6i. So it seems the brakes are the issue.

A couple of things to note however.:

1. You need to be careful to make sure the throttle stick is centred when switching on as it will arm and start the motor in any position!

2. The rated voltage is 4.8-8.4V ie 1S Lipo does not work. This could be a consideration for motor choice - the MFA RE-140 I was hoping to use is rated 1.5-3V
Jun 17, 2019, 03:48 PM
Just Plane Nutts
AirDOGGe's Avatar
If you go into the programming of your DX6i, you can set servo throw for any servo channel to 125 % in each direction for more travel.
Sep 29, 2019, 06:01 PM
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The controller does this work.

The controller must have the ability to go into revers. My controller is an Mtronics 25 Amp controller, When installing it, it is only necessary to put the throttle sick in the mid position, turn on the radio then the receiver and controller, you have 2 seconds to push the button on the controller, the controller remembers the mid stick position as Zero throttle, then move the throttle stick to full throttle, the controller remembers this as full forward throttle. Then move the stick to full back position, the controller remembers this as full revers, return the stick to the mid position and turn off. The controller now does the forward and reverse decisions. The stick on the transmitter makes the radio send a frequency pulse to the receiver. The pulse gets wider as the stick nears the full position. So the controller can not determine when you are in the zero position. A reversing controller looks at the width of the pulse when it is at the mid point and remembers that as zero throttle, it then looks at the width of the pulse at full up and remembers that as full throttle and when the sick is placed in the down position, the controller remembers that pulse width as max reverse. Any thing above the mid position is forward and any thing below the mid position is reverse. All done by the controller.
Oct 04, 2019, 11:01 AM
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