Mamba X aux wire glitch, can't get it to work properly

[Antsiranean]

Hi!
I am almost, almost finished with my Bomber, just trying to get the electronics right now.

I have a Mamba X, where I have coupled the aux crawler/rock racer mode with a 2-speed gearbod., just as I have in my Yeti. It took a while to get it to work, and I have just realized that I don't need a Y-harness with reverser as I do in the Yeti, but just a plain Y-harness. This is due to the shift servo being orientated in different directions in the two vehicles, that I had not realised before.

That's the background, now the problem. When I turn everything on, the aux function shifts between rock racer and crawler mode as it should, but it does not engage the shifting servo. Servo does nothing. If I then disconnect the aux wire from the receiver and reconnect it again (with power on) I get an "aux wire radio glitch" audio signal, but the shift servo works, as well as the switching between racer and crawler mode.

That means, that if I wan't channel 3 to work the way I want I have to power up the rig, then disconnect and reconnect the ch3 wire going in to the ESC. Very impractival, to say the least. In addition I get the annoying audio alert, even though the aux wire is clearly working. Especially impractical on a Bomber, where I have to unscrew a zillion screws to get to the receiver.

Strange thing is that when I started to get the ESC settings right, everything worked perfectly. Then, out of nowhere, this issue turned up.

Now what to do? Suggestions?

 

[mikemcE]

Hi!
I am almost, almost finished with my Bomber, just trying to get the electronics right now.

I have a Mamba X, where I have coupled the aux crawler/rock racer mode with a 2-speed gearbod., just as I have in my Yeti. It took a while to get it to work, and I have just realized that I don't need a Y-harness with reverser as I do in the Yeti, but just a plain Y-harness. This is due to the shift servo being orientated in different directions in the two vehicles, that I had not realised before.

That's the background, now the problem. When I turn everything on, the aux function shifts between rock racer and crawler mode as it should, but it does not engage the shifting servo. Servo does nothing. If I then disconnect the aux wire from the receiver and reconnect it again (with power on) I get an "aux wire radio glitch" audio signal, but the shift servo works, as well as the switching between racer and crawler mode.

That means, that if I wan't channel 3 to work the way I want I have to power up the rig, then disconnect and reconnect the ch3 wire going in to the ESC. Very impractival, to say the least. In addition I get the annoying audio alert, even though the aux wire is clearly working. Especially impractical on a Bomber, where I have to unscrew a zillion screws to get to the receiver.

Strange thing is that when I started to get the ESC settings right, everything worked perfectly. Then, out of nowhere, this issue turned up.

Now what to do? Suggestions?

Robert from Castle should be able to answer this, try a PM here on the forum

 

[Browneye]

My guess is you'll have to have a 100% switching back and forth for your third channel, not graduated or dynamic. You want the channel to throw one way or the other, as your shift servo won't respond to a dynamic range.
At least that's how I understand it. I fiddled with this when setting mine up and finally got it to work the way I wanted it to, but I skipped the 2-spd trans part of it. With brushless you only need one speed.

Robert Castle to the white courtesy phone please...

 

[robert@castle]

I'm honestly not entirely sure what is going on. It seems like the receiver might not be putting out a strong enough signal to split it when both are hooked up. Do you have a different servo(maybe of a different brand) you could hook up to the splitter as a quick test to see if the not running is something specific to Savox not liking a low signal voltage when turning on. I'm thinking that maybe it has an 'arming' process just like an ESC and it doesn't exit out of the startup code until it sees a signal it likes and then accepts a lower voltage signal when it's running.

I have a strong suspicion that something like this:
https://www.towerhobbies.com/cgi-bi...ChYHfZRVDSc51111Ank7ra31Ml18ZtSBoCKYUQAvD_BwE
or this:
https://www.servocity.com/12-boosted-y-harness
would fix the issue, but I feel bad recommending someone spends money when I'm not 100% sure it will fix the issue.

 

[Antsiranean]

I'm honestly not entirely sure what is going on. It seems like the receiver might not be putting out a strong enough signal to split it when both are hooked up. Do you have a different servo(maybe of a different brand) you could hook up to the splitter as a quick test to see if the not running is something specific to Savox not liking a low signal voltage when turning on. I'm thinking that maybe it has an 'arming' process just like an ESC and it doesn't exit out of the startup code until it sees a signal it likes and then accepts a lower voltage signal when it's running.

I have a strong suspicion that something like this:
https://www.towerhobbies.com/cgi-bi...ChYHfZRVDSc51111Ank7ra31Ml18ZtSBoCKYUQAvD_BwE
or this:
https://www.servocity.com/12-boosted-y-harness
would fix the issue, but I feel bad recommending someone spends money when I'm not 100% sure it will fix the issue.

Thanks a lot for the reply Robert! Reading your thoughts, my to-do list will look like this:

1. solder a Y harness (without reverse)
2. try current servo with the new Y-harness
3. try changing the servo (I am now running a Virus RC (?) that I got at my LHS) to a Savox SW-0231MG.
4. consider powering the shift servo from the Castle BEC that powers my steering. A rx bypass with dual output should do the trick, right? I could solder one like this myself.
5. consider buying one of the gizmos you feel bad recommending.

Good to have a plan! Is it a good one? It should keep me busy over the weekend. Thanks for helping out everyone!

 

[robert@castle]

Thanks a lot for the reply Robert! Reading your thoughts, my to-do list will look like this:

1. solder a Y harness (without reverse)
2. try current servo with the new Y-harness
3. try changing the servo (I am now running a Virus RC (?) that I got at my LHS) to a Savox SW-0231MG.
4. consider powering the shift servo from the Castle BEC that powers my steering. A rx bypass with dual output should do the trick, right? I could solder one like this myself.
5. consider buying one of the gizmos you feel bad recommending.

Good to have a plan! Is it a good one? It should keep me busy over the weekend. Thanks for helping out everyone!

I think 1-3 sound like a good plan, but I don't expect 2 to give any different results because I suspect that it is an issue with the way the servo works conflicts with how we are reading the signal.

4. I don't think it is a BEC power issue since the AUX wire doesn't have a power and ground wires on it. I think it is a signal voltage issue, where the signal is being degraded by too many items trying to observe it. It's really hard to say without hooking it up to oscilloscope. The pieces I recommended would pull the signal voltage back up and make it a clean signal for both to see.

 

[Antsiranean]

I think 1-3 sound like a good plan, but I don't expect 2 to give any different results because I suspect that it is an issue with the way the servo works conflicts with how we are reading the signal.

4. I don't think it is a BEC power issue since the AUX wire doesn't have a power and ground wires on it. I think it is a signal voltage issue, where the signal is being degraded by too many items trying to observe it. It's really hard to say without hooking it up to oscilloscope. The pieces I recommended would pull the signal voltage back up and make it a clean signal for both to see.

Thanks for the input, seems like you were right. It wasn't a BEC power issue, my Savox castle worked fine in the exact same setup.

What I did in the end, was to buy a switch from my LHS (support your LHS when you can...) and put the switch between the rx and the shift servo. I turn on the car and once the ESC has done its startup sequence, I then turn on my shift servo with the switch, and it then works perfectly.

I have a signal booster on order, which should enable me to remove the switch, but it will take a couple of weeks before it arrives and this solution works fine for now. I think it will work fine until the switch gets soaked and dies, at which point I will remove it and put the booster in instead.