BEC and other wiring (see diagram)

[pritch]

Hi folks,

Purchased a BEC and am currently trying to make it all work in my new X-Crawler. I'm trying to fix glitching I've been getting, especially in reverse.

If you didn't see my build thread (it's in the XTM forum section) the back story is I'm trying to re-use all these electrics from my old crawler, which I did not build myself.

So this is a new "build" for me and a learning curve - I figured I'd do a complete wiring diagram of how I've hooked it up today and include everything that is present in a bid to find out some more info - for example, if you take a look, can you tell me what the capacitor wired to the ESC might be for?

I soldered in the BEC input to the ESC tabs as the wires aren't long enough to reach the deans plug - is that ok?

I was kinda surprised to discover the red wire to the RX from the ESC had already been taped. I hadn't noticed that before - could it be that capacitor is some kind of homebrew BEC?

Here's my diagram;




Sorry if it's a bit huge, but I wanted it to be clear! This is an approximate layout as if you were facing the truck from the front - so the Airtronics is the front steering servo, Hitec rear steer etc.

BTW the TX is a Tower 4-chan intended for flying I think with a rudder at Ch2 - hence skipping straight to Ch3.

My mind has blurred a bit and I'm not sure things are plugged in where they should be, so any help you can provide will be much appreciated! Thanks.

[SMR 510RR]

The only thing I see wrong is the use of a cheap BEC. Do yourself a favor and grab a Castle Creations 10A BEC. With the use of 2 mildly powerful servos you will need the extra current.

Also I may suggest wiring the BEC directly to the servos rather than through the RX to the servos. This will make sure that the servos are going to get the full 10A (or 5A with your turnigy BEC) and wont be fighting with anything else for power. Basically the + and - of each servo will go to the BEC and then the signal wire will go directly to the RX. You can either build a little harness to attach everything or pull the signal wires out to run to the RX and use a Y harness from the BEC to the + and - of the servos.

What was your initial glitching like?
Glitching can be caused by many things, probably the one we see the most is cheap radio gear. A BEC won't necessarily fix glitching, what it will do is keep a constant flow of juice going to whatever is plugged into it. If you were experiencing brown outs then it should fix that, if you were experiencing something else it may not have been the problem.


Also that capacitor should stay there, a lot of ESC's use them to even out the power input...Its not uncommon.

[pritch]

Thanks SMR.

Yes, I must admit I was advised to get the CC BEC, but knowing that if I got it I'd just have to get the CC link too, well I wanted to see if a £5 bec might do anything before I spent £40. I might take a deep breath and do it. It's only money

I read elsewhere about that wiring idea - so you end up with two sets of + and - wires going through a Y harness to the output of the BEC, then two futabas with just a single white wire plugging back into the respective RX channels? If that's right and assuming the BEC is then outputting direct to the servos, I need to replace the + - lead that ran from the ESC to the 8/B socket on the RX to give the RX power?

I'm really puzzled now about that taped red wire - if it was taped prior to me installing the BEC, what was acting as a BEC before?

The glitching looked like flashes of the ESC LED red and occasionally green when under part throttle and steering, with the occasional steering "wobble" both front and rear. Reversing, the truck often cuts out altogether if I try the servos, until the throttle is returned to neutral and I apply it again. Any insights?

Thanks for your help

[Charlie-III]

A single red wire from a ESC (to the RX) will power the RX and whatever else is connected to the RX.
If an external BEC is wired direct to it (like a steering servo) the RX supplies a control signal (through the white or yellow wire) to the servo and the BEC wil supply power.

[SMR 510RR]

Originally Posted by pritch

Thanks SMR.

Yes, I must admit I was advised to get the CC BEC, but knowing that if I got it I'd just have to get the CC link too, well I wanted to see if a £5 bec might do anything before I spent £40. I might take a deep breath and do it. It's only money

Look at the castle link as an investment. Once you get more castle stuff it makes it really nice to be able to adjust settings for ESCs and stuff in the computer. You could also order it from Holmes Hobbies and he will set it to whatever voltage you want before shipping it out.

Originally Posted by pritch

I read elsewhere about that wiring idea - so you end up with two sets of + and - wires going through a Y harness to the output of the BEC, then two futabas with just a single white wire plugging back into the respective RX channels? If that's right and assuming the BEC is then outputting direct to the servos, I need to replace the + - lead that ran from the ESC to the 8/B socket on the RX to give the RX power?

Yea, servos get power from the BEC and signal from the RX. All of the ports on the RX are interconnected so your power can plug in from any port, it does not have to go through the 8/B port.

Originally Posted by pritch

I'm really puzzled now about that taped red wire - if it was taped prior to me installing the BEC, what was acting as a BEC before?

I'm not sure, seem strange as it is getting power from somewhere. There is no red wire in the servo connector coming from the ESC?

Originally Posted by pritch

The glitching looked like flashes of the ESC LED red and occasionally green when under part throttle and steering, with the occasional steering "wobble" both front and rear. Reversing, the truck often cuts out altogether if I try the servos, until the throttle is returned to neutral and I apply it again. Any insights?

Thanks for your help

The flashing lights seem typical, I dont have any Novak gear so I cant say for sure. Typically the esc will have lights that indicate that throttle (forward or reverse) is being applied and also may indicate the temperature of the ESC. My advice would be to look in the manual, there should be some talk about the lights and what they mean.

A steering wobble would typically indicate a glitch that has to do with interference. Try keeping your RX away from everything else related to electronics and make sure your antenna doesnt touch any metal.

As far as everything cutting out when going into reverse I dont have a idea why this would happen in reverse only. Could be a ESC issue or a TX/RX issue. What happens to the light on the RX when it cuts out? If it turns off then you have a brown out or black out situation, this will be cured by the BEC. If it stays on then you have something else going on.


As always, it is very hard to troubleshoot electronics without actually seeing what is happening. I suggest troubleshooting the problem by the process of elimination. Try the BEC, if that doesnt help you know you have something else going on. Also a good way to troubleshoot TX/RX issues is to plug in a couple of servos in place of other components (esc) and see if you can duplicate the glitch by pretending to drive with it like that. If you see a glitch you know you have some interference going on.