Scorpion XXL

Tried the XXL I got to replace the horrible mess of speedos I was using in Cicatrix over the past few days and had a few wee glitches. Ive been called out to work so havent fully messed about with it and might manage to get it done myself but if anyone can suggest common problems that would be great.

Ive got it connected to 4 drills on 19.2v. Firstly, the BEC wasnt playing, took me a long time to get that to behave itself to the point were I may run a reciever pack instead, this had been suggested as a good idea anyway be a few people so I was eventually going to give that a go. After thia was working, the motors only seem to want to work in small bursts, turning on and off once every second or so. Does that sound like a current limiter is kicking in or maybe calebration problems? Might even be the BEC loosing power although it didnt look like it to me. I will post videos if I ever get enough time off, just seeing what peoples thoughts on it might be.

With Tron (old) I had all kinds of problems like this, in the end I just used a sidewinder I had. But that went into Seraph so now I use the Wotty 100 speed controller this seems to work fine.

Now the Scorpion is in the walker (Pilgrim) running two 250w motors and has never missed a beat!

I think the speedo just doesn't like running 2 motors off one channel. I think there is enough power to run the drill motors but the software or what ever these things have just thinks the load is somehow wrong,

I am no electronics expert, but perhaps if you fitted a capacitor across the motors this may reduce the spike or noise or what ever the problem is and the speedo might play ball.
you can run the motors in series then the speedo would only see one load. but you would mess up the electrics and have to adjust the battery voltage.
I am sure you will get better advice than the above :uhoh: :uhoh: :uhoh: but that's my take on it. :mrgreen:

Cheers Craig, I hope it is something simpler than you have suggested but i'm glad to know i'm not the only one having this problem. I was hoping for a simple plugin and go part, but I suppose that isn't quite the case :? . Hopefully there is someone out there who has successfully run 4 motors from an XXL and can let me know, I may even work it out after a few more hours messing about with it.

drop the guys that make it an email and see what they say

Is that just the robot power guys Gary yeah? I'm not sure if its an original XXL or a mod, David did tell me but it has slipped my mind at the moment, but I suppose that shouldn't matter too much. I have emailed them before, they're pretty helpful. I will give it another bash later or tomorrow morning and if its still misbehaving then i'll drop them an email.

http://i1214.photobucket.com/albums/...9-23-44-12.jpg

Thats a video of how it is running at the moment, seems to work at the start of the video then it starts with the stopping and starting I was talking about. The second section of the video is when I turned the receiver off and it didn't seem to failsafe, it just continued to drive and when I tried to show the receiver on camera it accelerated forwards. Very strange indeed....

I think the XXL goes into current limiting. I guess overvolted motors?
We had that in Kashei, on 6S 2P with 2 speed 900's on the MSR 12-54 drivetrain.

2 options.
Lower the voltage.
Or run the motors in series.

For Kashei, we now use a Sidewinder.

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Thats a video of how it is running at the moment, seems to work at the start of the video then it starts with the stopping and starting I was talking about. The second section of the video is when I turned the receiver off and it didn't seem to failsafe, it just continued to drive and when I tried to show the receiver on camera it accelerated forwards. Very strange indeed......

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Odd ..yes.

However the last part ...transmitter OFF rather than reciever? ...indicates that it's probably NOT current limiting as it happily accelerates to flat out with no motor hunting.

Questions
Did you bind the BR6000 at the drive OFF failsafe position?
How have you got the XXL Jumpers set...are you using a voltage above 16v .. and if you are have you clipped the HV jumper wire?

Things to fiddle/play with.

Disconnect 2 drive motors ...one each side....see if it helps by reducing the load.
Try with a reciever battery ..remembering to clip the BEC jumper wire.

I have recently had an issue with the Spektrum recievers output signal being unable to drive a homebrew R/C steering servo ... the hunting was some what similar to your XXL symptoms.... this was solved by buying a signal line booster. http://www.spektrumrc.com/Products/Defa ... odID=SPMCP

EDIT I see from further up this thread that your running 19.2 v...you might be getting voltage sag after running for a few seconds and thus dropping under the 16v jumper limit. I remember reading that there is asolution to this ..but can't for the life of me think what it was.

Been dredging my memory ... the 16v jumper ..as I recall is to do with the voltage supply to the BEC chip.

You're right Woody, the transmitter was off and receiver on in the last section of the video.

The BR6000 should be bound in failsafe mode yes, as it was failsafing properly when I was running with the old setup and I haven't redone it since then. The BEC wire is still connected and the HV wire has been cut.

I was told by a few people that the BEC can be problematic on the scorpions, I will get hold of a receiver battery and see if that solves the problem.

I will give those experiments a go and get back to you when I have.

I found an old receiver battery that I thought was busted in a mixture of HW electrics waiting to be reassembled and it seems to be a vast improvement. I still have to nurse the throttle up to full whack but it does get there after a few seconds, but that might be something to do with the battery not being charged for the last 10 years. I did also try the 2 motor thing and it worked better, but not properly before I added the receiver battery, it would go faster than with the 4 motors before it began to stutter but still stuttered before getting to full throttle.

Will probably look at getting a better receiver battery and getting it tried out with that as it seems to have fixed the problem. Is there anything specific I should be looking for in a receiver battery? I have never really had to use one before.

The failsafing is still not playing though, I may have to rebind the transmitter and receiver and see if that is the problem. Also only getting forward and reverse drive at the moment, but i'm sure thats a problem thats easy to fix once its all working.

I'd also check your main batteries ... stick a meter on them whilst they're underload ...see what the voltage sag is.... I've a feeling that one pack is fudged.

They seem ok Woody, 11.something v when under no load and between 9.2v and 9.6v when running full tilt.

You said the BEC wasn't working, generally speaking the XXL's BEC is utter testicles when used with Spektrum, thats why I used a seperate one (and why the BEC loop was cut on the XXL when I sent it to you).

As for current limiting, it may well be because it was with my Speed 900's, but that was due more to my motors than the controller.

The BEC was working to a point, but not well at all so I agree with you there. I charged that battery a bit and it seems like its getting better the more charged it is, but it is still very jumpy. The one I found has a max charge of rate of 900mA so takes ages to charge. Think I will have to get a battery ordered along with my new batteries for Daiske. Should I just get any reciever battery or am I better with a specific rating or anything like that? Also, is 4.8v NiCad the way to go on that front?

You could consider a BEC ...I've one of these ...OTT on the voltage but it gives the possibility of going mad should you ever wish to.
http://cgi.ebay.co.uk/UBEC-5A-8-40v-SBE ... 564298d0ea

Look like a good shout Woody, it talks about being for Li-Po's, does that matter that i'm using NiMH? I shouldn't think so, but thought I should ask.

volts is volts ...Use it on any battery type combo in the stipulated range

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The BEC is the part that drops the battery pack voltage (7.4v, 11.1v, or whatever) down to 5v or 6v for use by the receiver and servos. It's called a battery eliminator circuit because it eliminates the requirement for you to use a separate 4-cell NiCd or NiMh receiver battery to power them.

The BEC is usually incorporated into the ESC, so that simply plugging the ESC into the receiver is all you need to supply power to it. But often the built-in BECs are insufficient to deal with all the servos you have, or the high voltage of a 4S and upwards LiPo pack, so you can get a stand-alone BEC to do the job.

Stand-alone BECs are usually the switching kind, so they can deal with higher voltage and current than the linear kind which are usually built into the ESCs. SBEC, UBEC, and other terms have become generic terms for, usually, switching BECs. But it's always wise to check the BEC's specs, irrespective of what the manufacturer calls it, to make sure it is switching if you want high-power and/or high-voltage use.

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Have you checked the calibration? We use the XLs on our P2D and if the trims get knocked, they 'over travel' and it cuts out when you get to the end of the travel on the stick.

Sorry Alan I didn't see your post there, I will check that tomorrow when I get the chance.

I got hold of that SBEC today and still getting the same sort of problems, the motors begin to turnoff and off quickly, but I suppose that is just a case of decreasing the amount I move the stick or the acceleration on the transmitter (however that might happen) and that will fix that if it is unavoidable for the moment, the more worrying thing is the failsafe playing up, its still driving the front 2 wheels forward when I switch the transmitter off and I have tried binding the transmitter again with no joy. Is this something the XXL was also known to cause? :?

do you have a vtail mixer in there or a gyro?

Mixing is on the speed controller when you add the pin jumper in. It may be an idea to calibrate the XXL, as it was stated somewhere else recently, the sticks could be going beyond their pre-set range, you need to calibrate it so it shouldn't keep shutting off like that.

I don't have either a v-tail mixer on or a gyro, i'm pretty certain no mixing is on on the handset either because I was running an external v-tail at the championships but have now sent it back to Jamie.

All the jumpers are off right now, I will try calibrating it again and see if that fixes the problems, I am hoping it will do. Right now the control is forward and back on the left stick and left and right on the right stick but only the front wheels are moving for left and right, but I have been kind of forgetting about that at the moment to try to get the other stuff sorted first.

Partial success to report. I have reset the tx so there is no mixing or anything strange going on there, binded the tx and rx again with the failsafe set properly and also re calibrated the XXL.

The failsafe is now working properly so at least I will pass tech check but still having a problem with the small jumps forward when I accelerate beyond about 60% of the travel on the stick. Also a problem which has probably existed the whole time that I haven't noticed is that only the front wheels seem to steer, the rear wheels do nothing when turning.

That is quite a confusing way to put it so will say it a different way.

Left stick: Forward and back
Right stick: Left and right, front wheels only

Any idea how I might fix that?

You've got some weird wiring...and or some mixing happening in the tx.

Just to check your setup ... ONE XXL nothing else no additional weirdness like another speed controller for one pair of wheels?

Then..XXL.
BOTH RH Motor wires should be joined together...and connected to the XXL
BOTH LH Motor wires should be joined together...and connected to the XXL

Making sure that both paired motors rotate the correct way.

[attachment=0:245gc9bh]2M.JPG[/attachment:245gc9bh]

Haha thats correct Woody, only the one speed controller this time, none of that one Scorpion two Electronize nonsense anymore.

The way you have drawn it is the way I believe I have done it, or at least the way I meant to do it anyway, but I am beginning to think electronics is not my strong point...

I think they do rotate the same way, because forward and back work fine, its just the turning that makes only the front wheels rotate.

I reset the tx to try to eliminate any sort of mixing craziness after all this was happening but that doesn't seem to have fixed it. I will try resetting it again, that seems like the most logical solution, but I am totally stumped otherwise.

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I think they do rotate the same way, because forward and back work fine, its just the turning that makes only the front wheels rotate.

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IMO It's impossible for this to happen IF wired as I've shown...and NO mixing anywhere.

Start your wiring from scratch....in fact lets start everything from scratch!

ONE SIDE AT A TIME.

Make sure ALL mixing is OFF on the TX and XXL

pick an unused and NEVER used model number if you have that option.

Connect drive side MOTOR pairs to the XXL as shown.

TX using single RH. stick control

Connect ELE on the RX ( up - down ) lead to the XXL.

Push stick forwards ..both motors ON ONE SIDE should rotate in the same direction.
Push stick backwards ..both these motors should now reverse and rotate in the same direction.

DONE for that side.

You might find it easier to disconnect the ELE lead before trying the next step.

connect the AIL RX lead to the XXL

Repeat stick movements with the RH STICK. ( left - right )
Push stick left ..both motors ON THE OTHER SIDE should rotate in the same direction.
Push stick right ..both these motors should now reverse and rotate in the same direction.


When that is sorted we can look at wether the motors are rotating correctly to give the bot forwards and backwards... just a simple servo reverse selection in the TX menu ... ..THEN we can look at mixing.

Thanks Woody, I'll try all that out tomorrow and post some results, I appreciate the time you're taking to help.

I have tried several channels and there doesn't seem to be any difference, also I have tried turning off all mixing and the result is the same. I will try it with the Planet 5 set tomorrow too, just to rule out the possible mixing problem. I'm surprised with myself that I haven't done that earlier actually, seeing as the failsafe decided to mess itself up for no reason, who knows what else might be happening.

I took everything apart as you suggested and stuck it all back together again and after a few tweaks it works again! :D .

Just to sort out the mixing then its ready just in time for RL Edinburgh.

Thanks again Woody.

Are you driving using BOTH channels on the right stick and have you currently got the bot working like this ...?

To check everything is fine ...pre-mix ...take your transmitter and rotate it 1/4 turn clockwise ... your bot should follow the stick movement vertically and horizontally and drive correctly with the transmitter twisted like this.


Everything OK?
Then turn on the mixing..... EITHER the XXL's mixing ...OR the Transmitter mix....that will probably be Delta Wing an Ele / Ail mix.

That is how I wanted it to work yes, but currently it isn't.

Its running forward-reverse on the left and right-left is on the right. The jumpers are all off the XXL and mixing is off on the transmitter.

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Originally Posted by Anttazz

That is how I wanted it to work yes, but currently it isn't.

Its running forward-reverse on the left and right-left is on the right. The jumpers are all off the XXL and mixing is off on the transmitter.

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NO .... All on one stick ... AILeron and ELEvator R.H. Stick.

left stick - forward reverse - is THR on the rx

right stick -forward reverse - unplug from THR and plug into ELE on the rx.

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TX using single RH. stick control

Connect ELE on the RX ( up - down ) lead to the XXL.

Push stick forwards ..both motors ON ONE SIDE should rotate in the same direction.
Push stick backwards ..both these motors should now reverse and rotate in the same direction.

DONE for that side.

You might find it easier to disconnect the ELE lead before trying the next step.

connect the AIL RX lead to the XXL

Repeat stick movements with the RH STICK. ( left - right )
Push stick left ..both motors ON THE OTHER SIDE should rotate in the same direction.
Push stick right ..both these motors should now reverse and rotate in the same direction.

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Now ...having said all that it occurs to me that you might have a different mode transmitter to normal :roll:

Which mode do you have?... mode 2 is our norm

http://www.rc-airplane-world.com/rc-tra ... modes.html

The throttle has a rachet and will stay where you put it.

It is mode 2, so normal. Seeing that picture has cleared up exactly why leads get connected where though, instead of just guessing, so thats a help.

I think it is just me not reading things properly that is abnormal. I had connected throttle and aileron instead of aileron and elevator and it now seems to be working properly with full control on the right stick and mixing turned on. The batteries are dead so I cant say for certain but i'm pretty sure it's all working.

I MUST remember in future to read exactly what you're saying and not have people explaining things more than once to me.

Thanks for your help though, even if it did take me a while to pick up on it.

Happy to help.