Savox servo question.....

[captain-codpiece]

Please can someone help me before I jump off the Severn Bridge? I have a losi excelorin 6.5, in a xxx 2wd, and have just bought a savox servo. Now it's not FET so should be ok. My friend has the same car/brushless and servo combo and it works fine. Only difference is mine is the 20kg torque servo, and he runs the 12kg torque servo. The problem is once the new servo fitted the speedo randomly cuts out. Its running 4600 nimh, and is on factory setting. I have v2 software. I have changed receiver/tranny/crystals, and it makes no difference. As soon as I put the old crappy servo back in, problem goes away. I am thinking maybe it's because the servo is drawing too much power? Has anyone got any ideas?

Captain

[edvin]

Originally Posted by captain-codpiece

I am thinking maybe it's because the servo is drawing too much power? Has anyone got any ideas?

Captain

You are right. BEC is too weak for such a huge servo.

[3975dave]

Would a power cap in the reciever help?

[captain-codpiece]

Sorry if I sound a bit dense but what is BEC? I haven't tried a cap yet, would that help?

Thanks

[General Accident]

BEC = battery eliminator circuit ie, on 1/10th cars the power for the servo/receiver comes from the main battery and eliminates the need for a separate receiver pack. Such a high torque servo would normally be used in a 1/8th nitro car I'm guessing and they of course have a dedicated receiver battery pack to run the servo as they don't have a battery for the motor (unless you have a new fangled electric 1/8th of course).

[General Accident]

Originally Posted by 3975dave

Would a power cap in the reciever help?

Dunno if that'd help as I'd guess a high current draw from the servo would override it fairly quickly but it might. Will the shop exchange the servo for a 12kg one, that would seem to be the simplest solution.

[edvin]

Or to by external bec http://www.hobbycity.com/hobbycity/s...oise_Reduction

[The Doctor]

Blimey Lloyd, I can't believe your luck. The 12kg Savox I've got is great. Definitely try to swap yours for the 12 kg version if you can.

[captain-codpiece]

Ok so this still isn't sorted. I swapped for the 12kg servo. still the same symptoms. I have changed my radio gear to 40mhz, still the same.It just seems as though this servo won't work with my excelorin.....but I know it does as someone else has the same speedo/servo combo. Does anyone out there have any idea as to what I can do? Other than to sell it all and take up knitting.........

[RogerM]

Your Severn Bridge comment says you not far from Bristol or South Wales. There are plenty of people around that area that would work out what the problem is with the set-up for you! If your on my side of the bridge I'd happily look at it.

[The Doctor]

Lloyd, is that the radio gear I lent you last night? There shouldn't be any problem with that radio/receiver, so must definitely be something else.

How about we plug your servo into my receiver and see what happens on Friday before we start racing?

I've got a spare Novak XXL 40Mhz receiver you could try aswell (although I do want to keep that!). However as I say, I am sure it's not the radio gear I've lent you that's causing the problem.

Cheers mate, give me a buzz and we'll sort it.

[Northy]

Does the Losi speedo have a programmable BEC output voltage, I seem to think I've seen it does somewhere.

G

[The Doctor]

Not that I know of. I don't remember reading about that in the instructions for mine.

[captain-codpiece]

Cheers Paul, got your voicemail. Its a bit late to call now but will drop you a line tomorrow. And thanks everyone else for the offers earlier but unfortunately I'm nowhere near the Severn bridge...lol. Probably a good job just in case. I am not sure about programable bec voltage but it does say something about 2.4ghz or legacy in the software menu.......but now my friggin usb adaptor has just packed up on my PC... Do you ever get one of those days?????? In fact just to totally take the p155 not only has this broken today, but when I got in from work I managed to break my toilet too. I think I am cursed. Good job I got a sense of humour.

[Casper]

The 2.4ghz setting should not effect the BEC at all. It will make the speedo run a little cooler though if you have a 2.4 system. Everything runs a little faster switching wise which helps keep the ESC cooler. Other then that you should not feel anything different in the speedo setting.

What a weird problem. I am running the new orion servos which seem to be the same as the Savox servo's. I am running the 1007 version though. No issues so far?

See if you can get your hands on another ESC to plug into the system to see if it goes away. Just to elminate the ESC from the equation. I know you basically have replaced everything else but woth the try just to know.

[mikeyscott]

Hi mate,

Good racing at the weekend, did you ever get this fixed as I had a similar issue, but my Savox died on me?

[mpg200]

Ive had a similar issue with a 12Kg servo, and after a bit of thinking and testing power caps etc. i have decided to make a separate BEC that is man enough for the job. it turns out its not my esc cutting out its the reciver crapping out at low input voltage.

Why do some ESCs (mines an LRP brushless sphere) have such weak BEC circuits? Most recivers and servos are happy at 6V input. so why are BEC set at 5.4V (mine is) and why the silly thin wire!!! the current to the servo has to come all the way from the ESC on wofully inadequte wire. it makes no difference haviing manly servo wire if the esc wire to the Rx is thin.

And power caps... has anyone done the calculations on how much energy an Rx and servo need to stay alive for say 200ms while the BEC has a transient crap out? very large i say grrrrrr, power caps just take up space.

so come ESC people make some better BECs and the problem will go away

sorry for the rant but this has bothered me for while

Discuss....

[Northy]

Originally Posted by mpg200

And power caps... has anyone done the calculations on how much energy an Rx and servo need to stay alive for say 200ms while the BEC has a transient crap out? very large i say grrrrrr, power caps just take up space.

Discuss....

I have cure interference 'glitches' in the past by fitting a power cap and can 100% say that was what fixed it. Me and the god that is Jim Dicko spent a long time one Saturday night at a regional last year fixing some 'issues' I had. The power cap solved them.

I now run the biggest one I can fit in ALL my cars religiously, imho it would be silly not to.

Sorry they didn't fix your problem, but they can fix other problems. I do also agree that not all BEC circuitry is created equally though

G

[Answer-RC-Pete]

Make sure that the EPA (End Point Adjustment) of the servo is properly adjusted as if not it will be getting to the travel end of the cars steering geometry then continuing to pull causing a spike in current drawn and the dropping of power to the motor / esc.

What radio do you have? Anything half way ok will have EPA. Just set it so the servo is not straining you will see the steering stop traveling and the servo trying ever harder to move the imovable wheels.

A capcitor would help somewhat..
G does a Nortech Super Dogs Do Dahs one which some say has been eaten by the devil prior to make it even harder!

Other than that a External BEC of 5amp rating should solve the issues if nothing else does.