Radio Interference - bugy going crazy
 

Hello,

I am driving my new buggy in the parking lot to break in the engine but after 4 tanks of fuel the buggy is like is not responding. Basically when I turn the buggy left and the car slides it tries to turn right on its own or goes a bit crazy.

I hold it in the air and I press full throttle and I see the front wheels turning left right very fast. I charged the receiver battery for a couple of hours but the same happened. My transmitter is a Futaba 3VCS 2.4 Ghz and I synched the transmitter with the receiver a couple of times to make sure it wasn't the problem.

Any clue?

loose wire connection, bad servo, antenna issue, bad cell in battery pack, many things...

Try another location and see if the problem is external. Wireless-n routers are particularly offensive as they run on the 2.4GH spectrum now as well as many cordless phones.

Examine every inch of the antenna wire for nicks or scrapes, especially any part of the antenna wire thats close to the chassis.

Hello again,

its been a month now and I have tried everything mentioned in this thread and many more. I have send the receiver to Futaba and they state that nothing is wrong with it. The only thing tha they suspect is that my servos could be drawing to much current and thus causing a problem. Has anyone heard of such a thing?

Thanks

Yes, servos can be causing prob. Only way to find out is to swap them out with known good servos. If servos are not bad and its just drawing enoughcurrent tha its momentarily causing your rcvr to hit failsafe or turn off (if not failsafe), try a cap and see if that fixes prob. A cap helps smooth out the big voltage swings that can cause probs.

What is a cap?

capacitor

^^^^ like this one -

http://www3.towerhobbies.com/cgi-bin...&I=LXNRE0&P=ML

Please people I really need your help here!

I have sent the Futaba receiver to Futaba service center and they say there is no problem with it. They said it might be the Savox servos drawing to much current which the receiver can't handle. I took the eceiver to an electrician and he reenforced the wiring to be able to draw more current. I also checked the receiver battery with a battery checker after I charged it and it is Fully Charged!

The problem occurs when the engine is ON and not when it is OFF.


Any ideas are welcome since its been now 6 months and I haven't figured out the problem! PLEASE :weird:

You need to check the rcvr batt voltage actually while the engine is running while the trouble is happening. I've seen folks use a data recorder (that's usually hooked up to the esc) on the rcvr battery to figure out what was happening while RC was running - data recorder will tell you what voltage and current was doing while the RC was running.

NiMh voltage with no load is not a good enough way to judge a batt, its the voltage when the batt is under load (connected) that matters.

Why is this problem happening when engine is running and not when the engine is off?

There is vibration when the engines running and no vibration when its not running. If there is anything that can move anywhere on the buggy thats metal and make intermittent contact with the chassis, maybe its generating some kind of RF noise??


I'm still suspicious of your rcvr batt - did you upgrade the batt after you upgraded the rcvr wiring? You think the current draw is the same when you're running on the track versus just sitting with the engine off while working the servos?

Other than that, I don't have a suggestion. If it was mine, I'd take it completely apart, clean it and put it back together replacing anything that look suspicious. I've seen that work in similar cases like you're having. You never know what it problem was, but its gone.

well the buggy and everything is brand new. I didnt upgrade the battery though its still my new 6v one. I really dont know if the current draw is the same when the engine is on but i guess it is.

Engine off vs engine on, buggy sitting on stand - amp draw is the same. Buggy running on the track, amp draw higher.

I would try another batt borrowed from someone who has proven it works in his buggy - or better yet, get him to run your battery and see if it works like its supposed to.

If you've tried everything, then what's left is to start swapping out components with new ones cause one of yours is not right. Beyond that, if everything is new, I don't know what to tell you.

You mentioned full throttle and the steering starts acting up. The left turn issue you describe, are you turning full left on the radio, possibly with full throttle also? What about partial throttle and steering, is it OK then?

My WAG: Have you set the servo endpoints correctly? It’s possible the endpoints are set too high, at full input the servos might be binding up and causing problems. Granted one would expect this problem to occur with the motor off as well, but perhaps they are right on the edge, motor vibration and/or any flexing under load then contributes.

Thanks for the reply. Since I am a beginner could you please explain what do you mean by too high?:)

Meaning the servos might be set to move too far. For example the steering on the buggy can only move only so far before hitting some physical travel limit. If the servo is trying to move farther than that limit, bottoming out the steering, it can draw a lot of power, especially if it’s a modern high power digital servo. Possibly causing the type of issues you seem to be experiencing due to resulting voltage sag of the receiver battery. Also it’s very hard on the servo.

At full left and right turn of the radio, there should be a little play/clearance left in the steering mechanism. Through out the suspension travel too. The same applies for throttle and any other channels.

Not familiar with your radio, but a quick check of the model on Futaba’s site indicates it has EPA for all channels (End Point Adjustment). This allows adjustment of how far the servos will move in each direction.

The EPA was one of the first things I have set on the transmitter so I guess it shouldn't be that thats causing the problem.

I think he's not saying that EPA not being set is not whats causing the prob, but that its been set wrong and thats causing servos to strain which may be the prob.


At least thats the way I read it....

I know that my battery has a capacity of 1600 mA but when I discharged it completely and charged it again the charger indicates that it charged it with 980 mA. Does that seem odd?

Also when I begun to discharge the battery, the battery checker indicated that the battery wasn't "safe" and it was in the "attention" levels and I only used the battery for 3-4 minutes of buggy runtime. Does that seem odd as well?

put some kind of padding inside of the reciever box and move all wires as far away from the motor as possible. And dont cross any other wires with your antenna wire.

You need to cycle the rcvr batt a few times to get it back into optimum shape. Looking at the figures, apparently its been sitting a while unused? NiMh self discharges and needs to be cycled every 30 days to maintain good condition. Cycle it until you see the discharge mah level off. Thats as good as the batt is going to get. It will be better for the batt if you don't use charge/discharge rates more than 1amp. It takes some time, but I cycle mine at 0.5a/0.5a.

It could be worth considering the crystals as the culprit. I had the same issues, but when I changed the crystals, it disappeared. Try with another set of crystals, and see if it works then. If the rcvr is not properly secured and left to move about while your're driving, it can get banged around, and that may have damaged the rcvr or crystal. Good luck mate.

That would be something to try if it was an AM or FM radio, but the Tx/Rx he is using is 2.4GHz, so no crystals.

I had a similar problem with a old school T-Maxx and the battery was the culprit. I could of swore the battery was good it was newer and took a charge. But I borrowed a friend on mines battery and son-of-gun if that wasn't the problem. Try it, it might work. Good Luck...