Running in circles

[G-UNIT]

After about 1-2 min running the boat it starts to just go in circles,
1. replaced batterys in tx no change.
2. while in dry dock I noticed that the rudder stops in one direction or the other, and when it does that I
noticed that the rx light flashes.
3.this happens weather Im useing 4s 5s 6s.
4 motor is a 1090kv
5. stock rx spectrum mr200
6. is the bec in the rx giong south?
7. is the servo going south on me?
8. should I try and remove the black wire and run a battery pack to power the servo?
any help here would be great.
thank you.
sorry also runing a t120 esc

[dana]

Try another servo. The try another tx. Process of elimination man

[G-UNIT]

That looks like the road i'm going down, just thought the bec in the reciever was going bad if thats possible, if that was the case would the whole reciver be bad or just that bec side of it.

[1945dave]

A couple of things come to mind.

First as long as the boats power or batteries seems okay and it is just the turning issue it is a good bet to say the problem is either servo related or perhaps the ESC. But it kind of sounds like a fail safe problem I had a while back. The fail safe sets the rudder into a gentle turn and also drops the throttle down to about half speed. This can occur because of range issues (but not in dry dock) or signal strength, battery voltage to the receiver and / or interferrance.

As much as we would like to nail the problem with words in this thread I have to agree with Dana, start by replacing the servo and see if this fixes the problem. The one hesitation I have in condemming the servo is the 1-2 minute comment. Usually a servo problem is consistant. It would not normally fix itself and fail after a unit of time. I am assuming this servo is of a standard power variety. I recently bought a "mega" servo for one of my high powered Nitro twin outriggers. I quickly found out why the instructions tell you to power the servo directly and not pull the power through the receiver or BEC. Most BEC circuits are limited to 3 amp current draw. Depending on the receiver the current available without damaging the receiver is also in the 3 amp range. This Mega servo can draw 7 amps. Presto something fails.

Good luck keep us posted as to your findings.

Dave

[G-UNIT]

Ok, I'll swap out the servo first then if it still happens i'll try a battery pack.
even when it starts to run in circles I can give it full throttle, no power loss.

[1945dave]

The other comment you made that concerns me is that the light on the receiver starts to blink. On my receivers this light tells me if the transmitter has binded. I can't think of any reason for this light to blink because of a servo problem.

Keep us posted.

Dave

[G-UNIT]

yea it will blink when the rudder is in a full turn when on the bench, also when I disconnect and reconnect the batterys and every thing is working
fine but moving the wheel left and right continuesly then it starts to act up and wants to stay in one direction or the other, if I turn off the transmitter with the batterys connected the rudder returns to a center position
and when I turn it back on it picks up he signal again and works fine untill I turn the wheel left and right continusley and it starts all over again. WEIRD.

[1945dave]

Now that is good information and seems to support the bad servo theory. If your receiver is a 3 channel try plugging the servo in the third channel and see if anything changes?
Or swap the throttle position with the rudder position on the conections of the receiver. No need to run the boat just try operating the servo.

Dave

[G-UNIT]

Ok I'll try that first when I get off work and post my results, Thanks for all your suggestions.

[JimClark]

You didn't. Say where your antenna is? Sounds like you lost the signal and it went to failsafe


Sent from my MB611 using Tapatalk 2

[G-UNIT]

Antenna is in the stock position, one on the back of the boat and the other is in the hull perpendiculer to the external one.

[1945dave]

I discounted the signal strength range issue when he said that he observed the problem in "dry dock".So I doubt that is the problem.

[G-UNIT]

Well after trying a few things, switching connections on the reciever, where the trigger is the steering and the wheel is the the throttle, only a two channel rx there was no change.
pulled the servo out only to see a small burn hole just about a 1/4 inch above and to the left of where the servo wires exit the servo.
so I said this must be the the problem, NOT.
tryed another servo and it did the same thing after repeatly moving the rudder.
THEN I felt the esc and it was hot, not the whole esc but just the section near or above the caps this temp was around 135,
is this due to no cooling,
I don't think so but I maybe wrong.
trying to get some shots of the burn hole but having problems downloading them imto my album so I can get them here.
next i'm going to try and hook up a battery pack and run the servo off it indapendently.
any other suggestions?

well this servo is still good, don't ask me. see post down the line

[TheShaughnessy]

if it was a version one t120 and you ran 6 s though the bec there is a good chance you took it out. Proceed with an external battery and see what happens. I had my bec on a 120 go out and starting feeding whatever the motor battery was to the rx, it was a new radio so i thought it was to blame when the rx burnt out but it was actually the bec dumping 16 volts into the rx. Used the speedo on a airtronics air rx and ended up taking out 4 servos. So it could be the bec

[G-UNIT]

Thanks, first I'll try another esc same kind and then I'll try a external battery pack.