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[jaywayne75]

I seem to have an issue on my queen mary
it has 4 motors of unknown origin they have pink plastic sleeves the motor can fits in the ends are open at the back and i can see the brushes the back is grey plastic
i have two mtroniks viper 15s on them in side pairs so left two on one controller and right pair on another
i have the robbe f14 radio and the pairs are on the dual stick throttles
when i accelerate all the motors are fine but once at full throttle the right pair seem to judder whilst this happens the red led on that speedcontrol blinks too
the left side continues unaffected
all is well until max throttle
the speed controllers have their own 12v7ah battery thats charged fully
i have suppressed the motors to over come this issue but still it plays up
the motors are 385 sized 5 pole and should i go for a new motor setup? or is it a speed controller issue?
help please!!!   

[unbuiltnautilus]

Hi,
Are the motors rated for 12 volt operation, if you are unsure, try running the model on 6 volts. If the problem persists, it could be a speed control issue. Try swapping over the two speed controls and see if the problem follows the controllers or stays with the motors.
If the problem dissapears on 6 volts, then the motors may not be rated for 12v operation, although being 5 pole this is unlikely, but dont discount it.
Hope this helps a bit.

[Netleyned]

385s are rated 4.5 to 15 Volts so should be ok at 12V


Ned

[jaywayne75]

the motors are not 385s they are that size but not that make they are unknown voltage and make
i will try on 6 volts

[dodgy geezer]

I seem to have an issue on my queen mary
....
i have suppressed the motors to over come this issue but still it plays up
....

How have you suppressed the motors?

You should have a capacitor between the brushes, and one from each brush to earth, or the motor frame. That cuts down on the sparks, which emit RF interference.

But the motors may also send glitches up their power lines and into your ESC and Rx that way. So to do a full suppression you should also put a ferrite ring on the motor power lines. There is a diagram I drew on this page: http://taycol.hobby-site.com/install.html - but I am sure you will find many better diagrams on the net....

[jaywayne75]

the motors have the three capacitors on them now but no ferrite ring
so this could be the problem?
i hope so....
where do i get one from?

[Martin (Admin)]

Shouldn't need a ferrite ring if it has capacitors.
It might be worth isolating the motors and testing one at a time, it might only be one motor causing the problem.....

[flashtwo]

Hi,

Have you checked that the connections are sound and are not developing a resistance to the current and causing a voltage drop and subsequent interference. Check that any push-on connectors haven't built up any corrosion and that soldered connectors are not "dry".

Have you tried tying all the negatives individually to one common point  to avoid current loops.

I had interference from an ESC / motor (385s with capacitors) combination and on the oscilloscope I could see not only both the positive and negative had spikes, but also the metal bracket that the motor was mounted on. The motor insulation wasn't perfect and leakage current was causing the spikes. By fitting an earthing wire back to the common negative point the interference spikes were eliminated; it was cheaper than buying new motors.

Ian

[dodgy geezer]

Shouldn't need a ferrite ring if it has capacitors......

Not my understanding - and here is another reference which may be of interest: http://modelsolutions.ca/articles/DavidsOriginalArticles/RFIArticleMarch2006.pdf

I suspect that interference may travel along many paths, and in any particular installation one path will be more important than the others - which that is will depend on a lot of unquantifiables. Capacitors alone are usually fine. However, I did find that in my little Edwardian Steam Yacht, which used a tiny cheap toy electric motor, the capacitors cut down a lot of interference, but it was still bad until I put a ferrite bead in. That cured the problem.... 

[malcolmfrary]

385s come in a wide range of voltages, so it could be that one of them is different, but -
The problem happens on the right hand side.  If the ESCs are swapped over, does the problem stay on the right hand side or go with the ESC?
A known happening with some Vipers (mine and others) is that if they are not programmed for the transmitter, at full throttle from the TX, which may be "more" than they were programmed for, instead of thinking that "The human has asked for more than full speed, so I will just give him full speed" it thinks "OUT OF LIMITS!  PANIC, WILL ROBINSON! SWITCH OFF FOR A BIT".  And either stops or splutters, but only around full speed.
It could also be that one of the right hand motors is taking its ESC up to its current limit at full speed, and the limiter is cutting in, but unlikely.
If you check the motors with a resistance meter, do they all measure the same?  Measure, rotate a bit, measure again, repeat until the motor has done a full 360 degrees, repeat for the other motors, all readings should be very similar.
The capacitors have to be in working order.  A dead one looks exactly like a good one, and to most domestic test gear at the low values used,a disconnection tests just like a good one.  The only fault to show up is a short.
Some motors are just totally resistant to suppression, and this is always a risk with unknown motors.  Any batch might have a bad one.

[wombat]

I would tend to agree with Malcolm - it could be an over limit on the Viper - I have the same problem on the Aziz. The other possibility is that it is an overcurrent - this is possible given that it only happens on one set of motors - brushed motors do run preferentially in one direction - running at full speed in the other direction can result in more current.

The other possibility is that running in one direction is being affected by the timing of the commutator - this will give occaisional shorted windings which will give a spike of current.

I don't think that adding ferrites will make much difference - there is no evidence of interference on the reciever - ferrites are only really effective at very high frequencies - and really only with anything coming from the ESC. The capacitors on the motor will effectively deal with anything coming from the motor - certainly more effectively than a ferrite