Re: Victor 883 problem, please help.
 

Thanks for the reply Al.

I checked cont in both PWM cables and they are showing identical properties as I described.

I am pretty sure the victor side of the PWM cable is seated, because when I plugged my reciever end into the reciever the motor would flick on for a second. If I wiggled the reciever end, it would flicker again.

Get this, I happened to be resting my futaba radio on the table next to me and my arm bumped into the antenna and then everything started to work.

Once I moved my arm away from the antenna it went back into orange LED mode.

So I unscrewed the back case of my Futaba 6XAS to see if anything was loose. Nothing that I could see. I tried to turn my radio on and nothing. Dead radio, wont turn on.

So I know my ESCs work, but for some reason my Futaba died. Just great!

Re: Victor 883 problem, please help.
 

DB,
I would not conclude that the controllers are working. If the PWM cables are just straight wires there should be no (read zero) series resistance on all three. It may be you have two bad cables. Happens all the time.

What is the model of the receiver you are using to drive the Victors?

Re: Victor 883 problem, please help.
 

Al, see below:

Post#4:
Posts #6&7:

Re: Victor 883 problem, please help.
 

I am using a Futaba 6XAS stock receiver system for any RC car or airplane.

It could very well be i have two bad cables. But i find it odd the resistances of both are almost within 0.1% of eachother at the signal wire.

Re: Victor 883 problem, please help.
 

With everything set up and turned on, and a full-speed command being issued, unplug the PWM connecter from the Vic and use a voltmeter set for 15VDC to measure the signal voltage between the two outer pins (black and white) of the connector.

Re: Victor 883 problem, please help.
 

This will not read 5 volts. You may not read anything depending on the device in the PWM cable since it would be pulled up in the Victor by the internal power supply and opto coupler.

Re: Victor 883 problem, please help.
 

The PWM Signal Driver cable that the OP said he was using gets its power from the receiver via the red wire¹. The signal driver cable then sources the current required to drive the Victor's PWM input².


@DBFIU: If you aren't getting a voltage signal at the Victor end of your PWM signal cable (as described in earlier post), check to make sure the cable is getting power from the receiver.


¹ http://www.ifirobotics.com/victor-88...r-robots.shtml

² http://www.robotcombat.com/products/IFIW-SIG36.html

Re: Victor 883 problem, please help.
 

thanks for the help guys it is greatly appreciated.. i am going to test my reciever and cables right now.

Re: Victor 883 problem, please help.
 

A run-of-the-mill digital volt meter connected between signal and ground on the output end of the PWM cable sending a standard Victor spec signal (from a cRIO) will read:

Neutral = .75v
Forward = 1.0v
Reverse = .5v

The meter reading isn't bothered by the pulsed nature of the PWM signal.
(These voltages are as measured)

P.S. Joe reminded me that the IFI signal voltage was lower, and I'd assume that the signal driver cable would mirror those lower voltages that Joe listed.
However, the PWM voltage I measure off an old pBasic IFI controller has neutral at .32v, rather than .375, so some variation between controlling devices should be expected. If the OP measures the signal cable output, please post the voltages you get for our future reference.

(For completeness for those robotics teams wanting to measure this on a cRIO, a Jaguar range signal will read:

Neutral = 1.49v
Forward = 2.29v
Reverse = .67v

Re: Victor 883 problem, please help.
 

I couldn't find a spec anywhere for the period of a "standard Victor spec signal".

Is it 20ms period with 1ms, 1.5ms, and 2ms pulses at 5v for reverse, neutral, and forward? And is this what the OP's Futaba 6XAS is sending?

If so, and assuming that the voltmeter on DC setting responds to the algebraic average of a PWM signal, then one would expect the meter to read (2ms/20ms)*5v = 0.5 volts at full forward.

On the other hand, if the meter on DC setting responds the the RMS of the signal, then one would expect the meter reading to be sqrt(2/20*25)=1.6V

Re: Victor 883 problem, please help.
 

The attachment shows what the parameters are for the IFI system, the cRIO when used with a Victor, and the cRIO when used with a Jaguar. I suspect the Futaba system would be the same as the IFI system (20ms period).

Re: Victor 883 problem, please help.
 

To toss out another idea, the Victors themselves have been damaged in some fashion. Hopefully this isn't the case, but did you recalibrate the Victor successfully, or did it fail (that is, did the LED change colors appropriately?) You can check the procedure and the colors that you should see here.

Re: Victor 883 problem, please help.
 

Thanks, Mark.

Re: Victor 883 problem, please help.
 

I think the measured IFI signal voltage is lower (than the signal from the cRIO) lower because the IFI period is longer. They both have 5v pulses.

If you look at the chart Joe posted, the following formula holds true for all 3 columns:

S = W/L*H

where:

S is the measured (with a voltmeter) output signal voltage

W is the ontime (pulse width)

L is the period length

H = 5v is the height of the pulse (pulse voltage)


That seems reasonable. The measured (with a voltmeter) output signal voltage "H" would be affected by tolerances off all three terms on the right, as follows:

∆S = (H/L)∙∆W + (W/L)∙∆H - (H∙W/L²)∙∆L ¹

Since you already have a testbed setup there, if you have the time and inclination an oscilloscope trace would reveal which of the three terms is making the largest contribution to the difference.



¹ This is derived from the above formula S=W/L*H for the algebraic average of the signal. I wonder if all voltmeters respond precisely to this metric. If not, that could be an additional reason why the measured voltage differs.

Re: Victor 883 problem, please help.
 

Hello all,

Thank you so much for your insight. I have since replaced my 15 year old futaba controller, it was the main cause of the problem. The Vic was not getting a PWM signal. I have a new controller and it delivers a proper strong PWM signal.

Now there is a new problem. I have a small 550 mabuchi size brushed motor in my RC car. This thing pulls maybe a 60 amps with this 7.2v nimh pack. It is hooked up to my vic 883 and my new controller. If I floor it, it STUTTERS badly.

I calibrated the vic, got the green light for a good calibration. So that worked out. But the stuttering is occuring in both forward and in reverse.

If I dont floor the throttle, it wont stutter. If I pull gradually into throttle it wont do it, only when I got wide open throttle. It might be a large current surge, but how on earth can this little motor affect the vic 883? I used to put close to 200 amps through this vic NO PROBLEM. I dont think it is a current carrying capability. I am not sure where the stuttering problem is coming from now.

Please help if you can,

Thanks

- D