Victor 888 "y" cable issues

[Marc P.]

We noticed the same thing with 888s. My suspicion is the 888's may have significantly lower "deadband" than the 884s, making them much more susceptible to slight variations in PWM input. If the calibration is slightly different between the victors, one might be seeing "neutral" while the other sees "+1% power". It didn't seem to affect our performance much- full forward on the joysticks gave us the green LED, full reverse gave us the red LED, just the neutral position seems to be slightly off. Gently bumping the joysticks one way or the other would reverse which 888 didn't have the orange neutral LED, and on occasion when the joysticks came to rest, both would be orange.

We haven't tried calibrating them yet, but based on what we observed of the symptoms, it may solve the problem.

[Ether]

Originally Posted by Marc P.

My suspicion is the 888's may have significantly lower "deadband" than the 884s

There's no "may" about it. They do.

[theawesome1730]

Originally Posted by Ether

There's no "may" about it. They do.

Does that essentially mean that we have nothing "wrong" with victors on a y cable, but since the operating deadbands vary from Victor to Victor we had two in tandem that were not compatible? The "screaming" we experienced would be explained by the +or - 1% like Marc noted above with one victor making since I know that 888s normally make a high pitched sound under normal operation. I do not however understand how a victor running 1% output can put out 12 volts.

[Al Skierkiewicz]

Has anybody tried contacting IFI to check on this?

[RufflesRidge]

Originally Posted by theawesome1730

I do not however understand how a victor running 1% output can put out 12 volts.

Was that measured unloaded?

I agree that the cause of this is almost certainly the added load of a second Victor affecting the rise and fall times of the PWM signal enough to land just outside the 888s deadband. Try calibrating the Victors while they are attached to the Y cable and I expect the problem will go away.

[Ether]

Originally Posted by RufflesRidge

Was that measured unloaded?

Here's a graph of an 884's output voltage vs input pulse width, with the output essentially unloaded (1500 ohms).

[Racer26]

I found when working with 4343 that we had to calibrate our Victor 888's on the Y cables to get them to behave nicely. Took a few tries to get "off" to be "off" and not "on just a hair"