Problems With Victors

Technical Electrical
#1

Hello, Chief Delphi. I am posting on behalf of Team 3175 because we are having major problems. For the past 3 days, we have been having trouble with our Victors (888, if it helps), because they are not responding when we put any value into them. We have tried putting different sidecars in, using a different PWM cables, using different Victors, using Ethernet cables instead of wireless, and using a different cable from the crio to the sidecar. All the victors are powering fine, but whenever we try to use them, only 2 out of 6 Victors respond, but which 2 are random every single time. This is not a motor problem, as we have tested, but we need an answer immediately, as B&T is tonight.

Thank You in advance,
Team 3175.

#2

Is the digital sidecar powered from the 12 volt connector and all three power lights on?

#3

Yes, it is. If it helps, the robot was fully operational until Saturday night.

#4

Is software the ONLY thing you changed since it was last working?

#5

We have changed the PWM cables, 4 Victors, the cord that connects the sidecar to the cRIO, the code, and the connection (we tried going with Ethernet instead of Wireless).

#6

Let me re-phrase that.

Let t0 be the last time it was working.

Let t1 be when you first noticed it was** not** working.

What changes did you make between t0 and t1?

#7

Thank you for the clarification. The only thing changed between those two times was the code.

Sorry if I am taking a while to reply, the internet in our team’s room is very sketchy.

#8

I hate to hijack this thread, but my team is having a big problem with victors as well.

one of our mentors told us about the “magic smoke” in the motor controllers, but they started laughing afterwards, so none of us believed him. when we reversed the polarity of the wires to run the motors backwards (programming issue) it got out! how do we get the magic smoke back in?!?

#9

Then post this in the Programming forum, not Electrical, and you’ll get more help. Make sure to post to C++, Java, or LabVIEW subforum, depending on what language you are using.

#10

Oh, there’s a special tool for that.

It’s called a credit card.

#11

As lead programmer, please let me make a clarification:

We simplified the code to the simplest possible driving code. Several of our drive train Victors still failed to run. We even loaded two previous versions of our code that ran the same Victors perfectly in previous tests. Those same Victors still failed to run.

I believe this is conclusive evidence that the code changes were not the issue.

#12

With conflicting information it’s difficult to troubleshoot.

“Several” of your drivetrain Victors “fail to run”. How many is “several”? And what exactly does “fail to run” mean? Is the problem repeatable and is it always the same “several” that “fail to run”? What is the LED doing on the fail-to-run Victors?

Put your robot securely up on blocks and run the following tests.

Take a cheap handheld digital voltmeter set to an appropriate DC scale and probe the power input to one of the several fail-to-run Victors. If it’s not roughly 12 volts then trace it backwards to find the problem. If it is roughly 12 volts then measure the voltage across the Victor’s M+ M- power output terminals, using the same DC scale when the motor is being commanded full forward. If it’s roughly 12 volts (or -12 volts) and your motor is not turning, you may have a bad motor, or you may have excessive friction in the drivetrain, or you may have 2 motors fighting each other. Post here for more details. If you don’t get +/-12 volts, then pull the PWM cable from the Victor input and measure the voltage between the black and white pins. Post results here.