Out of Control Drivetrain

[M.Kong-Sivert]

Some of my teammates and I have spent all day today, and have blown a jag, trying to get our robot to stop malfunctioning. Every time we turn on the robot, the two CIMs that make up our drivetrain spin at full power even though nobody is touching the controls. We replaced the program with the FRC LabVIEW default code and made sure the PWM positions corresponded to the correct motors according to that program, so we know it's not a programming issue. We replaced the PD board, the sidecar, the cRIO, and the jag, so it's not a problem with any of those pieces. Can somebody figure out what's wrong with our robot? Thank you.

[geomapguy]

Honestly sounds like faulty motor controllers.....have had the same thing happen to our team

[Cecil]

Try unplugging your joysticks/control method and reattaching them. Sometimes, someone just happens to be holding the joysticks in some other position than their default "home" position. Make sure when you are plugging them back in that they are correctly centered.

[Al Skierkiewicz]

Do the motors spin when the robot is not enabled? They should not.
Are the Jags wired correctly? They are not protected and could have shorted due to a wiring mishap.

[Joe Ross]

If you remove the DB-37 cable from the digital sidecar, does the robot still go crazy? With the cable removed, are all three power LEDs on the digital sidecar brightly lit?

[M.Kong-Sivert]

Originally Posted by Al Skierkiewicz

Do the motors spin when the robot is not enabled? They should not.
Are the Jags wired correctly? They are not protected and could have shorted due to a wiring mishap.

I'm pretty sure the jags are wired correctly, but I took some pictures of it, so someone with a fresh pair of eyes can see if there is a problem.

[page2067]

Looks to me you have the Jaguar wired backwards - the wires from the PD board with yellow tape should go to the left side - marked with a V+. the right side is marked with a M+ is the output to go to the motors.

see: http://content.vexrobotics.com/docs/...e_20130215.pdf


As Al said they are not protected from being wired in reverse so the Jaguars may be dead now.

[Tem1514 Mentor]

Sure looks like the power and motor wires are wired on the wrong inputs/outputs to me as well.

Looking at your pictures, the wires that have the yellow/white electrical tape on them, do these wires go to the PDB? If they do, you have it wired wrong as the colored tape wires must go on the same side as the PWM cable.

Look carefully on the Jag and you will see + - on one side (for power in) and on the other side M+ M- (to go to the motor).

[Cecil]

As they have said, your Jaguars are wired backwards. Power goes in on the left side, goes out on the right. Personally, I would not risk using those controllers in a competition environment. If they are not blown up now, there is a very high chance that they will fail when you really don't want them to.

Throw them away, or make them into a display and label which wires go where on them. I guarantee nobody will ever make the mistake again if they have a physical guide on how to do it.

[Ether]

Originally Posted by Cecil

I guarantee nobody will ever make the mistake again if they have a physical guide on how to do it.

Is that a 100% money-back guarantee?

[Cecil]

Originally Posted by Ether

Is that a 100% money-back guarantee?

I know it worked 100% for our team at least (of course, we now have someone double and triple check the wiring so it doesn't happen again).

Originally Posted by Alan Anderson

The Jaguar terminals are 1) labeled and 2) color-coded. In spite of that, people get it wrong. There's no way to prevent it.

I also noticed they removed screws and replaced them with some of their own. That in itself can be confusing, especially for people who don't know that the inputs are marked on the casing. I like the new labels on all of the new ones. A bright yellow label is hard to miss, but I agree that it can still be overlooked.

[yash101]

I think you may have shorted some FETs inside the Jags. Try replacing one jag and wire it 100% correctly. If that solves the problem to that motor, kudos to you...You've found the problem. Now, go and replace the Jag on every other motor and wire it the same way as the working motor.
Read through the FRC 2014 electrics setup guides and the Jag manuals as they will prevent you from turning a nice, well made cake into a burnt one.

If the problem persists, I suggest that you postt a video of it, so we can debug what is happening.

[Alan Anderson]

Motors going full speed immediately on application of power is a definite symptom of having the Jaguar power connected to the motor terminals and vice versa. I was going to suggest looking at that even before seeing the photos.

Originally Posted by Cecil

I guarantee nobody will ever make the mistake again if they have a physical guide on how to do it.

The Jaguar terminals are 1) labeled and 2) color-coded. In spite of that, people get it wrong. There's no way to prevent it.