The burnout of a 775 pro motor when it is wired with Limelight in parallel

Since we don’t have a PDH, we can only use the CTRE’s PDP. In order to deal with the shortage of the ports on the PDP, we decide to wire the hood motor (a 775 pro with Talon SRX) and the Limelight in parallel. However, after spending some time testing, the 775 pro seems to be burned out and the Limelight is also off. Meanwhile, l can smell the smell of the motor burning off. How to deal with this situation if we don’t want to remove our motors? Can a limelight be wired on VRM if necessary?

You can, but it is not recommended, as Limelight contains its own voltage regulators. Referring to this page:

Your PDP slots should be plenty (unless you use motors on basically everything) even if you run a swerve drive (if you optimize your use of motors).

If your 775 pro got burned, I think you have no choice but to remove the motor and replace it. If you mean “change to another type of motor” (such as NEO or Falcon), theoretically a 775 pro is fine for controlling a hood mechanism, but brushless options will be a bit safer, as 775 pros are at risk of being toasted.
BTW, I don’t know if this burnout is related to your 100:1 hood reduction.

Are you saying that you connected the Limelight in parallel to the 775 controller’s input, or its output? If it’s connected in parallel with the input, that should be okay. All of the PDP branches are essentially connected in parallel inside the PDP anyway. If you connected it to the output, that’s no good as the voltage will change depending on the motor setpoint. I should note that neither method is legal for competition, as each branch circuit can only power one motor (with certain exceptions) or a custom circuit.

A photo of this setup would be very interesting, and helpful in assisting you.


Yes only one motor per port but multiple custom circuits are allowed as long as the Y connector is away from the PDP; an inch will do and a couple of inches might be easier to handle.

Yes, but a motor and custom circuit in one port is not allowed. So unless you already have another port taken by a custom circuit you’ll have to lose a motor to connect to the PDP.

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True. I didn’t think OP has 16 motors. He has to Y off of a non-motor port for the LL.

I didn’t remember it, but l think l have found the problem. It’s the problem of my hood’s zeroOffset, after l remeasure it, it works well again.

We use 16 motors on our robot. (A swerve drive)

First of all, I am not an EE so this isn’t my area of expertise.

A motor is able to produce extra voltage and weird transients on their circuit (actually everywhere else too but to a lesser degree). I wouldn’t be surprised at if the motor was able to produce transients that were able to damage the limelight.

In terms of the 775, it’s much more likely that there’s a mechanical issue putting too much load on that motor. They’re very easy to burn out because of their low (thermal) mass and you generally have to be careful about how they’re being loaded.

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