Broken Motor Controller

During our time at NYTR, we had an issue with a motor controller. The lights were all irregular and the motor it was connected and mapped to didn’t work. At one point our Anderson connectors came out (just the green and white ones) so i changed those out, and after that the entire controller didn’t turn on, even though I didn’t touch the power wires. Could this simply be a bad motor controller or is there something more happening here that I don’t realize?

It is always possible it is a bad motor controller, but based on having some of your Andersons coming out I would suspect it is most likely a wiring or connection issue.

What type of motor controller are you using (Talon SRX, Victor SPX)? Are you using CAN or PWM? Any sensors connected?


I did check all the connections multiple times and didn’t see anything, but i suppose there could be something i missed.

Talon SRX, CAN wire. No sensors, these control our drive motors

It sounds like you’re talking about a Talon SRX or similar, running on CAN? Please confirm.

If so, first thing I’d check the red and black power wires to make sure they aren’t loose. Tug on the connectors a bit to make sure. Second, check your CAN wires to make sure they are secure as well.

Even if you disconnect the motor wires (green and white) you should be able to run the controller and see it transition from yellow to green and then red for reverse.

If the connections all look good on the red and black power lines swap out the breaker on the PDP with one you know is good.

I checked the red and black wires. They are connected and fine. I’m going to check the breaker on the PDP at NYSU, our robot is currently in the bag. Thank you for the suggestions

We had a Talon SRX fail at a comp over the weekend. It was the one that controlled our elevator so we basically just had to play defense for that match. It had power since we had the Advanced Talon Breakout Board installed on it its blue status lights were on, and the limit switch lights still worked. There were no CAN BUS status lights, they were completely dark. It did not show up in the CTR Tuner page, its like it didn’t exist at all.

You should do a pull test on all of your wires. Both the power wires (red and black) and the signal wires (yellow and green).

It sounds like you are using Anderson connectors for your CAN bus connections. They are not meant for such small wires. How are you making it work? Can you post a photo of an example? We are using Andersons for our CAN bus connections too. We strip 3 to 4 x the length normally needed and double the exposed conductors back on themselves several times to make a thicker bundle so the contact will hold the wire securely.

Please check that the contact is pushed all the way into the housing so that the “claw” at the end of the contact has slipped over the end of the retaining spring tab. Verify with a pull test.

we do not use Andersons for the CAN wire. we use Andersons only for the power wires and the wires that go to the motors. We use butt connections for the CAN wires, and we have them running in series, so if one were to not work, non of the controllers in that row would work either.
we did have a case of upside-down andersons at one point, so i can check if thats the case.

Also check that the port you’re using on your PDP isn’t fudged up. Wire can break off inside, or the terminal can be damaged if the proper tool isn’t used to insert the wire.

Try a different port as well.

You should still do a pull test on the butt connections for the CAN bus wires.

If you have swapped the + and - inputs of the motor controller and powered on at some time, it is very likely the motor controller is damaged. The CAN bus to other components in your system may still work.

It may be best to swap that motor controller for a fresh one that is known to work. If the fresh one works, swap the original one back in. If it is still not working, it is very likely to be damaged. You can then contact CTRE and ask for advice. They have been very responsive when I have called them in the past.

I have been doing this FRC thing for a few (10) years now and the current field of available motor controllers seem pretty reliable and hard to kill unless you are trying or doing stupid stuff like plugging them in backwards or stalling a CIM for 5 minutes at 40 amps just to see what happens.

I would assume that a controller failure is unlikely but possible. I would prep a spare controller outside of the bag and swap it over ASAP upon unbagging and check all the stupid stuff on the “bad” controller when you get time. Dont throw it out, just mark it and check it when you have time.

@philso @BeardyMentor thankfully, i prepped ahead and we did have 2 extra controllers wired and mounted but just not in use. i swapped the motor wires with one of those while we were at comp and the problem was fixed and the motor worked. i can check the CAN next week when we unbag. thanks for your input :slight_smile:

Not necessarily. The two green wires are soldered to each other and then to a pad inside the controller housing; the same with the yellow. If the soldered pair came loose of the solder pad, devices down the line would not be affected.

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Even if the wires are connected to the board but the CAN transceiver chip is dead, it is quite likely that the rest of the system will continue to work.

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