Talon SRX causes fuse to blow out

Our team was wondering how we should calibrate our Tallon SRX on our intake. As soon as we turn the robot on the motor starts to spin and the fuse pops. We tried disconnecting it from the motor and the Tallon SRX still causes the fuse to pop. Because the Tallon causes the fuse to pop every time we turn the robot on, we are unable to calibrate it. We tried with multiple different tallons but the same issue arrises every time.

Remove the Talon from the robot.

Use a multimeter to do a continuity check between the red and black wires for it back at the PDP. 95% chance it beeps. (Also check that red is in red (+) and black is in black (-).) The other 5% says you’ve got a short to your frame instead of between the wires.

Track those down and replace the breaker (it’s probably worn out with all that tripping). You’re looking for places where the insulation is worn away or otherwise damaged, whiskers of wire that might be bridging the wires, or anything else that doesn’t look like normal wire.

After you’ve found and fixed the short, recheck your Talons and install a known good one. At the same time, focus on preventing future shorts.

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Secondary thought on further reflection:

The short I’m suspecting exists may also be a reversed Talon. If your motor is connected to the red and black wires, particularly if you tried with multiple Talons, you probably fried every Talon you set up that way. Motors go to green and white; power in goes to red and black. Doing it any other way is a recipe for sending a lot of money to VEX.

The reason I started suspecting this was the motor starting up immediately. A short generally wouldn’t do that… but a Talon connected in reverse? Yeah, I can see that one happening.

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Brilliant deduction!
If OP can upgrade, a little backwards is okay but still not that much backwards!

The Talon FX is the first motor controller in FRC history to have reverse polarity protection . This eliminates the single largest cause of motor controller failure in FRC. Unlike any other motor controller, you won’t severely damage or destroy the Talon FX if you hook up power backwards. Feel free to trust the freshmen on your team with motor controllers again!

The FX does mistake-proof backwards ins & outs. Can’t mess-up soft copper wires for hard rotating shaft.

This post also brings to mind the question how many replacement devices are you willing to destroy before you figure out you’re destroying them all? Be very careful swapping out a bad device for a good device. You often end up with two (or more) bad devices.

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Have 2 meticulous people do the checks that @EricH suggested. If possible, have one of your mentors assist.

Use a bright flashlight held at different angles, shining on where the wires go into the PDP. Look at these connections to see if there are any strands of the wires that are sticking out. They will appear shiny under the bright light.

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To be clear: This thread is about a Talon SRX which does NOT have reverse polarity protection. There are 4 different way to wire a SRX. 3 will permanently break it.

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