What causes cortex motor/sensor ports to die

I currently have 3 cortex microcontrollers in my classroom that do not work at full capacity due to some sort of damage where certain motor ports don’t work on 1 and all analog ports not work on the othe other 2. I imagine there some sort of electrical surge causing this. I’ve come across finicky batteries that have loose connectors and also students would plug in motors and sensors while the cortex is on. Can those reasons cause ports to basically die? What can be done to prevent this in the future? Is there documentation for best practices to help protect the cortex? Thanks in advance.

I have a similar cortex and Would like to add a question: how can you fix it?

Some things that will damage the cortex.

Motor ports 1 and 10. Motors that have damaged wires and short the two connections can cause damage to these ports.

Motor ports 2 through 9. Plugging a motor directly into these ports (ie. not using an MC29) has been know to damage them. I don’t know the exact specific set of conditions needed, but the ESD (static protection) diodes that protect these ports have been damaged.

Analog ports, digital ports. I’ve never heard of these being damaged before but trying to use motors in them may perhaps do that.

Plugging anything in to the sensor ports that will draw a significant current is bad for the cortex. We did this briefly last season with LED lights, and we ended up heating the cortex and causing VexNet problems. We didn’t keep it up for long enough to actually break anything, but it seems possible that the damage could affect only the analog ports.

These are unlikely to be the source of your problems. Loose connectors are fairly common particularly on old batteries and I haven’t seen them cause a broken cortex before. Plugging things in while the cortex is on (or even while a program is running) is usually fine.

So basically carelessness and/or lack of experience on the part of students plugging things in the wrong ports or without the mc29 may be causing this. I have come across these scenarios several times in my classroom. Good to know.

How can we fix this? I’m assuming these ports are fried and can only be fixed by Vex.

There have been a few threads about repairing various issues related to the vex cortex, Im hoping someone else can link them. To be honest, probably your best option is just to send them into vex to be repaired. :smiley: