Let me start this off by saying I WILL be contacting Vex about this ASAP, but wanted to gather some preliminary knowledge if possible.

Back to my issues, I’ve blown 4 ports since Monday, and I’m not sure why. I had received my V5 stuff October 27th and had everything mounted and functioning within a few days, then my robot sat for a few weeks due to other obligations. Monday rolled around and I started to hardcore work on it.

On Monday, my robot was behaving normally while practicing until one of my motors had suddenly stopped working. I noticed the red LED was flashing red and I originally assumed the motor had died, because I’ve already had 3 die on me up to this point. (sigh, another story for another day) Just to confirm my theory that the motor was dead, I simply unplugged the cable from the presumed bad motor and plugged it into a new one, and same issue. At this point I realized we blew a port and swapped it, but did not swap motors.

Next day I worked on the robot was Wednesday. The same motor that did the exact same behavior as the day before, but on the fresh port. At this point, I unplugged the motor and left it unplugged because I was worried that the motor was shorting my ports. We were two ports down, but decided to keep practicing and that’s when one of our lift motors died. Same issue with the flashing light and everything. I went to the forums after the third port blew and read that some were having issues with the custom-cut cables killing ports, and the motors I was having issues with were all wired with custom-cut cables. So later that night, I rewired the whole robot using the precut cables and avoiding cutting custom length ones. As a precaution, I also decided to update the firmware on the cortex, joystick, and batteries. After doing the update, one of my ports came back, so I was down to 2 blown ports.

Thursday rolls around and I go to practice, and the port that died then came back to life then decided to die again. So I was now down 3 ports. I did not practice much on Thursday due to working on mechanical stuff.

Friday, I finished all the mechanical stuff I started Thursday and everything was running smooth for the most part, until my lift started acting funky again, and it started to flash again. As I went to change ports, it still was flashing, so I narrowed the issue down to a bad motor. As I went to replace the motor, I decided to do a quick sanity check and made sure that the motor was dead. When I powered the robot up, the motor was back to normal as if nothing happened and left it at that. Not 5 minutes later did the motor stop working again, and swapping ports did not fix it, so I replaced the motor and kept it in the same port. After tweaking some mechanical stuff, my programmer and I decided to bang out a programming skills. We had a basic skills running and were tweaking angles of turns, except for one run where the lift went shooting up and the robot tipped over. The odd-part was that the lift was never called in the code. Right after that, our 4th port had died.

Today, Saturday, we had a competition. I’m on a VexU team and we’re only doing skills. Within the span of 2 hours, we blew 3 MORE ports. Two were on my lift and one was to a wire that didn’t even have a motor on it! I removed a motor that went to my fork but had it wired for it. It still managed to blow a port WITHOUT a motor on it.

So I don’t know what to do at this point but call customer service and try and get a new cortex and hope I don’t blow any on the new one. If any of you have any suggestions as to why my ports are dropping like flies, PLEASE let me know. I feel like I’m doing something wrong here… but I can’t imagine what could be causing this.

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Apparently the issue can be caused by static discharge. It could also be an issue with your particular brain.

None of us have a lot of experience with v5 yet, but other people have had the same issue. Giving this thread a read might help you out. https://vexforum.com/t/v5-brain-ports-break-continually/49750/1

Good luck!


Does spraying that on your robot help at all?

I’m not confident that this will help because we can’t spray that at competitions. It’s out of my control to modify a field.

Static electricity kills v5 for some reason.

If that’s the case, then that’s really pathetic. However, it seems like some cortexes are either perfect or just absolute garbage. I’m assuming I got a garbage cortex and that’s what’s going on, but wanted others’ feedback.

Lots of discussion on what’s going on, but this comment may be one of the most important in the debate.

Honestly, if they did not protect the ports from ESD (we don’t know yet, just speculation) after the fiasco with the IEM ESD, it would be surprising…

I’ve made sure to ground myself to the c-channel on my robot, making sure not to touch the brain first. That seems to help, and we haven’t had anything die on us yet. knocks on wood

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@TriDragon, I also find this part very interesting:

According to @nenik in V5 motor wiring thread, FPGA is handling motor communication interface:

Could it be that I/O block on the FPGA has multiple paths for input data and in some cases not all paths are destroyed by an ESD and, if firmware update reconfigured which paths are utilized, then some ports are potentially recoverable?

Firmware update and bad V5 ports are completely unrelated. We have also not revised the FPGA bitstream in any of the recent firmware updates, the last time we did that was back in May.

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I think you’re right. It’s good evidence for ESD being the killer of ports. I just purchased some ESD protecting sleeving and I’m going to give it a shot and hope for the best

My team has also lost 3 ports on one of our cortexes, all connected to 200rpm motors using stock long (900mm+) wires.

Something I noticed was that before (all) the ports died, the motors would run at significantly reduced speed and torque (and by integration, power).

Last year, my solution to static buildup was to run a grounding wire (under the VEXU excuse that it was for sensing the ground) from the chassis to the field mat. It was literally a jumper wire just hanging off the back of the robot and dragging on the field mat. Worked surprisingly well.

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If the event coordinators at an event don’t spray down their fields with staticide you can try rubbing your wheels with dryer sheets. if you can’t do that then try to touch metal on your robot first whenever you pick it up after matches. This may shock you a little bit but you would be grounded so you shouldn’t have as many issues with blown ports.

In the case your team uses some liquid based anti-static treatment, be sure to notify the EP / Head Referee before using it.

The ports die in the middle of matches for us. Our lift stopped working 30 seconds into the match.

Ugh, that’s awful. I hope it wasn’t elims and you were out after one round

@Keith_Horton1826 it mainly did happen in eliminations but we some how still one. We had to have our laptop and change the port basically after every match.

Update: I contacted VEX Monday and received my new cortex this morning without any hiccups

The anti-static sprays that I tried (including the staticide) dry in less than 20 minutes and leaves no residue.

great! getting good field reports is helpful.