Is it legal to use a V5 brain with a microUSB port we had to replace?

So a couple of days ago we managed to break the micro USB port on our V5 brain. This meant we couldn’t upload code to the brain or anything like that. We managed to open up the brain, take out the broken micro USB port, and replace it with another one. The functionality of the brain was fully restored and doesn’t have issues anymore.

Is it still legal to use this brain in competition? We know that we are not allowed to alter any microcontrollers or motors or anything like that. But we didn’t really alter the function, we just restored a very basic function of the brain that had broken. Still not sure if this is legal though.



Some part modifications are permitted, with the following restrictions and clarifications:
a. Motors(includingtheinternalPTCorSmartMotorfirmware),microcontrollers(includingV5 Robot Brain firmware), extension cords, sensors, controllers, battery packs, reservoirs, solenoids, pneumatic cylinders, and any other electrical component or pneumatics component of the VEX EDR platform may NOT be altered from their original state in ANY way.
i. Official VEXos firmware updates, found at, are permitted and highly recommended. Custom firmware modifications are not permitted.
b. Internal or external mechanical repairs of VEX Limit and Bumper switches are permitted. Modifying the metal arm on the Limit Switch is permitted. Using components from these devices in other applications is prohibited.
c. External wires on VEX electrical components may be repaired by soldering, using twist/crimp connectors, electrical tape or shrink tubing such that the original functionality / length is not modified in any way. Wire used in repairs must be identical to VEX wire. Teams may make these repairs at their own risk; incorrect wiring may have undesired results.
i. Using the V5 Smart Cable Crimp Tool, V5 Smart Cable Stock, and V5 Smart Cable Connectors to create custom-length Smart Cables is permissible. Teams who create custom cables (using these tools) acknowledge that incorrect wiring may have undesired results. Teams MUST use official V5 Smart Cable Stock if creating custom- length cables.

No, unfortunately it would not. If you want an official answer you could ask on the Q&A. Since they can not be altered in any way, and the micro USB port is not an external wire, it is illegal.

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IMO it’s probably not. Granted, it would really suck to have an illegal v5 brain just laying around.


This sort of thing lights me off. If someone were to research the top repairs for phones, tablets and laptops, the USB port is very near the top of the list. However, posts here have shown their weaknesses on the brains. Even the pictures someone posted of the internals showed the connections being weak. Another poster is using the magsafe-like cables and adapters as a way to avoid this issue.

Really??? No one foresaw this coming at the design stage??? I view this as a HUGE negligence on the product designers part. These products are being used by students, many of which are in a competition situation where the first thing on their minds is not “Being Gentle with the Electronics”.

I’m guessing you did this out of desperation because of an upcoming competition, but I’m also guessing this renders a warranty exchange null and void. I would still try however, considering the number of real world failures that these products have experienced. They must have large piles of these rendered useless for damaged smart ports and usb ports.


If it cannot be identified, and it does not give you an advantage, it doesn’t really matter. I would not lose any sleep over it.


I have never been particularly impressed by any of the products that come from VEX’s design table.

RECF has my confidence and support. VEX has not really shown any merit in their ability to design, produce, or deliver any sort of product. to an acceptable degree.


Things like this and the continued smart port issue I think will drive us to run cortex as long as the rules will allow it. At least the shortcomings are known and understood. Its hard to be a beta tester when trying to compete. At the US open, I think every team we were on the field with (partner or opponent) who died or did nothing were using V5. I don’t know the issue, of course, as I wasn’t on the field but it sure didn’t look good.


Yeah the connection was super weak when we took out the original port. I’m not sure about a warranty exchange so I’ll have to look into that. 4 of the ports have also stopped working on the same brain but we’re not really sure how to fix those.

Considering the rule of common sense and G2, I think you should be just fine as you are repairing the brain to its original state. If there even is a chance that a referee/judge would get on you for the port being replaced, and doesn’t make you compete because you repaired it to its as-sold state, I don’t think that would be right.

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Since you did repair the microUSB port yourself, you must realize you just voided the warranty. But I highly doubt that you would be punished in competition for repairing something that doesn’t even affect the robots performance. And for that reason that is why I believe you should be in the clear to compete with a brain that has the microUSB port repaired, as you would be protected by G2.
The Q&A forum is down right now, so if necessary you can ask the question at VEX Worlds Q&A when you are there. If necessary, you can always message me in discord a specific question and I can ask them in person.

Of course nobody would identify this, but the question was if it was legal, and the answer is no. Yes, it makes total sense that replacing a USB port has no advantage to other brains, but it hasn’t been ruled legal by the GDC, and is illegal as the rules are currently written.

As for G2, I don’t think thats a reliable thing. G2 is open to interpretation, one inspector could be fine, one wouldn’t. (obviously they aren’t going to notice). I wouldn’t bank on using G2 as an excuse for obviously violating a rule, unless an official Q&A question is answered by the GDC.

VEX didn’t do a “bad” job designing V5. However, they didn’t test their product for the environment it would be in. Their testing phase must’ve been much shorter than ideal, and that was probably the fault of the higher ups, rushing to implement this new system, not the actual engineers. Obviously it has problems with improper isolation from static with white screens, USB port rigidity, and Smart Port failures. I don’t foresee anything changing with these, unless they possibly added a little bit of epoxy around the USB connector during manufacture, but I doubt this would happen. Maybe V6 will fix these problems!


We encourage our teams to leave a USB extension cable connected so they don’t wear out the port on the brain.


I think this may be worth asking at VEX Worlds to see their responses. As someone who really enjoys testing the limits of the VEX Q&A I’ve gained some good knowledge on what to expect from them. If worst comes to worst I bet a team will be willing to loan another V5 brain.


I suspect the best course of action with the limited time left before Worlds, is to see if they can borrow a brain for World from a local team first and then see if they can swap the brain at Worlds.

Q&A is CLOSED now :frowning: