Motor Locked Up

So the motor on our flywheel has locked up. I mean we physically can’t turn it at all. We’ve taken it apart down to the motor itself and the actual motor is locked, it’s not one of the gears.

Is this a common issue? Is there anything we can do to fix?

Thanks in advance


That is definitely strange, especially as there is not that much horizontal force on the motor shaft inside the vex motors. I have only had motors lock up like that in other projects where the motor shaft had perpendicular forces. Unfortunately, you probably will need to just replace the whole V5 motor as just the motor is not replaceable. Vex custom ordered their motors and you sadly cannot get them and are not allowed to repair them.


You could try driving the motor from a separate power supply to figure out if it is the motor thats the problem or if it is the v5 motor electronics .

I think that the op means that even unpowered the motor is unable to turn. This is likely a motor issue. Its happened to me once or twice before you just have to replace it.

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What’s happened is something inside the internal motor worked its way to a place it’s not supposed to be.
It happened to several of our motors last season.
While you can dislodge whatever’s jamming it, it may or may not work, and even then it is at very high risk of jamming again so I wouldn’t recommend using it.
If you can’t get a free replacement from VEX, you can swap the internal motor with another motor that has a fried board, so that one of them works and the other is just more dead.
The board has pins that stick into little sockets on the motor, and you can easily separate them.


I’ve experienced this twice actually, the motor just completely seized up. I was recommended to take the motor apart completely and put it back together because usually, it’s a loose pin or gear on the inside. Both times I tried this and it was able to fix the problem. If this continues to happen for you on the same motor then I suggest replacing it as it most likely has a defect.

There are multiple reasons for “locking up.”
First of all, you should be aware of how a motor works. If you give it power, the energy from the electricity turns into mechanical energy. But if you spin the motor with your hand, it will convert mechanical energy back into electricity (Which is how hand cranks work). That being said, if you spin the motor on a faulty circuit, the motor may be almost impossible to spin with your hand if there’s nowhere for the electricity to go. I would suggest trying to change the port for the motor first before changing the motor entirely.

If changing the port did not work, the next option is to check the cartridges. If you change the cartridges and the problem persists then the problem is the motor itself. Then I would suggest replacing the motor.


Note that any motors you repair this way will no longer be legal for use in VRC under <R22>.


Thanks to all who replied

We tried hooking a small DC power source directly on to the pins of the small motor. When we did this it made a faint clicking sound (almost like gears stripping). Also when we shook the small motor, we could hear something loose inside it.

At this point we should just call vex, yes?

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I would think that is in terms of physically modifying.
They sell replacement caps and standoffs which aren’t listed in <R22>. They also ruled in the TP Q&A (which I know doesn’t carry over) that replacing the cap screws with ones with different heads was legal.
The motors with swapped parts are identical in every way to originals, and all parts are from legal VEX motors. We have several of those motors mixed in with the rest and can’t determine which are modified, and as a private team can’t afford to buy all new ones.
I think it’s worth asking on the Q&A to get an official ruling.

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I think you need to email them an RMA form.
I think you should get a free replacement if the parts are less than a year old, but I don’t know beyond that. I really wish VEX sold replacement internal motors since they break so much, but I don’t think they ever will.


Shorting out a motor can cause seize up to some extent, however in the case of a V5 motor it can still be turned slowly with some effort. That’s what setting the brakeType to break does, but in that state, the motor can still be turned even though it’s geared up substantially from the perspective of back driving it.

(sorry I should have replied to all 3 with one message)


<R22> prohibits electrical modifications to motors etc. too:

That’s true, I think the argument there is that since the caps and standoffs are individually-available parts that don’t contain any electronics, they’re not “electrical components” and thus not subject to <R22>. Neither of those things is true of the motors themselves, though.

See also this similar discussion, which is from last season but the wording of the rule is the same.


Although the motors are electrical parts, they are only physically connected and I am pretty sure you can replace them with the motor out of a broken board. The motors are not soldered on and are only pushed onto pins that are soldered to the main board.


It is, actually, the other way around. If there is a way (path) for electricity (electric current) to go (flow) then it will be converting mechanical energy into electrical and eventually heat.

But if there is no path for electricity to go (flow through) then no round circuit is formed, no current flows, and no energy is converted. So would be easy to spin.

The board could be damaged in various ways. If h-bridge has burned and baked itself into short, then it will be very hard to turn the motor. But if h-bridge has blown itself open, then no circuit will ever be formed and it should be very easy to turn the motor.

In this case, it looks like mechanical damage, because of the rattling parts inside V5 motor.

Probably, a brush or solder point fell off and got stuck somewhere between rotor and case or collectors.

See here: Broken V5 Motor... Again

Also very similar to this: