Chassis/ Base Problems

Hello Vex Forum,

At our previous tournament, half way during the game the base began to die. I’m not sure why, we put new batteries and a new 9 Volt and it still died. Even when we practiced. Anyone have any solutions or had the same problem. The base is a chain drive with 4 269 motors connected to a power expander.

Based on your description, it sounds like you’re tripping a breaker the drive motors are on. It’s probably the breaker in the power expander.

A test to support this hypothesis would be to see if just driving it around for a while makes it cut out, then, when let rest for a few minutes, can drive again.

To solve this problem, you could spread the drive motors on the Cortex’s ports (i.e. 1 and 2, 9 and 10). Others who are more electrically inclined can explain the reason, but it has to do with putting too much load on the breakers controlling groups of ports on the Cortex/power expander. The Cortex has two breakers (I think they’re 1-5 and 6-10), while the power expander just has one for all ports.


The internal breakers inside the motors are tripping. Basically they are under too much load. Your options are to try and reduce friction in your drive, make your robot lighter, and/or gear the drive more for power.

EDIT: Or it could be what the guy above said. I’ve just never actually experienced that myself.

Or you could switch out two of the 269s for 2 393s for more torque. During the Bellarmine tournament, our base was also having problems as well which we later found out was caused by one of our 269 motors that was not moving at all and our high strength 393 was doing all the work and eventually overheated. So we switched it out for another one. You should try unplugging one of the motors on one side of the base to see if it moves the base. And then plug it back in and take out the other one and then do the same for the other side. If there aren’t any problems with that, it is probably tripping the circuits. and you should follow the advice of the people before this post.