Troubleshooting the 123 Robot

The following article will provide guidance on how to troubleshoot the VEX 123 Robot if you are experiencing one or more of the following issues:

  • The 123 Robot is not responding
  • The 123 Robot is not moving well, or driving straight


Updating the 123 Robot’s Firmware


If your 123 Robot is not behaving properly, or at all, the firmware may need to be updated. The 123 Robot’s firmware can be updated using VEXcode 123, or the Classroom App.


To update the 123 Robot’s firmware using VEXcode 123, connect your 123 Robot to your device running VEXcode 123. If the firmware on your 123 Robot needs to be updated, it will begin automatically updating upon successful connection.


You can also use the VEX Classroom app to update your 123 Robot. To learn how to update your 123 Robot’s firmware using the VEX Classroom app, view this article from the VEX Library.

Removing and Cleaning the 123 Robot’s Wheels


If your 123 Robot is not driving straight or turning accurately, the wheels on the bottom of the 123 Robot may need to be cleaned.


To remove the wheels, first remove the four screws holding the bottom base plate in place. The screws should remain connected to the base plate after unscrewing.


Next, locate the wheels underneath the base plate.


Remove the wheels by lifting them straight up and out of place. Remove any dirt and debris from the wheels themselves, and the track where they were contained.


Once the wheels and the track they are contained in have been cleaned, the wheels can be replaced. When placing the wheels back into the 123 Robot, ensure that the gear on the wheel is on the same side as the gear in the track of the 123 Robot. The prongs on the wheel also need to slide into the grooves in the 123 Robot.


Once both wheels have been reinserted correctly, replace the base plate on the bottom of the 123 Robot and tighten the screws. Ensure the base plate is oriented in the correct direction, where the tab on the plate aligns with the groove in the bottom of the 123 Robot.

Hard Resetting the 123 Robot


If your 123 Robot is not responding properly or not connecting to a device, it may need a hard reset. There is a small button hidden inside the 123 Robot near the left wheel when the 123 Robot is upside down and the Eye Sensor is facing upwards.


To access the hard reset button, the left wheel needs to be removed. To remove the left wheel, follow the steps above in the ‘Removing and Cleaning the 123 Robot’s Wheels’ section of this article to remove the base plate and the left wheel. Once the left wheel has been removed, you will see a small hole containing a button next to the wheel track.


Take a small item, such as the end of a paperclip, to press the button. You will hear a ‘click’ sound once the button has been successfully pressed.


Once the button has been pressed. Follow the steps above in the ‘Removing and Cleaning the 123 Robot’s Wheels’ section of this article to replace the base plate on the 123 Robot.

For more information, help, and tips, check out the many resources at VEX Professional Development Plus

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