Troubleshooting the WPI RBE Development Board

5V Rail Not Working

Option 1:

There is a thermal fuse built into the 5V rail on the board to prevent it from sustaining damage in the case of a short circuit. If a short circuit does occur, then the thermal fuse will trip and the 5V rail will be temporarily unusable. Turn the board off and leave it alone for 5 minutes. Then turn the board back on again and see if the 5V rail is functional. Be aware that shorting the 5V rail to ground, or pulling more than 500mA out of it will result in a thermal shutdown.

Option 2:

If a potentiometer is plugged in backwards and is set to a low enough internal resistance, then it can also cause a short between the 5V rail and ground, causing the same thermal shutdown process described in Option 1. On the axis control boards, the signal wire of the potentiometer should be facing the DB15 connector. If it is not, then switch the orientation of the potentiometer connector, shut down the board, wait for the thermal fuses to reset, and try powering on the board again to see if that fixes the problem.

Option 1:

The problem may be a blown capacitor shorting the 18/16V rail to ground. Power off the board, then immediately check all the capacitors for the boost converter to see if any of them are hot (Please do so carefully...capacitors that are shorting power lines to ground get VERY hot). If any of the capacitors are hot, please mark them and send the board in for repairs. It is important to mark the capacitors, because doing so will make the repair process faster and less expensive.

Option 1:

Make sure you are testing the -5V rail in the correct manner. Make sure to take your voltage reading from either the inside of the connector itself, or from a wire directly connected to the connector. If you take a voltage reading from the screw built into the connector, you will most likely not get an accurate reading. Also, there are no indicator LEDs on the -5V rails anymore, so keep that in mind when you are debugging.