RoboRIO Red Power LED

[crake]

And for those who are curious, the returned units end up on my desk where we take them apart to see what is going on.

[diverson]

Originally Posted by crake

And for those who are curious, the returned units end up on my desk where we take them apart to see what is going on.

Cool, if you get a roboRIO with a shorted 5V bus in the next week or two, I'd love to know what caused the problem when you figure it out!

[jdh042397]

I may have a solution to your problem. We had the same issue with the solid red power light. We went through and unplugged all the fuses except the ones to the vrm. That wasnt the problem. So we went one by one on the PWM's and discovered that on one of them, some knucklehead switched the red and black wires on it so that the negative was in the middle instead of the positive. I unplugged it and swapped the wires back to normal and it worked.

Hope this helps.

[diverson]

Originally Posted by jdh042397

I may have a solution to your problem. We had the same issue with the solid red power light. We went through and unplugged all the fuses except the ones to the vrm. That wasnt the problem. So we went one by one on the PWM's and discovered that on one of them, some knucklehead switched the red and black wires on it so that the negative was in the middle instead of the positive. I unplugged it and swapped the wires back to normal and it worked.

Hope this helps.

I appreciate the tip. We're not using PWMs, unfortunately. So that's not the problem we had, but I'm glad you were able to successfully debug your problem. Nice detective work!

[crake]

Originally Posted by diverson

Cool, if you get a roboRIO with a shorted 5V bus in the next week or two, I'd love to know what caused the problem when you figure it out!

I found a shorted 5V roboRIO today and knocked on it really hard and the short went away. When I opened the roboRIO a thin copper wire was peeking out from under DIO 9. This wire had apparently found its way under the 3 pin header and shorted 5V to GND. Once I pulled the wire out the problem went away and roboRIO was happy again.

The controller has conformal coating so things that can be permanently damaged are protected from swarf (or random wires), but IO pins are exposed and while no lasting damage occurs, there can be a short condition that requires a little cleaning to clear up.... or a violent hit, especially if your robot's name is "tippy".

[diverson]

We're not "tippy", but it is possible that something lodged under one of the IO pins that we couldn't find. If you come across one that's set for team 4499, that's the one we messed up.

[crake]

Originally Posted by diverson

We're not "tippy", but it is possible that something lodged under one of the IO pins that we couldn't find. If you come across one that's set for team 4499, that's the one we messed up.

On Friday I performed an IR scan on this unit and found the over current protection engaged (expected for a 5V short) but no other hot spots. Compressed air under the AI/Relay IO connectors seemed to have cleared the fault. I suspect that the air dislodged whatever was causing the short condition though I never did see what was shorting it.

[diverson]

Originally Posted by crake

On Friday I performed an IR scan on this unit and found the over current protection engaged (expected for a 5V short) but no other hot spots. Compressed air under the AI/Relay IO connectors seemed to have cleared the fault. I suspect that the air dislodged whatever was causing the short condition though I never did see what was shorting it.

Thank you! I'll add the compressed air treatment under the connectors to our list of troubleshooting steps. We blew off the board in general, but obviously not well enough! I really appreciate you taking the time to let us know.

Dean

[E Dawg]

Quick side note: make sure the fuses on your RoboRIO are in all the way and properly secured. Our fuse kept on getting knocked out of place, causing the RoboRIO to reboot during matches.