Eric,
I am grasping at straws here to understand what might be happening. Pat seems to have checked most of the obvious stuff so now it is time to move onto the other not so obvious. I know one of my students assembled this encoder backwards on the base a few weeks ago. The board cracked in the exercise due to the mounting screws but it is also possible to bend over the tabs on the connector and cause a short between the 5 volts and the adjacent pin. I know another student from last year had managed to push in the connector backwards but the result was almost ripping the connector off the board. I don’t have one here at work but as I remember there is only one LED assembly with two photo transistors or diodes and a couple of resistors. There is even the possibility that the mounting screws had been substituted for larger screws which could play havoc as well. I can’t wait to hear what Pat finds out.
Assuming we manage to track it down next Thursday, you can be assured I’ll be posting the results here (though likely not until after Buckeye is over.)
Update: We could not recreate the problem.
The good news is that this means we were shooting in autonomous and even scoring some balls at Buckeye. The bad news is that we have no idea what happened or why.
I’ve spent the past few days going over the robot with a fine-toothed comb (and oscilloscope) after school, and I can’t find a single, solitary issue with the electronics, wiring, or sensors.
Thanks, everyone, for your input into this problem… I wish I had a more satisfactory conclusion in terms of problem identification and resolution, but I don’t.