Gremlin found and exterminated; M1000 card reader still not working

 THE CLUE THAT LED ME TO THE PROBLEM

I noticed that at some positions of the card cage, which was unfastened to let me get to the rear connections, the lights went out even though the blower motor ran. I checked the voltage on the rails of one card and found it was zero!

Some jiggling convinced me that the conductors in the wires had breaks or defective joints. There are a couple of areas covered with insulating wrap which may have solder joints inside. Rather than try to patch them up, I will replace the wires entirely. 

I stripped and soldered the wires on very carefully to be sure this doesn't cause future issues. Once I had reassembled everything it was time to try some runs to continue debugging and repair.

ON TO THE NEXT IN A SEEMINGLY INFINITE SERIES OF MISBEHAVIORS

The reader stays powered and responds well to the controller, but no data came out. The same pick error is occuring, where it passes a few cards past the phototransistor station but acts as if the cards didn't move. I turned on the logic analyzer and captured the signals to determine what was behind the issue.

When a pick is issued and the reader grabs a card, it waits until the OneDark signal is activated which indicates that the leading edge of the card has reached the phototransistor station. This will trigger a Good Pick Reset (GPR) signal that kicks off all the remaining steps in reading the card.

I see the OneDark go active, but no GPR is issued. The magnetic sensor pulses seem to be arriving okay, but the reader sits as if no card passed through it. 

I want to look carefully at all the signals I collected in the logic analyzer to see what anomalies might exist alongside the failure of the GPR signal to be raised. The logic analyzer prints an ASCII listing file of the signals, which I put on a 3.5" diskette and transferred over to my laptop. Tonight I will pore over the files and devise a set of tests to zoom in to the ultimate.