More erratic behavior from M1000 reader

 FAILURE TO COMPLETE A READ CYCLE, MOSTLY

I hooked up the reader to my laptop with my modified cardread.exe application, thinking I would be debugging the modification that lets me accept the portion of a verified deck prior to a mismatch stop using the new Trunc button. 

I had a short initial period where it read cards into the application, but the blank card on the end, with its right hand diagonal notch, triggered a Read Check. Since I had a modification to the reader that should block that, I turned on the oscilloscope to observe the issue. It would trigger at CR81 time (when the card to the right of column 80 is under the read station), letting me check for the source of the error condition. 

While I saw one or two pulses from CR81, the reader moved on to failing to read at all. It would pick a group of cards but not send any data to my controller. Looking at the logic analyzer, it wasn't recognizing a good end of the pick so that it was really moving multiple cards while believing that it had mispicks being handled by reissue. 

ORIGINAL FLAW WAS CONTINUOUS ONEDARK SIGNAL FROM ROW9

When I last saw this pick failure symptom, the signal from row 9 of the card was triggering OneDark, as if that row was obscured (by the card body without a hole in the location). Since this was steady, the circuitry couldn't detect the proper start of the card and thus read garbage data. 

The problem went away by itself but I did reflow all the solder connections in the row 9 signal path. This time, both OneDark (one or more rows are blocked) and OneLight (one or more rows has light falling on the phototransistor) were working properly.

ANOTHER FLAW WAS ABSENCE OF MAGNETIC SENSOR PULSES

Another earlier episode of balkiness was characterized by lack of any pulses from the magnetic sensor reading the toothed timing wheel. My preliminary look at the logic analyzer implied these are working properly. I had only a short time at the shop thus will have to dig into this when I return. 

I am not happy at all because of the many and varied sporadic failures I am seeing in the circuitry. I can't just swap the cards from the M600 because there is a preset built into the card based on the reader speed - 600 cpm versus the 1000 cpm of the machine I want to get working.