November 6, 2010

Testing the pedal contact rail

The AC adapter for the pedalboard MIDI encoder arrived, so today was the first MIDI test of the pedal contact rail. There's good news and bad news, and the good news is pretty good:

  • The MIDI encoder works
  • The diode board works 100%
  • The wiring connections all work
  • The USB/MIDI stuff works
The first problem is that the contact wires themselves appear to be too corroded to respond appropriately to the contact surface. After the test, I took some sandpaper to them just down to the bare metal, and my preliminary tests of the conductivity look better.

The bigger problem has to do with the wiring. My cable is twisted-pair telco cable. Each pair has a two-color code, for example white-blue. I assumed that the white wire of that pair would precede the blue in the sequence of 50 wires. Apparently I was wrong; so playing the notes from the bottom, you might get C#-C-D#-D-F-E, etc. Actually the registers skip around as well, because of the way the scanmatrix is put together, but you get the idea.

For the bus wire connections, it was easy enough to swap those on the diode circuitboard. But for the 32 individual wires, that wouldn't be practical. The two possibilities seem to be make a new diode board and fix the wiring, or switch the wires on the contact rail itself. I think the latter would be faster, but it's woefully hack. Sigh. But this was pretty good for an initial test. Excelsior!

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