Kinda quiet 'round here these days. End of summer doldrums (for those of us over here) maybe?
However, this problem of the setter piston toggling instead of being momentary (as it was originally) has bugged me.
Finally found the answer. When trouble shooting, I tell myself : "Self, don't overlook the obvious". Well, this time I should have listened to that advice. Then there's the adage that if you do what you've always done, etc.
Long story shortened, I didn't realize the setter piston was one of those rubber 'bubbles' (Conductive Keypad Switches) that so called shorts out 2 traces on a PCB. The final clue was when I jumpered the setter input at the encoder, the setter worked as it should, as a momentary. Measuring the (encoder) input voltage when pushing the setter piston, I read 4.56 VDC instead of the supply voltage of 5.2 VDC. That drop in voltage was due to the (series) resistance added by the rubber bubble of the setter piston. After using some of that contact "restorer"
https://www.ebay.com/itm/MUSIC-KEYBOARD-PIANO-SYNTH-REPAIR-Fix-Conductive-Keypad-Switches-Key-Contacts/181662188354the setter again worked correctly. As a better cure, so as not to have to do this bit again, I replaced the setter piston with a (real) legitimate solid contact thumb piston. Part of my mental hangup was that I knew for sure the setter worked properly at the beginning. Another part of the issue was that MIDI Ox reported the correct Note On-Note Off, etc. I haven't completely figured why the lower (than 5 volts) caused the problem, but for sure that was it and the issue was repeatable. Will have to keep that in mind, i.e., if I want to change from a momentary to a toggle, lower the encoder input voltage (by adding a series resistor), hmmm? Dunno.
Rgds,
Ed