SysExJohn wrote: ↑Sat Feb 15, 2020 10:39 am
Sadly, I rather suspect that the issue has absolutely nothing to do with the pots, but with the, in effect, analogue to digital convertor.
The erratic behavior experienced by ITFlyer certainly seems to have been due to poor contact of the PB pot's wiper to the resistance track. It's not an uncommon problem.
Yamaha has decided (in its infinite wisdom) that, since 7 bit resolution is good enough for all the other CC's, then it shall be 7 bit for ALL controllers, including pitch bend.
That is, not all these keyboards are faulty, but Yamaha in its pursuit to drive down costs to has decided to do away with 14 bits (or even 10 bits) on its implementation of pitch bend.
Call me cynical if you wish, but why else?
The issue of 7-bit PB resolution is nothing new. Yamaha Motif owners have complained about the stepping effect of pitch bend for many years. It's not much of a concern when the bending range is just a few semitones, but becomes obvious with more extreme bends. It's somewhat surprising that Yamaha chose to continue the "tradition" on the MODX and Montage.
As to why...
I don't have schematics (yet) for the MODX and Montage to compare with the Motif XF and MOXF models, but I suspect that certain parts of the circuit design of the earlier models were incorporated without change in the current ones. That's probably especially likely for controllers such as PB, MW, and the keyboard. Indeed, not having to redesign things is a cost-cutting measure.
The only other thing I can think of is data density. Pitch Bend generates a lot of MIDI events, and 14-bit resolution of course would create many more of them than 7-bit. Perhaps under certain circumstances there was the potential for MIDI data overload (more likely on the Montage, since it has aftertouch), and Yamaha decided to limit the possibility. (I realize that's not a strong argument, but without design details, that's all I've got.