[sdiy] This OB-8 is sending me up the wall

[Tony Allgood]

A cry of help from one tech who's about to throw this synth out of the
window. I have finally sorted out the majority of weird and wonderful
things that were wrong with it, but I have one last fault I am
completely stuck with.

It all plays perfectly, but for one thing: In dual or split mode, the
upper and lower voices play out of tune with each other. They each play
in tune with themselves, but are around 3/4 semitone out with each
other. In normal full mode, both upper and lower voice sets track
perfectly, and there is no discernible differences in the two.

The fault lies within the controller hardware and software. The keyboard
pitch CV lines take a jump up for the upper voices, and a jump down for
the lower voices the moment the dual or split mode buttons are pressed.
They instantly hop back again when the switches are pressed again.

The other pitch control lines (scale and tune offset) are not affected
by the mode change.

Any ideas? Any help would be most appreciated.

Many thanks,

Tony Allgood                       Penrith, Cumbria, England

Oakley Sound Systems                     www.oakleysound.com
Modular Synthesisers        www.oakleysound.com/projects.htm