[sdiy] AX60 Voice Issue

[gregory zifcak]

Hey all,
Strange behavior from this AX60:
In split modes 2-4 and 4-2, all voices work. I can simultaneously hear 6 pitches when I hold 6 keys. the balance slider functions normally, mixing between the two patches.
In single mode and in split modes 6-0 and 0-6, only voices 5 and 6 are sounding. I can hear the other four faintly in the background. I have checked the CV going to the VCA, and it's a consistent 4v across all CEM3394s.
The signal paths for the mixed voices are split into two groups; 5 and 6, and 1 thru 4. What I don't understand is why all voices would be present in split modes but not in single mode.
Any ideas?
Service manual can be found here:http://manuals.fdiskc.com/flat/Akai%20AX-60%20Service%20Manual.pdf
Thanks in advance,Greg