[sdiy] Jupiter 6 experts?

[Eric Frampton]

Hi all -

After my unusually vague, slightly panicked initial post, I've narrowed the symptom down to this: the Oscillator 2's on all four voices on the 4-voice board aren't working properly.

All four of them are out of tune (one of them is out of audio range - I can see it on the scope, but can't hear it), and two of the three I can hear seem to have some sort of modulation even when all the mod routings are turned off.

If I change the front panel tuning while triggering those voices, the oscillators move smoothly together (as opposed to jumpy, or randomly) with the front panel controls.

If I put the unit into calibration mode and do Test 7 (Linearity) and go down the line (test program D-1, D-2, etc.), all four Oscillator 1's respond perfectly, but all four Oscillator 2's go completely flatline on my scope.

Hitting Autotune doesn't make a difference on these oscillators - it works fine for the rest of them, though.

I tried swapping eproms between the two voice boards, no change.

All other functions on that board seem to be working fine, and everything on the 2-voice board is responding correctly.

Thoughts?

Thanks,
Eric