[sdiy] Oberheim OB-XA autotune procedure questions

[Roy J. Tellason]

On Thursday 28 April 2005 05:44 pm, doof wrote:
> Hi all,
>
> I've just finished replacing the battery in my OB-XA (along with installing
> new bushings and cleaning some problematic J-wires) and I've found that all
> voices now fail the autotune procedure.  When I press the button, it cycles
> through all 8 voices, then the 8 LEDs flash for about 2 seconds.  All 8
> voice cards are perfectly functional.
>
> I have both versions of the service manual, and neither address the
> autotune function other than using it in calibration routines.  How
> autotuning is implemented and any specific troubleshooting/calibration
> strategies are completely neglected.
>
> So I'm wondering what could possibly be contributing to this problem. 
> Autotune worked before the battery replacement, although tuning wasn't
> perfect.  Does something within the circuit rely on battery power to retain
> memory for the autotune algorithm?
>
> At first I thought bad tuning might be causing the problem.  Turning the
> voice disable feature off with the test2 switch, I've started calibrating
> the individual voice boards to achieve better tuning, yet reagardless of
> the more accurate initial tuning the autotune function still does not want
> to cooperate.
>
> Looking back at the AH archives, it seems a few people have experienced
> this exact problem, though no answer ever surfaced.
>
> ...Anyone?
>
> Thanks.

I've little direct experience with that brand,  but this sounds awfully 
familiar.  I suspect that what you're running into is something in the memory 
of the thing with screwy values.  If there's a way to re-initialize or reset 
it somehow,  try that,  and see if that doesn't fix this...