[sdiy] Oberheim Xpander Res fail

[Csaba Zvekan]

Thank you Tony,

I just checked the Xpander again took Patch 07 "Spheric2" went ahead and adjusted VCF settings to self oscillate . Played all the notes from C1 to C8 and it seems just fine. Also played one note in several registers to compare them and they sound all fantastic :). 
So I think my problem is not in the Voice / Filter section rather it is around the DAC. Or  it can be what ever is responsible for either generating the necessary voltages for the "Res auto tune procedure DAC (which I think is fine tune as the synth sounds perfectly OK). The other variant I can think of is the microprocessor section where it's sensing the 'oscillation break point' and simply can't . 
Like Tom explained in an earlier mail . Thank you for that as well.

What I'm trying to figure out is what parts are involved in this "Res tuning " procedure.  I believe somewhere there in that chain lays my problem.
 
Csaba


On 15 Jan 2012, at 10:42, Oakley Sound wrote:

> > Even the percussive patches with high resonance work excellent.
> 
> Have you checked that all voices go into resonance in the same way? That is, set up a simple self oscillating filter patch and check that all six voices can be heard and each can be made to oscillate over a wide range.
> 
> I had a T8 once that refused to do the filter tuning part of the calibration because one of the VCFs didn't oscillate over the full audio range. This was due, in the end, to a bad capacitor in the feedback of the filter.
> 
> Tony
> 
> www.oakleysound.com                    Oakley Modular Synthesisers
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