[sdiy] Smith's Evolver Desktop's spikey VCO waveforms

Michael Zacherl sdiy-mz01 at blauwurf.info
Wed Jun 5 23:53:20 CEST 2013

a friend's Evolver Desktop has a peculiar glitch in its VCO's waves.
First, from his description, I suspected a trim pot being not adjusted properly but now he sent me some pics of the screen of his oscilloscope, and I can't tell what it is. [1]
Of course it's audible.

Shipping for repair is apparently very expensive so I thought I give it a shot and see if I can find out anything about it. But alas, without a schematic or a service manual and already gotten a bit rusty myself it's a bit hard.
Strange, at the first glance, is that it's on both VCOs and given the digi scope's coarse resolution  it also might be identical (which I'm not sure).
Smith's service replied laconically "it's broken, must be repaired" - so no big help from there, at first.

Any thoughts what that could be?

Thanks a lot, Michael.
[1] http://blauwurf.at/temp/EvolverWave-Glitches.png

keep your ears open: http://blauwurf.at

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