Elka Synthex ring modulator oddities

YouTube via MusicMiK. follow-up to this post.
"Seen as a repair, this was a failure. But i think, it could be of interest anyway.

Now this happens if you try to repair phantom problems. If you use both ring modulators on the Synthex, especially in conjunction with oscillator synchronization, you can get very strange sounds that sound like a defect of a voice. This is strengthened by the fact that when playing through the notes, it likes to happen on the same voice(s) all the time.

I measured around in the voice boards for hours and looked for differences between 2 voices, the only assumption was that the analog control of the 4070s used for waveform inversion are the problem - aging might lead to the problems. And i also suspected such aging factors in some analog switches. Couldn't prove this by measurement, so i could just replace all chips in doubt.

Fascinating enough, the problem was nearly gone after this - same test procedure. So i did the replacement in 2 other voices. But the next test procedure showed the same defects on one of the repaired voices. Evil stuff. Diving deeper into this just led me to the conclusion that this is the little bit of analog behaviour in the digital oscillators of the Synthex. It's not a bug, it's a feature.

Don't try to repair this. There is nothing to repair. And if you already did - don't take it too serious. I wasted a lot of time on this, but not everything in life, and especially in electronics DIY, can lead to success.

At least i hope you have some fun with the strange behaviour with this special sound configuration.

If you have a Synthex, please try around with this and tell me the results - as comments on this video or so. Would be interesting if this is reproducible on other units also."