It's CEM3396 which is a synth-on-a-chip; 2xDCOs, VCF, VCA, all in one. Pretty much the definition of a voice chip.
Individual clock inputs for the 2 DCOs. So if one DCO gets a bad clock input of course the pitch will be off.
On Tue, 5 Nov 2019 at 12:02, José Ángel Morente msxjam@... [oberheim] <oberheim@yahoogroups.com> wrote:
What CEMs are the wrong frequency? Aren’t the M6 oscillators DCOs?If i’m not wrong, the CEM chips you talk about should be filters or maybe VCAs but no voice chips.On Mon, 4 Nov 2019 at 23:38, Andy Birko andy.birko@gmail.com [oberheim] <oberheim@yahoogroups.com> wrote:Tried to send a message before but it seems to have been lost.Picked up a used M6R with a couple bad voices. Voice 2 was dead and just needed a re-seat of the CEM chip.Voice 3 though - DCO 2 is all wonky. Its pitch is way high and doesn't track correctly at all. When changing the frequency through param 10 is generally trends in the right direction but any given value might be higher or lower than the one before.I've probed around with a lousy scope a bit and it seems that pin 8 of the voice 3 CEM is at the wrong frequency. i.e. I checked pin 4 and 8 of all the chips and only pin 8 of voice 3 seems to be at the wrong frequency. As I said, it's a pretty lousy scope so info is limited.Any thoughts on how to proceed?Thanks in advance!-Andy