Hi All,
I'd be suspcious of a bad potentiometer (trimpot) before the I suspected the EG chip. Maybe you can probe the output of the potentiometer while adjusting it and be sure that the voltage chagnes appropriately as you turn the trimpot, if this is one of those trimpots that has its ends connected to the +/- power supplies and is simply putting out a reference voltage to the IC.
Regarding the waveform adjustment, I have always found that the waveforms matched the service manual very well. I'll check on the details of what you are saying (no manual handy right now).
One thing I found was that it was very important (as is usual) to perform all of the adjustments in the order shown in the manual. For example, if you think an EG is out of whack and you simply jump to the step that you think is the one that is relevant, you are just wasting time, and you really need to start that EG's calibration procedure right from step one. (My point is that, if steps 1 or 2 are out of whack, step 3 will never be able to be calibrated properly, even if your ears and scope are telling you that step 3's parameter is the one out of whack. Whent he EG's or VCAs are out of adjustment, the synth can sound very flat and tweezy; and generally not good.
Also I can say that it was very important to be sure all of the front panel settings are correct for each adjustment procedure, and that you are clear that the voice you are adjusting is the one presently sounding. (Not to imply that you folks are not aware of this, I'm just throwing it out there.
Regards,
Kyle Jarger
-------------- Original message --------------
From: "Quazimodo" <
noddyspuncture@...>
> I think the filter envelope chip is IC12 on the 'M' board.
>
> I also had strange results recently when trying to perform the
> calbrations as per the CS80 manual. I wasn't getting the waveform
> shown in Step#1 (on TP1) when you're supposed to be adjusting VR's 15&19.
>
> Although in the end mine sounded OK to my ears (eventually) but you
> just end up feeling as though there might be something amiss. And the
> explanation in the 'How To Adjust' column isn't very clear either.
>
> Anyone any ideas on these calibrations...?
>
> Cheers,
> TOM
>
>
> --- In yamahacs80@yahoogroups.com, rj krohn wrote:
> >
> > hi folks, got an issue im wondering if you could point me in the
> right direction of....
> >
> > the VCF envelope of one voice on my cs-80 wont open/close properly.
> im 100% sure its not a HPF/LPF issue, as they both sweep through the
> ranges properly. its just that the attack/decay settings dont cause it
> to open/close. i tried to calibrate this, but using the service manual
> instructions, i couldnt get the attack ttime to change at all via the
> trim pots.
> >
> > i believe there is a filter EG chip on the voice cards, right?
> possibly a bad chip?
> >
> > im looking forward to getting her to 100% shape. i honestly think
> the last time i enjoyed an instrument this much was learning "stairway
> to heaven" on gtr when i was 12 yrs old. i walk away from this thing
> in awe every time i sit down to play it....
> >
> >
> > thanks guys!
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