[sdiy] MG-1 issues

[Metrophage]

--- john mahoney <jmahoney at gate.net> wrote:
> Is there an audio signal at the filter's input? If so, the problem is
> likely the filter. If not...

Sound faintly plays through the filter, but there is no low-pass being
done to it. I can tweak the cutoff pot and trimmer, but I never hear
any difference. The resonance does work though, It oscillates at about
80%. I can hear any of the "mixer" sources: VCO1, VCO2, noise, ringmod,
top-octave-ic. I would not be surprised if the reduced volume had
something to do with the weird VCF behavior.

> This may be the time to fall back to the standard diagnostic
> procedure of tracing the signal path. Start at the beginning: 

This is what I have started to do! Problem is that I guessed I'd find
something more obviously wrong by now. I know I have not tried
"Everything" yet, but I have tested quite a lot. What I fear i that it
comes down to something which I lack the knowledge to recognize. Still,
there is more I can try!

> The ever-inspiring Ray Wilson has the  how-to on his Odds & Ends
page:
>
http://www.musicfromouterspace.com/analogsynth/oddsandends.html#AMPSIGNALTRACER

Kewl.. I made something like that for an amp/computer speaker on my
bench! I don't think I can really detect or measure fast pulses though,
the needle just ticks
and it's often not audible. Also, my Rat Shack analog meter is
practically useless for anything much less than 1v DC.

> Good luck!

Thanks, John - I guess I need it! Hopefully I can use what I learn to
also fix the synths of others.

CJ

__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around 
http://mail.yahoo.com