OBERHEIM SYNTH

I tried your suggestions.  I still only hear the distortion from OSC 1.  I also hear it with 
either saw or pulse waves (yes, the pulse width knob changes the sound).  Panning the 
voice makes no difference.  I did notice that when I first power on the synth, I don't hear 
the distortion, but as it warms up the distortion becomes more and more evident.  
Hmmmmm...

I really appreciate your help.  Any other suggestions?  I have access to a volt meter...

Jonathan


--- In oberheim@yahoogroups.com, "nelsonj_sce" <nelsonj_sce@...> wrote:
>
> Before you said if you changed the voice board you still had the same 
> problem.  If that is the case, the problem is not on your voice card 
> so don't try changing parts on the voice card. 
> 
> You say the problem it is only with OSC1.  So if you ONLY have OSC1 
> on you hear distortion, but if you ONLY have OSC2 on there is no 
> distortion (make sure OSC2 is at full level), correct?  If the 
> problem really is with just OSC 1, see the next paragraph.  If the 
> problem only happens when both OSCs are on, the output level is 
> likely too high.  Each voice passes through a passive (i.e. resistor 
> divider with a pan) before the final output stage.  The pan was the 
> most likely cause, but you already tried that.  Try panning the voice 
> hard left and hard right.  Do you have the distortion in both 
> positions? 
> 
> Does the problem happen on both the Saw and the Pulse shapes?  Does 
> the Pulse Width change as you spin the PW knob? If the problem is 
> only with the Pulse Wave I have some ideas. 
> 
> Let me know what happens.  
> 
> 
> --- In oberheim@yahoogroups.com, "jringmrath" <jringmrath@> wrote:
> >
> > I tried panning the distorting voice card and cleaning the pots- it 
> didn't help.  I do only 
> > hear it when I have OSC 1 engaged - with just OSC 2 I don't hear 
> the distortion.  The weird 
> > thing is that I tried replacing the Curtis 3340 for OSC 1 and I get 
> the same distortion, so I 
> > don't think it is the chip.  Any other thoughts?
> > 
> > Jonathan
> > 
> > --- In oberheim@yahoogroups.com, "nelsonj_sce" <nelsonj_sce@> wrote:
> > >
> > > As for the distortion, try panning your bad voice and see if that 
> > > helps the problem.  Also clean the pan pot with some component 
> > > cleaner.   
> > > 
> > > As for the "ghost" note...I have to think more about that. 
> > > 
> > > --- In oberheim@yahoogroups.com, "jringmrath" <jringmrath@> wrote:
> > > >
> > > > I have an 8-voice OBXa and have a couple of nagging issues I 
> > > haven't been able to resolve.  
> > > > 
> > > > First, I seem to get some slight distortion from voice board 
> #8.  
> > > If I move the board to 
> > > > another location, it sounds fine.  If I move a known good voice 
> > > board to the #8 position I 
> > > > get the same distortion.  It is most obvious on the organ-type 
> > > sounds.  I have been using 
> > > > it as a 7-voice until I can track down the problem.
> > > > 
> > > > Second, if I play the chord "G,C and Eb" in the middle octave 
> of 
> > > the keyboard, it also 
> > > > sounds the "E" below the G.  Needless to say, this can be 
> > > annoying!  Must be something 
> > > > having to do with the keyboard scanning, but I don't know what 
> > > exactly.  The double mode 
> > > > also doesn't seem to work 100%.  Maybe a related issue?
> > > > 
> > > > Any thoughts on what might be causing these and how to fix 
> them?  I 
> > > have the schematics, 
> > > > but I don't really know what I'm looking at since I'm not a 
> tech.
> > > > 
> > > > Thanks for any help or advice!
> > > > 
> > > > Jonathan
> > > >
> > >
> >
>