Discussion about the Korg PolySix synthesizer

Thanks so much!
 I will break out the meter tonight and let you know what I find. I
REALLY do appreciate it as while this synth arrived in pristine shape,
 I can only get a saw and basic square out of it. I really do want to
get the PWM fixed.
Thanks again!

--- In PolySix@yahoogroups.com, Johannes Hausensteiner <jo.synth@c...>
wrote:
> On KLM-367 check the following:
> * IC12 (TL072) pin1: must be -5V .. +5V according to PW/PWM poti
>    if not, replace IC12
> * IC13 (4558) pin1: must be -5V .. +5V according to PWM SPEED poti
>    if not, replace IC13
> * Set PWM SPEED to slowest and check IC1 (4066)/pin9: must change from
>    minus to plus voltage and back (I dont know the exact values; will
>    be at least -3V..+3V)
>    if not, replace IC20 (LM13600) and/or IC15 (4558)
> * IC1/pin6: must be +5V when WAVEFORM is at PWM position, otherwise 0V.
>    if not, replace IC3 (LM339)
> * IC1/pin8: must be the same as IC1/pin9 when WAVEFORM is at PWM
>    position, if not replace IC1 (4066).
> * TP1 (PW/PWM) near IC12: according to service manual "PW/PWM check
>    and adjustment"
>    if not OK, replace IC20 (LM13600) and/or IC15 (4558)
> 
> I hope this helps,
> 
> Johannes
> 
> 
> ciscomanvann wrote:
> > Nothing happens. It plays, but the width or pwm does not change. I 
> > have a multimeter, how do i check this stuff out? I dont know a whole 
> > lot about ICs.
> > 
> > --- In PolySix@yahoogroups.com, The Old Crow <oldcrow@o...> wrote:
> > 
> >>  First thing to do is set VCO to PW and move the width knob from 0 
> > 
> > to 10 
> > 
> >>and back to 0 and listen to see if it changes accordingly.  Then 
> > 
> > set it to 
> > 
> >>10 and change the VCO mode to PWM and move the PWM speed knob from 
> > 
> > 0 to 10 
> > 
> >>slowly and note if the cyclic modulation is audible.
> >>
> >>  If nothing is working then I would imagine either IC20 (LM13600) 
> > 
> > needs 
> > 
> >>replaced, or the analog switch section IC1C died and IC1 needs 
> > 
> > replaced, 
> > 
> >>or perhaps the control voltages off deMUX IC19 aren't getting there 
> > 
> > and 
> > 
> >>IC19, IC12 or IC13 is to blame (least likely though).
> >>
> >>  Use my schematic as it is much easier to read than the old 
> > 
> > service 
> > 
> >>manual copy.  PWM circuit is on the far right, about 2/3 of the way 
> > 
> > down.  
> > 
> >>It is marked "PWM MG":
> >>
> >>
> > 
> > http://www.oldcrows.net/~oldcrow/synth/korg/polysix/crowlm367/klm367a_
> > eagle_schem.gif
> > 
> >>
> >>  Hope this helps,
> >>
> >>Crow
> >>/**/
> >>
> >>On Wed, 31 Dec 2003, ciscomanvann wrote:
> >>
> >>
> >>>I know this sounds stupid, but how can i tell if the PWM is 
> > 
> > working?
> > 
> >>>If it is not, where do I start looking to fix it?
> >>>Thanks!
> > 
> > 
> > 
> > PolySix "Digiest" Page: http://www.acc.umu.se/~amber/Poly6 
> > 
> > Yahoo! Groups Links
> > 
> > To visit your group on the web, go to:
> >  http://groups.yahoo.com/group/PolySix/
> > 
> > To unsubscribe from this group, send an email to:
> >  PolySix-unsubscribe@yahoogroups.com
> > 
> > Your use of Yahoo! Groups is subject to:
> >  http://docs.yahoo.com/info/terms/ 
> > 
> > 
> > 
> >