Discussion about the Korg PolySix synthesizer

Yes. When you measure on pin1 there will be a certain voltage. The
PWM SPEED will be fixed at this point.
When you measure at IC13/pin3, does the voltage change according to
the PWM SPEED pot? If yes, replace IC13. If no, then IC19 (4051 analog
mux/demux) may be the reason.
Do you have access to an oscilloscope? This would speed up searching
for the defective component...

Johannes


ciscomanvann wrote:
> Well, if that is the case ic13 is craped out. Would that cause my synth to play when in 
> PWM mode but not be able to change the PWM shape or speed?
> 
> --- In PolySix@yahoogroups.com, Johannes Hausensteiner <jo.synth@c...> wrote:
> 
>>Hi,
>>
>>How to determine the pin number of an IC:
>>
>>e.g. DIL-8 case:
>>
>>
>>          8 7 6 5
>>         +|-|-|-|+
>>notch:  >       |
>>         +|-|-|-|+
>>          1 2 3 4
>>          ^
>>pin no. one
>>
>>I hope this helps ...
>>
>>ciscomanvann wrote:
>>
>>>OK, when I am looking at the IC how do i know which pin is pin 1? I
>>>found one pin on IC12 that measures +/- 4.7 v but no pin that changes
>>>on IC13. Hmm
>>>
>>>--- 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:
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>>>>>
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>>>>>
>>>>>
>>>>>
>>>>>
>>>
>>>
>>>
>>>PolySix "Digiest" Page: http://www.acc.umu.se/~amber/Poly6 
>>>
>>>Yahoo! Groups Links
>>>
>>>To visit your group on the web, go to:
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>>>
>>>
> 
> 
> 
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