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!
>
>
>
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