Korg Mono/Poly

Change your electrolytics, maybe. I had to replace mine on my filters a 
couple years ago.

If you're having global problems, maybe it's your power supply. Maybe 
your caps are going there...?

Good luck,
Scott Deyo
The Bridechamber
contact@bridechamber.com
www.bridechamber.com


On Dec 26, 2007, at 9:21 PM, Chase Smith wrote:

> Hello,
>     Upon the previous suggestion, I was able to get a bit closer to 
> the problem, but still no solution.  However, I am hoping that my new 
> information makes the problem easier to solve.
>
> First, I replaced all the op/amps and it did not help.  After that, I 
> tried various combinations of cables to see if I could eliminate the 
> noise.  I was able to significantly reduce the noise by unplugging the 
> orange cable from the CV board to the board with the LFO knobs.  Doing 
> this almost eliminates the noise.  A noise is still there, but it is 
> much quieter.  However, a click is present in the audio at max res and 
> cutofff which happens at each cycle of the LFO.
>
> It appears as if the LFO (s) and (most importantly) the arpeggiator 
> are bleeding into the audio and creating much of this noise.  What 
> could cause this kind of thing to happen?  Dead capacitors?  There are 
> some capacitors on this board but I'm not  sure what kind they are 
> (polypropylene?).
>
> I believe that fixing this bleeding problem will fix it all.  Any help 
> is appreciated.
>
> Thanks,
> Chase Smith
>
> Florian Anwander <Florian.Anwander@consol.de> wrote:
>>
>> > should which is creating the noise. So now I am changing the
>> > capacitors, op amps, and voltage regulators and if that does not 
>> work,
>> > then I am out of ideas.
>> You might try to isolate the error also by disconnecting some boards,
>> and measure the rest:
>> '+++' means switch power on
>> '---' means switch power off
>>
>> disconnect all boards
>> +++
>> check powersupply out with oscilloscope
>> ---
>> connect KLM-356 (uP board) to powersupply and keyboard to KLM-356
>> (perhaps also the 353 with the keyboardmode switches is required)
>> +++
>> check the CVs at the connector  pins 27-1 to 27-4 with oscilloscope
>> ---
>> connect the VCO-board
>> +++
>> check the CVs at the connector pins 1,3, 9, and 11 of IC-7 with
>> oscilloscope.
>> check the outputs of IC-22 (opamp after Ext VCO in) with oscilloscope.
>> check at the four summing points for VCO-CVs
>> check the output of all four VCOs separately.
>> ---
>> add VCF board
>> +++
>> Check again the output of the VCOs
>>
>> and so on....
>>
>> If the constant FM appears, the let the constellation as it is, but go
>> back in the measurement chain to check how far 'back' the FM can be
>> traced (e.g. already on VCO board, but not at the uP-board-output).
>>
>> I don't remember wether the ICs originally are socketed. But if they
>> are, you might also remove some relevant ICs.
>>
>> Florian
>>
>>
>>
>> Yahoo! Groups Links
>>
>>
>>
>
> Never miss a thing.  Make Yahoo your homepage.
>
>  
>