CGS58 with mods not working correctly
2012-07-15 by Joachim
Hello,
I have finally found the time to test a 20K 10-turn pot for the speed pot on a
CGS58 but I have at least one error somewhere:
The mods I installed are:
- 20K speed pot (10-turn) instead of 100K, tested it with a normal 100K pot which didn't change the odd behavior
- 4K7: At first I tried 200 Ohm and then a 2K trim pot which is currently set to 1K (that didn't change much though, just the
speed range)
- 330N instead of 47N for the timing capacitor
I stuffed only half of the CGS58 plus the TL072 which means the TL074 for the second LFO is left and the pots and jacks for it are
not connected. I think that is OK because they only seem to be connected via the join and swap switches.
With this I got a pretty strange output:
- A low level waveform at a constant speed which looks the same on all four outputs and is not affected by any of the knobs
- Some kind of click which is affected by the speed knob and is most noticeable with the square output. I couldn't view on the
triangle output but something audible changes with the speed knob there, too.
- Funnily enough the LED reacts as I would have supposed (speed knob affects it).
- The join switch (which only connects or disconnects pin 3 of the shape pot by now) doesn't seem to have any effect
Oscilloscope picture from the square output, see the EM thread where I have posted this, too:
http://electro-music.com/forum/viewtopic.php?p=365448#365448
Does anybody have an idea where the error could be?
The 330N and 1K have been tested by others so I'm pretty sure the error is not in the mods I have installed.
Thanks
Joachim
I have finally found the time to test a 20K 10-turn pot for the speed pot on a
CGS58 but I have at least one error somewhere:
The mods I installed are:
- 20K speed pot (10-turn) instead of 100K, tested it with a normal 100K pot which didn't change the odd behavior
- 4K7: At first I tried 200 Ohm and then a 2K trim pot which is currently set to 1K (that didn't change much though, just the
speed range)
- 330N instead of 47N for the timing capacitor
I stuffed only half of the CGS58 plus the TL072 which means the TL074 for the second LFO is left and the pots and jacks for it are
not connected. I think that is OK because they only seem to be connected via the join and swap switches.
With this I got a pretty strange output:
- A low level waveform at a constant speed which looks the same on all four outputs and is not affected by any of the knobs
- Some kind of click which is affected by the speed knob and is most noticeable with the square output. I couldn't view on the
triangle output but something audible changes with the speed knob there, too.
- Funnily enough the LED reacts as I would have supposed (speed knob affects it).
- The join switch (which only connects or disconnects pin 3 of the shape pot by now) doesn't seem to have any effect
Oscilloscope picture from the square output, see the EM thread where I have posted this, too:
http://electro-music.com/forum/viewtopic.php?p=365448#365448
Does anybody have an idea where the error could be?
The 330N and 1K have been tested by others so I'm pretty sure the error is not in the mods I have installed.
Thanks
Joachim