Problems with square wave

i apologise for my mistake in my last readings - missed the minus signs.

Pins 1,2,3 of the PW pot (reading left to right from the front) are as follows:

@ centre position.

  1. -5v
  2. 0v
  3. +5v

@ anticlockwise pin 2 goes to -5v (1&3 stay the same)
@ clockwise pin 2 goes to +5v (1&3 stay the same)

The cutoff pot is similar.

So I think this is normal after all?

One side of R30 is at 0V, and the other side must be at the same voltage as the PW pot. If this is not the case:

  • There’s a problem with the PW CV input jack.
  • There’s a bad connection between both boards.

the wiper of the pw pot is the same as the r30 voltage.

Your last post from april 27th indicated:

cw ccw

r28 0v,0.1v 0v,0v

r30 0v,5v 0v,5v

pin6 3.3v

Is that correct?

Yes , except the detail for r 30 in ccw position which is 0v,-5v

pin6 Is at 3.3V for all cases, or does it change to -3.3V too?

It changes to -3.3v with pw in a a fully cw position

  • Try listening the signal at IC10 pin 7. This should be the rectangle/square wave, with the PW change applied to be.
  • If this doesn’t sound right, please post a picture of a scope trace of IC10 pin 1.

i have recorded ic 10 pin 1 on audacity , which provides an oscilloscope trace , the recording was done directly onto a laptop soundcard as i do not have access to an oscilloscope .
The forum will not allow me to upload it however , but if you could give me an email address to send to i i can send it via that.
the sound on pin 7 did change with pw adjustment but the trace on audacity did not look like a pulse wave.

Or upload it to, then paste the soundcloud url like this :
"" ?
Here it is on soundcloud (thanks v’cent) , I do have it as a .wav (uncompressed) if you cannot mp3 from soundcloud .

The pw is swept from large to small on the recording and the osc. is at a low frequency

This sounds very strange because IC10 pin 1 is supposed to be the sawtooth waveform. What do you have on IC7 pin 7?

At this stage, I suggest trying to get someone with a scope to help you and post waveform traces, with proper DC coupling.

Here is the recording for pin 7
ignore all before 30 seconds the useful section of the recording is 30-44sec. - contact with the pin is occasionally broken in recording ,

I will try and find somewhere with an oscilloscope I can use , and if possible , post the traces

(I also noticed a faint tone which tracks the pitch of the oscillators , but is unaffected by cutoff and possibly volume also , it is only audible when the gate is on )