Cgs synth

>IN BYPASS MODE:
>
>-Channel "A" & "B" are duplicate suboscillators.

Yes.

>-Each channel should output audio through either of the OUTPUTs (normal or

inverted).

To both at all times.

>-Turning up "A/2" will output a sub division one octave down. Turning up

"A/4" is four octaves down etc. Volume level blending is with the knobs.

a/4 = 2 octaves down. a/8 = 3 octaves down.
Dividing by 2 (/2) drops a single octave. So dividing by 4 (/4) only drops
two octaves.

>IN PRE-SCALE MODE:
>
>-The divisions switch selects partials for ring modulated outputs.

(generally speaking)

>
>-This only works in the MULTIPLIER MODE. (?)

Prescale will work in both divide and multiply modes.

>I get sound out of both outputs through the A channel but not through the B

channel. The B channel does affect the sound of the audio signal but only in
a strange manner.

Something is certainly wrong. In divide mode, B should behave exactly like A

Have you earthed the CCW tabs of your pots? Yo don't mention this in your
4pole switch wiring (which otherwise looks correct).

>The A/2 knob doesn't bring up any audio sound even with high frequency

pitches into the channel A. I have to turn up all division knobs before the
A/8 or A/16 start out-putting audio. They are definitely suboscillator in
nature but there is very little audible divisions happening with A/2 or A/4
knobs. I seemed to hear it very faintly with only A/2 up yet very clearly
when all pots including A/8 & A/16 are up.

Did you install a level pot or the 22k resistor marked with "*"?

>A similar effect happens with the B channel knobs. I must turn up the lower

division knobs (B/2 & B/4) in order for the larger division knobs to have
any effect. They do divide the A channel audio further and I was able to get
some fun trigger patterns to my envelope generators last night. (Bonus bacon)

Again, not right. Again, check as above.

>All that happens when in BYPASS mode. I'm not hearing any prescale values

modifying anything at this point, so I'm not happening with the ring
modulation at all yet (I think).

>
>This doesn't seem right and I suspect an IC or something isn't right. I did

have a pad lift on one of the 10uF coupling caps but I got that fixed. I
didn't detect it until I'd already powered the module once. Is there a
possibility I've damaged a chip with improper Vbe inputs?

Have you used LM358 or TL072 at the inputs? If LM358, try TL072.


Cheers,
Ken

>Some places to check would be handy. I'm rather ignorant of some of these

logic chips. I can put together a video tonight to demonstrate the
malfunctioning module if that will help.

>
>
>Here is how I wired up the multi-function 4P switch and "B" knobs.
>
>The resistor bank (47k) out to the middle lug of the pots B/2 - B/16. The

right (from the back of the pot) lug goes to the four pole switch middle
posts. The switch outer posts are sent to the channel B divisons of the 4024
and to the multiplier inputs (M1-M4) of the 4030. I tried to pay attention
to which division knob tied to which place on the PCB. (e.g. A/2 through the
switch to "0" on channel B & M1. A/4 through the switch to "1" on channel B
& M2, etc.)

>
>If this is wrong I wouldn't be surprised. (you would have to know me)
>A new wiring diagram for the revision 2 setup might help old farm boys like

me. This was a head-scratcher.

>
>Thanks,
>
>-David

_______________________________________________________________________
Ken Stone sasami@... otherunicorn@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>
Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>