Cgs synth

Ditto. I've built many CGS projects, and I've had two temporary failures. I
screwed up a Psycho LFO by switching wires between two pots. I had to put it
down for a week before I could see it, it was so obvious!

My Synthacon filter worked, but not the highpass input. Solder joints good,
components good, polarities good. But after poking in there w/ test probes,
I noticed where the input signal stopped. The trace underneath had lifted
off for some reason. After soldering on a wire to connect the trace,
everything's golden and I have a very strange and lovely filter.

For any kits/ pcb's you do, there is going to be at least one that won't
work right. It's usually something obvious that makes you smack yourself in
the forehead when you finally see it. I have yet to have a bad component
unless I put it in backwards (TL071s can put out some smoke!! :)

Eventually you'll figure it out, but getting to know your test equipment is
always helpful.

Good luck!
Scott

>From: <cgs@...>
>Reply-To: cgs_synth@yahoogroups.com
>To: <cgs_synth@yahoogroups.com>
>Subject: Re: [cgs_synth] Synthacon nightmare (difficult and unclear)
>Date: Thu, 3 Jun 2004 16:23:49 -0700 (PDT)
>
>On mine, I had different issues, but like this user, at first my synthacon
>didn't work. I ended up fixing things by checking each resistor value
>with a DVM. I didn't have a value wrong, but, I did find a short (no
>resistance, where there should have been some). Correcting this--it was a
>solder blob-- fixed my filter, and it's worked ever since.
>
>Just visually inspecting my solder joints, component placement, and what
>not has never been that helpful for me solving whatever is wrong with my
>build, unless it's something really obvious, like putting an IC or diode
>in backwards. I always do a visual inspection, and I usually catch those
>really major foul-ups before I power up the board for the first time.
>
>But I never catch them all! For anything subtle, I tend to miss the same
>mistake over and over unless I use a scope and/or DVM to troubleshoot.
>
>--CL
>
>On Wed, 2 Jun 2004, earthtodylan2000 wrote:
>
> > Ken,
> > I've gone over the whole board all the whole board and it look
> > alright.
> >
> > 1. I am only getting this very wrong and noisy signal when I put
> > something through the Hi Pass filter and nothing when running
> > through the Band and Lo pass inputs
> >
> > 2. I have used the exact transistors(metal can 2N2907, 2N222A)
> > you call for. Everything else too is from you exact specs.
> >
> > 3. Fair enough...I'm sure this will work out once it becomes clear
> > how to correctly wire things up.
> >
> > 4. This is the confusing part. How was I supposed to know the
> > frequency pot is wired with its CW end to+15, its CCW end to
> > ground/0V and its wiper to one of the CV inputs? Schematics?
> > And where is +15 on the board? Is it just one of the +
> > openings?
> >
> > 5. I have a link instead of the pot.
> >
> >
> >
> > How simple would it be to have a little diagram that show how to
> > wire this thing up like on some of your other PCB pages?
> >
> > I'm still not so sure that It's going to work after I make these
> > changes.
> >
> > Wire +15(or the + opening)to the Frequency pot.
> >
> > What are all the other openings for and what goes to them?
> >
> > The other "+"
> >
> > "-"
> > "+VE"
> > "+6V"
> > "-VE"
> >
> > And are all the pots sopposed to get some sort of voltage?
> >
> > Thanks,
> >
> > Dave
> >
> >
> >
> > --- In cgs_synth@yahoogroups.com, sasami@h... wrote:
> > >
> > > > I just tried to build up my Synthacon. Total nightmare...
> >
> >
> >
> > > I'd suggest you go very carefully over the board looking for
> > construction
> > > errors. If you have not used the exact transistors specified,
> > make sure they
> > > are in the correct way around. of the very few that haven't
> > worked, it has
> > > almost always been a construction error. Once or twice it was
> > a faulty
> > > transistor.
> > >
> > > >1. Only getting sound out of the Hi Pass input
> > >
> > > out of? do you mean that you only get an output when you feed
> > the signal
> > > INTO the HP input and not when you feed a signal into either
> > the band pass
> > > or low pass inputs?
> > >
> > > >2. The sound is super fuzzy with lots of harmonics.
> > >
> > > If the resonance is too high it can distort some, but I would not
> > call it a
> > > fuzz box. If you have used the wrong transistors, you may have
> > way too much
> > > gain. I specified metal can 2N2222 (or 2N222A) and 2N2907
> > for a reason.
> > >
> > > >3. Ground hum.
> > >
> > > Now that you can only blame yourself for. Wither you have an
> > earth loop
> > > somewhere in your system, or you have a poorly sheilded input
> > somewhere that
> > > is picking up hum.
> > >
> > > >4. Pots dont' seem to control anything.
> > >
> > > If wired correctly, they will. Is the frequency pot wired with its
> > CW end to
> > > +15, its CCW end to ground/0V and its wiper to one of the CV
> > inputs?
> > >
> > > The resonance pit needs only two wires - one the the wiper,
> > and one to one
> > > end. The other end is left not connected to anything at all.
> > >
> > > >5. My Binary Zone does seem to control the CV frequency
> > input.
> > >
> > > which would indicate there is at least some voltage control -
> > ans if your
> > > pots aren't doing anything, that means at the very least, the
> > frequency pot
> > > is incorrectly wired.
> > >
> > > >Does someone have a wiring diagram?
> > >
> > > All the wiring info is in the circuit diagram itself. That should be
> > all you
> > > need.
> > >
> > > >I did ground all the 1/8 inputs together.
> > >
> > > Yes, the sleeve of all jacks need to be grounded.
> > >
> > > >I first tried it with the Level pot and then took it out of the
>circut.
> > >
> > > Do you have a link in place or the level pot instead?
> > >
> >
> > __________________________________________________
> > _____________________
> > > Ken Stone sasami@h... or sasami@c...
> > > Modular Synth PCBs for sale
> > <http://www.blaze.net.au/~sasami/synth/>
> > > Australian Miniature Horses & Ponies
> > <http://www.blaze.net.au/~sasami/>
> >
> >
> >
> >
> > See the following URLS for the CGS Modular Synth home page:
> > Main: http://www.cgs.synth.net/
> > Secondary: http://otherunicorn.0catch.com/synth/
> > Yahoo! Groups Links
> >
> >
> >
> >
> >
>

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